1
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Chen R, Ni C, Zhu J, Fan F, Li C. Surface photovoltage microscopy for mapping charge separation on photocatalyst particles. Nat Protoc 2024; 19:2250-2282. [PMID: 38654135 DOI: 10.1038/s41596-024-00992-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2023] [Accepted: 02/22/2024] [Indexed: 04/25/2024]
Abstract
Solar-driven photocatalytic reactions offer a promising route to clean and sustainable energy, and the spatial separation of photogenerated charges on the photocatalyst surface is the key to determining photocatalytic efficiency. However, probing the charge-separation properties of photocatalysts is a formidable challenge because of the spatially heterogeneous microstructures, complicated charge-separation mechanisms and lack of sensitivity for detecting the low density of separated photogenerated charges. Recently, we developed surface photovoltage microscopy (SPVM) with high spatial and energy resolution that enables the direct mapping of surface-charge distributions and quantitative assessment of the charge-separation properties of photocatalysts at the nanoscale, potentially providing unprecedented insights into photocatalytic charge-separation processes. Here, this protocol presents detailed procedures that enable researchers to construct the SPVM instruments by integrating Kelvin probe force microscopy with an illumination system and the modulated surface photovoltage (SPV) approach. It then describes in detail how to perform SPVM measurements on actual photocatalyst particles, including sample preparation, tuning of the microscope, adjustment of the illuminated light path, acquisition of SPVM images and measurements of spatially resolved modulated SPV signals. Moreover, the protocol also includes sophisticated data analysis that can guide non-experts in understanding the microscopic charge-separation mechanisms. The measurements are ordinarily performed on photocatalysts with a conducting substrate in gases or vacuum and can be completed in 15 h.
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Affiliation(s)
- Ruotian Chen
- State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.
| | - Chenwei Ni
- State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jian Zhu
- State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
| | - Fengtao Fan
- State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.
| | - Can Li
- State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.
- University of Chinese Academy of Sciences, Beijing, China.
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2
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Kutbay E, Ince S, Suzer S. AC-Modulated XPS Enables to Externally Control the Electrical Field Distributions on Metal Electrode/Ionic Liquid Devices. J Phys Chem B 2024; 128:4139-4147. [PMID: 38642062 DOI: 10.1021/acs.jpcb.4c00152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/22/2024]
Abstract
X-Ray Photoelectron Spectroscopy (XPS) has been utilized to extract local electrical potential profiles by recording core-level binding energy shifts upon application of the AC [square-wave (SQW)] bias with different frequencies. An electrochemical system consisting of a coplanar capacitor with a polyethylene membrane (PEM) coated with the Ionic Liquid (IL) N,N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium bis(trifluoromethanesulfonyl)imide (DEME-TFSI) as the electrolyte is investigated. Analyses are carried out in operando, such that XPS measurements are recorded simultaneously with current measurements. ILs have complex charging/discharging processes, in addition to the formation of Electrical Double Layers (EDL) at the interfaces, and certain properties of these processes can be captured using AC modulation within appropriate time windows of observation. Herein, we select two frequencies, namely, 10 kHz and 0.1 Hz, to separate effects of the fast polarization and slow migratory motions, respectively. Moreover, the local potential developments after adding two equivalent series resistors at three different physical positions of the device have been carefully evaluated from the binding energy shifts in the F 1s peak representing the anion of the IL. This circuit modification allows us to quantify the AC currents passing through the device, as well as the system's impedance, in addition to revealing the potential variations due the IR drops. The complex AC-modulated local XPS data recorded can also be faithfully reproduced using the unmodulated F 1s spectrum and by convoluting it with electrical circuit output provided by the LT-Spice software. The outcome of these efforts is a more realistic equivalent circuit model, which can be related to chemical/physical makeup of the electrochemical system. An important finding of this methodology emerges as the possibility to induce additional local electrical field developments within the device, the directions of which can be reversed controllably.
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Affiliation(s)
- Ezgi Kutbay
- Department of Chemistry, Bilkent University, Ankara 06800, Turkey
| | - Suleyman Ince
- Department of Chemistry, Bilkent University, Ankara 06800, Turkey
| | - Sefik Suzer
- Department of Chemistry, Bilkent University, Ankara 06800, Turkey
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3
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Biglarbeigi P, Morelli A, Pauly S, Yu Z, Jiang W, Sharma S, Finlay D, Kumar A, Soin N, Payam AF. Unraveling Spatiotemporal Transient Dynamics at the Nanoscale via Wavelet Transform-Based Kelvin Probe Force Microscopy. ACS NANO 2023; 17:21506-21517. [PMID: 37877266 PMCID: PMC10655243 DOI: 10.1021/acsnano.3c06488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 10/11/2023] [Indexed: 10/26/2023]
Abstract
Mechanistic probing of surface potential changes arising from dynamic charge transport is the key to understanding and engineering increasingly complex nanoscale materials and devices. Spatiotemporal averaging in conventional heterodyne detection-based Kelvin probe force microscopy (KPFM) inherently limits its time resolution, causing an irretrievable loss of transient response and higher-order harmonics. Addressing this, we report a wavelet transform (WT)-based methodology capable of quantifying the sub-ms charge dynamics and probing the elusive transient response. The feedback-free, open-loop wavelet transform KPFM (OL-WT-KPFM) technique harnesses the WT's ability to simultaneously extract spatial and temporal information from the photodetector signal to provide a dynamic mapping of surface potential, capacitance gradient, and dielectric constant at a temporal resolution 3 orders of magnitude higher than the lock-in time constant. We further demonstrate the method's applicability to explore the surface-photovoltage-induced sub-ms hole-diffusion transient in bismuth oxyiodide semiconductor. The OL-WT-KPFM concept is readily applicable to commercial systems and can provide the underlying basis for the real-time analysis of transient electronic and electrochemical properties.
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Affiliation(s)
- Pardis Biglarbeigi
- Nanotechnology
and Integrated Bio-Engineering Centre (NIBEC), School of Engineering, Ulster University, York Street, Belfast BT15 1AP, Co. Antrim, Northern
Ireland, United Kingdom
- School
of Science and Engineering, University of
Dundee, Nethergate, Dundee, DD1 4NH, Scotland, United Kingdom
| | - Alessio Morelli
- Nanotechnology
and Integrated Bio-Engineering Centre (NIBEC), School of Engineering, Ulster University, York Street, Belfast BT15 1AP, Co. Antrim, Northern
Ireland, United Kingdom
| | - Serene Pauly
- School
of Mathematics and Physics, Queen’s
University Belfast, University Road, Belfast BT7 1NN, Northern Ireland, United Kingdom
| | - Zidong Yu
- Institute
for Materials Research and Innovation (IMRI), University of Bolton, Deane Road, Bolton BL3
5AB, United Kingdom
| | - Wenjun Jiang
- College
of Transportation Engineering, Dalian Maritime
University, Dalian 116026, China
| | - Surbhi Sharma
- Centre
for New Energy Transition Research Technologies (CfNETR), Federation University Australia, Gippsland Campus, Churchill, Victoria 3810, Australia
| | - Dewar Finlay
- Nanotechnology
and Integrated Bio-Engineering Centre (NIBEC), School of Engineering, Ulster University, York Street, Belfast BT15 1AP, Co. Antrim, Northern
Ireland, United Kingdom
| | - Amit Kumar
- School
of Mathematics and Physics, Queen’s
University Belfast, University Road, Belfast BT7 1NN, Northern Ireland, United Kingdom
| | - Navneet Soin
- Nanotechnology
and Integrated Bio-Engineering Centre (NIBEC), School of Engineering, Ulster University, York Street, Belfast BT15 1AP, Co. Antrim, Northern
Ireland, United Kingdom
- School of
Science, Computing and Engineering Technologies, Swinburne University of Technology,
P.O. Box 218, Hawthorn Victoria 3122, Australia
| | - Amir Farokh Payam
- Nanotechnology
and Integrated Bio-Engineering Centre (NIBEC), School of Engineering, Ulster University, York Street, Belfast BT15 1AP, Co. Antrim, Northern
Ireland, United Kingdom
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4
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Checa M, Fuhr AS, Sun C, Vasudevan R, Ziatdinov M, Ivanov I, Yun SJ, Xiao K, Sehirlioglu A, Kim Y, Sharma P, Kelley KP, Domingo N, Jesse S, Collins L. High-speed mapping of surface charge dynamics using sparse scanning Kelvin probe force microscopy. Nat Commun 2023; 14:7196. [PMID: 37938577 PMCID: PMC10632481 DOI: 10.1038/s41467-023-42583-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Accepted: 10/15/2023] [Indexed: 11/09/2023] Open
Abstract
Unraveling local dynamic charge processes is vital for progress in diverse fields, from microelectronics to energy storage. This relies on the ability to map charge carrier motion across multiple length- and timescales and understanding how these processes interact with the inherent material heterogeneities. Towards addressing this challenge, we introduce high-speed sparse scanning Kelvin probe force microscopy, which combines sparse scanning and image reconstruction. This approach is shown to enable sub-second imaging (>3 frames per second) of nanoscale charge dynamics, representing several orders of magnitude improvement over traditional Kelvin probe force microscopy imaging rates. Bridging this improved spatiotemporal resolution with macroscale device measurements, we successfully visualize electrochemically mediated diffusion of mobile surface ions on a LaAlO3/SrTiO3 planar device. Such processes are known to impact band-alignment and charge-transfer dynamics at these heterointerfaces. Furthermore, we monitor the diffusion of oxygen vacancies at the single grain level in polycrystalline TiO2. Through temperature-dependent measurements, we identify a charge diffusion activation energy of 0.18 eV, in good agreement with previously reported values and confirmed by DFT calculations. Together, these findings highlight the effectiveness and versatility of our method in understanding ionic charge carrier motion in microelectronics or nanoscale material systems.
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Affiliation(s)
- Marti Checa
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
| | - Addis S Fuhr
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Changhyo Sun
- School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Rama Vasudevan
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Maxim Ziatdinov
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
- Computational Sciences and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37923, USA
| | - Ilia Ivanov
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Seok Joon Yun
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
- Department of Semiconductor, University of Ulsan, Ulsan, 44610, Korea
| | - Kai Xiao
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Alp Sehirlioglu
- Department of Materials Science and Engineering, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Yunseok Kim
- School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Pankaj Sharma
- College of Science and Engineering, Flinders University, Bedford Park, SA, 5042, Australia
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies (FLEET), UNSW Sydney, Sydney, NSW, 2052, Australia
| | - Kyle P Kelley
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Neus Domingo
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Stephen Jesse
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Liam Collins
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
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5
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Karaoglu G, Kutbay E, Ince S, Ulgut B, Suzer S. Assessing Local Electrical Properties of Ionic Liquid/Metal Interfaces with Operando-XPS and by Incorporating Additional Circuit Elements. Anal Chem 2023; 95:14861-14869. [PMID: 37768186 DOI: 10.1021/acs.analchem.3c01614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/29/2023]
Abstract
X-ray photoelectron spectroscopy (XPS) has been utilized to record binding energy changes upon applying direct current (DC) and/or alternating current (AC) (square-wave) bias with different frequencies on a coplanar capacitor, having an ionic liquid (IL) film as the electrolyte. Electrical potential developments in numerous locations on the device are extracted from the variations in binding energy positions of the atomic core levels, which together with electrochemical measurements are used to extract local information before and after insertion of additional resistors in series. The presence of the IL introduces complex charging/discharging processes with a direct influence on the electrical double layer (EDL) formation, some of which can be untangled from each other via AC modulation by choosing appropriate time windows of observation. Accordingly, under 10 kHz modulation, fast processes are sampled, which are associated with electronic currents, and effects of slow migratory currents can be measured using 0.1 Hz. The addition of serial resistors allows us to quantify AC currents passing through, which reveals the magnitude of the system's impedance under different conditions. This process surprisingly reverses differences(s) in the voltage developments between the low and high frequencies over the electrified electrodes compared to those over the porous membrane in between. Our approach turns XPS into a powerful electrical and surface-sensitive tool for extracting localized electrochemical properties in a noninvasive and direct way. We expect that a wider utilization of the technique will lead to better identification of the obstacles for developing the next-generation sensing, energy harvesting, and storage systems as well as devices for iontronic/neuromorphic applications.
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Affiliation(s)
- Gozde Karaoglu
- Department of Chemistry, Bilkent University, 06800 Ankara, Turkey
| | - Ezgi Kutbay
- Department of Chemistry, Bilkent University, 06800 Ankara, Turkey
| | - Suleyman Ince
- Department of Chemistry, Bilkent University, 06800 Ankara, Turkey
| | - Burak Ulgut
- Department of Chemistry, Bilkent University, 06800 Ankara, Turkey
| | - Sefik Suzer
- Department of Chemistry, Bilkent University, 06800 Ankara, Turkey
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6
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Recent Advances in In Situ/Operando Surface/Interface Characterization Techniques for the Study of Artificial Photosynthesis. INORGANICS 2022. [DOI: 10.3390/inorganics11010016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
(Photo-)electrocatalytic artificial photosynthesis driven by electrical and/or solar energy that converts water (H2O) and carbon dioxide (CO2) into hydrogen (H2), carbohydrates and oxygen (O2), has proven to be a promising and effective route for producing clean alternatives to fossil fuels, as well as for storing intermittent renewable energy, and thus to solve the energy crisis and climate change issues that we are facing today. Basic (photo-)electrocatalysis consists of three main processes: (1) light absorption, (2) the separation and transport of photogenerated charge carriers, and (3) the transfer of photogenerated charge carriers at the interfaces. With further research, scientists have found that these three steps are significantly affected by surface and interface properties (e.g., defect, dangling bonds, adsorption/desorption, surface recombination, electric double layer (EDL), surface dipole). Therefore, the catalytic performance, which to a great extent is determined by the physicochemical properties of surfaces and interfaces between catalyst and reactant, can be changed dramatically under working conditions. Common approaches for investigating these phenomena include X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), scanning probe microscopy (SPM), wide angle X-ray diffraction (WAXRD), auger electron spectroscopy (AES), transmission electron microscope (TEM), etc. Generally, these techniques can only be applied under ex situ conditions and cannot fully recover the changes of catalysts in real chemical reactions. How to identify and track alterations of the catalysts, and thus provide further insight into the complex mechanisms behind them, has become a major research topic in this field. The application of in situ/operando characterization techniques enables real-time monitoring and analysis of dynamic changes. Therefore, researchers can obtain physical and/or chemical information during the reaction (e.g., morphology, chemical bonding, valence state, photocurrent distribution, surface potential variation, surface reconstruction), or even by the combination of these techniques as a suite (e.g., atomic force microscopy-based infrared spectroscopy (AFM-IR), or near-ambient-pressure STM/XPS combined system (NAP STM-XPS)) to correlate the various properties simultaneously, so as to further reveal the reaction mechanisms. In this review, we briefly describe the working principles of in situ/operando surface/interface characterization technologies (i.e., SPM and X-ray spectroscopy) and discuss the recent progress in monitoring relevant surface/interface changes during water splitting and CO2 reduction reactions (CO2RR). We hope that this review will provide our readers with some ideas and guidance about how these in situ/operando characterization techniques can help us investigate the changes in catalyst surfaces/interfaces, and further promote the development of (photo-)electrocatalytic surface and interface engineering.
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7
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Deb S, Cao W, Raab N, Watanabe K, Taniguchi T, Goldstein M, Kronik L, Urbakh M, Hod O, Ben Shalom M. Cumulative polarization in conductive interfacial ferroelectrics. Nature 2022; 612:465-469. [PMID: 36352233 DOI: 10.1038/s41586-022-05341-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 09/13/2022] [Indexed: 11/10/2022]
Abstract
Ferroelectricity in atomically thin bilayer structures has been recently predicted1 and measured2-4 in two-dimensional materials with hexagonal non-centrosymmetric unit-cells. The crystal symmetry translates lateral shifts between parallel two-dimensional layers to sign changes in their out-of-plane electric polarization, a mechanism termed 'slide-tronics'4. These observations have been restricted to switching between only two polarization states under low charge carrier densities5-12, limiting the practical application of the revealed phenomena13. To overcome these issues, one should explore the nature of polarization in multi-layered van der Waals stacks, how it is governed by intra- and interlayer charge redistribution and to what extent it survives the addition of mobile charge carriers14. To explore these questions, we conduct surface potential measurements of parallel WSe2 and MoS2 multi-layers with aligned and anti-aligned configurations of the polar interfaces. We find evenly spaced, nearly decoupled potential steps, indicating highly confined interfacial electric fields that provide a means to design multi-state 'ladder-ferroelectrics'. Furthermore, we find that the internal polarization remains notable on electrostatic doping of mobile charge carrier densities as high as 1013 cm-2, with substantial in-plane conductivity. Using density functional theory calculations, we trace the extra charge redistribution in real and momentum spaces and identify an eventual doping-induced depolarization mechanism.
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Affiliation(s)
- Swarup Deb
- School of Physics and Astronomy, Tel Aviv University, Tel Aviv, Israel
| | - Wei Cao
- Department of Physical Chemistry, School of Chemistry, The Raymond and Beverly Sackler Faculty of Exact Sciences and The Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv, Israel
| | - Noam Raab
- School of Physics and Astronomy, Tel Aviv University, Tel Aviv, Israel
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - Moshe Goldstein
- School of Physics and Astronomy, Tel Aviv University, Tel Aviv, Israel
| | - Leeor Kronik
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovoth, Israel
| | - Michael Urbakh
- Department of Physical Chemistry, School of Chemistry, The Raymond and Beverly Sackler Faculty of Exact Sciences and The Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv, Israel
| | - Oded Hod
- Department of Physical Chemistry, School of Chemistry, The Raymond and Beverly Sackler Faculty of Exact Sciences and The Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv, Israel
| | - Moshe Ben Shalom
- School of Physics and Astronomy, Tel Aviv University, Tel Aviv, Israel.
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8
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Burgo TL, Pereira GKR, Iglesias BA, Moreira KS, Valandro LF. AFM advanced modes for dental and biomedical applications. J Mech Behav Biomed Mater 2022; 136:105475. [PMID: 36195052 DOI: 10.1016/j.jmbbm.2022.105475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 09/15/2022] [Accepted: 09/18/2022] [Indexed: 11/18/2022]
Abstract
Several analytical methods have been employed to elucidate bonding mechanisms between dental hard tissues, luting agents and restorative materials. Atomic Force Microscopy (AFM) imaging that has been extensively used in materials science, but its full capabilities are poorly explored by dental research community. In fact, commonly used to obtain topographic images of different surfaces, it turns out that AFM is an underestimated technique considering that there are dozens of basic and advanced modes that are scarcely used to explain properties of biomaterials. Thus, this paper addresses the use of phase-contrast imaging, force-distance curves, nanomechanical and Kelvin probe force techniques during AFM analysis to explore topological, nanomechanical and electrical properties of Y-TZP samples modified by different surface treatments, which has been widely used to promote adhesive enhancements to such substrate. The AFM methods are capable of access erstwhile inaccessible properties of Y-TZP which allowed us to describe its adhesive properties correctly. Thus, AFM technique emerges as a key tool to investigate the complex nature of biomaterials and highlighting its inherent interdisciplinarity that can be successfully used for bridging fragmented disciplines such as solid-state physics, microbiology and dental sciences.
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Affiliation(s)
- ThiagoA L Burgo
- Department of Chemistry and Environmental Sciences, Ibilce, São Paulo State University (Unesp), São Jose do Rio Preto, São Paulo State, Brazil.
| | - Gabriel Kalil Rocha Pereira
- MSciD and Ph.D. Post-Graduate Program in Oral Science, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Bernardo Almeida Iglesias
- Department of Chemistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Kelly S Moreira
- Department of Chemistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Luiz Felipe Valandro
- MSciD and Ph.D. Post-Graduate Program in Oral Science, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
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9
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Bonagiri LKS, Panse KS, Zhou S, Wu H, Aluru NR, Zhang Y. Real-Space Charge Density Profiling of Electrode-Electrolyte Interfaces with Angstrom Depth Resolution. ACS NANO 2022; 16:19594-19604. [PMID: 36351178 DOI: 10.1021/acsnano.2c10819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The accumulation and depletion of charges at electrode-electrolyte interfaces is crucial for all types of electrochemical processes. However, the spatial profile of such interfacial charges remains largely elusive. Here we develop charge profiling three-dimensional (3D) atomic force microscopy (CP-3D-AFM) to experimentally quantify the real-space charge distribution of the electrode surface and electric double layers (EDLs) with angstrom depth resolution. We first measure the 3D force maps at different electrode potentials using our recently developed electrochemical 3D-AFM. Through statistical analysis, peak deconvolution, and electrostatic calculations, we derive the depth profile of the local charge density. We perform such charge profiling for two types of emergent electrolytes, ionic liquids, and highly concentrated aqueous solutions, observe pronounced sub-nanometer charge variations, and find the integrated charge densities to agree with those derived from macroscopic electrochemical measurements.
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Affiliation(s)
- Lalith Krishna Samanth Bonagiri
- Materials Research Laboratory, University of Illinois, Urbana, Illinois61801, United States
- Department of Mechanical Science and Engineering, University of Illinois, Urbana, Illinois61801, United States
| | - Kaustubh S Panse
- Materials Research Laboratory, University of Illinois, Urbana, Illinois61801, United States
- Department of Materials Science and Engineering, University of Illinois, Urbana, Illinois61801, United States
| | - Shan Zhou
- Materials Research Laboratory, University of Illinois, Urbana, Illinois61801, United States
- Department of Materials Science and Engineering, University of Illinois, Urbana, Illinois61801, United States
| | - Haiyi Wu
- Walker Department of Mechanical Engineering and Oden Institute for Computational Engineering & Sciences, The University of Texas at Austin, Austin, Texas78712, United States
| | - Narayana R Aluru
- Walker Department of Mechanical Engineering and Oden Institute for Computational Engineering & Sciences, The University of Texas at Austin, Austin, Texas78712, United States
| | - Yingjie Zhang
- Materials Research Laboratory, University of Illinois, Urbana, Illinois61801, United States
- Department of Materials Science and Engineering, University of Illinois, Urbana, Illinois61801, United States
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10
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Kilpatrick JI, Kargin E, Rodriguez BJ. Comparing the performance of single and multifrequency Kelvin probe force microscopy techniques in air and water. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2022; 13:922-943. [PMID: 36161252 PMCID: PMC9490074 DOI: 10.3762/bjnano.13.82] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 08/04/2022] [Indexed: 06/16/2023]
Abstract
In this paper, we derive and present quantitative expressions governing the performance of single and multifrequency Kelvin probe force microscopy (KPFM) techniques in both air and water. Metrics such as minimum detectable contact potential difference, minimum required AC bias, and signal-to-noise ratio are compared and contrasted both off resonance and utilizing the first two eigenmodes of the cantilever. These comparisons allow the reader to quickly and quantitatively identify the parameters for the best performance for a given KPFM-based experiment in a given environment. Furthermore, we apply these performance metrics in the identification of KPFM-based modes that are most suitable for operation in liquid environments where bias application can lead to unwanted electrochemical reactions. We conclude that open-loop multifrequency KPFM modes operated with the first harmonic of the electrostatic response on the first eigenmode offer the best performance in liquid environments whilst needing the smallest AC bias for operation.
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Affiliation(s)
- Jason I Kilpatrick
- School of Physics and Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin, D04 V1W8, Ireland
| | - Emrullah Kargin
- School of Physics and Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin, D04 V1W8, Ireland
| | - Brian J Rodriguez
- School of Physics and Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin, D04 V1W8, Ireland
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11
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Lin S, Zhu L, Tang Z, Wang ZL. Spin-selected electron transfer in liquid-solid contact electrification. Nat Commun 2022; 13:5230. [PMID: 36064784 PMCID: PMC9445095 DOI: 10.1038/s41467-022-32984-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Accepted: 08/26/2022] [Indexed: 01/12/2023] Open
Abstract
Electron transfer has been proven the dominant charge carrier during contact electrification at the liquid-solid interface. However, the effect of electron spin in contact electrification remains to be investigated. This study examines the charge transfer between different liquids and ferrimagnetic solids in a magnetic field, focusing on the contribution of O2 molecules to the liquid-solid contact electrification. The findings reveal that magnetic fields promote electron transfer at the O2-containing liquid-solid interfaces. Moreover, magnetic field-induced electron transfer increases at higher O2 concentrations in the liquids and decreases at elevated temperatures. The results indicate spin-selected electron transfer at liquid-solid interface. External magnetic fields can modulate the spin conversion of the radical pairs at the O2-containing liquid and ferrimagnetic solid interfaces due to the Zeeman interaction, promoting electron transfer. A spin-selected electron transfer model for liquid-solid contact electrification is further proposed based on the radical pair mechanism, in which the HO2 molecules and the free unpaired electrons from the ferrimagnetic solids are considered radical pairs. The spin conversion of the [HO2• •e-] pairs is affected by magnetic fields, rendering the electron transfer magnetic field-sensitive.
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Affiliation(s)
- Shiquan Lin
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, 100083, P. R. China.,School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Laipan Zhu
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, 100083, P. R. China.,School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Zhen Tang
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, 100083, P. R. China.,School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Zhong Lin Wang
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, 100083, P. R. China. .,School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China. .,School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA, 30332-0245, USA.
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12
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Sun T, Lu Y, Lu J, Dong H, Ding W, Wang Y, Yang X, He H. Water-Controlled Structural Transition and Charge Transfer of Interfacial Ionic Liquids. J Phys Chem Lett 2022; 13:7113-7120. [PMID: 35900378 DOI: 10.1021/acs.jpclett.2c01822] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Clarification of the water-induced structural transitions and electron transfer between ionic liquids (ILs) and a solid surface allows for establishing a unified view of the electrical properties of interfacial ILs via a hitherto unexplored pathway. Here, we propose a simple and effective method to quantitatively identify and extract the transferred electrons between ILs and a solid surface, while demonstrating the critical structural transition of interfacial ILs from ordered stripe structures to disordered aggregation structures. The formation of hydrated anions, rooted in the hydrogen bonds of O-H···O between the anion and water, lies at the tipping point where electron transfer ends and aggregation structure begins. In addition, it is discovered to what extent the hydrophilicity of substrates can affect electron transfer, and a regulation method based on the electric field is explored. These experimental findings may refresh our knowledge of interfacial ILs and provide an effective method for evaluating the intrinsic electrical features of the ILs-solid surface.
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Affiliation(s)
- Tinglan Sun
- Beijing Key Laboratory of Ionic Liquids Clean Process, CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yumiao Lu
- Beijing Key Laboratory of Ionic Liquids Clean Process, CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Junfeng Lu
- Beijing Key Laboratory of Ionic Liquids Clean Process, CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
| | - Hao Dong
- Beijing Key Laboratory of Ionic Liquids Clean Process, CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Weilu Ding
- Beijing Key Laboratory of Ionic Liquids Clean Process, CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yanlei Wang
- Beijing Key Laboratory of Ionic Liquids Clean Process, CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Innovation Academy for Green Manufacture, Chinese Academy of Sciences, Beijing 100190, China
| | - Xiuhong Yang
- Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
| | - Hongyan He
- Beijing Key Laboratory of Ionic Liquids Clean Process, CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Innovation Academy for Green Manufacture, Chinese Academy of Sciences, Beijing 100190, China
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13
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Chen R, Fan F, Li C. Unraveling Charge-Separation Mechanisms in Photocatalyst Particles by Spatially Resolved Surface Photovoltage Techniques. Angew Chem Int Ed Engl 2022; 61:e202117567. [PMID: 35100475 DOI: 10.1002/anie.202117567] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Indexed: 11/08/2022]
Abstract
The photocatalytic conversion of solar energy offers a potential route to renewable energy, and its efficiency relies on effective charge separation in nanostructured photocatalysts. Understanding the charge-separation mechanism is key to improving the photocatalytic performance and this has now been enabled by advances in the spatially resolved surface photovoltage (SRSPV) method. In this Review we highlight progress made by SRSPV in mapping charge distributions at the nanoscale and determining the driving forces of charge separation in heterogeneous photocatalyst particles. We discuss how charge separation arising from a built-in electric field, diffusion, and trapping can be exploited and optimized through photocatalyst design. We also highlight the importance of asymmetric engineering of photocatalysts for effective charge separation. Finally, we provide an outlook on further opportunities that arise from leveraging these insights to guide the rational design of photocatalysts and advance the imaging technique to expand the knowledge of charge separation.
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Affiliation(s)
- Ruotian Chen
- State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian, 116023, China
| | - Fengtao Fan
- State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian, 116023, China
| | - Can Li
- State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian, 116023, China
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14
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Atomic Force Microscopy (AFM) on Biopolymers and Hydrogels for Biotechnological Applications-Possibilities and Limits. Polymers (Basel) 2022; 14:polym14061267. [PMID: 35335597 PMCID: PMC8949482 DOI: 10.3390/polym14061267] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 03/15/2022] [Accepted: 03/19/2022] [Indexed: 02/01/2023] Open
Abstract
Atomic force microscopy (AFM) is one of the microscopic techniques with the highest lateral resolution. It can usually be applied in air or even in liquids, enabling the investigation of a broader range of samples than scanning electron microscopy (SEM), which is mostly performed in vacuum. Since it works by following the sample surface based on the force between the scanning tip and the sample, interactions have to be taken into account, making the AFM of irregular samples complicated, but on the other hand it allows measurements of more physical parameters than pure topography. This is especially important for biopolymers and hydrogels used in tissue engineering and other biotechnological applications, where elastic properties, surface charges and other parameters influence mammalian cell adhesion and growth as well as many other effects. This review gives an overview of AFM modes relevant for the investigations of biopolymers and hydrogels and shows several examples of recent applications, focusing on the polysaccharides chitosan, alginate, carrageenan and different hydrogels, but depicting also a broader spectrum of materials on which different AFM measurements are reported in the literature.
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15
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Chen R, Fan F, Li C. Unraveling Charge‐Separation Mechanisms in Photocatalyst Particles by Spatially Resolved Surface Photovoltage Techniques. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202117567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Ruotian Chen
- State Key Laboratory of Catalysis Dalian National Laboratory for Clean Energy Dalian Institute of Chemical Physics Chinese Academy of Sciences Zhongshan Road 457 Dalian 116023 China
| | - Fengtao Fan
- State Key Laboratory of Catalysis Dalian National Laboratory for Clean Energy Dalian Institute of Chemical Physics Chinese Academy of Sciences Zhongshan Road 457 Dalian 116023 China
| | - Can Li
- State Key Laboratory of Catalysis Dalian National Laboratory for Clean Energy Dalian Institute of Chemical Physics Chinese Academy of Sciences Zhongshan Road 457 Dalian 116023 China
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16
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Aarts M, Reiser A, Spolenak R, Alarcon-Llado E. Confined pulsed diffuse layer charging for nanoscale electrodeposition with an STM. NANOSCALE ADVANCES 2022; 4:1182-1190. [PMID: 35308601 PMCID: PMC8846379 DOI: 10.1039/d1na00779c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 01/12/2022] [Indexed: 06/14/2023]
Abstract
Regulating the state of the solid-liquid interface by means of electric fields is a powerful tool to control electrochemistry. In scanning probe systems, this can be confined closely to a scanning (nano)electrode by means of fast potential pulses, providing a way to probe the interface and control electrochemical reactions locally, as has been demonstrated in nanoscale electrochemical etching. For this purpose, it is important to know the spatial extent of the interaction between pulses applied to the tip, and the substrate. In this paper we use a framework of diffuse layer charging to describe the localization of electrical double layer charging in response to a potential pulse at the probe. Our findings are in good agreement with literature values obtained in electrochemical etching. We show that the pulse can be much more localized by limiting the diffusivity of the ions present in solution, by confined electrodeposition of cobalt in a dimethyl sulfoxide solution, using an electrochemical scanning tunnelling microscope. Finally, we demonstrate the deposition of cobalt nanostructures (<100 nm) using this method. The presented framework therefore provides a general route for predicting and controlling the time-dependent region of interaction between an electrochemical scanning probe and the surface.
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Affiliation(s)
- Mark Aarts
- Center for Nanophotonics, AMOLF Science Park 109 Amsterdam Netherlands
| | - Alain Reiser
- Laboratory for Nanometallurgy, Department of Materials, ETH Zürich Vladimir-Prelog-Weg 1-5/10 Zürich Switzerland
| | - Ralph Spolenak
- Laboratory for Nanometallurgy, Department of Materials, ETH Zürich Vladimir-Prelog-Weg 1-5/10 Zürich Switzerland
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17
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Wu R, Matta M, Paulsen BD, Rivnay J. Operando Characterization of Organic Mixed Ionic/Electronic Conducting Materials. Chem Rev 2022; 122:4493-4551. [PMID: 35026108 DOI: 10.1021/acs.chemrev.1c00597] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Operando characterization plays an important role in revealing the structure-property relationships of organic mixed ionic/electronic conductors (OMIECs), enabling the direct observation of dynamic changes during device operation and thus guiding the development of new materials. This review focuses on the application of different operando characterization techniques in the study of OMIECs, highlighting the time-dependent and bias-dependent structure, composition, and morphology information extracted from these techniques. We first illustrate the needs, requirements, and challenges of operando characterization then provide an overview of relevant experimental techniques, including spectroscopy, scattering, microbalance, microprobe, and electron microscopy. We also compare different in silico methods and discuss the interplay of these computational methods with experimental techniques. Finally, we provide an outlook on the future development of operando for OMIEC-based devices and look toward multimodal operando techniques for more comprehensive and accurate description of OMIECs.
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Affiliation(s)
- Ruiheng Wu
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Micaela Matta
- Department of Chemistry, University of Liverpool, Liverpool L69 7ZD, United Kingdom
| | - Bryan D Paulsen
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Jonathan Rivnay
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois 60208, United States.,Simpson Querrey Institute, Northwestern University, Chicago, Illinois 60611, United States
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18
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Basaran M, Oz E, Ergoktas MS, Kocabas C, Ulgut B, Kocabas A, Suzer S. Localized X-Ray Photoelectron Impedance Spectroscopy (LoXPIS) for Tapping into Charge-Dynamics of Ionic-Liquid Electrolytes within Energy Storage Devices. Faraday Discuss 2022; 236:86-102. [DOI: 10.1039/d1fd00102g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Many electrochemical devices are based on the fundamental process of ion migration and accumulation on surfaces. Complex interplay of molecular properties of ions and device dimensions control the entire process...
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19
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Li P, Shao Y, Xu K, Qiu X. Development of a multi-functional multi-probe atomic force microscope system with optical beam deflection method. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:123705. [PMID: 34972423 DOI: 10.1063/5.0069849] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 12/01/2021] [Indexed: 06/14/2023]
Abstract
We developed a multi-probe atomic force microscope (MP-AFM) system with up to four probes and realized various functions such as topography mapping, probing electrical property, and local temperature measurement. Each probe mounted on the corresponding probe scanner was controlled independently, and the system employed the optical beam deflection method to measure the deflection of each cantilever. A high-performance MP-AFM system with a compact optical design and rigid actuators was finally established. We demonstrated AFM high-resolution imaging in air and performed four-probe imaging in parallel and multi-functional characterization with the MP-AFM system.
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Affiliation(s)
- Peng Li
- Faculty of Materials and Manufacturing, Beijing University of Technology, Beijing 100124, People's Republic of China
| | - Yongjian Shao
- School of Information and Control Engineering, Shenyang Jianzhu University, Shenyang 110168, People's Republic of China
| | - Ke Xu
- School of Information and Control Engineering, Shenyang Jianzhu University, Shenyang 110168, People's Republic of China
| | - Xiaohui Qiu
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, People's Republic of China
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20
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Su S, Siretanu I, van den Ende D, Mei B, Mul G, Mugele F. Facet-Dependent Surface Charge and Hydration of Semiconducting Nanoparticles at Variable pH. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2106229. [PMID: 34609757 DOI: 10.1002/adma.202106229] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 09/14/2021] [Indexed: 06/13/2023]
Abstract
Understanding structure and function of solid-liquid interfaces is essential for the development of nanomaterials for various applications including heterogeneous catalysis in liquid phase processes and water splitting for storage of renewable electricity. The characteristic anisotropy of crystalline nanoparticles is believed to be essential for their performance but remains poorly understood and difficult to characterize. Dual scale atomic force microscopy is used to measure electrostatic and hydration forces of faceted semiconducting SrTiO3 nanoparticles in aqueous electrolyte at variable pH. The following are demonstrated: the ability to quantify strongly facet-dependent surface charges yielding isoelectric points of the dominant {100} and {110} facets that differ by as much as 2 pH units; facet-dependent accumulation of oppositely charged (SiO2 ) particles; and that atomic scale defects can be resolved but are in fact rare for the samples investigated. Atomically resolved images and facet-dependent oscillatory hydration forces suggest a microscopic charge generation mechanism that explains colloidal scale electrostatic forces.
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Affiliation(s)
- Shaoqiang Su
- Physics of Complex Fluids Group and MESA+ Institute, Faculty of Science and Technology, University of Twente, P.O. Box 217, Enschede, 7500 AE, The Netherlands
| | - Igor Siretanu
- Physics of Complex Fluids Group and MESA+ Institute, Faculty of Science and Technology, University of Twente, P.O. Box 217, Enschede, 7500 AE, The Netherlands
| | - Dirk van den Ende
- Physics of Complex Fluids Group and MESA+ Institute, Faculty of Science and Technology, University of Twente, P.O. Box 217, Enschede, 7500 AE, The Netherlands
| | - Bastian Mei
- Photocatalytic Synthesis Group and MESA+ Institute, Faculty of Science and Technology, University of Twente, P.O. Box 217, Enschede, 7500 AE, The Netherlands
| | - Guido Mul
- Photocatalytic Synthesis Group and MESA+ Institute, Faculty of Science and Technology, University of Twente, P.O. Box 217, Enschede, 7500 AE, The Netherlands
| | - Frieder Mugele
- Physics of Complex Fluids Group and MESA+ Institute, Faculty of Science and Technology, University of Twente, P.O. Box 217, Enschede, 7500 AE, The Netherlands
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21
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Stan G, Namboodiri P. Open-loop amplitude-modulation Kelvin probe force microscopy operated in single-pass PeakForce tapping mode. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2021; 12:1115-1126. [PMID: 34703722 PMCID: PMC8505900 DOI: 10.3762/bjnano.12.83] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 09/29/2021] [Indexed: 06/13/2023]
Abstract
The open-loop (OL) variant of Kelvin probe force microscopy (KPFM) provides access to the voltage response of the electrostatic interaction between a conductive atomic force microscopy (AFM) probe and the investigated sample. The measured response can be analyzed a posteriori, modeled, and interpreted to include various contributions from the probe geometry and imaged features of the sample. In contrast to this, the currently implemented closed-loop (CL) variants of KPFM, either amplitude-modulation (AM) or frequency-modulation (FM), solely report on their final product in terms of the tip-sample contact potential difference. In ambient atmosphere, both CL AM-KPFM and CL FM-KPFM work at their best during the lift part of a two-pass scanning mode to avoid the direct contact with the surface of the sample. In this work, a new OL AM-KPFM mode was implemented in the single-pass scan of the PeakForce Tapping (PFT) mode. The topographical and electrical components were combined in a single pass by applying the electrical modulation only in between the PFT tip-sample contacts, when the AFM probe separates from the sample. In this way, any contact and tunneling discharges are avoided and, yet, the location of the measured electrical tip-sample interaction is directly affixed to the topography rendered by the mechanical PFT modulation at each tap. Furthermore, because the detailed response of the cantilever to the bias stimulation was recorded, it was possible to analyze and separate an average contribution of the cantilever to the determined local contact potential difference between the AFM probe and the imaged sample. The removal of this unwanted contribution greatly improved the accuracy of the AM-KPFM measurements to the level of the FM-KPFM counterpart.
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Affiliation(s)
- Gheorghe Stan
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Pradeep Namboodiri
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
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22
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Jakob DS, Li N, Zhou H, Xu XG. Integrated Tapping Mode Kelvin Probe Force Microscopy with Photoinduced Force Microscopy for Correlative Chemical and Surface Potential Mapping. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2102495. [PMID: 34310045 DOI: 10.1002/smll.202102495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 06/30/2021] [Indexed: 06/13/2023]
Abstract
Kelvin probe force microscopy (KPFM) is a popular technique for mapping the surface potential at the nanoscale through measurement of the Coulombic force between an atomic force microscopy (AFM) tip and sample. The lateral resolution of conventional KPFM variants is limited to between ≈35 and 100 nm in ambient conditions due to the long-range nature of the Coulombic force. In this article, a novel way of generating the Coulombic force in tapping mode KPFM without the need for an external AC driving voltage is presented. A field-effect transistor (FET) is used to directly switch the electrical connectivity of the tip and sample on and off periodically. The resulting Coulomb force induced by Fermi level alignment of the tip and sample results in a detectable change of the cantilever oscillation at the FET-switching frequency. The resulting FET-switched KPFM delivers a spatial resolution of ≈25 nm and inherits the high operational speed of the AFM tapping mode. Moreover, the FET-switched KPFM is integrated with photoinduced force microscopy (PiFM), enabling simultaneous acquisitions of high spatial resolution chemical distributions and surface potential maps. The integrated FET-switched KPFM with PiFM is expected to facilitate characterizations of nanoscale electrical properties of photoactive materials, semiconductors, and ferroelectric materials.
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Affiliation(s)
- Devon S Jakob
- Department of Chemistry, Lehigh University, Bethlehem, PA, 18015, USA
| | - Nengxu Li
- Department of Materials Science and Engineering, Peking University, Beijing, 100871, China
| | - Huanping Zhou
- Department of Materials Science and Engineering, Peking University, Beijing, 100871, China
| | - Xiaoji G Xu
- Department of Chemistry, Lehigh University, Bethlehem, PA, 18015, USA
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23
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Checa M, Millan-Solsona R, Glinkowska Mares A, Pujals S, Gomila G. Dielectric Imaging of Fixed HeLa Cells by In-Liquid Scanning Dielectric Force Volume Microscopy. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:1402. [PMID: 34070690 PMCID: PMC8226567 DOI: 10.3390/nano11061402] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 05/21/2021] [Accepted: 05/23/2021] [Indexed: 01/16/2023]
Abstract
Mapping the dielectric properties of cells with nanoscale spatial resolution can be an important tool in nanomedicine and nanotoxicity analysis, which can complement structural and mechanical nanoscale measurements. Recently we have shown that dielectric constant maps can be obtained on dried fixed cells in air environment by means of scanning dielectric force volume microscopy. Here, we demonstrate that such measurements can also be performed in the much more challenging case of fixed cells in liquid environment. Performing the measurements in liquid media contributes to preserve better the structure of the fixed cells, while also enabling accessing the local dielectric properties under fully hydrated conditions. The results shown in this work pave the way to address the nanoscale dielectric imaging of living cells, for which still further developments are required, as discussed here.
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Affiliation(s)
- Martí Checa
- Nanoscale Bioelectric Characterization, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri I Reixac 11-15, 08028 Barcelona, Spain;
| | - Ruben Millan-Solsona
- Nanoscale Bioelectric Characterization, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri I Reixac 11-15, 08028 Barcelona, Spain;
- Departament d’Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, c/Martí i Franquès 1, 08028 Barcelona, Spain;
| | - Adrianna Glinkowska Mares
- Nanoscopy for Nanomedicine, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri I Reixac 11-15, 08028 Barcelona, Spain;
| | - Silvia Pujals
- Departament d’Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, c/Martí i Franquès 1, 08028 Barcelona, Spain;
- Nanoscopy for Nanomedicine, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri I Reixac 11-15, 08028 Barcelona, Spain;
| | - Gabriel Gomila
- Nanoscale Bioelectric Characterization, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri I Reixac 11-15, 08028 Barcelona, Spain;
- Departament d’Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, c/Martí i Franquès 1, 08028 Barcelona, Spain;
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24
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Gisbert VG, Amo CA, Jaafar M, Asenjo A, Garcia R. Quantitative mapping of magnetic properties at the nanoscale with bimodal AFM. NANOSCALE 2021; 13:2026-2033. [PMID: 33449980 DOI: 10.1039/d0nr08662b] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We demonstrate that a force microscope operated in a bimodal configuration enables the mapping of magnetic interactions with high quantitative accuracy and high-spatial resolution (∼30 nm). Bimodal AFM operation doubles the number of observables with respect to conventional magnetic force microscopy methods which enables to determine quantitatively in a single processing step several magnetic properties. The theory of bimodal AFM provides analytical expressions for different magnetic force models, in particular those characterized by power-law and exponential distance dependences. Bimodal AFM provides a self-evaluation protocol to test the accuracy of the measurements. The agreement obtained between the experiments and theory for two different magnetic samples support the application of bimodal AFM to map quantitatively long-range magnetic interactions.
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Affiliation(s)
- Victor G Gisbert
- Instituto de Ciencia de Materiales de Madrid, CSIC, c/Sor Juana Inés de la Cruz 3, 28049 Madrid, Spain
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25
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Choi Y, Kim SM, Heo Y, Lee G, Kang JY, Yoon DS. Nanoelectrical characterization of individual exosomes secreted by Aβ 42-ingested cells using electrostatic force microscopy. NANOTECHNOLOGY 2021; 32:025705. [PMID: 32957091 DOI: 10.1088/1361-6528/abba58] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Quantifying the physical properties of individual exosomes containing amyloid-β42 (Aβ42) is crucial for a better understanding of an underpinning mechanism of Alzheimer's disease expression which is associated with the Aβ42 transfer. Because of the lack of proper tools, however, there have been very few studies on how the amount of Aβ42 affects the physical properties of exosomes. To answer the question, we investigated the physical properties of exosomes secreted by neuroblastoma by probing individual exosomes using electrostatic force microscopy. Interestingly, we observed that when the higher concentration of Aβ42 oligomers was fed to cells, the higher surface charge of the exosomes appeared. This result indicates that the exosomes contain more Aβ42 with the increase in Aβ42 concentration in cell media, implying that they serve as transport vesicles for Aβ42. Our approach could help to better understand how the neuronal exosomes are related to the propagation of neurodegenerative diseases and to seek how to make an early diagnosis of those diseases.
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Affiliation(s)
- Yeseong Choi
- Bio-convergence Engineering, Korea University, Seoul, Republic of Korea
- Center for BioMicrosystems, Korea Institute of Science and Technology, Seoul, Republic of Korea
| | - Su-Mi Kim
- Center for BioMicrosystems, Korea Institute of Science and Technology, Seoul, Republic of Korea
- R&D Team, Public CMO for Microbial-based Vaccine, Hwasun, Republic of Korea
| | - Youhee Heo
- Center for BioMicrosystems, Korea Institute of Science and Technology, Seoul, Republic of Korea
- Department of Biomedical Engineering, Sogang University, Seoul, Republic of Korea
| | - Gyudo Lee
- Department of Biotechnology and Bioinformatics, Korea University, Sejong, Republic of Korea
| | - Ji Yoon Kang
- Center for BioMicrosystems, Korea Institute of Science and Technology, Seoul, Republic of Korea
- Division of Biomedical Engineering, KIST School, Korea University of Science and Technology, Seoul, Republic of Korea
| | - Dae Sung Yoon
- Bio-convergence Engineering, Korea University, Seoul, Republic of Korea
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26
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Li L, Steinmetz NF, Eppell SJ, Zypman FR. Charge Calibration Standard for Atomic Force Microscope Tips in Liquids. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:13621-13632. [PMID: 33155810 DOI: 10.1021/acs.langmuir.0c02455] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
An electric charge standard with nanoscale resolution is created using the known charge distribution of a single tobacco mosaic virus coat protein combined with the known packing of these proteins in the virus capsid. This advances the ability to measure charge on nanometric samples. Experimental atomic force microscope (AFM) force-distance curves are collected under aqueous conditions with controlled pH and ion concentration. A mathematical model that considers a polarizable dielectric tip immersed in an electrolyte is used to obtain charge density from the AFM measurements. Interactions between the tip and the sample are modeled using theory that includes monopolar electrostatic interactions, dipolar interactions, screening from both the dielectric nature of ambient water and solvated ions as described by the linear Poisson-Boltzmann equation, and hard-core repulsion. It is found that the tip charge density changes on a timescale of hours requiring recalibration of the tip for experiments lasting more than an hour. As an example of how a charge-calibrated tip may be used, the surface charge densities on 20 individual carboxylate-modified polystyrene (PS) beads are measured. The average of these AFM-measured bead charge densities is compared with the value obtained from conventional titration combined with electron microscopy. The two values are found to agree within 20%. While the comparison demonstrates similarity of the two charge measurements, hypotheses are put forward as to why the two techniques might be expected not to provide identical mean charge densities. The considerations used to build these hypotheses thus underscore the relevance of the method performed here if charge information is required on individual nanoparticles.
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Affiliation(s)
- Li Li
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Nicole F Steinmetz
- Departments of NanoEngineering, Bioengineering, and Radiology, Moores Cancer Center, Center for Nano-ImmunoEngineering, University of California-San Diego, La Jolla, California 92039, United States
| | - Steven J Eppell
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Fredy R Zypman
- Department of Physics, Yeshiva University, Manhattan, New York 10033, United States
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Millan-Solsona R, Checa M, Fumagalli L, Gomila G. Mapping the capacitance of self-assembled monolayers at metal/electrolyte interfaces at the nanoscale by in-liquid scanning dielectric microscopy. NANOSCALE 2020; 12:20658-20668. [PMID: 33043923 DOI: 10.1039/d0nr05723a] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Organic self-assembled monolayers (SAMs) at metal/electrolyte interfaces have been thoroughly investigated both from fundamental and applied points of view. A relevant figure of merit of metal/SAM/electrolyte interfaces is the specific capacitance, which determines the charge that can be accumulated at the metal electrode. Here, we show that the specific capacitance of non-uniform alkanethiol SAMs at gold/electrolyte interfaces can be quantitatively measured and mapped at the nanoscale by in-liquid scanning dielectric microscopy in force detection mode. We show that sub-100 nm spatial resolution in ultrathin (<1 nm) SAMs can be achieved, largely improving the performance of current sensing characterization techniques. The present results provide access to study the dielectric properties of metal/SAM/electrolyte interfaces at scales that have remained unexplored until now.
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Affiliation(s)
- Ruben Millan-Solsona
- Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology, c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain. and Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, C/Martí i Franquès 1, 08028, Barcelona, Spain
| | - Martí Checa
- Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology, c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain.
| | - Laura Fumagalli
- Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK and National Graphene Institute, University of Manchester, Manchester M13 9PL, UK
| | - Gabriel Gomila
- Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology, c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain. and Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, C/Martí i Franquès 1, 08028, Barcelona, Spain
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Collins L, Vasudevan RK, Sehirlioglu A. Visualizing Charge Transport and Nanoscale Electrochemistry by Hyperspectral Kelvin Probe Force Microscopy. ACS APPLIED MATERIALS & INTERFACES 2020; 12:33361-33369. [PMID: 32579328 DOI: 10.1021/acsami.0c06426] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Charge-transport and electrochemical processes are heavily influenced by the local microstructure. Kelvin probe force microscopy (KPFM) is a widely used technique to map electrochemical potentials at the nanometer scale; however, it offers little information on local charge dynamics. Here, we implement a hyperspectral KPFM approach for spatially mapping bias-dependent charge dynamics in timescales ranging from the sub-millisecond to the second regime. As a proof of principle, we investigate the role mobile surface charges play in a three-unit-cell LaAlO3/SrTiO3 oxide heterostructure. We explore machine learning approaches to assist with visualization, pattern recognition, and interpretation of the information-rich data sets. Linear unmixing methods reveal hidden bias-dependent interfacial processes, most likely water splitting, which are essentially unnoticed by functional fitting of the dynamic response alone. Hyperspectral KPFM will be beneficial for investigating nanoscale charge transport and local reactivity in systems involving a possible combination of electronic, ionic, and electrochemical phenomena.
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Affiliation(s)
- Liam Collins
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831, United States
| | - Rama K Vasudevan
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831, United States
| | - Alp Sehirlioglu
- Department of Materials Science and Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106, United States
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29
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Yu W, Fu HJ, Mueller T, Brunschwig BS, Lewis NS. Atomic force microscopy: Emerging illuminated and operando techniques for solar fuel research. J Chem Phys 2020; 153:020902. [PMID: 32668946 DOI: 10.1063/5.0009858] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Integrated photoelectrochemical devices rely on the synergy between components to efficiently generate sustainable fuels from sunlight. The micro- and/or nanoscale characteristics of the components and their interfaces often control critical processes of the device, such as charge-carrier generation, electron and ion transport, surface potentials, and electrocatalysis. Understanding the spatial properties and structure-property relationships of these components can provide insight into designing scalable and efficient solar fuel components and systems. These processes can be probed ex situ or in situ with nanometer-scale spatial resolution using emerging scanning-probe techniques based on atomic force microscopy (AFM). In this Perspective, we summarize recent developments of AFM-based techniques relevant to solar fuel research. We review recent progress in AFM for (1) steady-state and dynamic light-induced surface photovoltage measurements; (2) nanoelectrical conductive measurements to resolve charge-carrier heterogeneity and junction energetics; (3) operando investigations of morphological changes, as well as surface electrochemical potentials, currents, and photovoltages in liquids. Opportunities for research include: (1) control of ambient conditions for performing AFM measurements; (2) in situ visualization of corrosion and morphological evolution of electrodes; (3) operando AFM techniques to allow nanoscale mapping of local catalytic activities and photo-induced currents and potentials.
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Affiliation(s)
- Weilai Yu
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - Harold J Fu
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - Thomas Mueller
- Bruker Nano Surfaces, 112 Robin Hill Road, Santa Barbara, California 93111, USA
| | - Bruce S Brunschwig
- Beckman Institute, California Institute of Technology, Pasadena, California 91125, USA
| | - Nathan S Lewis
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA
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30
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Stan G. High-speed digitization of the amplitude and frequency in open-loop sideband frequency-modulation Kelvin probe force microscopy. NANOTECHNOLOGY 2020; 31:385706. [PMID: 32516761 PMCID: PMC7808407 DOI: 10.1088/1361-6528/ab9af0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A more inclusive and detailed measurement of various physical interactions is enabled by the advance of high-speed data digitization. For surface potential characterization, this was demonstrated recently in terms of open-loop amplitude modulation Kelvin probe force microscopy (OL AM-KPFM). Its counterpart, namely open-loop frequency modulation Kelvin probe force microscopy (OL FM-KPFM), is examined here across different materials and under various bias voltages in the form of OL sideband FM-KPFM. In this implementation the changes in the amplitude and resonance frequency of the cantilever were continuously tracked as a conductive AFM probe was modulated by a 2 kHz AC bias voltage around the first eigenmode frequency of the cantilever. The contact potential difference (CPD) between the AFM probe and sample was determined from the time series analysis of the high-speed 4 MHz digitized amplitude and frequency signals of the OL sideband FM-KPFM mode. This interpretation is demonstrated to be superior to the analysis of the parabolic bias dependent response, which is more commonly used to extract the CPD in OL KPFM modes. The measured OL sideband FM-KPFM amplitude and frequency responses are directly related to the electrostatic force and force-gradient between the AFM probe and sample, respectively. As a result, clear distinction was observed for the determined CPD in each of these cases across materials of different surface potentials, with far superior spatial resolution when the force-gradient detection was used. In addition, the CPD values obtained from OL sideband FM-KPFM amplitude and frequency measurements perfectly matched those determined from their closed-loop AM-KPFM and FM-KPFM counterparts, respectively.
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Affiliation(s)
- Gheorghe Stan
- Material Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899, United States of America
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31
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Li L, Eppell SJ, Zypman FR. Method to Quantify Nanoscale Surface Charge in Liquid with Atomic Force Microscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:4123-4134. [PMID: 32208713 DOI: 10.1021/acs.langmuir.9b03602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A theory is presented to obtain surface charge density on nanoscale objects from data in the snap-to-contact portion of an atomic force microscope force-separation curve. The mathematical model takes into account the tip's dielectric constant using the Self-Consistent Sum of Dipoles theory which includes the charge-charge interaction and the charge-dipole interaction with electrolyte-induced exponentially decaying screening, Debye and London dipolar force, and fluid viscosity including confined fluid layers to account for energy dissipation. Using previously published experimental data, the mathematical model is applied to measure the surface charge density on an individual nanoscale amine-modified polystyrene bead immobilized on the basal plane of highly oriented pyrolytic graphite in buffered aqueous solution. Within the experimental uncertainty, the magnitude of the charge density on a single bead obtained using the new method falls within the distribution of values determined by the manufacturer using titration and electron microscopy.
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Affiliation(s)
- Li Li
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106, United States
| | - Steven J Eppell
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106, United States
| | - Fredy R Zypman
- Department of Physics, Yeshiva University, 2495 Amsterdam Avenue, Manhattan, New York 10033, United States
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32
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Collins L, Muckley ES, Tsai H, Ghosh D, Neukirch AJ, Tretiak S, Kalinin SV, Nie W, Ivanov IN. Correlation of Spatiotemporal Dynamics of Polarization and Charge Transport in Blended Hybrid Organic-Inorganic Perovskites on Macro- and Nanoscales. ACS APPLIED MATERIALS & INTERFACES 2020; 12:15380-15388. [PMID: 32159935 DOI: 10.1021/acsami.0c00561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Progress in flexible organic electronics necessitates a full understanding of how local inhomogeneities impact electronic and ionic conduction pathways and underlie macroscopic device characteristics. We used frequency- and time-resolved macro- and nanoprobe measurements to study spatiotemporal characteristics of multiscale charge transport dynamics in a series of ternary-blended hybrid organic inorganic perovskites (HOIPs) (MA0.95-xFAxCs0.05PbI3). We show that A-site cation composition defines charge transport mechanisms across broad temporal (102-10-6 s) and spatial (millimeters-picometers) scales. Ab initio molecular dynamic simulations suggest that insertion of FA results in a dynamic lattice, improved ion transport, and dipole screening. We demonstrate that correlations between macro- and nanoscale measurements provide a pathway for accessing distribution of relaxation in nanoscale polarization and charge transport dynamics of ionically conductive functional perovskites.
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Affiliation(s)
- Liam Collins
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Eric S Muckley
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Hsinhan Tsai
- Materials Physics and Application Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Dibyajyoti Ghosh
- Materials Physics and Application Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Amanda J Neukirch
- Materials Physics and Application Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Sergei Tretiak
- Materials Physics and Application Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Sergei V Kalinin
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Wanyi Nie
- Materials Physics and Application Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Ilia N Ivanov
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
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33
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Strelcov E, Arble C, Guo H, Hoskins BD, Yulaev A, Vlassiouk IV, Zhitenev NB, Tselev A, Kolmakov A. Nanoscale Mapping of the Double Layer Potential at the Graphene-Electrolyte Interface. NANO LETTERS 2020; 20:1336-1344. [PMID: 31990570 DOI: 10.1021/acs.nanolett.9b04823] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The electrical double layer (EDL) governs the operation of multiple electrochemical devices, determines reaction potentials, and conditions ion transport through cellular membranes in living organisms. The few existing methods of EDL probing have low spatial resolution, usually only providing spatially averaged information. On the other hand, traditional Kelvin probe force microscopy (KPFM) is capable of mapping potential with nanoscale lateral resolution but cannot be used in electrolytes with concentrations higher than several mmol/L. Here, we resolve this experimental impediment by combining KPFM with graphene-capped electrolytic cells to quantitatively measure the potential drop across the EDL in aqueous electrolytes of decimolar and molar concentrations with a high lateral resolution. The surface potential of graphene in contact with deionized water and 0.1 mol/L solutions of CuSO4 and MgSO4 as a function of counter electrode voltage is reported. The measurements are supported by numerical modeling to reveal the role of the graphene membrane in potential screening and to determine the EDL potential drop. The proposed approach proves to be especially useful for imaging spatially inhomogeneous systems, such as nanoparticles submerged in an electrolyte solution. It could be suitable for in operando and in vivo measurements of the potential drop in the EDL on the surfaces of nanocatalysts and biological cells in equilibrium with liquid solutions.
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Affiliation(s)
- Evgheni Strelcov
- Physical Measurement Laboratory , National Institute of Standards and Technology , Gaithersburg , Maryland 20899 , United States
- Maryland NanoCenter , University of Maryland , College Park , Maryland 20742 , United States
| | - Christopher Arble
- Physical Measurement Laboratory , National Institute of Standards and Technology , Gaithersburg , Maryland 20899 , United States
| | - Hongxuan Guo
- SEU-FEI Nano-Pico Center, Key Laboratory of MEMS of Ministry of Education , Southeast University , Nanjing 210096 , China
| | - Brian D Hoskins
- Physical Measurement Laboratory , National Institute of Standards and Technology , Gaithersburg , Maryland 20899 , United States
| | - Alexander Yulaev
- Physical Measurement Laboratory , National Institute of Standards and Technology , Gaithersburg , Maryland 20899 , United States
- Department of Chemistry and Biochemistry , University of Maryland , College Park , Maryland 20742 , United States
| | - Ivan V Vlassiouk
- Oak Ridge National Laboratory , Oak Ridge , Tennessee 37830 , United States
| | - Nikolai B Zhitenev
- Physical Measurement Laboratory , National Institute of Standards and Technology , Gaithersburg , Maryland 20899 , United States
| | - Alexander Tselev
- Department of Physics and CICECO-Aveiro Institute of Materials , University of Aveiro , 3810-193 Aveiro , Portugal
| | - Andrei Kolmakov
- Physical Measurement Laboratory , National Institute of Standards and Technology , Gaithersburg , Maryland 20899 , United States
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34
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Laskowski FAL, Oener SZ, Nellist MR, Gordon AM, Bain DC, Fehrs JL, Boettcher SW. Nanoscale semiconductor/catalyst interfaces in photoelectrochemistry. NATURE MATERIALS 2020; 19:69-76. [PMID: 31591528 DOI: 10.1038/s41563-019-0488-z] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 08/18/2019] [Indexed: 05/12/2023]
Abstract
Semiconductor structures (for example, films, wires, particles) used in photoelectrochemical devices are often decorated with nanoparticles that catalyse fuel-forming reactions, including water oxidation, hydrogen evolution or carbon-dioxide reduction. For high performance, the catalyst nanoparticles must form charge-carrier-selective contacts with the underlying light-absorbing semiconductor, facilitating either hole or electron transfer while inhibiting collection of the opposite carrier. Despite the key role played by such selective contacts in photoelectrochemical energy conversion and storage, the underlying nanoscale interfaces are poorly understood because direct measurement of their properties is challenging, especially under operating conditions. Using an n-Si/Ni photoanode model system and potential-sensing atomic force microscopy, we measure interfacial electron-transfer processes and map the photovoltage generated during photoelectrochemical oxygen evolution at nanoscopic semiconductor/catalyst interfaces. We discover interfaces where the selectivity of low-Schottky-barrier n-Si/Ni contacts for holes is enhanced via a nanoscale size-dependent pinch-off effect produced when surrounding high-barrier regions develop during device operation. These results thus demonstrate (1) the ability to make nanoscale operando measurements of contact properties under practical photoelectrochemical conditions and (2) a design principle to control the flow of electrons and holes across semiconductor/catalyst junctions that is broadly relevant to different photoelectrochemical devices.
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Affiliation(s)
| | - Sebastian Z Oener
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, OR, USA
| | - Michael R Nellist
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, OR, USA
| | - Adrian M Gordon
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, OR, USA
| | - David C Bain
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, OR, USA
| | - Jessica L Fehrs
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, OR, USA
| | - Shannon W Boettcher
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, OR, USA.
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35
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Boinovich LB. Boundary layers and surface forces in pure nonaqueous liquids. Curr Opin Colloid Interface Sci 2019. [DOI: 10.1016/j.cocis.2019.10.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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36
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Chen Y, Meng Q, Xiao Y, Zhang X, Sun J, Han CB, Gao H, Zhang Y, Lu Y, Yan H. Mechanism of PbI 2 in Situ Passivated Perovskite Films for Enhancing the Performance of Perovskite Solar Cells. ACS APPLIED MATERIALS & INTERFACES 2019; 11:44101-44108. [PMID: 31680509 DOI: 10.1021/acsami.9b13648] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Perovskite solar cells (PSCs) have gained tremendous research interest because of their tolerance of defects, low cost, and facile processing. In PSC devices, PbI2 has been utilized to passivate defects at perovskite film surfaces and GBs; however, a systematic mechanism of PbI2 in situ passivation for enhancing the solar cells efficiency has not been fully explored. Here, this work, we systematically studies the effect of the precise PbI2 ratio and the PbI2 in situ passivation mechanism based on trap density, carrier lifetime, Fermi level, and so forth. This study finds the appropriate ratio of I/Pb to be around 2.57:1 using energy-dispersive spectroscopy. After the moderate excess PbI2 in situ passivation, the trap density is reduced from 6.12 × 1016 to 3.38 × 1016 cm-3, and the carrier lifetime is extended from 168.35 to 368.77 ps by using fs-TA spectroscopy. This result indicates that the moderate excess PbI2 in situ passivation can reduce the trap density and suppress the nonradiative recombination. The efficiency of solar cell has shown a nearly 11.3% improvement of 19.55% for an I/Pb ratio of 2.57:1 compared with 2.69:1. It also demonstrates that the efficiency of PSCs can be enhanced effectively by PbI2 in situ passivation.
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Affiliation(s)
| | | | - Yueyue Xiao
- College of Materials Science and Engineering , Hebei University of Science and Technology , Shijiazhuang 050027 , Hebei , China
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37
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Aarts M, Alarcon-Llado E. Directed nanoscale metal deposition by the local perturbation of charge screening at the solid-liquid interface. NANOSCALE 2019; 11:18619-18627. [PMID: 31584050 DOI: 10.1039/c9nr05574f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Understanding and directing electrochemical reactions below the micrometer scale is a long-standing challenge in electrochemistry. Confining reactions to nanoscale areas paradoxically requires both isolation from and communication with the bulk electrolyte in terms of electrochemical potential and access of ions, respectively. Here, we demonstrate the directed electrochemical deposition of copper nanostructures by using an oscillating nanoelectrode operated with an atomic force microscope (AFM). Strikingly, the writing is only possible in highly dilute electrolytes and for a particular combination of AFM and electrochemical parameters. We propose a mechanism based on cyclic charging and discharging of the electrical double layer (EDL). The extended screening length and slower charge dynamics in dilute electrolytes allow the nanoelectrode to operate inside, and disturb, the EDL even for large oscillation amplitudes (∼100 nm). Our unique approach can not only be used for controlled additive nano-fabrication but also provides insights into ion behavior and EDL dynamics at the solid-liquid interface.
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Affiliation(s)
- Mark Aarts
- Center for Nanophotonics, NWO-I Amolf, Science Park 104, 1098 XG Amsterdam, Netherlands.
| | - Esther Alarcon-Llado
- Center for Nanophotonics, NWO-I Amolf, Science Park 104, 1098 XG Amsterdam, Netherlands.
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38
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Weng YJ. Forming of Dynamic Microstructure of Flexible Polymer. MATERIALS 2019; 12:ma12203332. [PMID: 31614847 PMCID: PMC6829512 DOI: 10.3390/ma12203332] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 10/04/2019] [Accepted: 10/11/2019] [Indexed: 01/05/2023]
Abstract
This study focuses on the forming of dynamic microstructure of flexible polymer. The dynamic tensile control microstructure of the polymer mold, along with the gasbag, was used to exert pressure to achieve forming. This study simulated the dynamic control of the flexible mold, and proposed four mechanical models of material viscoelastic response for modeling and evaluation. MATLAB software was used to calculate the imprint prediction calculation theory construction according to the imprint result of curved surface and asymmetric imprint forming. This study designed and developed a gasbag-assisted dynamic forming system, and tested the proposed system for verification. The test results showed that the mechanical stability, curved surface, and asymmetric imprint prediction calculation of the mechanical model of the viscoelastic response of flexible mold material, as proposed in this study, can display the geometric features of the imprinted microstructure. The dynamic mold microstructure control process can accurately transfer a bifacial microstructure and construct the confidence interval for transfer printing forming.
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Affiliation(s)
- Yung-Jin Weng
- Department of Mechanical and Energy Engineering, National Chiayi University, Chiayi City 60004, Taiwan.
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39
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Checa M, Millan-Solsona R, Gomila G. Frequency-dependent force between ac-voltage-biased plates in electrolyte solutions. Phys Rev E 2019; 100:022604. [PMID: 31574759 DOI: 10.1103/physreve.100.022604] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Indexed: 12/26/2022]
Abstract
We analyze the frequency dependence of the force between ac-voltage-biased plates in electrolyte solutions. To this end we solve analytically the Poisson-Nernst-Planck transport model in the dilute concentration and low voltage regime for a 1:1 symmetric electrolyte with blocking electrodes under a dc+ac applied voltage. The total force, which is the resultant of the electric and osmotic forces, shows a complex dependence on plate separation, frequency, ion concentration, and compact layer properties, different from that predicted from electrostatic current models or equivalent circuit models, due to the relevance of the osmotic force contribution in almost the whole range of frequencies. For the total dc force, we show that it decays at fixed ion concentration, linearly with plate separation for separations larger than a few times the Debye screening length. This linear dependence is due to the assumption about the conservation of the number of ions in the system. Moreover, the 1ω and 2ω ac harmonics of the total force show a broad peak at intermediate frequencies; it is centered at about the inverse of the charging time of the double layer capacitance, and covers the frequency range between the inverse of the diffusion time and the inverse of the electrolyte dielectric relaxation time. Finally, the 1ω ac harmonic component attains its high frequency asymptotic value at frequencies much higher than the inverse of the electrolyte dielectric relaxation time due to the very slow relaxation of the osmotic 1ω harmonic component at high frequencies. The derived analytical expressions for the total force remain valid up to voltages of the order of the thermal voltage, as has been assessed by means of numerical calculations. The numerical calculations are also used to explore the onset of higher force harmonics for larger applied voltages. Understanding the frequency dependence of the force acting on voltage-biased plates in electrolyte solutions can be of relevance for electrical actuation strategies in microelectromechanical systems and for the interpretation of some emerging electric scanning probe force microscopy techniques operating in electrolyte solutions.
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Affiliation(s)
- M Checa
- Institut de Bioenginyeria de Catalunya (IBEC), c/ Baldiri i Reixac 11-15, 08028, Barcelona, Spain
| | - R Millan-Solsona
- Institut de Bioenginyeria de Catalunya (IBEC), c/ Baldiri i Reixac 11-15, 08028, Barcelona, Spain
| | - G Gomila
- Institut de Bioenginyeria de Catalunya (IBEC), c/ Baldiri i Reixac 11-15, 08028, Barcelona, Spain.,Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, C/ Martí i Franquès 1, 08028, Barcelona, Spain
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40
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Fukuma T, Garcia R. Atomic- and Molecular-Resolution Mapping of Solid-Liquid Interfaces by 3D Atomic Force Microscopy. ACS NANO 2018; 12:11785-11797. [PMID: 30422619 DOI: 10.1021/acsnano.8b07216] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Hydration layers are ubiquitous in life and technology. Hence, interfacial aqueous layers have a central role in a wide range of phenomena from materials science to molecular and cell biology. A complete understanding of those processes requires, among other things, the development of very-sensitive and high-resolution instruments. Three-dimensional atomic force microscopy (3D-AFM) represents the latest and most successful attempt to generate atomically resolved three-dimensional images of solid-liquid interfaces. This review provides an overview of the 3D-AFM operating principles and its underlying physics. We illustrate and explain the capability of the instrument to resolve atomic defects on crystalline surfaces immersed in liquid. We also illustrate some of its applications to imaging the hydration structures on DNA or proteins. In the last section, we discuss some perspectives on emerging applications in materials science and molecular biology.
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Affiliation(s)
- Takeshi Fukuma
- Nano Life Science Institute (WPI-NanoLSI) , Kanazawa University , Kanazawa 920-1192 , Japan
| | - Ricardo Garcia
- Materials Science Factory , Instituto de Ciencia de Materiales de Madrid (ICMM) , 28049 Madrid , Spain
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Kilpatrick JI, Collins L, Weber SAL, Rodriguez BJ. Quantitative comparison of closed-loop and dual harmonic Kelvin probe force microscopy techniques. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:123708. [PMID: 30599628 DOI: 10.1063/1.5025432] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 11/26/2018] [Indexed: 06/09/2023]
Abstract
Kelvin probe force microscopy (KPFM) is a widely used technique to map surface potentials at the nanometer scale. In traditional KPFM, a feedback loop regulates the DC bias applied between a sharp conductive probe and a sample to nullify the electrostatic force (closed-loop operation). In comparison, open-loop techniques such as dual harmonic KPFM (DH-KPFM) are simpler to implement, are less sensitive to artefacts, offer the unique ability to probe voltage sensitive materials, and operate in liquid environments. Here, we directly compare the two techniques in terms of their bandwidth and sensitivity to instrumentation artefacts. Furthermore, we introduce a new correction for traditional KPFM termed "setpoint correction," which allows us to obtain agreement between open and closed-loop techniques within 1%. Quantitative validation of DH-KPFM may lead to a wider adoption of open-loop KPFM techniques by the scanning probe community.
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Affiliation(s)
- Jason I Kilpatrick
- Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | - Liam Collins
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | | | - Brian J Rodriguez
- Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
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Collins L, Ahmadi M, Qin J, Liu Y, Ovchinnikova OS, Hu B, Jesse S, Kalinin SV. Time resolved surface photovoltage measurements using a big data capture approach to KPFM. NANOTECHNOLOGY 2018; 29:445703. [PMID: 30084391 DOI: 10.1088/1361-6528/aad873] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Optoelectronic behavior in materials such as organic/inorganic hybrid perovskites depend on a complex interplay between fast (electronic) and slower (ionic) processes. These processes are thought to be influenced by structural inhomogeneities (e.g. interfaces and grain boundaries) bringing forward the necessity for development of techniques capable of correlating nanostructure and photo-transport behavior. While Kelvin probe force microscopy (KPFM) is ideally suited to map surface potentials on relevant length scales, it lacks sufficient temporal resolution to extract the meaningful system dynamics. Here, we develop a time resolved surface photovoltage (SPV) measurement based on full information capture of the photodetector stream during open loop KPFM operation. G-Mode, or G-KPFM allows quantification of SPV with microsecond temporal and nanoscale spatial resolution. Using this technique, we observe concurrent spatial and fast temporal variations in the SPV generated across a methylammonium lead bromide (MAPbBr3) thin film, a possible indicator relating microstructure with heterogenous photo-transport behavior. We further demonstrate the advantage of adopting big data analytics including unsupervised clustering methods to quickly discern spatial variability in the information rich SPV dataset. Beyond G-KPFM, such clustering methods will be useful for interpretation of the multidimensional datasets arising from the growing number of time resolved KPFM approaches now available.
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Affiliation(s)
- Liam Collins
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States of America. Institute for Functional Imaging of Materials, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States of America
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