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Zhao K, Janulaitis N, Rumptz JR, Campbell CT. Size-Dependent Energy and Adhesion of Pd Nanoparticles on Graphene on Ni(111) by Pd Vapor Adsorption Calorimetry. ACS Catal 2023. [DOI: 10.1021/acscatal.2c06343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Affiliation(s)
- Kun Zhao
- Department of Chemistry, University of Washington, Seattle, Washington98105-1700, United States
- Advanced Institute for Materials Research, Tohoku University, Sendai, Miyagi980-8577, Japan
| | - Nida Janulaitis
- Department of Chemical Engineering, University of Washington, Seattle, Washington98105-1700, United States
| | - John R. Rumptz
- Department of Chemical Engineering, University of Washington, Seattle, Washington98105-1700, United States
| | - Charles T. Campbell
- Department of Chemistry, University of Washington, Seattle, Washington98105-1700, United States
- Department of Chemical Engineering, University of Washington, Seattle, Washington98105-1700, United States
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Besenbacher F, Lauritsen J. Applications of high-resolution scanning probe microscopy in hydroprocessing catalysis studies. J Catal 2021. [DOI: 10.1016/j.jcat.2021.02.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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El Barraj A, Chatelain B, Barth C. High-temperature oxidation and reduction of the inverse ceria/Cu(111) catalyst characterized by LEED, STM, nc-AFM and KPFM. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 34:014001. [PMID: 34525469 DOI: 10.1088/1361-648x/ac26f9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 09/15/2021] [Indexed: 06/13/2023]
Abstract
The inverse catalyst 'cerium oxide (ceria) on copper' has attracted much interest in recent time because of its promising catalytic activity in the water-gas-shift reaction and the hydrogenation of CO2. For such reactions it is important to study the redox behaviour of this system, in particular with respect to the reduction by H2. Here, we investigate the high-temperature O2oxidation and H2reduction of ceria nanoparticles (NPs) and a Cu(111) support by low energy electron diffraction (LEED), scanning tunnelling microscopy (STM), non-contact atomic force microscopy (nc-AFM) and Kelvin probe force microscopy (KPFM). After oxidation at 550 °C, the ceria NPs and the Cu(111) support are fully oxidized, with the copper oxide exhibiting a new oxide structure as verified by LEED and STM. We show that a high H2dosage in the kilo Langmuir range is needed to entirely reduce the copper support at 550 °C. A work function (WF) difference of △ϕrCeria/Cu-Cu≈ -0.6 eV between the ceria NPs and the metallic Cu(111) support is measured, with the Cu(111) surface showing no signatures of separated and confined surface regions composed by an alloy of Cu and Ce. After oxidation, the WF difference is close to zero (△ϕCeria/Cu-Cu≈ -0.1…0 eV), which probably is due to a WF change of both, ceria and copper.
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Toca‐Herrera JL. Atomic Force Microscopy Meets Biophysics, Bioengineering, Chemistry, and Materials Science. CHEMSUSCHEM 2019; 12:603-611. [PMID: 30556380 PMCID: PMC6492253 DOI: 10.1002/cssc.201802383] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 12/12/2018] [Indexed: 05/12/2023]
Abstract
Briefly, herein the use of atomic force microscopy (AFM) in the characterization of molecules and (bioengineered) materials related to chemistry, materials science, chemical engineering, and environmental science and biotechnology is reviewed. First, the basic operations of standard AFM, Kelvin probe force microscopy, electrochemical AFM, and tip-enhanced Raman microscopy are described. Second, several applications of these techniques to the characterization of single molecules, polymers, biological membranes, films, cells, hydrogels, catalytic processes, and semiconductors are provided and discussed.
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Affiliation(s)
- José L. Toca‐Herrera
- Institute for Biophysics, Department of NanobiotechnologyUniversity of Natural Resources and Life Sciences Vienna (BOKU)Muthgasse 111190ViennaAustria
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Garrett JL, Leite MS, Munday JN. Multiscale Functional Imaging of Interfaces through Atomic Force Microscopy Using Harmonic Mixing. ACS APPLIED MATERIALS & INTERFACES 2018; 10:28850-28859. [PMID: 30113805 DOI: 10.1021/acsami.8b08097] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The spatial resolution of atomic force microscopy (AFM) needed to resolve material interfaces is limited by the tip-sample separation ( d) dependence of the force used to record an image. Here, we present a new multiscale functional imaging technique that allows for in situ tunable spatial resolution, which can be applied to a wide range of inhomogeneous materials, devices, and interfaces. Our approach uses a multifrequency method to generate a signal whose d-dependence is controlled by mixing harmonics of the cantilever's oscillation with a modulated force. The spatial resolution of the resulting image is determined by the signal's d-dependence. Our measurements using harmonic mixing (HM) show that we can change the d-dependence of a force signal to improve spatial resolution by up to a factor of two compared to conventional methods. We demonstrate the technique with both Kelvin probe force microscopy (KPFM) and bimodal AFM to show its generality. Bimodal AFM with harmonic mixing actuation separates conservative from dissipative forces and is used to identify the regions of adhesive residue on exfoliated graphene. Our electrostatic measurements with open-loop KPFM demonstrate that multiple force modulations may be applied at once. Further, this method can be applied to any tip-sample force that can be modulated, for example, electrostatic, magnetic, and photoinduced forces, showing its universality. Because HM enables in situ switching between high sensitivity and high spatial resolution with any periodic driving force, we foresee this technique as a critical advancement for multiscale functional imaging.
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Fernández Garrillo PA, Grévin B, Chevalier N, Borowik Ł. Calibrated work function mapping by Kelvin probe force microscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:043702. [PMID: 29716375 DOI: 10.1063/1.5007619] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We propose and demonstrate the implementation of an alternative work function tip calibration procedure for Kelvin probe force microscopy under ultrahigh vacuum, using monocrystalline metallic materials with known crystallographic orientation as reference samples, instead of the often used highly oriented pyrolytic graphite calibration sample. The implementation of this protocol allows the acquisition of absolute and reproducible work function values, with an improved uncertainty with respect to unprepared highly oriented pyrolytic graphite-based protocols. The developed protocol allows the local investigation of absolute work function values over nanostructured samples and can be implemented in electronic structures and devices characterization as demonstrated over a nanostructured semiconductor sample presenting Al0.7Ga0.3As and GaAs layers with variable thickness. Additionally, using our protocol we find that the work function of annealed highly oriented pyrolytic graphite is equal to 4.6 ± 0.03 eV.
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Affiliation(s)
| | - Benjamin Grévin
- Univ. Grenoble Alpes, CNRS, CEA, INAC, SYMNES, 38000 Grenoble, France
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Arima E, Wen HF, Naitoh Y, Li YJ, Sugawara Y. KPFM/AFM imaging on TiO 2(110) surface in O 2 gas. NANOTECHNOLOGY 2018; 29:105504. [PMID: 29313525 DOI: 10.1088/1361-6528/aaa62c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We have carried out high-speed imaging of the topography and local contact potential difference (LCPD) on rutile TiO2(110) in O2 gas by atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM). We succeeded in KPFM/AFM imaging with atomic resolution at 1 frame min-1 and observed the adsorbate on a hydroxylated TiO2(110) surface. The observed adsorbate is considered to be oxygen adatoms (Oa), hydroperoxyls (HO2), or terminal hydroxyls (OHt). After adsorption, changes in the topography and the LCPD of the adsorbate were observed. This phenomenon is thought to be caused by the charge transfer of the adsorbate. This technique has the potential to observe catalytic behavior with atomic resolution.
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Affiliation(s)
- Eiji Arima
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita 565-0871, Japan
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Yurtsever A, Fernández-Torre D, Onoda J, Abe M, Morita S, Sugimoto Y, Pérez R. The local electronic properties of individual Pt atoms adsorbed on TiO 2(110) studied by Kelvin probe force microscopy and first-principles simulations. NANOSCALE 2017; 9:5812-5821. [PMID: 28225121 DOI: 10.1039/c6nr07550a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Noble metal nanostructures dispersed on metal oxide surfaces have applications in diverse areas such as catalysis, chemical sensing, and energy harvesting. Their reactivity, chemical selectivity, stability, and light absorption properties are controlled by the interactions at the metal/oxide interface. Single-atom metal adsorbates on the rutile TiO2(110)-(1 × 1) surface have become a paradigmatic model to characterize those interactions and to understand the unique electronic properties of these supported nanostructures. We combine Kelvin probe force microscopy (KPFM) experiments and density functional theory (DFT) calculations to investigate the atomic-scale variations in the contact potential difference of individual Pt atoms adsorbed on a hydroxylated (h) TiO2(110)-(1 × 1) surface. Our experiments show a significant drop in the local contact potential difference (LCPD) over Pt atoms with respect to the TiO2 surface, supporting the presence of an electron transfer from the Pt adsorbates to the substrate. We have identified two characteristic regimes by LCPD spectroscopy. At far tip-sample distances, LCPD values show a weak distance dependence and can be attributed to the intrinsic charge transfer from Pt to the oxide support. Beyond the onset of short-range chemical interactions, LCPD values exhibit a strong distance dependence that we ascribe to the local structural and charge rearrangements induced by the tip-sample interaction. These findings also apply to other electropositive adsorbates such as potassium and the hydrogen atoms forming the OH groups that are present on the h-TiO2(110) surface, promoting KPFM as a suitable tool for the understanding of electron transfer in catalytically active materials.
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Affiliation(s)
- Ayhan Yurtsever
- Graduate School of Engineering, Osaka University, 2-1 Yamada Oka, Suita, Osaka 565-0871, Japan.
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Altman EI, Baykara MZ, Schwarz UD. Noncontact Atomic Force Microscopy: An Emerging Tool for Fundamental Catalysis Research. Acc Chem Res 2015; 48:2640-8. [PMID: 26301490 DOI: 10.1021/acs.accounts.5b00166] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Although atomic force microscopy (AFM) was rapidly adopted as a routine surface imaging apparatus after its introduction in 1986, it has not been widely used in catalysis research. The reason is that common AFM operating modes do not provide the atomic resolution required to follow catalytic processes; rather the more complex noncontact (NC) mode is needed. Thus, scanning tunneling microscopy has been the principal tool for atomic scale catalysis research. In this Account, recent developments in NC-AFM will be presented that offer significant advantages for gaining a complete atomic level view of catalysis. The main advantage of NC-AFM is that the image contrast is due to the very short-range chemical forces that are of interest in catalysis. This motivated our development of 3D-AFM, a method that yields quantitative atomic resolution images of the potential energy surfaces that govern how molecules approach, stick, diffuse, and rebound from surfaces. A variation of 3D-AFM allows the determination of forces required to push atoms and molecules on surfaces, from which diffusion barriers and variations in adsorption strength may be obtained. Pushing molecules towards each other provides access to intermolecular interaction between reaction partners. Following reaction, NC-AFM with CO-terminated tips yields textbook images of intramolecular structure that can be used to identify reaction intermediates and products. Because NC-AFM and STM contrast mechanisms are distinct, combining the two methods can produce unique insight. It is demonstrated for surface-oxidized Cu(100) that simultaneous 3D-AFM/STM yields resolution of both the Cu and O atoms. Moreover, atomic defects in the Cu sublattice lead to variations in the reactivity of the neighboring O atoms. It is shown that NC-AFM also allows a straightforward imaging of work function variations which has been used to identify defect charge states on catalytic surfaces and to map charge transfer within an individual molecule. These advances highlight the potential for NC-AFM-based methods to become the cornerstone upon which a quantitative atomic scale view of each step of a catalytic process may be gained. Realizing this potential will rely on two breakthroughs: (1) development of robust methods for tip functionalization and (2) simplification of NC-AFM instrumentation and control schemes. Quartz force sensors may offer paths forward in both cases. They allow any material with an atomic asperity to be used as a tip, opening the door to a wide range of surface functionalization chemistry. In addition, they do not suffer from the instabilities that motivated the initial adoption of complex control strategies that are still used today.
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Affiliation(s)
| | - Mehmet Z. Baykara
- Department
of Mechanical Engineering and UNAM − Institute of Materials
Science and Nanotechnology, Bilkent University, Ankara 06800, Turkey
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