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Guo J, Chen PK, Chang S. Molecular-Scale Electronics: From Individual Molecule Detection to the Application of Recognition Sensing. Anal Chem 2024; 96:9303-9316. [PMID: 38809941 DOI: 10.1021/acs.analchem.3c04656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2024]
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2
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Su Y, Wang T, Zhang F, Huang J, Zhu Z, Shah FU, Xu F, An R. Effect of Electrode Surface Chemistry on Ion Structuring of Imidazolium Ionic Liquids. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023. [PMID: 37289976 DOI: 10.1021/acs.langmuir.3c00710] [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
Surface chemistry plays a critical role in the ion structuring of ionic liquids (ILs) at the interfaces of electrodes and controls the overall energy storage performance of the system. Herein, we functionalized the gold (Au) colloid probe of an atomic force microscope with -COOH and -NH2 groups to explore the effect of different surface chemical properties on the ion structuring of an IL. Aided by colloid-probe atomic force microscopy (AFM), the ion structuring of an imidazolium IL, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6], abbreviated as BP hereafter), on the Au electrode surface and the ion response to the change in the surface chemistry are investigated. AFM morphologies, contact angles, and approaching force-distance curves of the BP IL on the functionalized Au surfaces exhibited that the IL forms a more obvious layering structure on the -COOH-terminated Au surface (Au-COOH), while it forms heterogeneous and aggregating droplets on the -NH2 surface (Au-NH2). The formed uniform and aggregation-free ion layers in the vicinity of the Au-COOH surface are due to the π-π+ stacking interaction between the delocalized π+ electrons from the imidazolium ring in the IL [BMIM]+ cation and the localized π electrons from the sp2 carbon on the -COOH group. The in situ observation of nano-friction and torsional resonance frequency at the IL-electrode interfaces further demonstrated the ion structuring of the IL at Au-COOH, which results in a more sensitive electrochemical response associated with a faster capacitive process.
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Affiliation(s)
- Yiqun Su
- School of Materials Science and Engineering/Herbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Tiantian Wang
- School of Materials Science and Engineering/Herbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Fan Zhang
- Department of Engineering and Design, School of Engineering and Information, University of Sussex, Brighton BN1 9RH, U.K
| | - Junsen Huang
- School of Materials Science and Engineering/Herbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Zhehang Zhu
- School of Materials Science and Engineering/Herbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Faiz Ullah Shah
- Chemistry of Interfaces, Luleå University of Technology, 97187 Luleå, Sweden
| | - Feng Xu
- School of Materials Science and Engineering/Herbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Rong An
- School of Materials Science and Engineering/Herbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology, Nanjing 210094, China
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Dief EM, Low PJ, Díez-Pérez I, Darwish N. Advances in single-molecule junctions as tools for chemical and biochemical analysis. Nat Chem 2023; 15:600-614. [PMID: 37106094 DOI: 10.1038/s41557-023-01178-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 03/02/2023] [Indexed: 04/29/2023]
Abstract
The development of miniaturized electronics has led to the design and construction of powerful experimental platforms capable of measuring electronic properties to the level of single molecules, along with new theoretical concepts to aid in the interpretation of the data. A new area of activity is now emerging concerned with repurposing the tools of molecular electronics for applications in chemical and biological analysis. Single-molecule junction techniques, such as the scanning tunnelling microscope break junction and related single-molecule circuit approaches have a remarkable capacity to transduce chemical information from individual molecules, sampled in real time, to electrical signals. In this Review, we discuss single-molecule junction approaches as emerging analytical tools for the chemical and biological sciences. We demonstrate how these analytical techniques are being extended to systems capable of probing chemical reaction mechanisms. We also examine how molecular junctions enable the detection of RNA, DNA, and traces of proteins in solution with limits of detection at the zeptomole level.
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Affiliation(s)
- Essam M Dief
- School of Molecular and Life Sciences, Curtin University, Bentley, Western Australia, Australia
| | - Paul J Low
- School of Molecular Sciences, University of Western Australia, Crawley, Western Australia, Australia
| | - Ismael Díez-Pérez
- Department of Chemistry, Faculty of Natural & Mathematical Sciences, King's College London, London, UK
| | - Nadim Darwish
- School of Molecular and Life Sciences, Curtin University, Bentley, Western Australia, Australia.
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Gardner Z, Rahpeima S, Sun Q, Zou J, Darwish N, Vimalanathan K, Raston CL. High Shear Thin Film Synthesis of Partially Oxidized Gallium and Indium Composite 2D Sheets. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023:e2300577. [PMID: 37010011 DOI: 10.1002/smll.202300577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 03/16/2023] [Indexed: 06/19/2023]
Abstract
Reducing resistance in silicon-based devices is important as they get miniaturized further. 2D materials offer an opportunity to increase conductivity whilst reducing size. A scalable, environmentally benign method is developed for preparing partially oxidized gallium/indium sheets down to 10 nm thick from a eutectic melt of the two metals. Exfoliation of the planar/corrugated oxide skin of the melt is achieved using the vortex fluidic device with a variation in composition across the sheets determined using Auger spectroscopy. From an application perspective, the oxidized gallium indium sheets reduce the contact resistance between metals such as platinum and silicon (Si) as a semiconductor. Current-voltage measurements between a platinum atomic force microscopy tip and a Si-H substrate show that the current switches from being a rectifier to a highly conducting ohmic contact. These characteristics offer new opportunities for controlling Si surface properties at the nanoscale and enable the integration of new materials with Si platforms.
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Affiliation(s)
- Zoe Gardner
- Flinders Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University, Adelaide, SA, 5001, Australia
| | - Soraya Rahpeima
- Flinders Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University, Adelaide, SA, 5001, Australia
- School of Molecular and Life Sciences, Curtin University, Bentley, WA, 6102, Australia
| | - Qiang Sun
- School of Mechanical and Mining Engineering and Centre for Microscopy and Microanalysis, University of Queensland, St Lucia, QLD, 4072, Australia
| | - Jin Zou
- School of Mechanical and Mining Engineering and Centre for Microscopy and Microanalysis, University of Queensland, St Lucia, QLD, 4072, Australia
| | - Nadim Darwish
- School of Molecular and Life Sciences, Curtin University, Bentley, WA, 6102, Australia
| | - Kasturi Vimalanathan
- Flinders Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University, Adelaide, SA, 5001, Australia
| | - Colin L Raston
- Flinders Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University, Adelaide, SA, 5001, Australia
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Porous silicon surface modification via a microwave-induced in situ cyclic disulfide (S-S) cleavage and Si-S bond formation. Colloids Surf B Biointerfaces 2023; 222:113055. [PMID: 36463610 DOI: 10.1016/j.colsurfb.2022.113055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 11/15/2022] [Accepted: 11/22/2022] [Indexed: 11/27/2022]
Abstract
Porous silicon (pSi) materials have gained a great deal of attention from various research fields, and their surface-functionalization is one of the critical points for their applications. In this study, a new surface modification method of Si-H-terminated pSi materials via microwave-induced Si-S bond formation is disclosed. The silicon hydride (Si-H) functionality on the pSi surface could react with the 5-membered cyclic disulfide (S-S) compound (DL-α-lipoic acid in this study) by microwave-induced in situ S-S bond cleavage and Si-S bond formation. This surface chemistry is fast responsive (<10 min) and more efficient than other methods such as vortexing, heating stirring, or ultrasonication. The reaction maintains the primary porous structure of pSi materials including pSi wafer, pSi rugate filer, and pSi nanoparticles. An additional functional group such as carboxylic acid is demonstrated to be readily introducible on the pSi surface for further applications. Overall, this study has successfully demonstrated the porous silicon surface modification via a microwave-induced in situ cyclic disulfide (S-S) cleavage and Si-S bond formation.
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Electro-polymerization rates of diazonium salts are dependent on the crystal orientation of the surface. J Colloid Interface Sci 2022; 626:985-994. [PMID: 35839679 DOI: 10.1016/j.jcis.2022.07.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 06/30/2022] [Accepted: 07/03/2022] [Indexed: 02/05/2023]
Abstract
Electro-polymerization of diazonium salts is widely used for modifying surfaces with thin organic films. Initially this method was primarily applied to carbon, then to metals, and more recently to semiconducting Si. Unlike on other surfaces, electrochemical reduction of diazonium salts on Si, which is one of the most industrially dominant material, is not well understood. Here, we report the electrochemical reduction of diazonium salts on a range of silicon electrodes of different crystal orientations (111, 211, 311, 411, and 100). We show that the kinetics of surface reaction and the reduction potential is Si crystal-facet dependent and is more favorable in the hierarchical order (111) > (211) > (311) > (411) > (100), a finding that offers control over the surface chemistry of diazonium salts on Si. The dependence of the surface reaction kinetics on the crystal orientation was found to be directly related to differences in the potential of zero charge (PZC) of each crystal orientation, which in turn controls the adsorption of the diazonium cations prior to reduction. Another consequence of the effect of PZC on the adsorption of diazonium cations, is that molecules terminated by distal diazonium moieties form a compact film in less time and requires less reduction potentials compared to that formed from diazonium molecules terminated by only one diazo moiety. In addition, at higher concentrations of diazonium cations, the mechanism of electrochemical polymerization on the surface becomes PZC-controlled adsorption-dominated inner-sphere electron transfer while at lower concentrations, diffusion-based outer-sphere electron transfer dominates. These findings help understanding the electro-polymerization reaction of diazonium salts on Si en route towards an integrated molecular and Si electronics technology.
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Li T, Peiris C, Dief EM, MacGregor M, Ciampi S, Darwish N. Effect of Electric Fields on Silicon-Based Monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:2986-2992. [PMID: 35220713 DOI: 10.1021/acs.langmuir.2c00015] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Electric fields can induce bond breaking and bond forming, catalyze chemical reactions on surfaces, and change the structure of self-assembled monolayers on electrode surfaces. Here, we study the effect of electric fields supplied either by an electrochemical potential or by conducting atomic force microscopy (C-AFM) on Si-based monolayers. We report that typical monolayers on silicon undergo partial desorption followed by the oxidation of the underneath silicon at +1.5 V vs Ag/AgCl. The monolayer loses 28% of its surface coverage and 55% of its electron transfer rate constant (ket) when +1.5 V electrochemical potential is applied on the Si surface for 10 min. Similarly, a bias voltage of +5 V applied by C-AFM induces complete desorption of the monolayer at specific sites accompanied by an average oxide growth of 2.6 nm when the duration of the bias applied is 8 min. Current-voltage plots progressively change from rectifying, typical of metal-semiconductor junctions, to insulating as the oxide grows. These results define the stability of Si-based organic monolayers toward electric fields and have implication in the design of silicon-based monolayers, molecular electronics devices, and on the interpretation of charge-transfer kinetics across them.
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Affiliation(s)
- Tiexin Li
- School of Molecular and Life Sciences, Curtin University, Bentley 6102, Western Australia, Australia
| | - Chandramalika Peiris
- School of Molecular and Life Sciences, Curtin University, Bentley 6102, Western Australia, Australia
| | - Essam M Dief
- School of Molecular and Life Sciences, Curtin University, Bentley 6102, Western Australia, Australia
| | - Melanie MacGregor
- Flinders Institute for Nanoscale Science & Technology, Flinders University, Bedford Park 5042, South Australia, Australia
| | - Simone Ciampi
- School of Molecular and Life Sciences, Curtin University, Bentley 6102, Western Australia, Australia
| | - Nadim Darwish
- School of Molecular and Life Sciences, Curtin University, Bentley 6102, Western Australia, Australia
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Electrochemical Detection of Dinitrobenzene on Silicon Electrodes: Toward Explosives Sensors. SURFACES 2022. [DOI: 10.3390/surfaces5010015] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Detection of explosives is vital for protection and criminal investigations, and developing novel explosives’ sensors stands at the forefront of the analytical and forensic chemistry endeavors. Due to the presence of terminal nitro groups that can be electrochemically reduced, nitroaromatic compounds (NACs) have been an analytical target for explosives’ electrochemical sensors. Various electrode materials have been used to detect NACs in solution, including glassy carbon electrodes (GCE), platinum (Pt), and gold (Au) electrodes, by tracking the reversible oxidation/reduction properties of the NACs on these electrodes. Here, we show that the reduction of dinitrobenzene (DNB) on oxide-free silicon (Si–H) electrodes is irreversible with two reduction peaks that disappear within the successive voltammetric scanning. AFM imaging showed the formation of a polymeric film whose thickness scales up with the DNB concentration. This suggest that Si–H surfaces can serve as DNB sensors and possibly other explosive substances. Cyclic voltammetry (CV) measurements showed that the limit of detection (LoD) on Si–H is one order of magnitude lower than that obtained on GCE. In addition, EIS measurements showed that the LoD of DNB on Si–H is two orders of magnitude lower than the CV method. The fact that a Si–H surface can be used to track the presence of DNB makes it a suitable surface to be implemented as a sensing platform. To translate this concept into a sensor, however, it would require engineering and fabrication prospect to be compatible with the current semiconductor technologies.
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Zhang S, Lyu X, Hurtado Torres C, Darwish N, Ciampi S. Non-Ideal Cyclic Voltammetry of Redox Monolayers on Silicon Electrodes: Peak Splitting is Caused by Heterogeneous Photocurrents and Not by Molecular Disorder. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:743-750. [PMID: 34989574 DOI: 10.1021/acs.langmuir.1c02723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Over the last three decades, research on redox-active monolayers has consolidated their importance as advanced functional material. For widespread monolayer systems, such as alkanethiols on gold, non-ideal multiple peaks in cyclic voltammetry are generally taken as indication of heterogeneous intermolecular interactions─namely, disorder in the monolayer. Our findings show that, contrary to metals, peak multiplicity of silicon photoelectrodes is not diagnostic of heterogeneous intermolecular microenvironments but is more likely caused by photocurrent being heterogeneous across the monolayer. This work is an important step toward understanding the cause of electrochemical non-idealities in semiconductor electrodes so that these can be prevented and the redox behavior of molecular monolayers, as photocatalytic systems, can be optimized.
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Affiliation(s)
- Song Zhang
- School of Molecular and Life Sciences, Curtin University, Bentley, Western Australia 6102, Australia
| | - Xin Lyu
- School of Molecular and Life Sciences, Curtin University, Bentley, Western Australia 6102, Australia
| | - Carlos Hurtado Torres
- School of Molecular and Life Sciences, Curtin University, Bentley, Western Australia 6102, Australia
| | - Nadim Darwish
- School of Molecular and Life Sciences, Curtin University, Bentley, Western Australia 6102, Australia
| | - Simone Ciampi
- School of Molecular and Life Sciences, Curtin University, Bentley, Western Australia 6102, Australia
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Zhu Y, Tan Z, Hong W. Simultaneous Electrical and Mechanical Characterization of Single-Molecule Junctions Using AFM-BJ Technique. ACS OMEGA 2021; 6:30873-30888. [PMID: 34841131 PMCID: PMC8613807 DOI: 10.1021/acsomega.1c04785] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 10/29/2021] [Indexed: 06/13/2023]
Abstract
The fabrication and characterization of single-molecule junctions provide a unique platform to study the physical phenomena of a single molecule, and the electrical characterization enables us to understand the electrical transport properties of a single molecule and guide the fabrication of molecular electronic devices. However, the electrical characterization of single-molecule junctions is sometimes insufficient to extract the structural information on single-molecule junctions, and an alternate method to address this problem is to characterize the mechanical properties of single-molecule junctions. Simultaneous measurement of mechanical and electrical properties can provide complementary information on single molecules to analyze the correlations of their electrical and mechanical properties in the evolution of single-molecule junctions. In this mini-review, we summarize the progress on the simultaneous characterizations of mechanical and electrical properties for single-molecule junctions, and discuss the challenges and perspectives of this research area.
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Rahpeima S, Dief EM, Ciampi S, Raston CL, Darwish N. Impermeable Graphene Oxide Protects Silicon from Oxidation. ACS APPLIED MATERIALS & INTERFACES 2021; 13:38799-38807. [PMID: 34342425 DOI: 10.1021/acsami.1c06495] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The presence of a natural silicon oxide (SiOx) layer over the surface of silicon (Si) has been a roadblock for hybrid semiconductor and organic electronics technology. The presence of an insulating oxide layer is a limiting operational factor, which blocks charge transfer and therefore electrical signals for a range of applications. Etching the SiOx layer by fluoride solutions leaves a reactive Si-H surface that is only stable for few hours before it starts reoxidizing under ambient conditions. Controlled passivation of silicon is also of key importance for improving Si photovoltaic efficiency. Here, we show that a thin layer of graphene oxide (GOx) prevents Si surfaces from oxidation under ambient conditions for more than 30 days. In addition, we show that the protective GOx layer can be modified with molecules enabling a functional surface that allows for further chemical conjugation or connections with upper electrodes, while preserving the underneath Si in a nonoxidized form. The GOx layer can be switched electrochemically to reduced graphene oxide, allowing the development of a dynamic material for molecular electronics technologies. These findings demonstrate that 2D materials are alternatives to organic self-assembled monolayers that are typically used to protect and tune the properties of Si and open a realm of possibilities that combine Si and 2D materials technologies.
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Affiliation(s)
- Soraya Rahpeima
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Perth, Western Australia 6102, Australia
- Flinders Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University, Bedford Park, South Australia 5042, Australia
| | - Essam M Dief
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Perth, Western Australia 6102, Australia
| | - Simone Ciampi
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Perth, Western Australia 6102, Australia
| | - Colin L Raston
- Flinders Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University, Bedford Park, South Australia 5042, Australia
| | - Nadim Darwish
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Perth, Western Australia 6102, Australia
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