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Huffman BL, Bredar ARC, Dempsey JL. Origins of non-ideal behaviour in voltammetric analysis of redox-active monolayers. Nat Rev Chem 2024:10.1038/s41570-024-00629-8. [PMID: 39039210 DOI: 10.1038/s41570-024-00629-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/06/2024] [Indexed: 07/24/2024]
Abstract
Disorder in redox-active monolayers convolutes electrochemical characterization. This disorder can come from pinhole defects, loose packing, heterogeneous distribution of redox-active headgroups, and lateral interactions between immobilized redox-active molecules. Identifying the source of non-ideal behaviour in cyclic voltammograms can be challenging as different types of disorder often cause similar non-ideal cyclic voltammetry behaviour such as peak broadening, large peak-to-peak separation, peak asymmetry and multiple peaks for single redox processes. This Review provides an overview of ideal voltammetric behaviour for redox-active monolayers, common manifestations of disorder on voltammetric responses, common experimental parameters that can be varied to interrogate sources of disorder, and finally, examples of different types of disorder and how they impact electrochemical responses.
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Affiliation(s)
- Brittany L Huffman
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Alexandria R C Bredar
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Jillian L Dempsey
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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Parambath JBM, Vijai Anand K, Alawadhi H, Mohamed AA. Flexible Copper Films Modification via Spontaneous Reduction of Aryldiazonium Gold Salts: Unraveling Surface Properties and Energy Profile. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:9797-9808. [PMID: 38669636 DOI: 10.1021/acs.langmuir.4c00977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/28/2024]
Abstract
In this study, we report the modification of flexible copper films via the spontaneous reduction of aryldiazonium gold salts [X-4-C6H4N≡N]AuCl4 (X═COOH, NO2). The electroless modification involves dipping of flexible copper films in the aryldiazonium gold solutions for a few seconds, under ambient conditions, followed by a washing step with deionized water to obtain a mechanically robust gold-aryl coating. The chemical composition, morphology, electronic structure, and optical properties of the gold-aryl layer and the flexibility of the modified copper films are supported by the results from X-ray photoelectron spectroscopy (XPS), electrochemistry, contact angle, scanning electron microscopy (SEM), and ultraviolet photoelectron spectroscopy (UPS). XPS surface analysis showed metallic gold in addition to C-C, C-O/C-N, and C═O functional groups from the grafted aryls. Cu 2p showed metallic copper as a major component and a small amount of Cu(II) ions. Wettability studies showed that Au-COOH@Cu increased the contact angle of the bare copper films from 68.0 ± 0.7° to 82.0° ± 0.7°, while Au-NO2@Cu increased the contact angle to 134.0° ± 0.3°. UPS energy profile analysis of [HOOC-4-C6H4N≡N]AuCl4 (valence band maximum = 1.91 eV) exhibited greater reducibility than [O2N-4-C6H4N≡N]AuCl4 (valence band maximum = 2.91 eV). The lower ionization potential of [HOOC-4-C6H4N≡N]AuCl4 (IP = 4.33 eV) enhanced the reactivity upon copper film contact, potentially inducing efficient energy level alignment, compared with [O2N-4-C6H4N≡N]AuCl4 (IP = 5.62 eV). UPS results were further supported by electrochemistry investigation which revealed that [HOOC-4-C6H4N≡N]AuCl4 is easily reducible compared with [O2N-4-C6H4N≡N]AuCl4. The findings presented here hold significant implications for developing flexible copper films and pave the way for future advancements in electronic material modification for industrial applications.
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Affiliation(s)
- Javad B M Parambath
- Center for Advanced Materials Research, Research Institute of Sciences and Engineering, University of Sharjah, Sharjah 27272, United Arab Emirates
- Department of Physics, Sathyabama Institute of Science & Technology, Chennai 600 119, Tamil Nadu, India
- Department of Chemistry, Sathyabama Institute of Science & Technology, Chennai 600 119, Tamil Nadu, India
| | - Kabali Vijai Anand
- Department of Physics, Sathyabama Institute of Science & Technology, Chennai 600 119, Tamil Nadu, India
| | - Hussain Alawadhi
- Center for Advanced Materials Research, Research Institute of Sciences and Engineering, University of Sharjah, Sharjah 27272, United Arab Emirates
- Department of Applied Physics & Astronomy, College of Sciences, University of Sharjah, Sharjah 27272, United Arab Emirates
| | - Ahmed A Mohamed
- Center for Advanced Materials Research, Research Institute of Sciences and Engineering, University of Sharjah, Sharjah 27272, United Arab Emirates
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3
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Huffman BL, Bein GP, Atallah H, Donley CL, Alameh RT, Wheeler JP, Durand N, Harvey AK, Kessinger MC, Chen CY, Fakhraai Z, Atkin JM, Castellano FN, Dempsey JL. Surface Immobilization of a Re(I) Tricarbonyl Phenanthroline Complex to Si(111) through Sonochemical Hydrosilylation. ACS APPLIED MATERIALS & INTERFACES 2023; 15:984-996. [PMID: 36548441 DOI: 10.1021/acsami.2c17078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
A sonochemical-based hydrosilylation method was employed to covalently attach a rhenium tricarbonyl phenanthroline complex to silicon(111). fac-Re(5-(p-Styrene)-phen)(CO)3Cl (5-(p-styrene)-phen = 5-(4-vinylphenyl)-1,10-phenanthroline) was reacted with hydrogen-terminated silicon(111) in an ultrasonic bath to generate a hybrid photoelectrode. Subsequent reaction with 1-hexene enabled functionalization of remaining atop Si sites. Attenuated total reflectance-Fourier transform infrared spectroscopy confirms attachment of the organometallic complex to silicon without degradation of the organometallic core, supporting hydrosilylation as a strategy for installing coordination complexes that retain their molecular integrity. Detection of Re(I) and nitrogen by X-ray photoelectron spectroscopy (XPS) further support immobilization of fac-Re(5-(p-styrene)-phen)(CO)3Cl. Cyclic voltammetry and electrochemical impedance spectroscopy under white light illumination indicate that fac-Re(5-(p-styrene)-phen)(CO)3Cl undergoes two electron reductions. Mott-Schottky analysis indicates that the flat band potential is 239 mV more positive for p-Si(111) co-functionalized with both fac-Re(5-(p-styrene)-phen)(CO)3Cl and 1-hexene than when functionalized with 1-hexene alone. XPS, ultraviolet photoelectron spectroscopy, and Mott-Schottky analysis show that functionalization with fac-Re(5-(p-styrene)-phen)(CO)3Cl and 1-hexene introduces a negative interfacial dipole, facilitating reductive photoelectrochemistry.
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Affiliation(s)
- Brittany L Huffman
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, United States
| | - Gabriella P Bein
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, United States
| | - Hala Atallah
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Carrie L Donley
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, United States
| | - Reem T Alameh
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Jonathan P Wheeler
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Nicolas Durand
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Alexis K Harvey
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, United States
| | - Matthew C Kessinger
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, United States
| | - Cindy Y Chen
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Zahra Fakhraai
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Joanna M Atkin
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, United States
| | - Felix N Castellano
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Jillian L Dempsey
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, United States
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Lyu X, Ciampi S. Improving the performances of direct-current triboelectric nanogenerators with surface chemistry. Curr Opin Colloid Interface Sci 2022. [DOI: 10.1016/j.cocis.2022.101627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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5
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Beine AK, Ludovicy J, Chai J, Hofmann JP, Glotzbach C, Hausoul PJC, Palkovits R. Ru on N‐doped carbon for the selective hydrogenolysis of sugars and sugar alcohols. ChemCatChem 2022. [DOI: 10.1002/cctc.202101908] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Anna Katharina Beine
- RWTH Aachen University: Rheinisch-Westfalische Technische Hochschule Aachen ITMC GERMANY
| | - Jil Ludovicy
- RWTH Aachen University: Rheinisch-Westfalische Technische Hochschule Aachen ITMC GERMANY
| | - Jiachun Chai
- TU/e: Technische Universiteit Eindhoven Chemical Engineering and Chemistry NETHERLANDS
| | - Jan P. Hofmann
- TU Darmstadt: Technische Universitat Darmstadt Materials and Earth Science GERMANY
| | | | - Peter J. C. Hausoul
- RWTH Aachen University: Rheinisch-Westfalische Technische Hochschule Aachen ITMC GERMANY
| | - Regina Palkovits
- RWTH Aachen University Institut für Technische und Makromolekulare Chemie Worringerweg 1 52074 Aachen GERMANY
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6
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Thermal Grafting of Benzaldehyde for Preparing Catalytically Active Silicon Surface Evaluated by Electrical Methods. Top Catal 2022. [DOI: 10.1007/s11244-022-01582-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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7
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McNeill AR, Martinez-Gazoni R, Reeves RJ, Allen MW, Downard AJ. Electroreduction of Aryldiazonium Ion at the Polar and Non-Polar Faces of ZnO: Characterisation of the Grafted Films and Their Influence on Near-Surface Band Bending. Chemphyschem 2021; 22:1344-1351. [PMID: 33942472 DOI: 10.1002/cphc.202100240] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 05/02/2021] [Indexed: 01/02/2023]
Abstract
ZnO is a strong candidate for transparent electronic devices due to its wide band gap and earth-abundance, yet its practical use is limited by its surface metallicity arising from a surface electron accumulation layer (SEAL). The SEAL forms by hydroxylation of the surface under normal atmospheric conditions, and is present at all crystal faces of ZnO, although with differing hydroxyl structures. Multilayer aryl films grafted from aryldiazonium salts have previously been shown to decrease the downward bending at O-polar ZnO thin films, with Zn-O-C bonds anchoring the aryl films to the substrate. Herein we show that the Zn-polar (0001), O-polar (000 1 ‾ ), and non-polar m-plane (10 1 ‾ 0) faces of ZnO single crystals, can also be successfully electrografted with nitrophenyl (NP) films. In all cases, X-ray photoelectron spectroscopy (XPS) measurements reveal that the downward surface band bending decreases after modification. XPS provides strong evidence for Zn-O-C bonding at each face. Electrochemical reduction of NP films on O-polar ZnO single crystals converts the film to a mainly aminophenyl layer, although with negligible further change in band bending. This contrasts with the large upward shifts in band bending caused by X-ray induced reduction.
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Affiliation(s)
- Alexandra R McNeill
- School of Physical and Chemical Sciences, University of Canterbury, Private Bag 4800, 4180, Christchurch, New Zealand.,Syft Technologies, 3 Craft Place, 8024, Christchurch, New Zealand
| | - Rodrigo Martinez-Gazoni
- School of Physical and Chemical Sciences, University of Canterbury, Private Bag 4800, 4180, Christchurch, New Zealand
| | - Roger J Reeves
- School of Physical and Chemical Sciences, University of Canterbury, Private Bag 4800, 4180, Christchurch, New Zealand
| | - Martin W Allen
- Department of Electrical and Computer Engineering, University of Canterbury, Private Bag 4800, 4180, Christchurch, New Zealand
| | - Alison J Downard
- School of Physical and Chemical Sciences, University of Canterbury, Private Bag 4800, 4180, Christchurch, New Zealand
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Derr JB, Tamayo J, Espinoza EM, Clark JA, Vullev VI. Dipole-induced effects on charge transfer and charge transport. Why do molecular electrets matter? CAN J CHEM 2018. [DOI: 10.1139/cjc-2017-0389] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Charge transfer (CT) and charge transport (CTr) are at the core of life-sustaining biological processes and of processes that govern the performance of electronic and energy-conversion devices. Electric fields are invaluable for guiding charge movement. Therefore, as electrostatic analogues of magnets, electrets have unexplored potential for generating local electric fields for accelerating desired CT processes and suppressing undesired ones. The notion about dipole-generated local fields affecting CT has evolved since the middle of the 20th century. In the 1990s, the first reports demonstrating the dipole effects on the kinetics of long-range electron transfer appeared. Concurrently, the development of molecular-level designs of electric junctions has led the exploration of dipole effects on CTr. Biomimetic molecular electrets such as polypeptide helices are often the dipole sources in CT systems. Conversely, surface-charge electrets and self-assembled monolayers of small polar conjugates are the preferred sources for modifying interfacial electric fields for controlling CTr. The multifaceted complexity of such effects on CT and CTr testifies for the challenges and the wealth of this field that still remains largely unexplored. This review outlines the basic concepts about dipole effects on CT and CTr, discusses their evolution, and provides accounts for their future developments and impacts.
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Affiliation(s)
- James B. Derr
- Department of Biochemistry, University of California, Riverside, CA 92521, USA
| | - Jesse Tamayo
- Department of Chemistry, University of California, Riverside, CA 92521, USA
| | - Eli M. Espinoza
- Department of Chemistry, University of California, Riverside, CA 92521, USA
| | - John A. Clark
- Department of Bioengineering, University of California, Riverside, CA 92521, USA
| | - Valentine I. Vullev
- Department of Biochemistry, University of California, Riverside, CA 92521, USA
- Department of Chemistry, University of California, Riverside, CA 92521, USA
- Department of Bioengineering, University of California, Riverside, CA 92521, USA
- Materials Science and Engineering Program, University of California, Riverside, CA 92521, USA
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Espinoza EM, Larsen-Clinton JM, Krzeszewski M, Darabedian N, Gryko DT, Vullev VI. Bioinspired approach toward molecular electrets: synthetic proteome for materials. PURE APPL CHEM 2017. [DOI: 10.1515/pac-2017-0309] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
AbstractMolecular-level control of charge transfer (CT) is essential for both, organic electronics and solar-energy conversion, as well as for a wide range of biological processes. This article provides an overview of the utility of local electric fields originating from molecular dipoles for directing CT processes. Systems with ordered dipoles, i.e. molecular electrets, are the centerpiece of the discussion. The conceptual evolution from biomimicry to biomimesis, and then to biological inspiration, paves the roads leading from testing the understanding of how natural living systems function to implementing these lessons into optimal paradigms for specific applications. This progression of the evolving structure-function relationships allows for the development of bioinspired electrets composed of non-native aromatic amino acids. A set of such non-native residues that are electron-rich can be viewed as a synthetic proteome for hole-transfer electrets. Detailed considerations of the electronic structure of an individual residue prove of key importance for designating the points for optimal injection of holes (i.e. extraction of electrons) in electret oligomers. This multifaceted bioinspired approach for the design of CT molecular systems provides unexplored paradigms for electronic and energy science and engineering.
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Affiliation(s)
- Eli M. Espinoza
- Department of Chemistry, University of California, Riverside, CA 92521, USA
| | | | - Maciej Krzeszewski
- Department of Bioengineering, University of California, Riverside, CA 92521, USA
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44-52, 01-224 Warsaw, Poland
| | - Narek Darabedian
- Department of Bioengineering, University of California, Riverside, CA 92521, USA
| | - Daniel T. Gryko
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44-52, 01-224 Warsaw, Poland
| | - Valentine I. Vullev
- Department of Chemistry, University of California, Riverside, CA 92521, USA
- Department of Bioengineering, University of California, Riverside, CA 92521, USA
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10
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Vilan A, Cahen D. Chemical Modification of Semiconductor Surfaces for Molecular Electronics. Chem Rev 2017; 117:4624-4666. [PMID: 28230354 DOI: 10.1021/acs.chemrev.6b00746] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Inserting molecular monolayers within metal/semiconductor interfaces provides one of the most powerful expressions of how minute chemical modifications can affect electronic devices. This topic also has direct importance for technology as it can help improve the efficiency of a variety of electronic devices such as solar cells, LEDs, sensors, and possible future bioelectronic ones. The review covers the main aspects of using chemistry to control the various aspects of interface electrostatics, such as passivation of interface states and alignment of energy levels by intrinsic molecular polarization, as well as charge rearrangement with the adjacent metal and semiconducting contacts. One of the greatest merits of molecular monolayers is their capability to form excellent thin dielectrics, yielding rich and unique current-voltage characteristics for transport across metal/molecular monolayer/semiconductor interfaces. We explain the interplay between the monolayer as tunneling barrier on the one hand, and the electrostatic barrier within the semiconductor, due to its space-charge region, on the other hand, as well as how different monolayer chemistries control each of these barriers. Practical tools to experimentally identify these two barriers and distinguish between them are given, followed by a short look to the future. This review is accompanied by another one, concerning the formation of large-area molecular junctions and charge transport that is dominated solely by molecules.
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Affiliation(s)
- Ayelet Vilan
- Department of Materials & Interfaces, Weizmann Institute of Science , Rehovot, Israel 76100
| | - David Cahen
- Department of Materials & Interfaces, Weizmann Institute of Science , Rehovot, Israel 76100
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Vilan A, Aswal D, Cahen D. Large-Area, Ensemble Molecular Electronics: Motivation and Challenges. Chem Rev 2017; 117:4248-4286. [DOI: 10.1021/acs.chemrev.6b00595] [Citation(s) in RCA: 243] [Impact Index Per Article: 34.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Ayelet Vilan
- Department
of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel
| | | | - David Cahen
- Department
of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel
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12
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Lee H, Kim Y, Kim MJ, Kim KJ, Kim BK. Comparative Study of the Catalytic Activities of Three Distinct Carbonaceous Materials through Photocatalytic Oxidation, CO Conversion, Dye Degradation, and Electrochemical Measurements. Sci Rep 2016; 6:35500. [PMID: 27762289 PMCID: PMC5071860 DOI: 10.1038/srep35500] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 09/30/2016] [Indexed: 11/24/2022] Open
Abstract
In order to compare the catalytic activities of reduced graphene oxide (rGO), graphene oxide (GO), and graphene, we conducted oxidation of 2-aminothiophenol (2-ATP) and reduction of nitrobenzene (NB) in their presence by using high-resolution photoemission spectroscopy (HRPES). In addition, we determined conversion rates of CO to CO2 in the presence of these catalysts by performing a residual gas analyzer (RGA) under a UHV condition, Orange II and methylene blue degradations UV-vis spectrophotometry, and electrochemistry (EC) measurements in an aqueous solution, as well as by obtaining cyclic voltammograms and determining the change of the condition of electrodes before and after the oxidation of 2-ATP. We found that we can successively fabricate GO (oxidation) and graphene (reduction) from rGO by controlling the oxidation or reduction procedure time and then clearly comparing the critical properties among them as we perform various oxidation and reduction activities.
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Affiliation(s)
- Hangil Lee
- Department of Chemistry, Sookmyung Women's University, Seoul 140-742, Republic of Korea
| | - Yeonwoo Kim
- Molecular-Level Interfaces Research Center, Department of Chemistry, KAIST, Daejeon 305-701, Republic of Korea
| | - Min Ji Kim
- Department of Chemistry, Sookmyung Women's University, Seoul 140-742, Republic of Korea
| | - Ki-Jeong Kim
- Beamline Research Division, Pohang Accelerator Laboratory (PAL), Pohang 790-784, Republic of Korea
| | - Byung-Kwon Kim
- Department of Chemistry, Sookmyung Women's University, Seoul 140-742, Republic of Korea
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Small LJ, Wheeler DR, Spoerke ED. Nanoporous membranes with electrochemically switchable, chemically stabilized ionic selectivity. NANOSCALE 2015; 7:16909-20. [PMID: 26411335 DOI: 10.1039/c5nr02939b] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Nanopore size, shape, and surface charge all play important roles in regulating ionic transport through nanoporous membranes. The ability to control these parameters in situ provides a means to create ion transport systems tunable in real time. Here, we present a new strategy to address this challenge, utilizing three unique electrochemically switchable chemistries to manipulate the terminal functional group and control the resulting surface charge throughout ensembles of gold plated nanopores in ion-tracked polycarbonate membranes 3 cm(2) in area. We demonstrate the diazonium mediated surface functionalization with (1) nitrophenyl chemistry, (2) quinone chemistry, and (3) previously unreported trimethyl lock chemistry. Unlike other works, these chemistries are chemically stabilized, eliminating the need for a continuously applied gate voltage to maintain a given state and retain ionic selectivity. The effect of surface functionalization and nanopore geometry on selective ion transport through these functionalized membranes is characterized in aqueous solutions of sodium chloride at pH = 5.7. The nitrophenyl surface allows for ionic selectivity to be irreversibly switched in situ from cation-selective to anion-selective upon reduction to an aminophenyl surface. The quinone-terminated surface enables reversible changes between no ionic selectivity and a slight cationic selectivity. Alternatively, the trimethyl lock allows ionic selectivity to be reversibly switched by up to a factor of 8, approaching ideal selectivity, as a carboxylic acid group is electrochemically revealed or hidden. By varying the pore shape from cylindrical to conical, it is demonstrated that a controllable directionality can be imparted to the ionic selectivity. Combining control of nanopore geometry with stable, switchable chemistries facilitates superior control of molecular transport across the membrane, enabling tunable ion transport systems.
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Affiliation(s)
- Leo J Small
- Sandia National Laboratories, PO Box 5800, MS 1411, Albuquerque, NM, USA 87185.
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Hybrid Organic/Inorganic Band-Edge Modulation of p-Si(111) Photoelectrodes: Effects of R, Metal Oxide, and Pt on H2 Generation. J Am Chem Soc 2015; 137:3173-6. [DOI: 10.1021/ja5126287] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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15
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Small LJ, Hibbs MR, Wheeler DR. Spontaneous aryldiazonium film formation on 440C stainless steel in nonaqueous environments. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:14212-14218. [PMID: 25379686 DOI: 10.1021/la503630f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The ability of three aryldiazonium salts to spontaneously assemble onto the surface of type 440C stainless steel is investigated in acetonitrile (ACN) and the model hydraulic fluids tributyl phosphate (TBP) and hexamethyldisiloxane (HMDS). Competition between native oxide formation and organic film growth at different diazonium salt concentrations is monitored by electrochemical impedance spectroscopy. At 1 mM diazonium salt, 70% of total assembly is complete within 10 min, though total surface coverage by organics is limited to ≈0.15 monolayers. Adding HCl to the electrolyte renders native oxide formation unfavorable, yet the diazonium molecules are still unable to the increase surface coverage over 1 M-10 μM HCl in solution. X-ray photoelectron spectroscopy confirms preferential bonding of organic molecules to iron over chromium, while secondary ion mass spectroscopy reveals the ability of these films to self-heal when mechanically removed or damaged. Aging the diazonium salts in these nonaqueous environments demonstrates that up to 90% of the original diazonium salt concentration remains after 21 days at room temperature, while increasing the temperature beyond 50 °C results in complete decomposition within 24 h, regardless of solvent-salt combination. It is concluded that the investigated diazonium molecules will not spontaneously form a continuous monolayer on 440C stainless steel immersed in ACN, TBP, or HMDS.
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Affiliation(s)
- Leo J Small
- Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
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16
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Arefi HH, Nolan M, Fagas G. Density functional theory with van der waals corrections study of the adsorption of alkyl, alkylthiol, alkoxyl, and amino-alkyl chains on the H:Si(111) surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:13255-13265. [PMID: 25260071 DOI: 10.1021/la502488c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Surface modification of silicon with organic monolayers tethered to the surface by different linkers is an important process in realizing future miniaturized electronic and sensor devices. Understanding the roles played by the nature of the linking group and the chain length on the adsorption structures and stabilities of these assemblies is vital to advance this technology. This paper presents a density functional theory (DFT) study of the hydrogen passivated Si(111) surface modified with alkyl chains of the general formula H:Si-(CH2)n-CH2 and H:Si-X-(CH2)n-CH3, where X = NH, O, S and n = (0, 1, 3, 5, 7, 9, 11), at half coverage. For (X)-hexane and (X)-dodecane functionalization, we also examined various coverages up to full monolayer grafting in order to validate the result of half covered surface and the linker effect on the coverage. We find that it is necessary to take into account the van der Waals interaction between the alkyl chains. The strongest binding is for the oxygen linker, followed by S, N, and C, irrespective of chain length. The result revealed that the sequence of the stability is independent of coverage; however, linkers other than carbon can shift the optimum coverage considerably and allow further packing density. For all linkers apart from sulfur, structural properties, in particular, surface-linker-chain angles, saturate to a single value once n > 3. For sulfur, we identify three regimes, namely, n = 0-3, n = 5-7, and n = 9-11, each with its own characteristic adsorption structures. Where possible, our computational results are shown to be consistent with the available experimental data and show how the fundamental structural properties of modified Si surfaces can be controlled by the choice of linking group and chain length.
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Affiliation(s)
- Hadi H Arefi
- Tyndall National Institute, Lee Maltings, and ‡Department of Electrical Engineering, University College Cork , Cork, Ireland
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Ullien D, Thüne PC, Jager WF, Sudhölter EJR, de Smet LCPM. Controlled amino-functionalization by electrochemical reduction of bromo and nitro azobenzene layers bound to Si(111) surfaces. Phys Chem Chem Phys 2014; 16:19258-65. [PMID: 25100049 DOI: 10.1039/c4cp02464h] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
4-Nitrobenzenediazonium (4-NBD) and 4-bromobenzenediazonium (4-BBD) salts were grafted electrochemically onto H-terminated, p-doped silicon (Si) surfaces. Atomic force microscopy (AFM) and ellipsometry experiments clearly showed layer thicknesses of 2-7 nm, which indicate multilayer formation. Decreasing the diazonium salt concentration and the reaction time resulted in a smaller layer thickness, but did not prevent the formation of multilayers. It was demonstrated, mainly by X-ray photoelectron spectroscopy (XPS), that the diazonium salts not only react with the H-terminated Si surface, but also with electrografted phenyl groups via azo-bond formation. These azo bonds can be electrochemically reduced at Ered = -1.5 V, leading to the corresponding amino groups. This reduction resulted in a modest decrease in layer thickness, and did not yield monolayers. This indicates that other coupling reactions, notably a biphenyl coupling, induced by electrochemically produced phenyl radicals, take place as well. In addition to the azo functionalities, the nitro functionalities in electrografted layers of 4-NBD were independently reduced to amino functionalities at a lower potential (Ered = -2.1 V). The presence of amino functionalities on fully reduced layers, both from 4-NBD- and 4-BBD-modified Si, was shown by the presence of fluorine after reaction with trifluoroacetic anhydride (TFAA). This study shows that the electrochemical reduction of azo bonds generates amino functionalities on layers produced by electrografting of aryldiazonium derivatives. In this way multifunctional layers can be formed by employing functional aryldiazonium salts, which is believed to be very practical in the fabrication of sensor platforms, including those made of multi-array silicon nanowires.
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Affiliation(s)
- Daniela Ullien
- Department of Chemical Engineering, Delft University of Technology, Julianalaan 136, 2628 BL Delft, The Netherlands.
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18
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Frederick E, Dickerson PN, Zhong YL, Bernasek SL. Substituent effects on the kinetics of bifunctional styrene SAM formation on H-terminated Si. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:7687-7694. [PMID: 24911116 DOI: 10.1021/la501417s] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Self-assembled monolayers (SAMs) on metal and semiconductor surfaces are of interest in electronic devices, molecular and biosensors, and nanostructured surface preparation. Bifunctionalized molecules, where one functional group attaches to the surface while the other remains free for further modification, allow for the rational design of multilayer chemisorbed thin films. In this study, substituted styrenes acted as a model system for SAM formation through an alkene moiety. Substituents ranging from activating to strongly deactivating for aromatic reactions were used to probe the effect of the electronic properties of functionalizing molecules on the rate of SAM formation. Substituted styrene SAMs were formed on hydrogen-terminated p-type Si(100) and n-type Si(111) via sonochemical functionalization. Monolayers were characterized via ellipsometry, IR spectroscopy, contact angle goniometry, and X-ray photoelectron spectroscopy (XPS). Initial rates of reaction for molecules that selectively attached through the alkene were further studied. A linear relationship was observed between the initial rates of surface functionalization and the substituent electron donating/withdrawing ability for the substituted styrenes, as described by their respective Hammett constants. This study provides precedent for applying well quantified homogeneous chemical reaction relationships to reactions at the solid-liquid interface.
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Affiliation(s)
- Esther Frederick
- Department of Chemistry, Princeton University , Princeton, New Jersey 08544, United States
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19
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Palma CA, Diller K, Berger R, Welle A, Björk J, Cabellos JL, Mowbray DJ, Papageorgiou AC, Ivleva NP, Matich S, Margapoti E, Niessner R, Menges B, Reichert J, Feng X, Räder HJ, Klappenberger F, Rubio A, Müllen K, Barth JV. Photoinduced C–C Reactions on Insulators toward Photolithography of Graphene Nanoarchitectures. J Am Chem Soc 2014; 136:4651-8. [DOI: 10.1021/ja412868w] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Carlos-Andres Palma
- Physik-Department, Technische Universität München, James-Franck-Strasse 1, 85748 Garching, Germany
| | - Katharina Diller
- Physik-Department, Technische Universität München, James-Franck-Strasse 1, 85748 Garching, Germany
| | - Reinhard Berger
- Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany
| | - Alexander Welle
- Institut für Funktionelle Grenzflächen, Karlsruher Institut für Technologie, Hermann-von-Helmholz-Platz
1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Jonas Björk
- Department
of Physics, Chemistry and Biology, IFM, Linköping University, 58183 Linköping , Sweden
| | - Jose Luis Cabellos
- Nano-Bio
Spectroscopy Group and ETSF Scientific Development Centre, Departamento
de Física de Materiales, Centro de Física de Materiales CSIC-UPV/EHU-MPC DIPC, Universidad del País Vasco UPV/EHU, Av. Tolosa 72, E-20018 San Sebastián, Spain
| | - Duncan J. Mowbray
- Nano-Bio
Spectroscopy Group and ETSF Scientific Development Centre, Departamento
de Física de Materiales, Centro de Física de Materiales CSIC-UPV/EHU-MPC DIPC, Universidad del País Vasco UPV/EHU, Av. Tolosa 72, E-20018 San Sebastián, Spain
| | - Anthoula C. Papageorgiou
- Physik-Department, Technische Universität München, James-Franck-Strasse 1, 85748 Garching, Germany
| | - Natalia P. Ivleva
- Chair
for Analytical Chemistry, Institute of Hydrochemistry, Technische Universität München, Marchioninistr. 17, 81377 München, Germany
| | - Sonja Matich
- Walter
Schottky Institut and Physik-Department, Technische Universität München, Am Coulombwall 4a, 85748 Garching, Germany
| | - Emanuela Margapoti
- Walter
Schottky Institut and Physik-Department, Technische Universität München, Am Coulombwall 4a, 85748 Garching, Germany
| | - Reinhard Niessner
- Chair
for Analytical Chemistry, Institute of Hydrochemistry, Technische Universität München, Marchioninistr. 17, 81377 München, Germany
| | - Bernhard Menges
- Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany
| | - Joachim Reichert
- Physik-Department, Technische Universität München, James-Franck-Strasse 1, 85748 Garching, Germany
| | - Xinliang Feng
- Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany
| | - Hans Joachim Räder
- Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany
| | - Florian Klappenberger
- Physik-Department, Technische Universität München, James-Franck-Strasse 1, 85748 Garching, Germany
| | - Angel Rubio
- Nano-Bio
Spectroscopy Group and ETSF Scientific Development Centre, Departamento
de Física de Materiales, Centro de Física de Materiales CSIC-UPV/EHU-MPC DIPC, Universidad del País Vasco UPV/EHU, Av. Tolosa 72, E-20018 San Sebastián, Spain
- Fritz-Haber-Institut Max-Planck-Gesellschaft, Berlin, Germany
| | - Klaus Müllen
- Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany
| | - Johannes V. Barth
- Physik-Department, Technische Universität München, James-Franck-Strasse 1, 85748 Garching, Germany
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20
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Jlassi K, Mekki A, Benna-Zayani M, Singh A, Aswal DK, Chehimi MM. Exfoliated clay/polyaniline nanocomposites through tandem diazonium cation exchange reactions and in situ oxidative polymerization of aniline. RSC Adv 2014. [DOI: 10.1039/c4ra10329g] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Exfoliated, conductive clay/polyaniline nanocomposites were prepared by polymerization of aniline in the presence of diazonium cation exchanged bentonite.
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Affiliation(s)
- Khouloud Jlassi
- Université de Carthage
- Faculté des Sciences de Bizerte (FSB)
- LACReSNE
- Bizerte, Tunisia
- Institut Supérieur des Sciences et Technologies de l'Environnement (ISSTE)
| | - Ahmed Mekki
- Univ Paris Diderot
- Sorbonne Paris Cité
- ITODYS
- , France
- Ecole Militaire Polytechnique
| | - Mémia Benna-Zayani
- Université de Carthage
- Faculté des Sciences de Bizerte (FSB)
- LACReSNE
- Bizerte, Tunisia
- Institut Supérieur des Sciences et Technologies de l'Environnement (ISSTE)
| | - Ajay Singh
- Technical Physics Division
- Bhabha Atomic Research Centre (BARC)
- Mumbai 400085, India
| | - Dinesh K. Aswal
- Technical Physics Division
- Bhabha Atomic Research Centre (BARC)
- Mumbai 400085, India
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21
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Yaffe O, Ely T, Har-Lavan R, Egger D, Johnston S, Cohen H, Kronik L, Vilan A, Cahen D. Effect of Molecule-Surface Reaction Mechanism on the Electronic Characteristics and Photovoltaic Performance of Molecularly Modified Si. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2013; 117:22351-22361. [PMID: 24205409 PMCID: PMC3814651 DOI: 10.1021/jp4027755] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Revised: 05/27/2013] [Indexed: 06/02/2023]
Abstract
We report on the passivation properties of molecularly modified, oxide-free Si(111) surfaces. The reaction of 1-alcohol with the H-passivated Si(111) surface can follow two possible paths, nucleophilic substitution (SN) and radical chain reaction (RCR), depending on adsorption conditions. Moderate heating leads to the SN reaction, whereas with UV irradiation RCR dominates, with SN as a secondary path. We show that the site-sensitive SN reaction leads to better electrical passivation, as indicated by smaller surface band bending and a longer lifetime of minority carriers. However, the surface-insensitive RCR reaction leads to more dense monolayers and, therefore, to much better chemical stability, with lasting protection of the Si surface against oxidation. Thus, our study reveals an inherent dissonance between electrical and chemical passivation. Alkoxy monolayers, formed under UV irradiation, benefit, though, from both chemical and electronic passivation because under these conditions both SN and RCR occur. This is reflected in longer minority carrier lifetimes, lower reverse currents in the dark, and improved photovoltaic performance, over what is obtained if only one of the mechanisms operates. These results show how chemical kinetics and reaction paths impact electronic properties at the device level. It further suggests an approach for effective passivation of other semiconductors.
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Affiliation(s)
- Omer Yaffe
- Department of Materials &
Interfaces, Weizmann Institute of Science, Rehovoth 76100, Israel
| | - Tal Ely
- Department of Materials &
Interfaces, Weizmann Institute of Science, Rehovoth 76100, Israel
| | - Rotem Har-Lavan
- Department of Materials &
Interfaces, Weizmann Institute of Science, Rehovoth 76100, Israel
| | - David
A. Egger
- Institute of Solid State Physics, Graz University of Technology, A-8010 Graz, Austria
| | - Steve Johnston
- National Renewable
Energy Laboratory, Golden, Colorado 80401, United States
| | - Hagai Cohen
- Department of Chemical Research
Support, Weizmann Institute of Science,
Rehovoth 76100, Israel
| | - Leeor Kronik
- Department of Materials &
Interfaces, Weizmann Institute of Science, Rehovoth 76100, Israel
| | - Ayelet Vilan
- Department of Materials &
Interfaces, Weizmann Institute of Science, Rehovoth 76100, Israel
| | - David Cahen
- Department of Materials &
Interfaces, Weizmann Institute of Science, Rehovoth 76100, Israel
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22
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Haj-Yahia AE, Yaffe O, Bendikov T, Cohen H, Feldman Y, Vilan A, Cahen D. Substituent variation drives metal/monolayer/semiconductor junctions from strongly rectifying to ohmic behavior. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2013; 25:702-706. [PMID: 23161521 DOI: 10.1002/adma.201203028] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Revised: 09/25/2012] [Indexed: 06/01/2023]
Abstract
An eight-orders of magnitude enhancement in current across Hg/X-styrene-Si junctions is caused by merely altering a substituent, X. Interface states are passivated and, depending on X, the Si Schottky junction encompasses the full range from Ohmic to strongly rectifying. This powerful electrostatic molecular effect has immediate implications for interface band alignment and sensing.
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Affiliation(s)
- Abd-Elrazek Haj-Yahia
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel
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23
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Ciampi S, James M, Choudhury MH, Darwish NA, Gooding JJ. The detailed characterization of electrochemically switchable molecular assemblies on silicon electrodes. Phys Chem Chem Phys 2013; 15:9879-90. [DOI: 10.1039/c3cp50355k] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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24
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Cottineau T, Morin M, Bélanger D. Surface band structure of aryl-diazonium modified p-Si electrodes determined by X-ray photoelectron spectroscopy and electrochemical measurements. RSC Adv 2013. [DOI: 10.1039/c3ra44366c] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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25
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Matmor M, Ashkenasy N. Modulating Semiconductor Surface Electronic Properties by Inorganic Peptide–Binders Sequence Design. J Am Chem Soc 2012. [DOI: 10.1021/ja3078494] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Maayan Matmor
- Department of Materials Engineering and the Ilze Katz
Institute for Nanoscale Science and Technology, Ben Gurion University of the Negev, Beer-Sheva, Israel
| | - Nurit Ashkenasy
- Department of Materials Engineering and the Ilze Katz
Institute for Nanoscale Science and Technology, Ben Gurion University of the Negev, Beer-Sheva, Israel
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26
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Yang S, Prendergast D, Neaton JB. Tuning semiconductor band edge energies for solar photocatalysis via surface ligand passivation. NANO LETTERS 2012; 12:383-388. [PMID: 22192078 DOI: 10.1021/nl203669k] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Semiconductor photocatalysts capable of broadband solar photon absorption may be nonetheless precluded from use in driving water splitting and other solar-to-fuel related reactions due to unfavorable band edge energy alignment. Using first-principles density functional theory and beyond, we calculate the electronic structure of passivated CdSe surfaces and explore the opportunity to tune band edge energies of this and related semiconductors via electrostatic dipoles associated with chemisorbed ligands. We predict substantial shifts in band edge energies originating from both the induced dipole at the ligand/CdSe interface and the intrinsic dipole of the ligand. Building on important induced dipole contributions, we further show that, by changing the size and orientation of the ligand's intrinsic dipole moment via functionalization, we can control the direction and magnitude of the shifts of CdSe electronic levels. Our calculations suggest a general strategy for enabling new active semiconductor photocatalysts with both optimal opto-electronic, and photo- and electrochemical properties.
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Affiliation(s)
- Shenyuan Yang
- Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
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27
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Torbensen K, Iruthayaraj J, Ceccato M, Kongsfelt M, Breitenbach T, Pedersen SU, Daasbjerg K. Conducting and ordered carbon films obtained by pyrolysis of covalently attached polyphenylene and polyanthracene layers on silicon substrates. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm32935b] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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28
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Lefèvre X, Segut O, Jégou P, Palacin S, Jousselme B. Towards organic film passivation of germanium wafers using diazonium salts: Mechanism and ambient stability. Chem Sci 2012. [DOI: 10.1039/c2sc01034h] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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29
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Bonifas AP, McCreery RL. Assembling molecular electronic junctions one molecule at a time. NANO LETTERS 2011; 11:4725-4729. [PMID: 21995487 DOI: 10.1021/nl202495k] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Diffusion of metal atoms onto a molecular monolayer attached to a conducting surface permits electronic contact to the molecules with minimal heat transfer or structural disturbance. Surface-mediated metal deposition (SDMD) involves contact between "cold" diffusing metal atoms and molecules, due to shielding of the molecules from direct exposure to metal vapor. Measurement of the current through the molecular layer during metal diffusion permits observation of molecular conductance for junctions containing as few as one molecule. Discrete conductance steps were observed for 1-10 molecules within a monolayer during a single deposition run, corresponding to "recruitment" of additional molecules as the contact area between the diffusing Au layer and molecules increases. For alkane monolayers, the molecular conductance measured with SDMD exhibited an exponential dependence on molecular length with a decay constant (β) of 0.90 per CH(2) group, comparable to that observed by other techniques. Molecular conductance values were determined for three azobenzene molecules, and correlated with the offset between the molecular HOMO and the contact Fermi level, as expected for hole-mediated tunneling. Current-voltage curves were obtained during metal deposition showed no change in shape for junctions containing 1, 2, and 10 molecules, implying minimal intermolecular interactions as single molecule devices transitioned into several molecules devices. SDMD represents a "soft" metal deposition method capable of providing single molecule conductance values, then providing quantitative comparisons to molecular junctions containing 10(6) to 10(10) molecules.
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Affiliation(s)
- Andrew P Bonifas
- Department of Materials Science and Engineering, The Ohio State University, 2041 College Road, Columbus, Ohio 43210, United States
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31
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Popoff RTW, Kavanagh KL, Yu HZ. Preparation of ideal molecular junctions: depositing non-invasive gold contacts on molecularly modified silicon. NANOSCALE 2011; 3:1434-1445. [PMID: 21290075 DOI: 10.1039/c0nr00677g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Recent advances in creating rectifying gold|monolayer|silicon (Au-M-Si) junctions (namely, molecular silicon diodes) are reviewed. It is known that direct deposition of gold contacts onto molecular monolayers covalently bonded to silicon surfaces causes notable disruption to the junction structure, resulting in deteriorated performance and poor reproducibility that are unsuitable for practical applications. In the past few years, several new experimental approaches have been explored to minimize or eliminate such damage, including the "indirect" evaporation method and the pre-deposition of a protective "non-penetrating" metal. To enhance the interactions at the gold-monolayer interface, head-groups that allow bonding to gold are used to maintain the monolayer integrity. Construction of the device via flip-chip lamination and the modified polymer-assisted lift-off techniques also prohibits monolayer damage. Refining the fabrication and design techniques towards reliable molecular junctions is crucial if they are to be used in nanoelectronics for the purpose of miniaturization.
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Affiliation(s)
- Richard T W Popoff
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
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32
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Bélanger D, Pinson J. Electrografting: a powerful method for surface modification. Chem Soc Rev 2011; 40:3995-4048. [DOI: 10.1039/c0cs00149j] [Citation(s) in RCA: 751] [Impact Index Per Article: 57.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Vilan A, Yaffe O, Biller A, Salomon A, Kahn A, Cahen D. Molecules on si: electronics with chemistry. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2010; 22:140-159. [PMID: 20217681 DOI: 10.1002/adma.200901834] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Basic scientific interest in using a semiconducting electrode in molecule-based electronics arises from the rich electrostatic landscape presented by semiconductor interfaces. Technological interest rests on the promise that combining existing semiconductor (primarily Si) electronics with (mostly organic) molecules will result in a whole that is larger than the sum of its parts. Such a hybrid approach appears presently particularly relevant for sensors and photovoltaics. Semiconductors, especially Si, present an important experimental test-bed for assessing electronic transport behavior of molecules, because they allow varying the critical interface energetics without, to a first approximation, altering the interfacial chemistry. To investigate semiconductor-molecule electronics we need reproducible, high-yield preparations of samples that allow reliable and reproducible data collection. Only in that way can we explore how the molecule/electrode interfaces affect or even dictate charge transport, which may then provide a basis for models with predictive power.To consider these issues and questions we will, in this Progress Report, review junctions based on direct bonding of molecules to oxide-free Si.describe the possible charge transport mechanisms across such interfaces and evaluate in how far they can be quantified.investigate to what extent imperfections in the monolayer are important for transport across the monolayer.revisit the concept of energy levels in such hybrid systems.
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34
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Yang F, Hunger R, Roodenko K, Hinrichs K, Rademann K, Rappich J. Vibrational and electronic characterization of ethynyl derivatives grafted onto hydrogenated Si(111) surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:9313-9318. [PMID: 19601568 DOI: 10.1021/la900871g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Covalent grafting of ethynyl derivatives (-C triple bond C-H, -C triple bond C-CH3, -C triple bond C-aryl) onto H-terminated Si(111) surfaces was performed by a one-step anodic treatment in Grignard electrolytes. The electrochemical grafting of such ethynyl derivatives, which tends to form ultrathin polymeric layers, can be controlled by the current and charge flow passing through the Si electrode. The prepared ultrathin layers cover the Si surface and had a thickness up to 20 nm, as investigated by the scanning electron microscopy (SEM) technique. Exchanging Cl for Br in the ethynyl Grignard reagent leads to very thin layers, even under the same electrochemical conditions. However, for all ethynyl derivatives, high-resolution synchrotron X-ray photoelectron spectroscopy (SXPS) investigations reveal the incorporation of halogen atoms in the organic layers obtained. Moreover, it was observed that the larger the end group of the ethynyl derivative, the thinner the thickness of the ultrathin polymeric layers as measured by both SXPS and SEM techniques after low and high current flow respectively. For the first time, these new types of ultrathin organic layers on Si surfaces were investigated using infrared spectroscopic ellipsometry (IRSE). The different possible reaction pathways are discussed.
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Affiliation(s)
- F Yang
- Helmholtz-Zentrum Berlin for Materialien und Energie GmbH, Institut for Si-Photovoltaik Kekulestrasse 5, 12489 Berlin, Germany.
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35
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Coll M, Miller LH, Richter LJ, Hines DR, Jurchescu OD, Gergel-Hackett N, Richter CA, Hacker CA. Formation of Silicon-Based Molecular Electronic Structures Using Flip-Chip Lamination. J Am Chem Soc 2009; 131:12451-7. [PMID: 19670858 DOI: 10.1021/ja901646j] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Mariona Coll
- Semiconductor Electronics Division, Electronics Electrical Engineering Laboratory and Surface and Microanalysis Science Division, Chemical Science and Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, and Physics Department and Laboratory for Physical Sciences, University of Maryland, College Park, Maryland 20740
| | - Lauren H. Miller
- Semiconductor Electronics Division, Electronics Electrical Engineering Laboratory and Surface and Microanalysis Science Division, Chemical Science and Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, and Physics Department and Laboratory for Physical Sciences, University of Maryland, College Park, Maryland 20740
| | - Lee J. Richter
- Semiconductor Electronics Division, Electronics Electrical Engineering Laboratory and Surface and Microanalysis Science Division, Chemical Science and Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, and Physics Department and Laboratory for Physical Sciences, University of Maryland, College Park, Maryland 20740
| | - Daniel R. Hines
- Semiconductor Electronics Division, Electronics Electrical Engineering Laboratory and Surface and Microanalysis Science Division, Chemical Science and Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, and Physics Department and Laboratory for Physical Sciences, University of Maryland, College Park, Maryland 20740
| | - Oana D. Jurchescu
- Semiconductor Electronics Division, Electronics Electrical Engineering Laboratory and Surface and Microanalysis Science Division, Chemical Science and Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, and Physics Department and Laboratory for Physical Sciences, University of Maryland, College Park, Maryland 20740
| | - Nadine Gergel-Hackett
- Semiconductor Electronics Division, Electronics Electrical Engineering Laboratory and Surface and Microanalysis Science Division, Chemical Science and Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, and Physics Department and Laboratory for Physical Sciences, University of Maryland, College Park, Maryland 20740
| | - Curt A. Richter
- Semiconductor Electronics Division, Electronics Electrical Engineering Laboratory and Surface and Microanalysis Science Division, Chemical Science and Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, and Physics Department and Laboratory for Physical Sciences, University of Maryland, College Park, Maryland 20740
| | - Christina A. Hacker
- Semiconductor Electronics Division, Electronics Electrical Engineering Laboratory and Surface and Microanalysis Science Division, Chemical Science and Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, and Physics Department and Laboratory for Physical Sciences, University of Maryland, College Park, Maryland 20740
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36
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Le Floch F, Simonato JP, Bidan G. Electrochemical signature of the grafting of diazonium salts: A probing parameter for monitoring the electro-addressed functionalization of devices. Electrochim Acta 2009. [DOI: 10.1016/j.electacta.2008.11.063] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Combellas C, Jiang DE, Kanoufi F, Pinson J, Podvorica F. Steric effects in the reaction of aryl radicals on surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:286-293. [PMID: 19067511 DOI: 10.1021/la8025792] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Steric effects are investigated in the reaction of aryl radicals with surfaces. The electrochemical reduction of 2-, 3-, 4-methyl, 2-methoxy, 2-ethyl, 2,6-, 2,4-, and 3,5-dimethyl, 4-tert-butyl, 3,5-bis-tert-butyl benzenediazonium, 3,5-bis(trifluoromethyl), and pentafluoro benzenediazonium tetrafluoroborates is examined in acetonitrile solutions. It leads to the formation of grafted layers only if the steric hindrance at the 2- or 2,6-position(s) is small. When the 3,5-positions are crowded with tert-butyl groups, the growth of the organic layer is limited by steric effects and a monolayer is formed. The efficiency of the grafting process is assessed by cyclic voltammetry, X-ray photoelectron spectroscopy, infrared, and ellipsometry. These experiments, together with density functional computations of bonding energies of substituted phenyl groups on a copper surface, are discussed in terms of the reactivity of aryl radicals in the electrografting reaction and in the growth of the polyaryl layer.
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Affiliation(s)
- Catherine Combellas
- Laboratoire Environnement et Chimie Analytique, UMR 7121, CNRS-ESPCI Paris Tech, 10 rue Vauquelin, 75231 Paris Cedex 05, France
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Leftwich TR, Madachik MR, Teplyakov AV. Dehydrative Cyclocondensation Reactions on Hydrogen-Terminated Si(100) and Si(111): An ex Situ Tool for the Modification of Semiconductor Surfaces. J Am Chem Soc 2008; 130:16216-23. [DOI: 10.1021/ja802645t] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Timothy R. Leftwich
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716
| | - Mark R. Madachik
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716
| | - Andrew V. Teplyakov
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716
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Hiremath RK, Rabinal MK, Mulimani BG, Khazi IM. Molecularly controlled metal-semiconductor junctions on silicon surface: a dipole effect. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:11300-11306. [PMID: 18788759 DOI: 10.1021/la800882e] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Silicon surface was chemically modified by covalent attachment of homologous organic molecules having different dipole moments. Surface photovoltage measurements clearly confirm that organic molecules have a profound effect on surface band bending of semiconductor. Metal-molecules--silicon junctions were constituted for molecules belonging to ethynylbenzene series using soft mercury contact. These junctions show a systematic change in the electrical charge transport with dipole moment of molecules. Parameters such as ideality factor, barrier height, and density of interface states of various junctions are estimated to understand the role of organic molecules. These studies offer the prospect to develop molecular electronics, which may find potential applications in solar cells and chemical and biological sensors.
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Affiliation(s)
- R K Hiremath
- Department of Physics, Karnatak University, Dharwad, India
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Toupin M, Bélanger D. Spontaneous functionalization of carbon black by reaction with 4-nitrophenyldiazonium cations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:1910-1917. [PMID: 18211105 DOI: 10.1021/la702556n] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The mechanism of the spontaneous chemical functionalization of Vulcan carbon black by reaction with 4-nitrophenyl diazonium cations was investigated by varying the reaction conditions. First, the carbon black was oxidized by nitric acid reflux to introduce oxygenated functionalities onto the surface prior to the functionalization step. Second, a reducing agent (H3PO2) was added to a solution containing 4-nitrobenzene diazonium tetrafluoroborate to generate 4-nitrophenyl radicals homogeneously in the bulk solution. The functionalized carbons were characterized by elemental analysis, X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption isotherms using the BET isotherm and DFT Monte Carlo simulations. These characterization methods were employed to determine the grafting yield as a function of the reaction conditions. Interestingly, the grafting yield was not affected by a change in the reaction conditions. An average nitrogen content of 1.4 +/- 0.1 atom % was found by elemental analysis, and XPS showed a nitrogen surface concentration of about 3.5%. XPS also indicated an important decrease in the concentration of oxygenated functionalities upon grafting 4-nitrophenyl moieties onto the oxidized carbon black. Presumably, in this case the grafting involves either the coupling of carboxylate and 4-nitrophenyl radicals or, more likely, a concerted decarboxylation where the diazonium cation, acting as an electrophile, replaces the oxygenated groups and loss of CO2. The nitrogen adsorption isotherms of the functionalized carbon blacks suggested that the grafted groups were most probably localized at the entrance of the micropores.
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Affiliation(s)
- Mathieu Toupin
- Département de Chimie, Université du Québec à Montréal, succursale Centre-Ville, Montréal, Québec H3C 3P8, Canada
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Hybrid coating on steel: ZnNi electrodeposition and surface modification with organothiols and diazonium salts. Electrochim Acta 2008. [DOI: 10.1016/j.electacta.2007.10.067] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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