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Hussain Z, Nafady A, Anderson SR, Al-Enizi AM, Alothman AA, Ramanathan R, Bansal V. Increased Crystallization of CuTCNQ in Water/DMSO Bisolvent for Enhanced Redox Catalysis. NANOMATERIALS 2021; 11:nano11040954. [PMID: 33917931 PMCID: PMC8068373 DOI: 10.3390/nano11040954] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 03/24/2021] [Accepted: 04/03/2021] [Indexed: 11/21/2022]
Abstract
Controlling the kinetics of CuTCNQ (TCNQ = 7,7,8,8-tetracyanoquinodimethane) crystallization has been a major challenge, as CuTCNQ crystallizing on Cu foil during synthesis in conventional solvents such as acetonitrile simultaneously dissolves into the reaction medium. In this work, we address this challenge by using water as a universal co-solvent to control the kinetics of crystallization and growth of phase I CuTCNQ. Water increases the dielectric constant of the reaction medium, shifting the equilibrium toward CuTCNQ crystallization while concomitantly decreasing the dissolution of CuTCNQ. This allows more CuTCNQ to be controllably crystallized on the surface of the Cu foil. Different sizes of CuTCNQ crystals formed on Cu foil under different water/DMSO admixtures influence the solvophilicity of these materials. This has important implications in their catalytic performance, as water-induced changes in the surface properties of these materials can make them highly hydrophilic, which allows the CuTCNQ to act as an efficient catalyst as it brings the aqueous reactants in close vicinity of the catalyst. Evidently, the CuTCNQ synthesized in 30% (v/v) water/DMSO showed superior catalytic activity for ferricyanide reduction with 95% completion achieved within a few minutes in contrast to CuTCNQ synthesized in DMSO that took over 92 min.
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Affiliation(s)
- Zakir Hussain
- Ian Potter NanoBioSensing Facility, NanoBiotechnology Research Laboratory (NBRL), School of Science, RMIT University, P.O. Box 2476, Melbourne, VIC 3000, Australia; (Z.H.); (S.R.A.)
| | - Ayman Nafady
- Chemistry Department, College of Science, King Saud University, Riyadh 11451, Saudi Arabia; (A.M.A.-E.); (A.A.A.)
- Correspondence: (A.N.); (R.R.); (V.B.); Tel.: +61-3-9925-2887 (R.R.); +61-3-9925-2121 (V.B.)
| | - Samuel R. Anderson
- Ian Potter NanoBioSensing Facility, NanoBiotechnology Research Laboratory (NBRL), School of Science, RMIT University, P.O. Box 2476, Melbourne, VIC 3000, Australia; (Z.H.); (S.R.A.)
| | - Abdullah M. Al-Enizi
- Chemistry Department, College of Science, King Saud University, Riyadh 11451, Saudi Arabia; (A.M.A.-E.); (A.A.A.)
| | - Asma A. Alothman
- Chemistry Department, College of Science, King Saud University, Riyadh 11451, Saudi Arabia; (A.M.A.-E.); (A.A.A.)
| | - Rajesh Ramanathan
- Ian Potter NanoBioSensing Facility, NanoBiotechnology Research Laboratory (NBRL), School of Science, RMIT University, P.O. Box 2476, Melbourne, VIC 3000, Australia; (Z.H.); (S.R.A.)
- Correspondence: (A.N.); (R.R.); (V.B.); Tel.: +61-3-9925-2887 (R.R.); +61-3-9925-2121 (V.B.)
| | - Vipul Bansal
- Ian Potter NanoBioSensing Facility, NanoBiotechnology Research Laboratory (NBRL), School of Science, RMIT University, P.O. Box 2476, Melbourne, VIC 3000, Australia; (Z.H.); (S.R.A.)
- Correspondence: (A.N.); (R.R.); (V.B.); Tel.: +61-3-9925-2887 (R.R.); +61-3-9925-2121 (V.B.)
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Zheng Y, Li J, Ji D, Dong H, Li L, Fuchs H, Hu W. Copper Tetracyanoquinodimethane: From Micro/Nanostructures to Applications. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2004143. [PMID: 33301234 DOI: 10.1002/smll.202004143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 09/08/2020] [Indexed: 06/12/2023]
Abstract
Copper tetracyanoquinodimethane (CuTCNQ) has been investigated around 40 years as a representative bistable material. Meanwhile, micro/nanostructures of CuTCNQ is considered as the prototype of molecular electronics, which have attracted the world's attention and shown great potential applications in nanoelectronics. In this review, methods for synthesis of CuTCNQ micro/nanostructures are first summarized briefly. Then, the strategies for controlling morphologies and sizes of CuTCNQ micro/nanostructures are highlighted. Afterwards, the devices based on these micro/nanostructures are reviewed. Finally, an outlook of future research directions and challenges in this area is presented.
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Affiliation(s)
- Yingshuang Zheng
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, Institute of Molecular Aggregation Science, Tianjin University, Tianjin, 300072, China
| | - Jie Li
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, Institute of Molecular Aggregation Science, Tianjin University, Tianjin, 300072, China
| | - Deyang Ji
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, Institute of Molecular Aggregation Science, Tianjin University, Tianjin, 300072, China
- Beijing National Laboratory for Molecular Sciences, Beijing, 100190, China
| | - Huanli Dong
- Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Liqiang Li
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, Institute of Molecular Aggregation Science, Tianjin University, Tianjin, 300072, China
| | - Harald Fuchs
- Physikalisches Institut, Westfälische Wilhelms-Universität, Wilhelm-Klemm-Straße 10, Münster, 48149, Germany
- Center for Nanotechnology, Heisenbergstraße 11, Münster, 48149, Germany
| | - Wenping Hu
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University, and Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300072, China
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Vo NT, Martin LL, Bond AM. Electrochemistry of TCNQF2 in acetonitrile in the presence of [Cu(CH3CN)4]+: Electrocrystallisation and characterisation of CuTCNQF2. Inorganica Chim Acta 2018. [DOI: 10.1016/j.ica.2018.04.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Yan R, Ghilane J, Phuah KC, Pham Truong TN, Adams S, Randriamahazaka H, Wang Q. Determining Li +-Coupled Redox Targeting Reaction Kinetics of Battery Materials with Scanning Electrochemical Microscopy. J Phys Chem Lett 2018; 9:491-496. [PMID: 29320194 DOI: 10.1021/acs.jpclett.7b03136] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The redox targeting reaction of Li+-storage materials with redox mediators is the key process in redox flow lithium batteries, a promising technology for next-generation large-scale energy storage. The kinetics of the Li+-coupled heterogeneous charge transfer between the energy storage material and redox mediator dictates the performance of the device, while as a new type of charge transfer process it has been rarely studied. Here, scanning electrochemical microscopy (SECM) was employed for the first time to determine the interfacial charge transfer kinetics of LiFePO4/FePO4 upon delithiation and lithiation by a pair of redox shuttle molecules FcBr2+ and Fc. The effective rate constant keff was determined to be around 3.70-6.57 × 10-3 cm/s for the two-way pseudo-first-order reactions, which feature a linear dependence on the composition of LiFePO4, validating the kinetic process of interfacial charge transfer rather than bulk solid diffusion. In addition, in conjunction with chronoamperometry measurement, the SECM study disproves the conventional "shrinking-core" model for the delithiation of LiFePO4 and presents an intriguing way of probing the phase boundary propagations induced by interfacial redox reactions. This study demonstrates a reliable method for the kinetics of redox targeting reactions, and the results provide useful guidance for the optimization of redox targeting systems for large-scale energy storage.
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Affiliation(s)
- Ruiting Yan
- Department of Materials Science and Engineering, Faculty of Engineering, National University of Singapore , Singapore 117576
| | - Jalal Ghilane
- Université Paris Diderot, Sorbonne Paris Cité, ITODYS , UMR 7086 CNRS, SIELE group, 15 rue Jean Antoine de Baïf, 75013 Paris, France
| | - Kia Chai Phuah
- Department of Materials Science and Engineering, Faculty of Engineering, National University of Singapore , Singapore 117576
| | - Thuan Nguyen Pham Truong
- Université Paris Diderot, Sorbonne Paris Cité, ITODYS , UMR 7086 CNRS, SIELE group, 15 rue Jean Antoine de Baïf, 75013 Paris, France
| | - Stefan Adams
- Department of Materials Science and Engineering, Faculty of Engineering, National University of Singapore , Singapore 117576
| | - Hyacinthe Randriamahazaka
- Université Paris Diderot, Sorbonne Paris Cité, ITODYS , UMR 7086 CNRS, SIELE group, 15 rue Jean Antoine de Baïf, 75013 Paris, France
| | - Qing Wang
- Department of Materials Science and Engineering, Faculty of Engineering, National University of Singapore , Singapore 117576
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Yang F, Zhao Q, Xu C, Zou Y, Dong H, Zheng Y, Hu W. Unveiling the Switching Riddle of Silver Tetracyanoquinodimethane Towards Novel Planar Single-Crystalline Electrochemical Metallization Memories. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2016; 28:7094-7100. [PMID: 27276441 DOI: 10.1002/adma.201600902] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Revised: 05/07/2016] [Indexed: 06/06/2023]
Abstract
The switching riddle of AgTCNQ is shown to be caused by the solid electrolyte mechanism. Both factors of bulk phase change and contact issue play key roles in the efficient work of the devices. An effective strategy is developed to locate the formation/disruption of Ag conductive filaments using the planar asymmetric configuration of Au/AgTCNQ/AlOx /Al. These novel electrochemical metallization memories demonstrate many promising properties.
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Affiliation(s)
- Fangxu Yang
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Qiang Zhao
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Chunhui Xu
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Ye Zou
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Huanli Dong
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Yonggang Zheng
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Wenping Hu
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry School of Sciences, Tianjin University, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300072, China
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Simpson BH, Rodríguez-López J. Redox Titrations via Surface Interrogation Scanning Electrochemical Microscopy at an Extended Semiconducting Surface for the Quantification of Photogenerated Adsorbed Intermediates. Electrochim Acta 2015. [DOI: 10.1016/j.electacta.2015.04.128] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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7
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Nafady A, O’Mullane AP, Bond AM. Electrochemical and photochemical routes to semiconducting transition metal-tetracyanoquinodimethane coordination polymers. Coord Chem Rev 2014. [DOI: 10.1016/j.ccr.2014.01.017] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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O'Mullane AP, Neufeld AK, Bond AM. Scanning electrochemical microscopy study of the solid–solid interconversion of TCNQ to phase I and phase II CuTCNQ. Electrochem commun 2012. [DOI: 10.1016/j.elecom.2012.05.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
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9
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Liu Y, He M, Meng Q, Tang Z, Li L, Hu W. Mass-production of single-crystalline device arrays of an organic charge-transfer complex for its memory nature. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2012; 8:557-478. [PMID: 22282399 DOI: 10.1002/smll.201101940] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Revised: 11/13/2011] [Indexed: 05/31/2023]
Abstract
Controllable synthesis of single-crystalline lamellae of copper tetracyano-p- quinodimethane (CuTCNQ, phase II) is achieved, and mass-produced devices or device arrays based on symmetrical Cr/Au gap electrodes are fabricated in situ. The devices exhibit semiconductor properties important for the understanding of CuTCNQ.
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Affiliation(s)
- Yaling Liu
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P.R. China
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Liu Y, Jiang L, Dong H, Tang Z, Hu W. Large-area single-crystalline nanocone arrays of an organic charge-transfer complex: controlling growth, characterization, and applications. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2011; 7:1412-1415. [PMID: 21449045 DOI: 10.1002/smll.201002261] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Revised: 01/17/2011] [Indexed: 05/30/2023]
Affiliation(s)
- Yaling Liu
- Beijing National Laboratory for Molecular, Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, P. R. China
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11
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Nafady A, Bond AM, O’Mullane AP. Electrochemically-Induced TCNQ/Mn[TCNQ]2(H2O)2 (TCNQ = 7,7,8,8-Tetracyanoquinodimethane) Solid−Solid Interconversion: Two Voltammetrically Distinct Processes That Allow Selective Generation of Nanofiber or Nanorod Network Morphologies. Inorg Chem 2009; 48:9258-70. [DOI: 10.1021/ic9011394] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ayman Nafady
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
| | - Alan M. Bond
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
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12
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O’Mullane AP, Zhang J, Brajter-Toth A, Bond AM. Higher Harmonic Large-Amplitude Fourier Transformed Alternating Current Voltammetry: Analytical Attributes Derived from Studies of the Oxidation of Ferrocenemethanol and Uric Acid at a Glassy Carbon Electrode. Anal Chem 2008; 80:4614-26. [DOI: 10.1021/ac0715221] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Anthony P. O’Mullane
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia, Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, The Nanos, Singapore 138669, and Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611
| | - Jie Zhang
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia, Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, The Nanos, Singapore 138669, and Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611
| | - Anna Brajter-Toth
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia, Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, The Nanos, Singapore 138669, and Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611
| | - Alan M. Bond
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia, Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, The Nanos, Singapore 138669, and Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611
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13
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Qu X, Nafady A, Mechler A, Zhang J, Harris AR, O’Mullane AP, Martin LL, Bond AM. AFM study of morphological changes associated with electrochemical solid–solid transformation of three-dimensional crystals of TCNQ to metal derivatives (metal = Cu, Co, Ni; TCNQ = tetracyanoquinodimethane). J Solid State Electrochem 2007. [DOI: 10.1007/s10008-007-0423-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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14
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Wittstock G, Burchardt M, Pust SE, Shen Y, Zhao C. Scanning electrochemical microscopy for direct imaging of reaction rates. Angew Chem Int Ed Engl 2007; 46:1584-617. [PMID: 17285666 DOI: 10.1002/anie.200602750] [Citation(s) in RCA: 313] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Not only in electrochemistry but also in biology and in membrane transport, localized processes at solid-liquid or liquid-liquid interfaces play an important role at defect sites, pores, or individual cells, but are difficult to characterize by integral investigation. Scanning electrochemical microscopy is suitable for such investigations. After two decades of development, this method is based on a solid theoretical foundation and a large number of demonstrated applications. It offers the possibility of directly imaging heterogeneous reaction rates and locally modifying substrates by electrochemically generated reagents. The applications range from classical electrochemical problems, such as the investigation of localized corrosion and electrocatalytic reactions in fuel cells, sensor surfaces, biochips, and microstructured analysis systems, to mass transport through synthetic membranes, skin and tissue, as well as intercellular communication processes. Moreover, processes can be studied that occur at liquid surfaces and liquid-liquid interfaces.
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Affiliation(s)
- Gunther Wittstock
- Carl von Ossietzky Universität Oldenburg, Institut für Reine und Angewandte Chemie und Institut für Chemie und Biologie des Meeres, 26111 Oldenburg, Germany.
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15
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Nafady A, Bond AM. Redox-Induced Solid−Solid Phase Transformation of TCNQ Microcrystals into Semiconducting Ni[TCNQ]2(H2O)2 Nanowire (Flowerlike) Architectures: A Combined Voltammetric, Spectroscopic, and Microscopic Study. Inorg Chem 2007; 46:4128-37. [PMID: 17447759 DOI: 10.1021/ic062470l] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The facile solid-solid phase transformation of TCNQ microcrystals into semiconducting and magnetic Ni[TCNQ]2(H2O)2 nanowire (flowerlike) architectures is achieved by reduction of TCNQ-modified electrodes in the presence of Ni2+(aq)-containing electrolytes. Voltammetric probing revealed that the chemically reversible TCNQ/Ni[TCNQ]2(H2O)2 conversion process is essentially independent of electrode material and the identity of nickel counteranion but is significantly dependent on scan rate, Ni2+(aq) electrolyte concentration, and the method of solid TCNQ immobilization (drop casting or mechanical attachment). Data analyzed from cyclic voltammetric and double-potential step chronoamperometric experiments are consistent with formation of the Ni[TCNQ]2(H2O)2 complex via a rate-determining nucleation/growth process that involves incorporation of Ni2+(aq) ions into the reduced TCNQ crystal lattice at the triple phase TCNQ|electrode|electrolyte interface. The reoxidation process, which includes the conversion of solid Ni[TCNQ]2(H2O)2 back to TCNQ0 crystals, is also controlled by nucleation/growth kinetics. The overall redox process associated with this chemically reversible solid-solid transformation, therefore, is described by the equation: TCNQ0(S) + 2e- + Ni2+(aq)+ 2 H2O <==> {Ni[TCNQ]2(H2O)2}(S). SEM monitoring of the changes that accompany the TCNQ/Ni[TCNQ]2(H2O)2 transformation revealed that the morphology and crystal size of electrochemically generated Ni[TCNQ]2(H2O)2 are substantially different from those of parent TCNQ crystals. Importantly, the morphology of Ni[TCNQ]2(H2O)2 can be selectively manipulated to produce either 1-D/2-D nanowires or 3-D flowerlike architectures via careful control over the experimental parameters used to accomplish the solid-solid phase interconversion process.
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Affiliation(s)
- Ayman Nafady
- School of Chemistry, Monash University, P.O. Box 23, Victoria 3800, Australia
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16
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Xiong H, Guo J, Amemiya S. Probing heterogeneous electron transfer at an unbiased conductor by scanning electrochemical microscopy in the feedback mode. Anal Chem 2007; 79:2735-44. [PMID: 17341057 PMCID: PMC2535815 DOI: 10.1021/ac062089i] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The theory of the feedback mode of scanning electrochemical microscopy is extended for probing heterogeneous electron transfer at an unbiased conductor. A steady-state SECM diffusion problem with a pair of disk ultramicroelectrodes as a tip and a substrate is solved numerically. The potential of the unbiased substrate is such that the net current flow across the substrate/solution interface is zero. For a reversible substrate reaction, the potential and the corresponding tip current depend on SECM geometries with respective to the tip radius including not only the tip-substrate distance and the substrate radius but also the thickness of the insulating sheath surrounding the tip. A larger feedback current is obtained using a probe with a thinner insulating sheath, enabling identification of a smaller unbiased substrate with a radius that is approximately as small as the tip radius. An intrinsically slow reaction at an unbiased substrate as driven by a SECM probe can be quasi-reversible. The standard rate constant of the substrate reaction can be determined from the feedback tip current when the SECM geometries are known. The numerical simulations are extended to an SECM line scan above an unbiased substrate to demonstrate a "dip" in the steady-state tip current above the substrate center. The theoretical predictions are confirmed experimentally for reversible and quasi-reversible reactions at an unbiased disk substrate using disk probes with different tip radii and outer radii.
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Affiliation(s)
| | | | - Shigeru Amemiya
- To whom correspondence should be addressed. E-mail: . Fax: 412-624-5259
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Wittstock G, Burchardt M, Pust S, Shen Y, Zhao C. Elektrochemische Rastermikroskopie zur direkten Abbildung von Reaktionsgeschwindigkeiten. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200602750] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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O'Mullane AP, Fay N, Nafady A, Bond AM. Preparation of Metal−TCNQ Charge-Transfer Complexes on Conducting and Insulating Surfaces by Photocrystallization. J Am Chem Soc 2007; 129:2066-73. [PMID: 17256937 DOI: 10.1021/ja066874o] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A generic method for the synthesis of metal-7,7,8,8-tetracyanoquinodimethane (TCNQ) charge-transfer complexes on both conducting and nonconducting substrates is achieved by photoexcitation of TCNQ in acetonitrile in the presence of a sacrificial electron donor and the relevant metal cation. The photochemical reaction leads to reduction of TCNQ to the TCNQ(-) monoanion. In the presence of M(x+)(MeCN), reaction with TCNQ(-)(MeCN) leads to deposition of M(x+)[TCNQ]x crystals onto a solid substrate with morphologies that are dependent on the metal cation. Thus, CuTCNQ phase I photocrystallizes as uniform microrods, KTCNQ as microrods with a random size distribution, AgTCNQ as very long nanowires up to 30 mum in length and with diameters of less than 180 nm, and Co[TCNQ](2)(H(2)O)(2) as nanorods and wires. The described charge-transfer complexes have been characterized by optical and scanning electron microscopy and IR and Raman spectroscopy. The CuTCNQ and AgTCNQ complexes are of particular interest for use in memory storage and switching devices. In principle, this simple technique can be employed to generate all classes of metal-TCNQ complexes and opens up the possibility to pattern them in a controlled manner on any type of substrate.
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O'Mullane AP, Neufeld AK, Harris AR, Bond AM. Electrocrystallization of Phase I, CuTCNQ (TCNQ = 7,7,8,8-Tetracyanoquinodimethane), on indium tin oxide and boron-doped diamond electrodes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:10499-505. [PMID: 17129021 DOI: 10.1021/la060408v] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The electrochemical reduction of TCNQ to TCNQ*- in acetonitrile in the presence of [Cu(MeCN)4]+ has been undertaken at boron-doped diamond (BDD) and indium tin oxide (ITO) electrodes. The nucleation and growth process at BDD is similar to that reported previously at metal electrodes. At an ITO electrode, the electrocrystallization of more strongly adhered, larger, branched, needle-shaped phase I CuTCNQ crystals is detected under potential step conditions and also when the potential is cycled over the potential range of 0.7 to -0.1 V versus Ag/AgCl (3 M KCl). Video imaging can be used at optically transparent ITO electrodes to monitor the growth stage of the very large branched crystals formed during the course of electrochemical experiments. Both in situ video imaging and ex situ X-ray diffraction and scanning electron microscopy (SEM) data are consistent with the nucleation of CuTCNQ taking place at a discrete number of preferred sites on the ITO surface. At BDD electrodes, ex situ optical images show that the preferential growth of CuTCNQ occurs at the more highly conducting boron-rich areas of the electrode, within which there are preferred sites for CuTCNQ formation.
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Affiliation(s)
- Anthony P O'Mullane
- School of Chemistry, Monash University, P.O. Box 23, Victoria, 3800, Australia
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Liu Y, Li H, Tu D, Ji Z, Wang C, Tang Q, Liu M, Hu W, Liu Y, Zhu D. Controlling the Growth of Single Crystalline Nanoribbons of Copper Tetracyanoquinodimethane for the Fabrication of Devices and Device Arrays. J Am Chem Soc 2006; 128:12917-22. [PMID: 17002388 DOI: 10.1021/ja0636183] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this paper, (1) a simple and controllable method to synthesize single crystalline nanoribbons of CuTCNQ in a large area was demonstrated by using a physical and chemical vapor combined deposition technique. (2) Nanoribbons synthesized by this method were identified to belong to phase I. (3) Devices and device arrays of nanoribbons were in situ fabricated by this method using gap electrodes and gap electrode arrays. (4) Current-voltage characteristics of crystalline devices and device arrays of nanoribbons exhibited semiconductor properties, and this conclusion was further confirmed by the results of devices based on an individual nanoribbon or microribbon of CuTCNQ (phase I). The controllable synthesis of nanoribbons for the in situ fabrication of crystalline nanodevices and device arrays will be attractive for nanoelectronics. Moreover, semiconductor current-voltage characteristics of the nanoribbons will be beneficial to the understanding of CuTCNQ.
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Affiliation(s)
- Yaling Liu
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, P. R. China
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Effect of the mediator in feedback mode-based SECM interrogation of indium tin-oxide and boron-doped diamond electrodes. J Solid State Electrochem 2006. [DOI: 10.1007/s10008-006-0180-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Harris AR, Neufeld AK, O'Mullane AP, Bond AM. Characterisation of two distinctly different processes associated with the electrocrystallization of microcrystals of phase I CuTCNQ (TCNQ = 7,7,8,8-tetracyanoquinodimethane). ACTA ACUST UNITED AC 2006. [DOI: 10.1039/b607290a] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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