Increased Crystallization of CuTCNQ in Water/DMSO Bisolvent for Enhanced Redox Catalysis.

Zakir Hussain,Abdullah M Al-Enizi,Samuel R Anderson,Vipul Bansal,Ayman Nafady,Rajesh Ramanathan,Asma A Alothman

doi:10.3390/nano11040954

Zakir Hussain, Abdullah M Al-Enizi + Show 5 more

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https://doi.org/10.3390/nano11040954

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Journal: Nanomaterials	Publication Date: Apr 8, 2021
Citations: 5	License type: CC BY 4.0

Affiliation: RMIT University, King Saud University

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.

Highlights

Published: 8 April 2021The rich electrical, chemical, magnetic, and optoelectronic properties of charge-transfer complexes based on 7,7,8,8-tetracyanoquinodimethane (TCNQ) has seen substantial interest in using these materials for a range of applications (Figure S1, SupplementaryMaterials show the chemical structure of TCNQ) [1,2,3,4,5,6,7,8]
While MeCN is most commonly employed as the reaction medium for the synthesis of CuTCNQ, our previous work has shown the potential of dimethyl sulfoxide (DMSO) as a preferred reaction solvent for CuTCNQ crystallization due to the superior catalytic performance of CuTCNQ
This suggests that TCNQ0 was consumed during the crystallization of CuTCNQ (≈10% TCNQ consumed during synthesis)

Summary

Introduction

Published: 8 April 2021The rich electrical, chemical, magnetic, and optoelectronic properties of charge-transfer complexes based on 7,7,8,8-tetracyanoquinodimethane (TCNQ) has seen substantial interest in using these materials for a range of applications (Figure S1, SupplementaryMaterials show the chemical structure of TCNQ) [1,2,3,4,5,6,7,8]. The pioneering work led by Dunbar, Miller, Robson, and Bond have seen the development of several strategies including physical [9,10], photochemical [11,12,13], vapor deposition [9,14,15], electrochemical [5,13,16,17,18,19,20,21,22], and wet-chemical synthesis methods [19,23,24,25,26,27,28,29,30,31,32,33,34,35,36] for the fabrication of TCNQ-based charge transfer complexes. The fabrication of phase I CuTCNQ using this approach

Methods

Results

Conclusion