Controlling the morphological and redox properties of the CuTCNQ catalyst through solvent engineering
Controlling the morphological and redox properties of the CuTCNQ catalyst through solvent engineering
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DOI：
10.1007/s42247-019-00026-8
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发表时间：
2019-03-01
影响因子：
3.8
通讯作者：
Bansal, Vipul
中科院分区：
文献类型：
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作者：
Hussain, Zakir;Ojha, Ruchika;Bansal, Vipul
基于溶液的配位聚合物CuTCNQ（TCNQ=7,7,8,8-四氰基醌二甲烷）的合成以两相存在，主要使用乙腈（MeCN）作为溶剂。然而，我们对 CuTCNQ 在其他溶剂中的生长和性能的了解仍然有限。在这项工作中，在两种质子溶剂（MeOH、EtOH）和四种非质子溶剂（MeCN、DMSO、DMF、THF）中在铜箔上合成 CuTCNQ，使我们能够对反应介质在 CuTCNQ 的离散形态和相自发结晶中的重要作用获得新的认识。还开发了一种新的相识别电化学方法来支持这项研究。研究结果表明：(i) 介电常数较高的溶剂有利于 CuTCNQ 结晶； (ii) 无论使用何种溶剂，使用高温（60℃与常规合成中的25℃）可促进CuTCNQ结晶并促进I相向II相的转化； (iii) I相CuTCNQ比II相CuTCNQ具有增强的氧化还原催化（硫代硫酸盐还原铁氰化物）性能； (iv)催化剂的量不一定是驱动催化反应的最重要因素，其他因素，例如形态、氧化还原特性和合成CuTCNQ的溶剂可能决定整体催化性能。这些发现强调了了解 CuTCNQ 合成中溶剂和温度等参数影响的重要性，作为提供具有改进催化活性的材料的一种手段。
The solution-based synthesis of the coordination polymer, CuTCNQ (TCNQ=7,7,8,8-tetracyanoquinodimethane), which exists in two phases, has predominately used acetonitrile (MeCN) as the solvent. However, our knowledge on the growth and properties of CuTCNQ in other solvents remains limited. In this work, the synthesis of CuTCNQ on Cu foil in two protic (MeOH, EtOH) as well as four aprotic (MeCN, DMSO, DMF, THF) solvents has allowed us to obtain new insights into the important role of the reaction medium in the spontaneous crystallization of CuTCNQ in discrete morphologies and phases. A new electrochemical method for phase identification also has been developed to support this study. Findings reveal that (i) the solvents with higher dielectric constants favor CuTCNQ crystallization; (ii) irrespective of the solvent, use of high temperature (60 degrees C vs. 25 degrees C in conventional synthesis) promotes CuTCNQ crystallization and facilitate conversion of phase I to phase II; (iii) phase I CuTCNQ possess enhanced redox catalysis (ferricyanide reduction by thiosulfate) performance over phase II CuTCNQ; and (iv) the amount of catalyst is not necessarily the most important factor for driving catalytic reactions, and other factors, such as, morphology, redox characteristics and solvent in which the CuTCNQ is synthesized may dictate the overall catalytic performance. These findings emphasize the importance of understanding the influence of parameters, such as, solvent and temperature in CuTCNQ synthesis as a means of providing materials with improved catalytic activity.