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Enhanced Molecular CO2 Electroreduction Enabled by a Flexible Hydrophilic Channel for Relay Proton Shuttling.
ChemSusChem ( IF 7.5 ) Pub Date : 2020-05-07 , DOI: 10.1002/cssc.202001037
Caroline K Williams 1 , Amir Lashgari 1 , Jingchao Chai 1 , Jianbing Jimmy Jiang 1
Affiliation  

The effects of primary and second coordination spheres on molecular electrocatalysis have been extensively studied, yet investigations of third functional spheres are rarely reported. Here, an electrocatalyst (ZnPEG8T ) was developed with a hydrophilic channel as a third functional sphere that facilitates relay proton shuttling to the primary and second coordination spheres for enhanced catalytic CO2 reduction. Using foot‐of‐the‐wave analysis, the ZnPEG8T catalyst displayed CO2‐to‐CO activity (TOFmax) thirty times greater than that of the benchmark catalyst without a third functional sphere. A kinetic isotopic effect (KIE) study, in conjunction with voltammetry and UV/Vis spectroscopy, uncovered that the rate‐limiting step was not the protonation step of the metallocarboxylate intermediate, as observed in many other molecular CO2 reduction electrocatalysts, but rather the replenishment of protons in the proton‐shuttling channel. Controlled‐potential electrolysis using ZnPEG8T displayed a faradaic efficiency of 100 % for CO2‐to‐CO conversion at −2.4 V vs. Fc/Fc+. A Tafel plot was also generated for a comparison to other reported molecular catalysts. This report validates a strategy for incorporating higher functional spheres for enhanced catalytic efficiency in proton‐coupled electron‐transfer reactions.

中文翻译:

增强的分子CO2电还原,通过用于亲子质子穿梭的灵活亲水通道实现。

一级和二级配位球对分子电催化作用的影响已得到广泛研究,但对第三功能团的研究却很少。在这里,开发了具有亲水通道作为第三功能球的电催化剂(ZnPEG8T),该功能球有助于将质子穿梭到第一和第二配位球上,以增强催化CO 2的还原。使用波峰分析,ZnPEG8T催化剂显示出CO 2到CO的活性(最大TOF)是没有第三个功能球的基准催化剂的三十倍。动力学同位素效应(KIE)研究结合伏安法和UV / Vis光谱分析发现,限速步骤不是金属羧酸盐中间体的质子化步骤,正如在许多其他分子CO 2还原电催化剂中观察到的那样,而是在质子穿梭通道中补充质子。使用ZnPEG8T进行的控制电位电解在-2.4 V相对于Fc / Fc +的条件下,CO 2到CO的转换显示法拉第效率为100%。还生成了Tafel图,用于与其他已报道的分子催化剂进行比较。本报告验证了在质子偶联的电子转移反应中结合使用更高功能的球体以提高催化效率的策略。
更新日期:2020-07-07
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