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Understanding Surface-Mediated Electrochemical Reactions: CO2 Reduction and Beyond
ACS Catalysis ( IF 12.9 ) Pub Date : 2018-07-20 00:00:00 , DOI: 10.1021/acscatal.8b02181
Marco Dunwell 1 , Wesley Luc 1 , Yushan Yan 1 , Feng Jiao 1 , Bingjun Xu 1
Affiliation  

Understanding reaction pathways and mechanisms for electrocatalytic transformation of small molecules (e.g., H2O, CO2, and N2) to value-added chemicals is critical to enabling the rational design of high-performing catalytic systems. Tafel analysis is widely used to gain mechanistic insights, and in some cases, has been used to determine the reaction mechanism. In this Perspective, we discuss the mechanistic insights that can be gained from Tafel analysis and its limitations using the simplest two-electron CO2 reduction reaction to CO on Au and Ag surfaces as an example. By comparing and analyzing existing as well as additional kinetic data, we show that the Tafel slopes obtained on Au and Ag surfaces in the kinetically controlled region (low overpotential) are consistently ∼59 mV dec–1, regardless of whether catalysts are polycrystalline or nanostructured in nature, suggesting that the initial electron transfer (CO2 + e → CO2) is unlikely to be the rate-limiting step. In addition, we demonstrate how initial mechanistic assumptions can dictate experimental design, the result of which could in turn bias mechanistic interpretations. Therefore, as informative as Tafel analysis is, independent experimental and computational techniques are necessary to support a proposed mechanism of multielectron electrocatalytic reactions, such as CO2 reduction.

中文翻译:

了解表面介导的电化学反应:CO 2的还原作用及其他

了解小分子(例如H 2 O,CO 2和N 2)向增值化学品进行电催化转化的反应途径和机理,对于合理设计高性能催化系统至关重要。塔菲尔分析广泛用于获得机理的见解,在某些情况下,塔菲尔分析已用于确定反应机理。在此“透视图”中,我们讨论了使用最简单的两电子CO 2可从Tafel分析中获得的机理见解及其局限性以Au和Ag表面上的CO还原反应为例。通过比较和分析现有以及其他动力学数据,我们发现在动力学控制区域(低超电势)的Au和Ag表面上获得的Tafel斜率始终约为59 mV dec –1,无论催化剂是多晶的还是纳米结构的在自然界中,这表明初始电子转移(CO 2 + e →CO 2 )不太可能成为限速步骤。此外,我们演示了初始的机械假设如何决定实验设计,其结果又可能反过来对机械的解释产生偏差。因此,就象Tafel分析一样有用的信息,必须有独立的实验和计算技术来支持提出的多电子电催化反应机理,例如CO 2还原。
更新日期:2018-07-20
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