Understanding the reaction mechanism of Kolbe electrolysis on Pt anodes
Understanding the reaction mechanism of Kolbe electrolysis on Pt anodes
复制标题
DOI：
10.1016/j.checat.2022.02.014
复制
发表时间：
2022-05-19
期刊：
影响因子：
--
通讯作者：
Chan, Karen
中科院分区：
文献类型：
--
作者：
Liu, Sihang;Govindarajan, Nitish;Chan, Karen
Kolbe 电解已被提议作为一种有效的电氧化过程，用于从生物质基羧酸合成（不）对称二聚体，但其机制仍存在争议。在这项工作中，我们开发了基于密度泛函理论的微动力学模型，以研究在原始和部分氧化的 Pt 阳极上科尔贝电解乙酸 (CH3COOH) 的反应机理。我们表明，Pt(111)@a-PtO2 表面上的析氧反应 (OER) 的速率决定步骤从 OH* 形成到 H2O 吸附的转变产生了大的塔菲尔斜率，即在 Pt 上高阳极电位下实验观察到的拐点。我们的模拟发现 CH3COO* 脱羧和 CH3* 二聚步骤决定了 Kolbe 反应的活性。这项工作解决了 Pt 阳极上 Kolbe 电解机理的主要争议：拐点区的起源和限速步骤的身份。
Kolbe electrolysis has been proposed as an efficient electro-oxidation process to synthesize ( un)symmetrical dimers from biomassbased carboxylic acids, but its mechanism remains controversial. In this work, we develop a microkinetic model based on density functional theory to study the reaction mechanismof Kolbe electrolysis of acetic acid (CH3COOH) on both pristine andpartially oxidized Pt anodes. We show that the shift in the rate-determining step of the oxygen evolution reaction (OER) on a Pt(111)@a-PtO2 surface from OH* formation to H2O adsorption gives rise to large Tafel slopes, i.e., the inflection zones observed experimentally at high anodic potentials on Pt. Our simulations find that the CH3COO* decarboxylation and CH3* dimerization steps determine the activity of the Kolbe reaction. This work resolves major controversies in the mechanism of Kolbe electrolysis on Pt anodes: the origin of the inflection zone and the identity of the rate-limiting step.