Proton-Coupled Electron Transfer Catalyst: Heterogeneous Catalysis. Application to an Oxygen Evolution Catalyst
Proton-Coupled Electron Transfer Catalyst: Heterogeneous Catalysis. Application to an Oxygen Evolution Catalyst
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DOI：
10.1021/acscatal.0c02532
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发表时间：
2020-07-17
期刊：
影响因子：
12.9
通讯作者：
Costentin, Cyrille
中科院分区：
文献类型：
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作者：
Costentin, Cyrille
在循环伏安法（CV）的框架下研究了质子耦合电子转移（PCET）催化剂。我们分析了多相催化剂，并提供了一个详细的动力学分析的PCET催化剂的情况下，无论是逐步或协调一致的途径预期的各种反应。缓冲溶液和非缓冲水性介质均被考虑。在第一种情况下，我们表明，除了可能的限制缓冲扩散，PCET序列可能是限速的。CV波的形状，位置和强度进行了讨论与每个机制相关的热力学和动力学处罚。当水是水溶液中的质子受体时，水合氢离子从电极表面的扩散是一个关键参数，并且我们表明，对于分步过程，平衡的PCET不是最佳的催化响应。最后，我们说明了这种形式的分析与电沉积的钴氧化物作为PCET催化剂在磷酸盐缓冲液中的析氧反应。PCET处于平衡状态，速率决定步骤是一个化学步骤，可能是O-O键的形成，但CV在研究条件下由缓冲扩散控制。
Proton coupled electron transfer (PCET) catalysts are investigated in the framework of cyclic voltammetry (CV). We analyze heterogeneous catalysts and provide a detailed kinetic analysis of the various responses expected in the case of a PCET catalyst following either stepwise or concerted pathways. Both buffered solution and nonbuffered aqueous media are considered. In the first case, we show that, besides possible limitation by buffer diffusion, the PCET sequence may be rate-limiting. CV wave shape, position, and intensity are discussed in terms of thermodynamic and kinetic penalties associated with each mechanism. When water is the proton acceptor in aqueous solution, diffusion of hydronium ions away from the electrode surface is a key parameter, and we show that, for stepwise processes, the equilibrated PCET is not the optimal catalytic response. Finally, we illustrate this formal analysis with an electrodeposited cobalt oxide behaving as a PCET catalyst for the oxygen evolution reaction in phosphate buffer. The PCET is at equilibrium, and the rate-determining step is a chemical step, presumably O-O bond formation, but the CV is controlled by buffer diffusion in the investigated conditions.