Kumeda Tomoaki, Laverdure Laura, Honkala Karoliina, Melander Marko M, Sakaushi Ken
Research Center for Energy and Environmental Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japan.
Department of Chemistry, Nanoscience Center, University of Jyväskylä, P.O. Box 35, 40014, Jyväskylä, Finland.
Angew Chem Int Ed Engl. 2023 Dec 18;62(51):e202312841. doi: 10.1002/anie.202312841. Epub 2023 Nov 20.
The proton-coupled electron transfer (PCET) mechanism of the oxygen reduction reaction (ORR) is a long-standing enigma in electrocatalysis. Despite decades of research, the factors determining the microscopic mechanism of ORR-PCET as a function of pH, electrolyte, and electrode potential remain unresolved, even on the prototypical Pt(111) surface. Herein, we integrate advanced experiments, simulations, and theory to uncover the mechanism of the cation effects on alkaline ORR on well-defined Pt(111). We unveil a dual-cation effect where cations simultaneously determine i) the active electrode surface by controlling the formation of Pt-O and Pt-OH overlayers and ii) the competition between inner- and outer-sphere PCET steps. The cation-dependent transition from Pt-O to Pt-OH determines the ORR mechanism, activity, and selectivity. These findings provide direct evidence that the electrolyte affects the ORR mechanism and performance, with important consequences for the practical design of electrochemical systems and computational catalyst screening studies. Our work highlights the importance of complementary insight from experiments and simulations to understand how different components of the electrochemical interface contribute to electrocatalytic processes.
氧还原反应（ORR）的质子耦合电子转移（PCET）机制是电催化领域长期存在的一个谜团。尽管经过了数十年的研究，但即使在典型的Pt(111)表面上，决定ORR-PCET微观机制随pH值、电解质和电极电位变化的因素仍未得到解决。在此，我们整合了先进的实验、模拟和理论方法，以揭示阳离子对明确的Pt(111)表面上碱性ORR的影响机制。我们揭示了一种双阳离子效应，即阳离子同时决定：i）通过控制Pt-O和Pt-OH覆盖层的形成来确定活性电极表面；ii）内球和外球PCET步骤之间的竞争。从Pt-O到Pt-OH的阳离子依赖性转变决定了ORR的机制、活性和选择性。这些发现提供了直接证据，表明电解质会影响ORR的机制和性能，这对电化学系统的实际设计和计算催化剂筛选研究具有重要意义。我们的工作强调了通过实验和模拟获得互补性见解对于理解电化学界面的不同组成部分如何促进电催化过程的重要性。
