近日，德国马普学会弗里茨-哈伯研究所教授Travis E. Jones研究团队揭示了偏压在电催化析氧反应中的关键作用。 该研究于2020年11月18日发表于国际一流学术期刊《自然》。

析氧反应在许多替代能源方案中扮演着重要角色，因为它提供将可再生电力转化为化学燃料所需的质子和电子。电催化剂通过促进电子转移以及化学键的形成和断裂来加速反应。这种涉及本质不同的过程导致电化学动力学复杂，并且通常指数级依赖过电位，最终导致理解和控制面临挑战。

当施加的偏压驱动反应符合现象学的布特勒-伏尔默理论时就会出现这种行为，该理论侧重于电子转移，使塔菲尔分析能够在准平衡或稳态假设下获得机械论见解。然而，偏压下催化剂表面的电荷也会影响键的形成和断裂，其对电催化速率的影响无法用现象学塔菲尔分析来解释，而且通常是未知的。

在该文中研究人员报道了氧化铱的脉冲伏安法和原位X射线吸收光谱的测量结果，表明施加的偏压并不直接作用于反应坐标，而是通过催化剂中电荷的积累来影响电催化产生的电流。结果表明，活化自由能随着氧化电荷的储存量增多呈线性下降，这种关系是电催化性能的基础，可通过测量和计算来评估。

研究人员期望这些发现和方法将有助于更好地理解其他电催化材料，并设计性能更好的系统。

附：英文原文

Title: Key role of chemistry versus bias in electrocatalytic oxygen evolution

Author: Hong Nhan Nong, Lorenz J. Falling, Arno Bergmann, Malte Klingenhof, Hoang Phi Tran, Camillo Spri, Rik Mom, Janis Timoshenko, Guido Zichittella, Axel Knop-Gericke, Simone Piccinin, Javier Prez-Ramrez, Beatriz Roldan Cuenya, Robert Schlgl, Peter Strasser, Detre Teschner, Travis E. Jones

Issue&Volume: 2020-11-18

Abstract: The oxygen evolution reaction has an important role in many alternative-energy schemes because it supplies the protons and electrons required for converting renewable electricity into chemical fuels1,2,3. Electrocatalysts accelerate the reaction by facilitating the required electron transfer4, as well as the formation and rupture of chemical bonds5. This involvement in fundamentally different processes results in complex electrochemical kinetics that can be challenging to understand and control, and that typically depends exponentially on overpotential1,2,6,7. Such behaviour emerges when the applied bias drives the reaction in line with the phenomenological Butler–Volmer theory, which focuses on electron transfer8, enabling the use of Tafel analysis to gain mechanistic insight under quasi-equilibrium9,10,11 or steady-state assumptions12. However, the charging of catalyst surfaces under bias also affects bond formation and rupture13,14,15, the effect of which on the electrocatalytic rate is not accounted for by the phenomenological Tafel analysis8 and is often unknown. Here we report pulse voltammetry and operando X-ray absorption spectroscopy measurements on iridium oxide to show that the applied bias does not act directly on the reaction coordinate, but affects the electrocatalytically generated current through charge accumulation in the catalyst. We find that the activation free energy decreases linearly with the amount of oxidative charge stored, and show that this relationship underlies electrocatalytic performance and can be evaluated using measurement and computation. We anticipate that these findings and our methodology will help to better understand other electrocatalytic materials and design systems with improved performance.

DOI: 10.1038/s41586-020-2908-2

Source: https://www.nature.com/articles/s41586-020-2908-2