Charge-transfer-energy-dependent oxygen evolution reaction mechanisms for perovskite oxides
Charge-transfer-energy-dependent oxygen evolution reaction mechanisms for perovskite oxides
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DOI：
10.1039/c7ee02052j
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发表时间：
2017-10-01
影响因子：
32.5
通讯作者：
Shao-Horn, Yang
中科院分区：
文献类型：
--
作者：
Hong, Wesley T.;Stoerzinger, Kelsey A.;Shao-Horn, Yang
大量的研究报道了单一反应机理下氧化物催化剂析氧反应（OER）的电子活性描述符。然而，最近的研究表明，一个单一的机制是不是在整个氧化物化学发挥作用。这些工作强调需要深入研究活性氧化物催化剂的电子结构细节，以及它们如何与OER电位对齐，这对于理解决定催化机制的界面电荷转移动力学至关重要。在这项工作中，我们使用软X射线发射和吸收光谱的钙钛矿分析的偏态密度的绝对能量尺度上，从能量的电子转移和表面去质子化的障碍估计和相关的OER活动。通过这个透镜，我们发现，降低钙钛矿的固态电荷转移能量可以改变OER的机制，从电子转移限制到质子-电子耦合，质子转移限制的反应。这个概念是支持的势能面的分析顺序和协调质子-电子转移途径，使用马库斯模型。我们的工作强调了理解实验OER活性趋势的物理起源与电子描述符的重要性，以及促进氧化物表面去质子化以发现具有增强活性的新催化剂的必要性。
Numerous studies have reported electronic activity descriptors of oxygen evolution reaction (OER) for oxide catalysts under a single reaction mechanism. However, recent works have revealed that a single mechanism is not at play across oxide chemistries. These works underscore a need to deeply investigate the electronic structure details of active oxide catalysts and how they align with the OER potential, which is critical to understanding the interfacial charge-transfer kinetics that dictate catalytic mechanisms. In this work, we use soft X-ray emission and absorption spectroscopy of perovskites to analyze the partial density of states on an absolute energy scale, from which energetic barriers for electron transfer and surface deprotonation were estimated and correlated with OER activity. Through this lens, we identify that decreasing the solid-state charge-transfer energy of perovskites can change the mechanisms of the OER from electron-transfer-limited to proton-electron-coupled, to proton-transfer-limited reactions. This concept is supported by the analysis of potential energy surfaces for sequential and concerted proton-electron transfer pathways using a Marcus model. Our work highlights the importance of understanding the physical origin of experimental OER activity trends with electronic descriptors and the need to promote surface deprotonation from oxides to discover new catalysts with enhanced activity.