Abstract By studying complex model catalysts based on well-defined oxide surfaces, fundamental insights have been obtained into the surface chemistry of many heterogeneously catalyzed processes. In this perspective, we summarize a series of studies, in which we have transferred this model catalysis approach to the field of electrocatalysis. Our model electrocatalysts consisted of Pt nanoparticles (NPs) grown on atomically-defined oxide films. Specifically, we used well-ordered Co 3 O 4 (111) thin films on an Ir(100) support. The Pt NPs were prepared by physical vapor deposition (PVD) and the particle size was varied from a few nanometers to the sub-nanometer size range. We prepared all model catalysts under ultra-high vacuum (UHV) conditions using a dedicated preparation system. This setup enables us to transfer the model catalysts from UHV into the electrochemical environment to apply various in-situ techniques without exposure to air. We investigated the stability window of pristine Co 3 O 4 (111) and Pt/Co 3 O 4 (111) using online inductively coupled plasma mass spectrometry (ICPMS), electrochemical infrared reflection absorption spectroscopy (EC-IRRAS), scanning tunneling microscopy (STM), ex-situ emersion X-ray photoelectron spectroscopy (XPS), and low energy electron diffraction (LEED). Within the stability window (pH 10, 0.3–1.1 V RHE ) the surface structure of the model electrocatalysts is preserved. We analyzed identical samples both in UHV and in the electrochemical environment. Specifically, we applied synchrotron radiation photoelectron spectroscopy (SR-PES) and ex-situ emersion XPS to analyze the electronic structure and we used infrared reflection absorption spectroscopy (IRAS), temperature programmed desorption (TPD), EC-IRRAS, and cyclic voltammetry (CV) to study CO adsorption and oxidation. The model electrocatalysts show pronounced particle size effects and metal support interactions are shown to play a key role in their catalytic reactivity. Of particular importance is an interfacial Pt oxide, which is stabilized by the oxide support and exists at electrode potentials as low as 0.5 V RHE . Moreover, spillover effects enable new reaction mechanisms, which involve oxygen from the oxide support. This review demonstrates the potential of the model electrocatalysis approach to provide fundamental insights into complex oxide-based electrocatalysis. Graphic Abstract

中文翻译：

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带电氧化物模型催化：基于原子定义氧化物膜的复杂电极

摘要 通过研究基于明确定义的氧化物表面的复杂模型催化剂，已经对许多非均相催化过程的表面化学有了基本的了解。从这个角度来看，我们总结了一系列研究，其中我们将这种模型催化方法转移到了电催化领域。我们的模型电催化剂由生长在原子定义的氧化膜上的 Pt 纳米粒子 (NPs) 组成。具体来说，我们在 Ir(100) 载体上使用了有序的 Co 3 O 4 (111) 薄膜。Pt NPs 是通过物理气相沉积 (PVD) 制备的，粒径从几纳米到亚纳米范围不等。我们使用专用的制备系统在超高真空 (UHV) 条件下制备了所有模型催化剂。这种设置使我们能够将模型催化剂从 UHV 转移到电化学环境中，以在不暴露于空气的情况下应用各种原位技术。我们使用在线电感耦合等离子体质谱 (ICPMS)、电化学红外反射吸收光谱 (EC-IRRAS)、扫描隧道显微镜 (EC-IRRAS) 研究了原始 Co 3 O 4 (111) 和 Pt/Co 3 O 4 (111) 的稳定性窗口。 STM)、非原位放射 X 射线光电子能谱 (XPS) 和低能电子衍射 (LEED)。在稳定性窗口（pH 10，0.3–1.1 V RHE）内，模型电催化剂的表面结构得以保留。我们在 UHV 和电化学环境中分析了相同的样品。具体来说，我们应用同步辐射光电子能谱 (SR-PES) 和异位发射 XPS 来分析电子结构，并使用红外反射吸收光谱 (IRAS)、程序升温脱附 (TPD)、EC-IRRAS 和循环伏安法 (CV)研究 CO 的吸附和氧化。模型电催化剂显示出明显的粒度效应，并且显示金属载体相互作用在其催化反应性中起关键作用。特别重要的是界面 Pt 氧化物，它由氧化物载体稳定并存在于低至 0.5 V RHE 的电极电位下。此外，溢出效应使新的反应机制成为可能，其中涉及来自氧化物载体的氧气。这篇综述展示了模型电催化方法为复杂氧化物基电催化提供基本见解的潜力。图形摘要