德国卡尔斯鲁厄理工学院Christof Wll小组近日取得一项新成果。经过不懈努力，他们的研究开发出了低温CO氧化铈表面的协同效应。该研究于2025年2月16日发表于国际一流学术期刊《美国化学会杂志》上。

在这项研究中，该研究组介绍了红外反射-吸收光谱在块状单晶CeO₂模型系统上的实验结果（111）。与预期相反，将还原表面暴露于80k的双氧（O₂）中不会产生活性氧，如超氧或过氧。值得注意的是，在吸附CO存在的情况下，发生了意想不到的低温氧化反应，在氧化CeO₂底物的同时消耗CO。由于在如此低的温度下，撞击的O₂和吸附的CO之间不太可能发生直接反应，因此提出了一种新的机理。广泛的自旋极化密度泛函理论（DFT）计算表明，氧空位在这种低温CO氧化中起着关键作用。这些空位最初位于亚表面区域（Vss），通过与CO和O₂的协同相互作用迁移到表面（Vs），导致O₂活化并形成超氧或过氧物质。详细的分析确定了关键的反应中间体，并量化了它们的吸附能和激活障碍。他们的研究结果表明，与碳酸盐途径相比，过氧化物介导的途径具有较低的活化屏障，更有利于CO在低温下氧化。该研究为研究地下氧空位在气体O₂和CO在CeO₂上的活化机制中的动态作用提供了有价值的见解。

据了解，在金属氧化物底物上，一氧化碳（CO）和活性氧产生二氧化碳的反应机制仍然知之甚少，特别是关于氧空位的作用和活性氧吸附物的性质。

附：英文原文

Title: Synergistic Effects in Low-Temperature CO Oxidation on Cerium Oxide Surfaces

Author: Pablo G. Lustemberg, Chengwu Yang, Yuemin Wang, M. Veronica Ganduglia-Pirovano, Christof Wll

Issue&Volume: February 16, 2025

Abstract: The mechanisms underlying the reaction between carbon monoxide (CO) and activated dioxygen on metal oxide substrates to produce CO₂ remain poorly understood, particularly regarding the role of oxygen vacancies and the nature of the activated O₂ adsorbate. In this study, we present experimental findings from infrared reflection–absorption spectroscopy on a model system of bulk monocrystalline CeO₂(111). Contrary to expectations, exposing the reduced surface to dioxygen (O₂) at 80K does not yield activated oxygen species, such as superoxo or peroxo. Notably, in the presence of adsorbed CO, an unexpected low-temperature oxidation reaction occurs, consuming CO while oxidizing the CeO₂ substrate. Since a direct reaction between impinging O₂ and adsorbed CO is unlikely at these low temperatures, a novel mechanism is proposed. Extensive spin-polarized density functional theory (DFT) calculations reveal that oxygen vacancies play a critical role in this low-temperature CO oxidation. Initially located in the subsurface region (Vss), these vacancies migrate to the surface (Vs) via a concerted interaction with coadsorbed CO and O₂, leading to O₂ activation and the formation of superoxo or peroxo species. Detailed analysis identifies key reaction intermediates and quantifies their adsorption energies and activation barriers. Our findings suggest that the peroxo-mediated pathway, with its lower activation barrier, is more favorable for CO oxidation at low temperatures compared to the carbonate pathway. This study provides valuable insights into the dynamic role of subsurface oxygen vacancies in the activation of gaseous O₂ and CO oxidation mechanisms on CeO₂.

DOI: 10.1021/jacs.4c17658

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.4c17658