Single-atom catalysts have attracted great attention in recent years due to their high efficiencies and cost savings. However, there is debate concerning the nature of the active site, interaction with the support, and mechanism by which single-atom catalysts operate. Here, using a combined surface science and theory approach, we designed a model system in which we unambiguously show that individual Pt atoms on a well-defined Cu₂O film are able to perform CO oxidation at low temperatures. Isotopic labelling studies reveal that oxygen is supplied by the support. Density functional theory rationalizes the reaction mechanism and confirms X-ray photoelectron spectroscopy measurements of the neutral charge state of Pt. Scanning tunnelling microscopy enables visualization of the active site as the reaction progresses, and infrared measurements of the CO stretch frequency are consistent with atomically dispersed Pt atoms. These results serve as a benchmark for characterizing, understanding and designing other single-atom catalysts.

单原子催化剂由于其高效率和节省成本而近年来引起了极大的关注。然而，关于活性位点的性质，与载体的相互作用以及单原子催化剂的作用机理存在争议。在这里，我们采用表面科学和理论相结合的方法，设计了一个模型系统，在该模型系统中，我们清楚地表明了定义明确的Cu ₂上的各个Pt原子O膜能够在低温下进行CO氧化。同位素标记研究表明，氧气是由载体提供的。密度泛函理论合理化了反应机理，并证实了Pt中性电荷状态的X射线光电子能谱测量。扫描隧道显微镜使反应过程中的活性位点可视化，并且CO拉伸频率的红外测量值与原子上分散的Pt原子一致。这些结果可作为表征，理解和设计其他单原子催化剂的基准。