The interfacial electronic and geometric effects behind the size effect are crucial in determining the catalytic performance of supported metal catalysts, whereas they remain still unknown for most of important heterogeneous catalytic reactions such as water-gas shift reaction (WGSR). In this work, we report a profound size effect in five Pt/CeO₂ catalysts among Pt single atoms, sub-nanoclusters (ca. 0.8 nm) and nanoparticles (3.8-9.3 nm) for the WGSR. The catalyst with about 3.8 nm Pt nanoparticles had the highest activity, superior to the other four Pt/CeO₂ catalysts. Pt^δ+-O_V-Ce³⁺ species served as the interfacial active sites, wherein the carboxyl pathway seemed more energetically preferred than the formate route, and favored high activity. Such high activity and pathway preference are due to both of the electronic and geometric effects. On the one hand, the electronic metal-support interaction (EMSI) modulated by the metal deposit size which tunes the activation of the CO adsorbed on Pt sites. On the other hand, the abundant interfacial oxygen vacancies for the geometric effect of providing the active sites to activate and dissociate H₂O.

尺寸效应背后的界面电子和几何效应对于确定负载型金属催化剂的催化性能至关重要，而对于大多数重要的非均相催化反应，例如水煤气变换反应（WGSR），它们仍然未知。在这项工作中，我们报告了WGSR的Pt单原子，亚纳米簇（约0.8 nm）和纳米颗粒（3.8-9.3 nm）中的五种Pt / CeO ₂催化剂的尺寸效应。具有约3.8nm Pt纳米颗粒的催化剂具有最高的活性，优于其他四种Pt / CeO ₂催化剂。铂^δ+ -O _V -Ce ³⁺物种途径作为界面活性位点，其中羧基途径似乎比甲酸途径在能量上更优选，并且倾向于高活性。如此高的活性和途径偏好是由于电子和几何效应。一方面，受金属沉积物大小调节的电子金属-载体相互作用（EMSI）调节了吸附在Pt位上的CO的活化。另一方面，大量的界面氧空位用于提供激活和解离H ₂ O的活性位的几何效应。