Atomically dispersed catalysts refer to substrate-supported heterogeneous catalysts featuring one or a few active metal atoms that are separated from one another. They represent an important class of materials ranging from single-atom catalysts (SACs) and nanoparticles (NPs). While SACs and NPs have been extensively reported, catalysts featuring a few atoms with well-defined structures are poorly studied. The difficulty in synthesizing such structures has been a critical challenge. Here we report a facile photochemical method that produces catalytic centers consisting of two Ir metal cations, bridged by O and stably bound to a support. Direct evidence unambiguously supporting the dinuclear nature of the catalysts anchored on α-Fe₂O₃ is obtained by aberration-corrected scanning transmission electron microscopy (AC-STEM). Experimental and computational results further reveal that the threefold hollow binding sites on the OH-terminated surface of α-Fe₂O₃ anchor the catalysts to provide outstanding stability against detachment or aggregation. The resulting catalysts exhibit high activities toward H₂O photooxidation.

原子分散的催化剂是指以一种或几种彼此分离的活性金属原子为特征的底物负载的非均相催化剂。它们代表了重要的一类材料，范围从单原子催化剂（SAC）和纳米颗粒（NP）。尽管已经广泛报道了SAC和NP，但对以几个原子具有明确结构的催化剂的研究却很少。合成这种结构的困难一直是一个严峻的挑战。在这里，我们报告了一种简便的光化学方法，该方法产生的催化中心由两个Ir金属阳离子组成，它们被O桥接并稳定地结合到载体上。直接的证据明确地支撑的催化剂的双核性质锚固在的α-Fe ₂ ö ₃通过像差校正的扫描透射电子显微镜（AC-STEM）获得。实验和计算结果进一步表明，α-Fe的OH封端的表面上的三倍中空结合位点₂ ö ₃锚催化剂以提供防止脱离或聚集突出的稳定性。所得催化剂显示出对H ₂ O光氧化的高活性。