A General Selenium-Anchoring Strategy for the Synthesis of Subnanometer Metal Cluster Catalysts

Supported subnanometer metal cluster catalysts possess catalytic sites with multiple metal atoms as in nanoparticles (NPs) and maintain high atomic utilization efficiency as in single-atom catalysts (SACs), making them an emerging type of catalyst to bridge SACs and NPs. However, their controllable synthesis remains a significant challenge. According to the “hard–soft acid–base” theory and the match of atom orbital energy, we herein demonstrate that selenium (Se) is a better choice as the coordinating atom to produce supported subnanometer metal cluster catalysts. A general selenium-anchoring strategy is further developed, and a series of subnanometer noble metal cluster catalysts with an average size of ∼0.7 nm are successfully fabricated, including subnanometer single-metallic clusters (Ir, Pt, Ru, Rh, and Pd) and their subnanometer alloy metal clusters. The highest metal loading can reach as high as 18 wt %. We chose quinoline hydrogenation and the reverse 1,2,3,4-tetrahydroquinoline (py-THQ) dehydrogenation as model reactions, and the results showed that the as-prepared Ir_n/SeC and Pt_n/SeC catalysts exhibited superior catalytic activity and stability, highlighting the geometric and electronic structural advantages of Se-anchored subnanometer metal cluster catalysts.