The Impact of Milling Energy on the Structure of Catalysts during the Mechanochemical Synthesis of Single-Atom Catalysts

In recent years, mechanochemical synthesis of single-atom catalysts (SACs) has attracted widespread attention due to its simplicity, low cost, and environmental friendliness. Moreover, it allows for the scalability and general applicability of SACs, making it one of the most promising methods for their industrial production. However, the mechanisms underlying the formation of atomically dispersed metal structures induced by mechanochemistry have not yet been fully explored. Here, the energy equation is used to calculate the energy transferred by the grinding ball to the unit mass of the metal precursor (U m) under different ball-milling parameters. It is observed that as U m increases, the Pt species' particle size, catalyst crystallinity, and catalyst pore size gradually decrease. When U m reaches a sufficiently high level (similar to 571.3 kJ/g), the Pt species are converted to be atomically dispersed, and the Pt species in Pt/ZnO exhibit a higher oxidation state. When the amount of metal precursor increases, the synthesis of Pt1/ZnO is successfully scaled up to 20 g (Pt1/ZnO-20g) by keeping the U m concentration at similar to 571.3 kJ/g. Additionally, Pt1/ZnO-20g exhibits a highly consistent catalytic performance in nitrobenzene hydrogenation, comparable to that of Pt1/ZnO.