Mesoporous carbon-supported ultrasmall metal nanoparticles via a mechanochemical-driven redox reaction: A "Two-in-One" strategy

Mesoporous carbon supported ultrasmall metal nanoparticles (MNPs) are attracting interests in various catalytic applications. Traditional synthetic methods usually involve tedious and time-consuming procedures. Therefore, it remains a grand challenge to prepare well-defined ultrasmall MNPs on mesoporous carbon support. Here, we successfully synthesized a series of mesoporous carbon-supported ultrasmall noble MNPs including Rh, Ru and Pd via a "Two-in-One" strategy which combines the synthesis of mesoporous carbon with ultrasmall MNPs based on a facile mechanochemical method. The key here is to employ CaC2 as both a carbon source for the construction of porous carbon network and an efficient reducing agent to facilitate the formation of ultrasmall MNPs via a solid-state redox reaction. This method circumvent high-temperature pyrolysis and other tedious procedures for the preparation of mesoporous carbon and MNPs, thus representing a versatile, ultrafast, and scalable strategy. Interestingly, the as-prepared Rh-BM-C after ball milling (BM) exhibits an extraordinary lowoverpotential of 28 mV@10 mA cm (-2) as well as a remarkable turnover frequency (TOF) value of 2.6 H-2 s(-1)@50 mV for hydrogen evolution. Density functional theory (DFT) calculations reveal that nitrogen-doping, type of noble metal and synergistic effect between metal layer and carbon support play a critical role in achieving this compelling HER performance.