Universal low-temperature oxidative thermal redispersion strategy for green and sustainable fabrication of oxygen-rich carbons anchored metal nanoparticles for hydrogen evolution reactions

Supported metal nanoparticles (MNPs) have shown great promise in catalytic hydrogen evolutions because of the highly efficient utilization of metal atoms, while the low binding strength between MNPs and supports results in the agglomeration of MNPs into larger particles, considerably decreasing the catalytic efficiency. Herein, we smartly develop a universal, green, and sustainable low-temperature oxidative thermal redispersion strategy to fabricate metal oxide precursors and subsequently well dispersing and stabilizing MNPs (M = Rh, Ru, Ir) over oxygenated carbons (Mesoporous carbon, Ketjen black, and Vulcan carbon), which can be utilized as efficient catalysts for hydrogen production from ammonia borane (AB) hydrolysis and hydrogen evolution reaction (HER). Such flexible modulation strategy enables the formation of oxidized metal species on oxygenated carbons, which is the key to synthesize ultrasmall MNPs against sintering and agglomeration during the reduction process. Attributing to the innately structural/componential/surficial superiorities, the optimal Rh/C-300A-350H exhibits the highest catalytic activity toward hydrogen evolution from AB hydrolysis and HER with turnover frequencies of 3308/5040 min(-1) in aqueous/basic solutions and an overpotential of 29 mV at 10 mA cm(-2) in 1.0 M KOH, respectively. With the similar activation mechanism for dissociation of O-H bond in H2O, the highly dispersed Rh NPs with ultrafine sizes and electronic metal-support interaction are responsible for the excellent catalytic activity toward the hydrogen evolution reactions. This study presents an extremely facile and sustainable modulation strategy for increasing the adhesion of MNP catalysts on oxygenated carbons for catalytic applications.