Boron-doping-induced modulation of structural parameters of pristine commercial carbon black for promoting Ru-catalyzed O[sbnd]H bond activation toward hydrogen evolution

Abstract

Owing to the lack of adequate nucleation sites for metal nanoparticles (NPs) and weak metal-support interaction, pristine carbon materials supported metal NPs suffer from limited surface-exposed active sites and thereby low catalytic activity. Herein, we report a sodium borohydride-mediated modification of commercial Valcan carbon (VC) to produce B-doped VC (BVC) as a useful support to deposit Ru NPs (Ru/BVC) for hydrogen production from ammonia borane hydrolysis (ABH). The B-doping endows BVC with not only more surface functional groups and defect sites but also abundant meso/macroporous structure and hydrophilic surface, facilitating the generation of uniformly dispersed ultra-small Ru NPs (d = 1.42 nm) with strong electronic metal-support interaction. The optimal Ru/BVC catalyst exhibits an excellent activity with a turnover frequency of 1577.0 min−1 (depending on Ru dispersion). Isotopic and alkali promotion experiments unveil the rate-determining step (RDS) for ABH is the oxidative cleavage of the OH bond in water. The copious surface-exposed active sites and the regulated electron distribution between Ru NPs and BVC efficiently reduce the energy barrier for RDS, thereby promoting catalytic performance of hydrogen evolution from ABH. This simple and efficient heteroatom-doping strategy is easily extended to fabricate efficient catalysts with promoted performance for catalytic applications.