Architecture of urchin-like TiO2 integrated ultrasmall Rh nanoparticles with oxygen vacancy-reinforced electronic metal-support interaction for boosting hydrogen production from ammonia borane hydrolysis

Metal oxide-supported Rh nanoparticles (NPs) can provide abundant catalytically active sites for hydrogen evolution from ammonia borane hydrolysis (ABH). Considering the scarcity and high cost, developing effective strategies to reduce the utilization of Rh and simultaneously improving its catalytic activity is absolutely needed. Here, we develop ultrafine Rh NPs anchored on oxygen vacancies (V-O)-bearing urchin-like TiO2 (U-TiO2). V-O can facilitate the formation of electron-rich metallic Rh surface and boost the H2O dissociation, leading to highly efficient hydrogen generation from ABH without alkali promoters. Noticeably, the temperature-controlled annealing of the Rh/U-TiO2 precursor at 450 degrees C in reducing atmosphere generates the maximum V-O concentration. This arouses strong electronic metal-support interaction between the Vo and Rh NPs to yield electron-rich metallic Rh surface. The obtained Rh/UT-450Vo exhibits a high initial turnover frequency of 1729 min(-1) for ABH without alkali promoters, outperforming that of the contrast samples and most of previously developed Rh catalysts. This finding offers an effective strategy to fabricate high-efficiency metal oxide-supported metal NPs toward catalytic hydrogen production.