Interfacial charge transfer bridge on SrTiO3 crystal boosts solar water splitting

SrTiO₃ particulate catalysts have demonstrated significant potential in solar water splitting, making them a cost-effective solution for green hydrogen generation. However, the exorbitant total cost associated with utilizing the ultra-precious metal Rh even at content as low as 0.1 wt% for hydrogen evolution necessitates the exploration of efficient and cost-effective alternatives. In this work, we developed Pt-Ni alloy hydrogen evolution cocatalysts to substitute for Rh. We deposited them with CrO_x passivation layers and CoOOH oxygen evolution cocatalysts onto the surface of the K-doped SrTiO₃ crystal for overall water splitting. Studies revealed that K⁺ can serve as an electron accumulation center during photoexcitation and the construction of an interfacial K-O-Pt bridge can effectively facilitate the charge transfer. After optimization, Pt₂Ni@CrO_x/K-SrTiO₃/CoOOH exhibits desirable photocatalytic overall water-splitting activity, with the apparent quantum yield (AQY) of 73.46 % (365 nm) and solar-to-hydrogen (STH) conversion efficiency of 0.54 %. This surpasses the catalytic activity of ultra-precious metal Rh and exceeds the catalytic activity of Pt-Ni alloys constructed in situ on Al-SrTiO₃ surfaces. This work would facilitate the development of efficient photocatalysts to produce hydrogen economically.