Enhancing Photocatalytic Overall Water Splitting Activity of SrTiO₃ Nanoparticles by a Synergetic Pt/CrOx Dual Cocatalyst System

Sunlight-driven photocatalytic overall water splitting (OWS) is a promising approach for solar-to-chemical energy conversion. However, its realization with a single photocatalyst by one-step excitation has been extremely limited due to the rapid recombination of photogenerated charges, slow surface redox kinetics, and undesired reverse reactions. Herein, we sought to enhance the OWS performance of SrTiO3 (STO) by exploring the synergistic effects of different kinds of metal/oxide dual cocatalysts. The results show that the Pt/CrOx-STO system had a superior activity, which achieved stoichiometric water splitting with H2/O2 evolution of 1814.17/1020.47 μmol g–1 h–1 under simulated sunlight, without using any sacrificial reagents. The enhanced efficiency can be attributed to the improved interfacial transport of photogenerated charges and the boosted surface kinetics. Importantly, the CrOx layer served as a selective membrane that prevented the O2 diffusion and facilitated H+ transport, while partially covering the highly active site of Pt nanoparticles, thus significantly inhibiting the reverse recombination reaction of H2 and O2. In particular, this dual catalyst system emphasized a low dependence on the properties of the substrate material and is therefore widely applicable and economical. This work demonstrated the potential of the Pt/CrOx dual cocatalyst modification strategy for optimizing photocatalytic OWS, providing a pathway toward selective and sustainable conversion of H2O to H2 and O2