Phosphatized GaZnInON nanocrystals with core-shell structures for efficient and stable pure water splitting via four-electron photocatalysis

Overall water splitting via solar-driven photocatalysis provides an ideal way to realizing a viable and sustainable hydrogen economy, while the development of efficient photocatalysts remains a grand challenge to date. Herein, we report the successful surface phosphorization of a gallium indium zinc oxynitride (GaInZnON) photocatalyst, which comprises a GaInZnON core and a thin InP shell. The success to the synthesis relies on the rapid diffusion of In from the bulk to the crystal surface and preferential combination of In with P to form an outer layer. The enhanced charge migration was confirmed with characterization and the charge redistribution difference around the heterojunction. The core-shell composite having an ideal type-II band alignment enables efficient charge separation within the particle scale and significantly improved photocatalytic activity toward pure water splitting for simultaneous and stoichiometric H₂ and O₂ evolution. The apparent quantum efficiencies can be up to 10.6% at 430 nm and 13.8% at 350 nm, respectively. Our results suggest that such core-shell GaInZnON@InP architectures hold great potential for efficient and scalable solar hydrogen generation.