Enhanced Z-scheme water splitting at atmospheric pressure with suppression of reverse reactions using Zr-doped BaTaO2N as hydrogen evolution photocatalyst

The present work demonstrates a Z-scheme overall water splitting (ZOWS) system for the photocatalytic production of H2 capable of operating under Ar at near-atmospheric pressure using a narrow-bandgap Zr-doped BaTaO2N photocatalyst. Reverse reactions are suppressed in this system as a consequence of a surface modification of the Pt-loaded, Zr-doped BaTaO2N (Pt/BaTaO2N:Zr) photocatalyst with Cr2O3. The introduction of a Cr2O3 shell was found to effectively inhibit the reduction of [Fe(CN)6]3- that otherwise competes with the H2 evolution reaction, resulting in an improved apparent quantum yield of 1.1 % at 420 nm. By combining this H2 evolution photocatalyst with an O2 evolution photocatalyst based on BiVO4, ZOWS was achieved at near-atmospheric pressure with a solar-to-hydrogen energy conversion efficiency of 0.08 %. This work demonstrates the importance of suppressing reverse reactions during ZOWS at atmospheric pressure and provides valuable guidance for the design and construction of practical green H2 production systems.