Enhanced hydrogen production from water splitting by Sn-doped ZnO/BiOCl photocatalysts and Eosin Y sensitization

The construction of semiconductor heterojunction for photocatalytic H₂ production from water splitting is an efficient and environment-friendly technology. In this work, ZnO/BiOCl (ZBC) and Sn-doped ZnO/BiOCl (ZBC-S) photocatalysts with Z-scheme heterojunction were successfully prepared by simple hydrothermal method. The photocatalytic H₂ evolution from water splitting by the as-prepared photocatalysts was investigated. The formation of ZnO/BiOCl heterojunction reduces the recombination probability of the photogenerated carriers. The impurity levels originated from Sn doping reduce the band gap width of ZnO and BiOCl to some extent, thereby enhancing the light absorption ability. The ZBC-S composite exhibits the best photocatalytic activity. In addition, the photocatalytic efficiency of H₂ production was improved by sensitization with Eosin Y (EY) dye. The H₂ production rate under simulated sunlight reaches 4146.77 μmol g^?1 h^?1, which is 27 times higher than that of pure ZnO. Finally, the Z-scheme electron transfer route in ZnO/BiOCl heterojunction was determined, and the photocatalytic H₂ production mechanism of EY sensitized ZBC-S was proposed.