Construction of Bi–Bi2S3/Zn0.5Cd0.5S tubular heterojunction for enhancing photocatalytic H2 production

Photocatalytic H₂ production is considered as a promising method to solve the energy crisis, and how to increase the photocatalytic efficiency is an urgent issues that need to be addressed. In this work, Bi–Bi₂S₃/Zn_0.5Cd_0.5S (BBS/ZCS) composites were successfully prepared by a simple hydrothermal method. By electrostatic attraction, Zn_0.5Cd_0.5S (ZCS) nanoparticles were loaded on the surface of Bi–Bi₂S₃ (BBS) microtubes, facilitating the formation of heterojunctions. Although BBS showed little activity in H₂ production, it largely enhanced the photocatalytic performance of ZCS. After optimizing the amount of BBS cocatalyst, it was found that 10% BBS/ZCS had the best H₂ production performance of 10.18 mmol g⁻¹ h⁻¹, which was 30 times higher than that of ZCS (0.34 mmol g⁻¹ h⁻¹). The enhanced photocatalytic performance could be ascribed to the formation of interfacial heterojunctions, as the photogenerated electrons of ZCS migrate to the Bi⁰ while photogenerated holes transfer to the valence band (VB) of Bi₂S₃. With BBS as the bridge to accept the photogenerated electrons and holes of ZCS, the fast recombination of photogenerated charge carriers (PCCs, including photogenerated electrons and holes) for ZCS was improved. This work not only promotes the separation of PCCs, but provides a new idea for the design of catalysts.