Hollow Nanobox-Shaped Cu2-xS@ZnxCd1-xS Heterojunction by Light Multireflection with Z-Scheme Mechanism for Enhanced Photocatalytic Hydrogen Production

Achieving efficient spatial photoinduced charge separation and light utilization for improving the high photocatalytic activity is still a major obstacle. Here, a Cu_2-xS@Zn_xCd_1-xS (Cu_2-xS@ZnCdS) heterojunction is reported featuring a distinctive core–shell hollow nanobox structure. The Cu_2-xS@Zn_xCd_1-xS exhibits high photocatalytic activity in hydrogen evolution reaction (HER) at the rate of 8175 µmol∙g⁻¹∙h⁻¹ under visible light irradiation, outperforming pristine ZnCdS nanoparticles and Cu_2-xS hollow nanoboxes. The remarkable activity and outstanding stability of Cu_2-x@ZnCdS are attributed to the development of robust interfacial electric fields, and improved light multireflection absorption efficiency as well as the Z-scheme mechanism. The electron paramagnetic resonance (EPR) and in situ X-ray photoelectron spectroscopy (XPS) measurements gave the direct evidence of the formation of the Z-scheme, which maintained the high redox potentials of each ZnCdS and Cu_2-xS. This study gives the guideline for the design of heterojunction with the Z-scheme mechanism, leading to the high photocatalytic performance and remarkable stability.