Embedding ZnCdS@ZnIn2S4 into thiazole-modified g-C3N4 by electrostatic self-assembly to build dual Z-scheme heterojunction with spatially separated active centers for photocatalytic H2 evolution and ofloxacin degradation

• The dual Z-scheme heterojunction improves the separation and migration efficiency of electron-hole pairs. • The space separation between the oxidation center and the reduction center improves the utilization rate of carriers. • Thiazoles as an electron acceptor to reconstruct electrons on the g-C 3 N 4 surface and adjust its HOMO and LUMO dispersion to improve electron mobility. • ZnCdS@ZnIn 2 S 4 @g-C 3 N 4 -vTA prepared by electrostatic self-assembly, and its intimate interfacial contact shortens the migration distance of carriers. The structural design of the photocatalyst has a great influence on photocatalytic performance. Here, the ZnCdS@ZnIn 2 S 4 @g-C 3 N 4 -vTA with a dual Z-scheme heterojunction structure is prepared by electrostatic self-assembly. It has high photocatalytic hydrogen evolution (11359.9 μmol g −1 h −1 ), excellent OFX degradation performance (95.7%), and good reusability under visible light. The hydrogen production performance of ZnCdS@ZnIn 2 S 4 @g-C 3 N 4 -vTA is about 56, 7, 2 times higher than g-C 3 N 4 , ZnCdS, and ZnIn 2 S 4 , respectively. The excellent photocatalytic performance mainly depends on the following aspects: (1) The dual Z-scheme heterojunction with spatial separation of active centers improves the migration and separation efficiency and utilization of electron-hole pairs. (2) The 4-methyl-5-vinylthiazole (vTA) molecular is grafted to the edge of g-C 3 N 4 by visible light to reconstruct the surface electrons so that the electrons can be transferred to the ZnIn 2 S 4 surface more efficiently to increase the overall carrier transport rate; (3) ZnCdS@ZnIn 2 S 4 @g-C 3 N 4 -vTA prepared by electrostatic self-assembly, and its intimate interfacial contact shortens the migration distance of carriers. In addition, the high specific surface area and pore size of ZnCdS@ZnIn 2 S 4 @g-C 3 N 4 -vTA improves the migration and separation of carriers. Our research provides an expandable idea for designing molecular engineering-based dual Z-scheme heterojunction photocatalysts and nanomaterial composite methods.