Two new inorganic–organic hybrid zinc phosphites and their derived ZnO/ZnS heterostructure for efficient photocatalytic hydrogen production

Abstract

Two novel inorganic–organic hybrid zinc phosphites, namely, [Zn(1,2-bimb)_0.5(HPO₃)]_n (1) and [Zn(1,4-bmimb)_0.5(HPO₃)]_n (2), (1,2-bimb = 1,2-bis(imidazol-1ylmethyl)benzene; 1,4-bmimb = 1,4-bis((2-methyl-1H-imidazol-1yl)methyl)benzene) were synthesized for the first time by hydrothermal reaction. Compound 1 generates a three-dimensional (3D) pillared-layer structure with a 2-nodal 3,4-connected 3,4T15 topology. While compound 2 exhibits a 2D hybrid zinc phosphite sheet with a 3,4-connected 3,4L83 topology network. Utilizing compound 1 and compound 2 as templates and Na₂S as an etching agent, a series of highly efficient ZnO/ZnS photocatalysts were obtained. The optimized 1-160 sample demonstrates the highest evolution rate of 22.6 mmol g⁻¹ h⁻¹, exceeding the rate of commercial ZnS samples by more than 14.5 times. The remarkable photocatalytic activity should be attributed to the unique heterojunction structure which shortens the free path of charge carriers and enhances the charge separation efficiency. This work provides a facile strategy for preparing photocatalysts with efficient photocatalytic hydrogen production derived from inorganic–organic hybrid material.