NiAl-LDH-Modified Core–Shell Rod-like ZnO@ZnS Heterostructures for Enhanced Photocatalytic Hydrogen Precipitation

Abstract

Photocatalytic hydrogen production technology is considered as an important approach to solve the problem of energy shortage. The ZnO@ZnS core–shell nanostructure can not only protect the nuclear material from chemical corrosion but also form heterojunctions to improve the catalytic performance; however, the photocatalysis of ZnO@ZnS only responds to the UV region, and its solar light utilization is low. In this paper, ZnO@ZnS rods were prepared and formed covalent bonding in the interface because of the in situ sulfidation process. Subsequently, the two-dimensional NiAl-LDH with positive charge was grown on the surface of ZnO@ZnS by electrostatic self-assembly due to the presence of negatively charged ZnS. So, the prepared ZnO@ZnS@NiAl-LDH composites have the stable interface structure. We compared the hydrogen production efficiency of ZnO, ZnO@ZnS, and ZnO@ZnS@NiAl-LDH under simulated sunlight. The maximum hydrogen production efficiency of the ZnO@ZnS@NiAl-LDH composite was 866.35 μmol g–1 h–1, which was 3.96 times higher than that of ZnO@ZnS (218.41 μmol g–1 h–1), and the sample also had a good stability and recyclability according to the results of the cycling test of photocatalytic H2 generation. Due to the presence of UV-responsive ZnO@ZnS and visible-light-responsive NiAl-LDH, ZnO@ZnS@NiAl-LDH can effectively utilize the entire solar spectrum. The interface structure affected the electron transfer rates so that the synergistic interaction between rod-shaped ZnO@ZnS and layered NiAl-LDH could improve the electron–hole separation rate and the transport rate of photogenerated charge pairs, thus optimizing the photocatalytic performance. This study provides new ideas for the research of ZnO-based materials as photocatalysts.