Interfacial construction of SnS/ZnCdS nanopolyhedron heterojunctions for enhanced photocatalytic hydrogen evolution.

ZnCdS, a metal chalcogenide solid solution, has attracted significant attention. However, two primary challenges hinder its widespread application in photocatalytic hydrogen evolution: the rapid recombination rate of photogenerated carriers and susceptibility to photo-oxidation in the aqueous environments. In this article, a facile hydrothermal route was employed for the first time to uniformly assemble SnS nanoparticles onto the surface of ZnCdS (ZCS) nanopolyhedra. The intimate contact of two materials resulted in the formation of heterojunctions. By adjusting the content of SnS, the hydrogen evolution reaction (HER) performance was optimized to reach up to 12170 μmol/gh, which is 1.9 times of the pristine ZCS. Notably, the photocatalyst demonstrated remarkable stability with an apparent quantum yield (AQY) of 15.5% at 420 nm. The enhanced photocatalytic performance can be attributed to the following factors: (i) The heterojunction composite, with larger surface area and more micropores, provides additional active sites and exhibits high photocatalytic activity; (ii) The internal electric field accelerates the separation of photogenerated carriers and reduces the recombination rate of electron-hole pairs; (iii) The photogenerated holes can be quickly transferred to the valence band of SnS and react with triethanolamine, thereby significantly reducing the photo-oxidation of ZCS. This work not only proposed a feasible route to improve the photocatalytic activity of ZCS, but also provided insights into the role of heterojunctions and the reaction mechanism.