Tuning ZnS/ZnAl–LDH heterostructures via Cd incorporation for enhanced photocatalytic hydrogen evolution

This work investigated incorporating Cd into sulphurated ZnAl layered double hydroxide (LDH)-derived materials, then using them as photocatalysts for hydrogen production. A series of ZnAlCd–LDHs was prepared by urea-assisted precipitation followed by partial sulphuration to obtain ZnS/LDH heterostructures. The materials were characterised by different optical and electrochemical techniques, and these results were correlated with hydrogen production under UV light using methanol as a sacrificial agent. The heterostructure containing 3% mol Cd exhibited the highest hydrogen evolution rate of 10 263 μmol g −1 h −1 , approximately 2.7 times that of the Cd-free counterpart. Sulphuration decreased the band gap from approximately 5.3 eV to 3.5–3.6 eV, and the electrochemical measurements supported improved interfacial charge transport in the optimised heterostructure. Nevertheless, no detectable hydrogen evolution was observed under the visible-light conditions tested. The results presented in this work identified Cd content and partial sulphuration as key parameters for enhancing UV-driven hydrogen evolution in ZnS/LDH heterostructures and are a step further in understanding how to develop more efficient hydrogen-production materials.