Construction of ZnIn₂S₄/CdS/PdS S-Scheme Heterostructure for Efficient Photocatalytic H₂ Production

It is facing a tremendous challenge to develop the desirable hybrids for photocatalytic H₂ generation by integrating the advantages of a single semiconductor. Herein, an all-sulfide ZnIn₂S₄/CdS/PdS heterojunction is constructed for the first time, where CdS and PdS nanoparticles anchor in the spaces of ZnIn₂S₄ micro-flowers due to the confinement effects. The morphology engineering can guarantee rapid charge transfer owing to the short carrier migration distances and the luxuriant reactive sites provided by ZnIn₂S₄. The S-scheme mechanism between ZnIn₂S₄ and CdS assisted by PdS cocatalyst is testified by in situ irradiated X-ray photoelectron spectroscopy and electron paramagnetic resonance (EPR), where the electrons and holes move in reverse driven by work function difference and built-in electric field at the interfaces. The optimal ZnIn₂S₄/CdS/PdS performs a glaring photocatalytic activity of 191.9 µmol h⁻¹ (10 mg of catalyst), and the largest AQE (apparent quantum efficiency) can reach a high value of 26.26%. This work may afford progressive tactics to design multifunctional photocatalysts.