Enhancing Photocatalytic Activities for Sustainable Hydrogen Evolution on Structurally Matched CuInS2/ZnIn2S4 Heterojunctions

Abstract

Effective charge separation and migration pose a critical challenge in the field of solar-driven hydrogen production. In this work, a Z-scheme structured CuInS2/ZnIn2S4 heterojunction was successfully fabricated through a two-step hydrothermal synthesis method to significantly enhance the efficiency of solar-to-hydrogen energy conversion. Structural characterization revealed that the lattice-matched CuInS2/ZnIn2S4 heterojunction exhibits an enlarged interfacial contact area, which facilitates the transfer and separation of photogenerated charges. Microscopic analysis indicated that the CuInS2/ZnIn2S4 composite material has a tightly interwoven interface and a morphology resembling small sugar cubes. Photoelectrochemical spectroscopy analysis demonstrated that the heterojunction structure effectively enhances visible light absorption and charge separation efficiency, leading to an improvement in photocatalytic activity. Hydrogen production experimental data indicated that the CuInS2/ZnIn2S4 heterojunction photocatalyst prepared with a CuInS2 content of 20 wt% exhibits the highest hydrogen evolution rate, reaching 284.9 μmol·g−1·h−1. Moreover, this photocatalyst maintains robust photocatalytic stability even after three consecutive usage cycles. This study demonstrated that the Z-scheme CuInS2/ZnIn2S4 heterojunction photocatalyst exhibits enhanced hydrogen evolution efficiency, offering an effective structural design for harnessing solar energy to obtain hydrogen fuel. Therefore, this heterojunction photocatalyst is a promising candidate for practical applications in solar hydrogen production.