Enhanced photocatalytic H2 evolution and H2O2 generation via ZnIn2S4/g-C3N4 heterojunction

Abstract

In this study, ZnIn₂S₄/g-C₃N₄ heterojunctions were synthesized via an ultrasonic-assisted solventevaporation strategy. The structure, morphology, surface chemistry, optical response, and photoelectrochemical behavior were systematically characterized by XRD, TEM, XPS, UV-Vis DRS and PEC measurements. Among the obtained samples, the 7%-ZnIn₂S₄/g-C₃N₄ nanocomposite delivered the best photocatalytic performance, achieving hydrogen (H₂) and hydrogen peroxide (H₂O₂ ) production rates of 1869.1 μmol•g^-1•h^-1 and 803.8 μmol•g^-1•h^-1 , respectively. The markedly enhanced activity is mainly ascribed to the formation of a well-defined heterojunction, which promotes efficient spatial separation and directional transfer of photogenerated charge carriers, thereby suppressing recombination. Mechanistic analysis suggests that charge migration in the ZnIn₂S₄/g-C₃N₄ nanocomposites follows a type-II heterojunction pathway. In addition, the photocatalysts exhibit excellent stability and recyclability over repeated cycles. This work highlights ZnIn₂S₄/g-C₃N₄ heterostructures as promising photocatalysts for sustainable H₂ and H₂O₂ production, and provides mechanistic insights that offer guidance for designing high-efficiency semiconductor systems for solar energy conversion and green chemical synthesis.