Enhanced Photocatalytic Hydrogen Production by Constructing Ca-Doped ZnIn₂S₄: Modulation of Internal Electric Field and H Adsorption/Desorption

Abstract

Developing efficient photocatalysts for hydrogen production remains a significant challenge due to limitations in charge carrier dynamics and surface reaction efficiency. ZnIn₂S₄, a promising visible-light-responsive photocatalyst, often suffers from rapid recombination of photogenerated carriers and suboptimal surface reactions. In this study, Ca-doped ZnIn₂S₄ was synthesized via a one-step hydrothermal method, demonstrating significantly improved hydrogen production performance. The doping of Ca enhances the internal electric field, facilitating the efficient separation and migration of photo-generated charge carriers. Additionally, Ca doping modifies the electronic structure around S active sites, weakening the S-H_ads bond and promoting H desorption, thereby optimizing the hydrogen production reaction pathway. The Ca-doped ZnIn₂S₄ photocatalyst achieved a hydrogen production rate of 661.32 μmol/g/h, approximately 2.4 times that of the pristine ZnIn₂S₄ (259.39 μmol/g/h). This study demonstrates that Ca doping not only enhances charge carrier dynamics but also precisely adjusts surface properties, providing an effective strategy for developing high-performance photocatalysts for sustainable hydrogen production.