HNO3 exfoliated ultrathin g-C3N4 loaded CuZnInS as a Z-scheme heterojunction photocatalyst for efficient photocatalytic hydrogen evolution

Abstract

Graphitic carbon nitride-based (g-C₃N₄) catalysts that respond to visible light have exhibited substantial potential for application in water splitting for hydrogen production. However, the material faces challenges such as low quantum efficiency and restricted utilization of visible light. In this study, we developed a Z-scheme heterojunction photocatalyst comprising ultrathin g-C₃N₄ (ExCN) and CuZnInS (CZIS), which significantly enhances the photocatalytic hydrogen production performance. Notably, the hydrogen production rate reached up to 185.23 μmol g⁻¹ h⁻¹ without platinum co-catalysts. Comprehensive characterization and mechanism analysis revealed that the ultrathin, porous structure and oxygen-doped characteristics of ExCN markedly increased the number of active sites and extend the visible light response range. Moreover, ExCN serves as an effective carrier for CZIS particles. The coupling of CZIS with ExCN to form a Z-scheme heterojunction effectively promoted the spatial separation of photogenerated charge carriers. The narrow bandgap of CZIS broadens the light response range, while metal sites function as electron traps, suppressing electron-hole recombination and further enhancing catalytic efficiency. This study offers new insights into the rational design of visible-light-responsive hydrogen production catalysts based on graphitic carbon nitride.