Enhanced solar-driven hydrogen evolution via C3N4/NiO/ZnO ternary heterojunction nanocomposite with efficient charge separation

The development of efficient photocatalysts for solar-driven hydrogen production remains a critical challenge in renewable energy research. This study presents a novel C₃N₄/NiO/ZnO (CNZO) ternary nanocomposite synthesized via a facile co-precipitation method for enhanced photocatalytic (PC) hydrogen (H₂) evolution under visible light irradiation. The structural and morphological properties of the nanocomposite were systematically characterized using X-ray Diffraction (XRD), Raman spectroscopy, and Scanning Electron Microscopy (SEM), confirming the successful integration of C₃N₄ with NiO and ZnO. Optical studies, including UV–vis absorbance and photoluminescence (PL) spectroscopy, revealed improved visible-light absorption and reduced charge recombination in the ternary system compared to its individual components. The optimized photocatalyst demonstrated exceptional hydrogen production performance, achieving a rate of 2.87 mmolg⁻¹h⁻¹, which was significantly higher than that of binary composites (C₃N₄/NiO, C₃N₄/ZnO, and NiO/ZnO) and pristine semiconductors. The improved activity was related to the synergistic effects of efficient charge separation at the heterojunction interfaces and extended light absorption. Furthermore, the photocatalyst exhibited excellent stability over multiple cycles, as confirmed by life cycle assessment. These findings highlight the potential of the CNZO ternary nanocomposite as a sustainable and high-performance photocatalyst for solar hydrogen generation, providing valuable insights for the design of advanced photocatalytic systems.