Efficient hydrogen production by γ-g-C3N4/Ag–CdS heterojunction photocatalyst via S-scheme mechanism

Abstract

Photocatalytic water splitting is a promising approach for sustainable hydrogen generation. This study aims to develop a simple and efficient photocatalyst and to investigate the influence of gamma irradiation on photocatalytic water splitting performance. A gamma irradiated graphitic carbon nitride/silver–cadmium sulfide (γ-g-C₃N₄/Ag–CdS) heterostructure composite was synthesized via microwave-assisted hydrothermal method, followed by melamine polymerization and the resultant catalyst was subsequently exposed to gamma radiation. The γ-g-C₃N₄/Ag–CdS catalyst exhibited enhanced photocatalytic hydrogen production, demonstrating the effectiveness of gamma irradiation and the incorporation of Ag nanoparticles, which enabled an S-scheme electron transfer pathway, thereby improving stability and catalytic performance while reducing reliance on high-cost noble metals such as platinum. Enhanced efficiency was achieved through suppressed charge carrier recombination, improved interfacial charge transfer, and increased visible-light absorption. Gamma irradiation promoted charge separation without additional chemical reagents, and microwave-assisted synthesis reduced reaction time and energy consumption. The hydrogen evolution rate of the gamma irradiated composite reached 5600 μmol g⁻¹ h⁻¹, compared to 4100 μmol g⁻¹ h⁻¹ for the unirradiated sample. The γ-g-C₃N₄/Ag–CdS photocatalyst delivers a ∼36% increase in hydrogen evolution rate compared to the untreated composite. This work provides valuable insights for the development of stable and high-performance photocatalysts for sustainable hydrogen generation.