Engineering an Ag/CuO/g-C₃N₄ heterojunction for high-efficiency solar-to-hydrogen conversion

A ternary Ag/CuO/g-C₃N₄ heterostructure was synthesized and evaluated as a photoactive electrode in photoelectrochemical water splitting. CuO provides broad visible-light absorption, g-C₃N₄ contributes excellent chemical stability, and Ag nanoparticles enhance electron transport through plasmonic resonance. Heterojunction formation and synergistic interfacial interactions collectively improve photoelectrochemical (PEC) efficiency. The effect of silver loading was investigated to identify the optimal composition for PEC performance. XPS and FTIR confirmed the successful formation of chemical bonds and heterojunctions between CuO and g-C₃N₄, along with the effective Ag incorporation into the nanocomposite structure. UV-vis spectroscopy revealed a pronounced enhancement in visible-light absorption with increasing Ag content, arising from the synergistic contributions of CuO (narrow band gap), g-C₃N₄ (UV-blue absorption), and Ag nanoparticles (plasmonic enhancement). This leads to a remarkable improvement in photocatalytic activity. PEC measurements revealed that the 3.34% Ag/CuO/g-C₃N₄ heterostructure exhibited the highest photocurrent density of -9.97 mA cm^-2. The 3.34% Ag/CuO/g-C₃N₄ heterostructure demonstrates potential as a highly hopeful photoelectrode for efficient and sustainable solar-driven hydrogen production.