Facile preparation of porous g-C₃N₄-based CuO@Ag nanocomposite for photocatalytic degradation of methylene blue dye and hydrogen evolution under visible light

In this work, a facile strategy was developed for the preparation of porous graphitic carbon nitride (g-C₃N₄) based CuO@Ag nanocomposite. A porous 2D g-C₃N₄ sheet was prepared via a simple glucose-mediated thermal polymerization reaction. CuO nanoparticles were decorated on the g-C₃N₄ surface using a simple precipitation method. Ag nanoparticles were formed on the g-C₃N₄ surface by the reduction method. In this process, glucose is responsible for both the reduction of Ag and the creation of porous material. This is the first report of dual-functional synthesis using glucose. The crystalline phase, functionality, formation, morphology, and optical properties of synthesized nanomaterials were determined using XRD, FTIR, FESEM, TEM, and UV-DRS. The resulting composite material exhibited remarkable photocatalytic activity for the degradation of methylene blue dye and hydrogen evolution under visible-light irradiation. The optimized nanocomposite achieved ∼98 % dye removal within 120 min and a hydrogen evolution rate of 2700 μmol h⁻¹ g⁻¹, which is much higher compared to single-component and pure g-C₃N₄. The degradation results also demonstrate excellent cyclic stability. The improved performance was ascribed to the localized surface plasmon resonance (LSPR) of Ag nanoparticles and effective electron–hole separation via a heterojunction process. The synergistic effect of CuO nanoparticles and plasmonic Ag on porous g-C₃N₄ significantly enhances visible light absorption, charge separation, and surface-active sites.