One-step thermal synthesis of Ag-modified g-C₃N₄/N-doped TiO₂ hybrids with enhanced visible-light photocatalytic activity

A series of silver nanoparticle-modified graphitic carbon nitride/N-doped TiO₂ hybrids (Ag/g-C₃N₄/N-TiO₂ or ACTs) were prepared by one-step in situ calcination process at 550 °C for 3 h in air atmosphere. The morphology, structure, and optical properties of ACTs with different Ag contents were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, photoluminescence spectra, and UV–vis diffuse reflectance spectroscopy. Ag nanoparticles with grain size of about 5 nm are anchored on the surface of ACTs. In UV–vis absorption test, a red-shift of light absorption edge and more visible light absorption (compared to N-TiO₂ and g-C₃N₄/N-TiO₂) are observed for ACTs. Moreover, the dependence of photocatalytic activity on Ag contents was investigated, and ACTs-3 presents the highest photocatalytic activity as the optimal Ag content under visible light irradiation. Remarkably enhanced UV–visible light photoelectrochemical response was also confirmed for ACTs compared with TiO₂, N-TiO₂, and g-C₃N₄/N-TiO₂. Ag-decorated g-C₃N₄/N-TiO₂ composites result in enhanced light absorption capacity and improved transfer of charge carriers, which prominently contribute to the improvement of photoactivity. This work demonstrates that Ag/g-C₃N₄/N-TiO₂ is a promising photocatalytic material for organic pollutant degradation under visible light irradiation.