Modification of g-C3N4's optical and dielectric properties by doping with Ag-TiO2 nanocomposites

A nanocomposite material with an Ag-TiO2 heterojunction was synthesized based on silver nitrate and titanium dioxide using a thermal shrinkage polymerization method, and then doped and modified with graphite-like carbon nitride (g-C3N4). After impregnation on activated alumina, the Ag-TiO2/g-C3N4 composite photocatalyst was obtained. In the degradation of volatile organic pollutants, the Ag-TiO2/g-C3N4 composite photocatalyst exhibited significant advantages over traditional TiO2 and g-C3N4 catalysts. The presence of ordered crystalline silver and titanium in the composite material was confirmed by Energy Dispersive Spectroscopy (EDS) and X-ray Diffraction (XRD). The strong chemical bond between the surfaces of Ag-TiO2 and g-C3N4 was confirmed by the absorption peaks of infrared spectra (IR) between 1562-1607 cm-1 and X-ray photoelectron spectroscopy (XPS) at 532.7 eV. To verify the photocatalytic mechanism, photoluminescence (PL) and electron paramagnetic resonance (EPR) experiments were performed on Ag-TiO2/g-C3N4, which confirmed the establishment of heterojunctions, as well as the formation of oxygen vacancies and superoxide radicals.