In situ synthesis of ultrafine TiO2 nanoparticles modified g-C3N4 heterojunction photocatalyst with enhanced photocatalytic activity

To improve the redox performance and light absorption property, the 2D/0D g-C 3 N 4 /TiO 2 heterojunction photocatalyst were successfully fabricated by co-annealing process based on melamine powder and ultrafine TiO 2 nanoparticles (about 9.87 nm) obtained from electrochemical etching technology. The surface micromorphology, crystal structure, basic element composition, chemical structure, specific surface and optical performance were analyzed by SEM-EDS, TEM, HR-TEM, XRD, XPS, FTIR and Ultraviolet–visible diffuse reflection spectra (UV–vis DRS). The photocatalytic performance of g-C 3 N 4 /TiO 2 photocatalyst was assessed by the degradation of tetracycline hydrochloride (TC) under simulated sunlight irradiation. The results showed that the obtained TiO 2 powder had extremely smaller particle size and higher photocatalytic activity than commercial P25. The coupling of 0D TiO 2 nanoparticles and 2D g-C 3 N 4 nanosheet further promoted the visible light absorption performance of TiO 2 . The unique g-C 3 N 4 /TiO 2 heterojunction photocatalyst exhibited remarkable photocatalytic performance for the degradation of TC, whose degradation rate could reach to 99.40% under 120 min irradiation. The kinetic constant of the g-C 3 N 4 /TiO 2 photocatalyst was 1.48 times of that of TiO 2 . The ESR results confirmed ·OH and ·O 2 – radicals produced in the photocatalytic process. This work could provide an effective reference for the fabrication of ultrafine TiO 2 powder and binary heterojunction photocatalyst with excellent photocatalytic activity for organic pollutants degradation in water purification.