Interface Nanoarchitectonics of TiO2/g-C3N4 2D/2D Heterostructures for Enhanced Antibiotic Degradation and Cr(VI) Reduction.

Abstract

Mixed-phase TiO2 nanosheets were loaded on superior thin g-C3N4 nanosheets by a one-step solvothermal synthesis to form unique two-dimensional (2D)/2D heterostructures, which increased the interface area between TiO2 and g-C3N4, resulting in the easy migration of photogenerated carriers between two components. The rate of photocatalytic reactions increased significantly. Ciprofloxacin, tetracycline hydrochloride, and oxytetracycline hydrochloride were selected as target substances to test the photocatalytic degradation properties of the sample. The photoreduction performance of Cr(VI) was also tested. The results indicate that the photocatalytic degradation rate of antibiotics using TiO2/g-C3N4 heterostructures under visible light irradiation was twice that of g-C3N4. It took only 30 min to remove Cr(VI) (20 mg/L) under full solar spectrum irradiation; the photoreduction rate of Cr(VI) is also nearly twice that of pure TiO2. The improved performance was attributed to the rich active sites brought by mixed-phase TiO2 nanosheets. The extensive interface made the rapid migration of photogenerated carriers possible. The heterostructures revealed a band gap of 2.81 eV, which is less than that of TiO2 (3.2 eV), resulting in the increased absorption of visible light. Meanwhile, the mixed phase of TiO2 was beneficial for the separation of photogenerated carriers.