Rhombic TiO2 grown on g-C3N4 nanosheets towards fast charge transfer and enhanced Cr(VI) and NO removal

The strong band-to-band visible light absorption obtained by changing the bandgap of photocatalysts is desirable but challenging for TiO 2 . In this paper, a mechanochemical pre-reaction and subsequent heat-treatment process were used to create TiO 2 /g-C 3 N 4 heterojunctions. Acid-treated H 2 Ti 3 O 7 nanobelts and superior thin g-C 3 N 4 nanosheets (CN) were ground evenly and further heat-treated to grow rhombic TiO 2 in situ on the nanosheets. The heterojunctions exhibited a band gap with the absorption in visible light region. Heterojunction formation effective tunes the surface and electronic structures of the composite, resulting in significant decrease of bandgap. g-C 3 N 4 -based heterojunctions (5TCN) exhibited excellent H 2 generation (4991 μmol/g/h) and NO removal. In contrast, a TiO 2 -based composite (95TCN) revealed efficient photo reduction of Cr(Ⅵ) which was 2 times of that of TiO 2 sample and 22 times of that of CN. The photochemical reaction mechanism of TiO 2 and g-C 3 N 4 -based composites was discussed with the ratio of TiO 2 and g-C 3 N 4 . The excellent performance is ascribed to single crystal rhombic TiO 2 nanoparticles grown in situ on g-C 3 N 4 to form well-developed heterojunctions which accelerate the carrier transfer. These results inspire the electronic structure engineering of photocatalysts to improve visible light absorption and provide a magic strategy for excellent photochemical activities.