TiO2/Graphitic Carbon Nitride Nanosheets for the Photocatalytic Degradation of Rhodamine B under Simulated Sunlight

Surface-fluorinated ultrathin anatase TiO2 nanosheets with exposed (001) crystal planes were synthesized via a relatively low temperature solvothermal route. These two-dimensional (2D) TiO2 nanosheets demonstrated higher photocatalytic activity for degrading Rhodamine B (RhB) under simulated sunlight illumination than the corresponding sample with less fluorine ions (F-) content, which indicates the positive effect of F- on the enhanced photocatalytic performance of TiO2 nanosheets. Furthermore, 2D/2D TiO2/g-C3N4 nanosheet heterojunctions were fabricated through a solvent evaporation process. The photocatalysis test showed that TiO2/g-C3N4 exhibited higher photocatalytic performance for degrading RhB under simulated solar light illumination than pure g-C3N4 and TiO2 nanosheets. Based on free radical trapping experiments, superoxide radicals (center dot O2-) and photoinduced holes (h(+)) were determined to be the predominant active species for photodegrading RhB. A direct Z-scheme charge transfer mechanism is proposed to understand the enhanced photocatalytic activity in TiO2/g-C3N4 nanosheet heterojunctions.