Hybridization of g-C_3N_4 quantum dots with 1D branched TiO_2 fiber for efficient visible light-driven photocatalytic hydrogen generation

摘要

The hybrid 1D branched TiO2 loaded with g-C3N4 QDs was successfully fabricated that plays a significant role in photocatalysis. The 1D branched TiO2 prepared by electro-spinning followed by alkali-hydrothermal process, and g-C3N4 QDs were grafted over it by a chemical vapor deposition method. The composite display enhancement in photocatalytic hydrogen evolution is about 10.57 mmol. g(-1).h(-1) in comparison to the g-C3N4 sample that only produces 0.32 mmol. g(-1).h(-1) while the HBTiO2 sample evolved a negligible amount of hydrogen under visible light. The composite sample shows quantum efficiency for HER at 420 nm light is 18.6% that is much higher than the other two samples. The specific surface area of the composite sample is 92.39 m(2)g(-1) that is about 13 times more than bulk g-C3N4. The bandgap of HBTiO2/g-C3N4 QDs, g-C3N4, and HBTiO2 samples calculated as 2.71 eV, 2.67eV, and 3.24eV, respectively. The TRPL spectra imply that the duration of the lifetime of composite becomes longer which effectually overwhelm the electron-hole recombination. The 1D branched TiO2 fiber reduces the charge recombination by fast transfer of electron while g-C3N4 QDs facilitate the visible light absorption by improving the optical properties. The formation of the type II heterostructure system remarkably promotes the separation and transfer of electron holes and facilitates the photo-reduction reaction. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.