Directional growth of graphene by microwave plasma CVD constructed TiO2@Ag@graphene ternary junction for efficient hydrogen production

This work proposes a novel strategy which the microwave plasma chemical vapor deposition (MPCVD) technology was used as one important preparation process for synthesizing TiO 2 @Ag@graphene ternary junction. The ternary junction exhibits an enhanced photocatalytic hydrogen production rate of 4.44 mmol·g −1 ·h −1 , which is approximately 9.25 times higher than that of pure TiO 2 (0.48 mmol·g −1 ·h −1 ). The remarkable photocatalytic activity can be attributed to the strong synergistic effect between TiO 2 @Ag and graphene. The loaded Ag and graphene can not only act as electronic conductors to effectively promote the separation of charges, but also obviously improve the response of visible light of TiO 2 . The photogenerated electrons are transferred from TiO 2 to graphene via the Ag medium was further verified by DFT calculations. Constructing an Ag-graphene interface can activate carbon atoms, which can quickly capture electron to fill the π* orbital of graphene. TiO 2 @Ag@graphene ternary junction exhibits a lower ΔG H* value of 0.51 eV than that of TiO 2 @Ag (1.49 eV), which indicates that TiO 2 @Ag@graphene ternary junction with optimal absorption energy for the hydrogen intermediate.