Synergistic material modification-induced optimization of interfacial charge transfer and surface hydrogen adsorption

Being chemically stable, low cost and made from abundant resources, titanium dioxide (TiO₂) possesses the most desired advantages for photocatalytic applications. However, the intrinsic limits of high surface hydrogen adsorption energy, wide band gap, low separation rate and rapid recombination of the photogenerated charge carriers greatly hamper its utilization. To address these issues, the present work combines density functional theory (DFT) calculations with rational modifications of TiO₂ with nickel doping and an ultra-thin shield of fluorinated carbon (FNT) for application in the photocatalytic hydrogen evolution reaction (HER). Comprehensive studies imply that the synergistic modifications not only optimize the surface H adsorption, but also facilitate the interfacial charge transfer and simultaneously prevent the photochemical and chemical corrosion of the catalysts. In good agreement with the theoretical predictions, the resulting FNT photocatalysts demonstrate an optimal HER efficiency of 13.0 mmol g^-1 h^-1, nearly 33-times and over three-times beyond that of the pristine TiO₂ (0.4 mmol g^-1 h^-1) and the Ni-doped TiO₂ (4.2 mmol g^-1 h^-1), respectively. Moreover, the composite also exhibits excellent stability with a well-reproducible HER performance over a 66-hour cyclic HER test of 15 cycles.