Regulating metal-oxygen covalency of TiO2 by Ru doping and phase transition for boosted hydrogen evolution

Titanium dioxide, with excellent stability, high catalytic activity and abundant reserves, is an ideal substitute for noble metals in hydrogen reaction reactions (HER). However, the strong *H adsorption makes it only a substrate. Tuning metal-oxygen covalency can effectively optimize the adsorption energy. Herein, Ru-modified TiO2 with different phases (rutile, anatase and their mixed-phase) is synthesized, where metal-oxygen covalency and phase transition synergistically boost HER. The target m-Ru@TiO2-x exhibits high HER activity under large current density in wide pH, requiring low overpotential of 87/284 mV (acidic), and 47/366 mV (alkaline) to deliver 10 and 1000 mA center dot cm(-2) respectively, superior to benchmark Pt/C. Theoretical calculation shows that Ru incorporation and mixed rutile-anatase endow m-Ru@TiO2-x with a more negative O p band and decreased overlap between Ti d and Op states, ultimately expediting the desorption of hydrogen during HER. This work enlightens an efficient pathway for tuning the metal-oxygen covalency in HER catalysts.