Hydrogen plasma reduced black TiO2B nanowires for enhanced photoelectrochemical water-splitting

Black TiO2 with various nanostructures and phase constitutions have been reported to exhibit excellent photocatalytic and photoelectrochemical (PEC) performance. Here, we report the fabrication of black nanostructured TiO2B through hydrogen plasma assisted reduction and its enhanced PEC properties for the first time. Both the obtained TiO2B and black TiO2B are single crystalline nanowires, while the black TiO2B samples exhibit much stronger visible and infrared light absorption. The optimal black TiO2B sample obtained by hydrogen plasma treatment at 425 °C yields a photocurrent density of 0.85 mA cm−2, a rather low onset potential of −0.937 VAg/AgCl and a high applied bias photon-to-current efficiency (ABPE) of 0.363%, which is far superior to the TiO2B (0.15 mA cm−2 photocurrent, −0.917 VAg/AgCl onset potential and 0.138% ABPE). The significantly enhanced PEC performance of the black TiO2B is ascribed to the introduction of moderate surface oxygen vacancies. These results indicate that the black TiO2B is a promising material for PEC application and solar energy utilization.