In Situ Preparation of a Ti3+ Self-Doped TiO2 Film with Enhanced Activity as Photoanode by N2H4 Reduction

A new synthetic method to fabricate Ti3+-modified, highly stable TiO2 photoanodes for H2O oxidation is reported. With Ti foil as both the conducting substrate and the Ti3+/Ti4+ source, one-dimensional blue Ti3+/TiO2 crystals were grown by a one-step hydrothermal reaction. The concentration of Ti3+ was further tuned by N2H4 reduction, leading to a greater photoelectrocatalytic activity, as evidenced by a high photo-current density of 0.64 mA cm(-2) at 1.0 V vs RHE under simulated AM 1.5 G illumination. Electron paramagnetic resonance and Mott-Schottky plots reveal that higher charge-carrier density owing to N2H4 reduction contributes to the observed improvement. The generality of this synthesis method was demonstrated by its effectiveness in improving the performance of other types of photoanodes. By integrating the advantages of the 1D TiO2 architecture with those of Ti3+ self-doping, this work provides a versatile tool toward the fabrication of efficient TiO2 photoanodes.