In situ metal doping during modified anodization synthesis of Nb₂O₅ with enhanced photoelectrochemical water splitting

Significance: A new technique of in situ doping of alkali metal (Li⁺, Na⁺, K⁺, Rb⁺, and Cs⁺) in Nb₂O₅ was showcased by the modified anodization of Nb foils at high frequency, negative-to-positive pulsed voltage. At the optimized dopant concentration and synthesis condition, the doped-Nb₂O₅ shows twofold enhancement in photoelectrochemical water splitting efficiencies compared with the undoped Nb₂O₅ electrode, as a result of improved charge carrier density and enhanced surface charge transfer.