Oxygen-Deficient Nanofiber WO_{3- x}/WO₃ Homojunction Photoanodes Synthesized via a Novel Metal Self-Reducing Method

Defect engineering of semiconductors has been identified as an efficient route toward enhancing the photoelectrochemical performances. There is a security threat in the traditional hydrogen annealing process. In this work, the oxygen-defective nanofiber WO_3-x/WO₃ homojunction photoanode was in situ-synthesized via a novel metal self-reducing method. The as-prepared photoanode exhibits 1.8 times higher solar water oxidation photocurrent density than that of the bare WO₃ film at 1.2 V versus Ag/AgCl. The enhanced photoelectrochemical properties originate from the effective charge separation and injection, attributed to the stronger built-in electric field created by the oxygen-deficient homojunction. Importantly, this novel method is universally applicable to synthesize oxygen-deficient semiconductor materials, including films and powders.