WO3 nanoneedles/α-Fe2O3/cobalt phosphate composite photoanode for efficient photoelectrochemical water splitting

We report the fabrication of the WO3 nanoneedles/α-Fe2O3 heterojunction photoanodes for efficient photoelectrochemical water splitting. The high-aspect-ratio single crystalline WO3 nanoneedles (NNs) act as both the photoanode framework and the light harvester in the UV and blue visible region. The porous layer of small α-Fe2O3 nanocrystals act as a cooperative light harvester in the visible region. The WO3 NNs/α-Fe2O3 heterojunction photoanodes exhibit an extended light absorption band in the visible region and a significantly enhanced photocurrent density, which is ca. 1.6 times higher than that obtained on the pure WO3 NNs. Cobalt phosphate (Co-Pi) was employed as an oxygen evolving catalyst to modify the heterojunction electrode, and the resulting WO3 NNs/α-Fe2O3/Co-Pi composite photoanodes show an excellent photostability for oxygen evolution reaction.