Tungsten oxide-coated copper oxide nanowire arrays for enhanced activity and durability with photoelectrochemical water splitting

The deposition of crystalline CuWO4 and WO3 layers on copper oxide nanowire arrays resulted in a five-fold improvement of the photocurrent density (∼1.7 mA cm−2 at −0.1 V vs. RHE) over titania-coated copper oxide NW arrays. The deposition of WO3 or CuWO4 reduced the CuO phase impurities in Cu2O. The improvement in the phase purity of the nanowire arrays led to a considerable enhancement in the resulting photoactivity. These protective coatings have been shown to play a dual role of marginally extending the durability of the electrode and promoting charge separation.