Boosting photoelectrochemical water splitting of bismuth vanadate photoanode via novel co-catalysts of amorphous manganese oxide with variable valence states

Bismuth vanadate (BVO) is a promising photoanode while suffers from sluggish oxygen evolution kinetics. Herein, an ultra-thin manganese oxide (MnOx) is selected as co-catalyst to modify the surface of BVO photoanode by a facile spray pyrolysis method. The photoelectrochemical measurements demonstrate that surface charge transport efficiency (gsurface) of MnOx modified BVO photoanode (BVO/MnOx) is strikingly increased from 6.7 % to 22.3 % at 1.23 VRHE (reversible hydrogen electrode (VRHE)). Moreover, the gsurface can be further boosted to 51.3 % at 1.23 VRHE after applying Ar plasma on the BVO/MnOx sample, which is around 7 times higher comparing with that of pristine BVO samples. Additional characterizations reveal that the remarkable PEC performance of the Ar-plasma treated BVO/MnOx photoanode (BVO/MnOx/Ar plasma) could be attributed to the increased charge carrier density, extended carrier lifetime and additional exposed Mn3+ active sites on the BVO surface. This investigation could provide a new understanding for the design of BVO photoanode with superior PEC performance based on the modification of MnOx and plasma surface treatment.

Automated summary

An ultra-thin manganese oxide (MnOx) was used as a co-catalyst to modify the surface of bismuth vanadate (BVO) photoanode, resulting in significantly improved surface charge transport efficiency. The surface charge transport efficiency of the modified BVO photoanode was further enhanced by applying Ar plasma treatment. These findings provide new insights for designing BVO photoanodes with superior photoelectrochemical (PEC) performance.