Effect and Mechanism of Co-catalyst Co-Pi Impregnation by Light Assisted Electrodeposition on Solar Water Splitting Properties of Ta3N5 Photoanodes

Co-Pi is a cheap and high efficient co-catalyst for water splitting. The impregnation method of co-catalyst is very important for water splitting property of photoanode. Therefore, in this work, for Ta3N5 photoanode, a series of studies about co-catalyst Co-Pi impregnation by light assisted electrodeposition have been developed. The results suggest that the incident light intensity during the Co-Pi impregnation process has little effect on the water splitting property, while the loading potential and the loading charge have great influence on the water splitting property of Ta3N5. In addition, the transfer of carriers on Ta3N5/electrolyte interface has been studied by electrochemical impedance spectroscopy test and simulation. The results suggest that the photo-generated carriers transfer can be efficiently regulated by controlling the loading potential and loading charge during the impregnation process to improve the water splitting property of Ta3N5. More importantly, the best loading potential of Co-Pi keeps almost unchanged for Ta3N5 with different roughness, while the best loading charge has positive correlation with the surface roughness of the phtoanode, therefore, the loading charge should be adjusted by the roughness of photoanode.