Nanostructured TaON/Ta3N5 as a highly efficient type-II heterojunction photoanode for photoelectrochemical water splitting

Abstract

Enhancing the charge separation by a semiconductor heterojunction is greatly promising and challenging for photoelectrochemical (PEC) water splitting. Here, we report for the first time the design and fabrication of a TaON/Ta₃N₅ heterojunction photoanode, in which the electrode Ta₃N₅ is the primary light absorber and TaON acts as an electron conductor. By combining the merits of the substantial light harvesting of Ta₃N₅ with the excellent charge transport capability of TaON, the TaON/Ta₃N₅ heterojunction photoanode, without any co-catalysts, shows a 350 mV negative shift of photocurrent onset potential to 0.65 V versus the reversible hydrogen electrode (RHE) compared to that of the Ta₃N₅ photoanode. The design and fabrication scheme can be readily extended to other (oxy)nitride semiconductors for heterojunction construction.