In-situ surface nanoetching WO3 photoanode for enhanced photoelectrochemical performance

Nanoarray films have received great attention in solar water splitting due to their high surface area and excellent photoelectrochemical (PEC) performance. However, it is difficult to further increase the surface area of the nanoarray film. In this work, we demonstrate an in-situ surface nanoetching method (WO3→WO3/Bi2WO6→WO3/Bi2S3→etching WO3) to increase surface area of WO3 nanosheet array film. The characterization results indicate rougher and more uneven surface of the etched WO3 (E-WO3) film compared with the pristine WO3 film. Moreover, the photocurrent density of E-WO3 film is about 0.40 mA cm−2 at 1.23 V (vs. RHE) under light illumination without cocatalyst, which is 2.7 times higher than that of pristine WO3 film. This may be due to an increased surface area of the E-WO3 photoanode, which provides more active sites for the catalytic reactions and accelerates the charge transfer. This research can provide a simple and effective method to further increase the surface area of the nanoarray photoelectrode.