An in situ transformation approach for fabrication of BiVO4/WO3 heterojunction photoanode with high photoelectrochemical activity

Abstract BiVO 4 /WO 3 heterojunction film is considered as a very promising candidate for photoelectrochemical water splitting. However, the BiVO 4 /WO 3 films prepared by a conventional method exhibit numerous grain boundaries in the BiVO 4 layer and a weak contact at the heterojunction interface. In this paper, we found that BiVO 4 could be formed from hydrothermal Bi 2 WO 6 in the weak acid solution dissolving V 2 O 5 and successfully developed an in situ transformation method to prepare BiVO 4 /WO 3 heterojunction films. The prepared BiVO 4 /WO 3 heterojunction films were characterized in detail and showed a high quality core/shell WO 3 /BiVO 4 structure. The formation mechanism of the BiVO 4 layer on the surface of WO 3 film has been put forward. In particular, the prepared BiVO 4 /WO 3 films were used as photoanodes and showed an excellent visible light response, a good photostability and high photoelectrochemical activity. The photocurrent density for BiVO 4 /WO 3 photoanode was up to 2.92 mA cm −2 at 1.81 V RHE without additional electrocatalyst or doping under visible light illumination.