Nanoscale Assembly of BiVO4/CdS/CoOx Core–Shell Heterojunction for Enhanced Photoelectrochemical Water Splitting

Porous BiVO4 electrodes were conformally decorated with CdS via a chemical bath deposition process. The highest photocurrent at 1.1 V vs. RHE was achieved for a BiVO4/CdS composite (4.54 mA cm−2), compared with CdS (1.19 mA cm−2) and bare BiVO4 (2.1 mA cm−2), under AM 1.5G illumination. This improvement in the photoefficiency can be ascribed to both the enhanced optical absorption properties and the charge separation due to the heterojunction formation between BiVO4 and CdS. Furthermore, the BiVO4/CdS photoanode was protected with a CoOx layer to substantially increase the photostability of the material. The new BiVO4/CdS/CoOx nanostructure exhibited a highly stable photocurrent density of ~5 mA cm−2. The capability to produce O2 was locally investigated by scanning photoelectrochemical microscope, which showed a good agreement between photocurrent and O2 reduction current maps. This work develops an efficient route to improve the photo-electrochemical performance of BiVO4 and its long-term stability.