Photodeposited CoOx as highly active phases to boost water oxidation on BiVO4/WO3 photoanode

Surface decoration of photoanodes with oxygen evolution cocatalysts is an efficient approach to improve the photoelectrochemical water splitting performance. Herein, ultrafine CoOx was selectively immobilized on the surface of BiVO4/WO3 photoanode by using the photogenerated holes to in-situ oxidize Co4O4 cubane. The composited photoanode (CoOx/BiVO4/WO3) displayed an enhanced photoelectrochemical (PEC) water oxidation performance, with a photocurrent density of 2.3 mA/cm(2) at 1.23 V-RHE under the simulated sunlight irradiation, which was 2 times higher than that of bare BiVO4/WO3. The characterization results for the morphological, optical and electrochemical properties of the photoelectrodes revealed that, the enhanced PEC performances could be attributed to the improved charge carrier separation/transport behaviors and the promoted water oxidation kinetics when the photoelectrodes were loaded with CoOx. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.