Facile loading of cobalt oxide on bismuth vanadate: Proved construction of p-n junction for efficient photoelectrochemical water oxidation.

Cobalt oxide is an excellent water oxidation cocatalyst used in photoelectrochemical (PEC) water splitting field. Finding a facial way to load cobalt oxide on a semiconductor anode is important to effectively realize PEC water splitting on a large scale. In this work, a simple impregnation and calcination method is developed to fabricate CoOx/BiVO4 anode. The constructed CoOx/BiVO4 anode provides a photocurrent of 3.1 mA cm-2 at 1.23 V vs. RHE, about 2.8 times that of BiVO4 anode (1.1 mA cm-2). Furthermore, both the charge separation and injection efficiency are improved by loading CoOx nanoparticles onto the BiVO4 layer. Importantly, input voltage-output current characteristic curves are used for the first time to prove the formation of p-n junction between CoOx and BiVO4, which benefits to the separation of photogenerated holes and electrons. All results indicate that the impregnation and calcination method is efficacious for facile fabrication of CoOx/BiVO4 photoanode with high performance.