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 CoO x /BiVO 4 anode. The constructed CoO x /BiVO 4 anode provides a photocurrent of 3.1 mA cm −2 at 1.23 V vs. RHE, about 2.8 times that of BiVO 4 anode (1.1 mA cm −2 ). Furthermore, both the charge separation and injection efficiency are improved by loading CoO x nanoparticles onto the BiVO 4 layer. Importantly, input voltage–output current characteristic curves are used for the first time to prove the formation of p-n junction between CoO x and BiVO 4 , 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 CoO x /BiVO 4 photoanode with high performance.