Boosting the photoelectrochemical water oxidation performance of bismuth vanadate by ZnCo2O4 nanoparticles

Due to the involvement of four-electron transfer process at photoanode, water oxidation is the ratelimiting step in water splitting reaction. To settle this dilemma, ZnCo2O4 nanoparticles are combined with BiVO4 to form a p-n ZnCo2O4/BiVO4 heterojunction photoanode, which is proved by an input voltage-output current test. The built-in electric field formed within the heterojunction structure promotes the effective separation of electrons and holes. ZnCo2O4 is also an effective water oxidation cocatalyst, since it could cause the holes entering the electrode/electrolyte interface rapidly for the subsequent water oxidation reaction. The photocurrent density of ZnCo2O4/BiVO4 composite photoanode reaches 3.0 mA/cm(2) at 1.23 V vs. RHE in 0.5 mol/L sodium sulfate under AM 1.5G simulated sunlight, about 2.1 times greater than that of BiVO4 (1.4 mA/cm(2)). These results suggest the potential of ZnCo2O4 nanoparticles for improving photoelectrochemical water splitting anode materials. (C) 2021 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.