Enhanced photoelectrochemical water oxidation of WO3/R-CoO and WO3/B-CoO photoanodes with a type II heterojunction

• Published in: Journal of materials science Vol. 56; no. 13; pp. 8079 - 8090
• Main Authors: Liu, Jiali, Yang, Qiang, Liu, Jikai, Luo, He’an
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.05.2021; Springer Nature B.V
• Subjects: absorption; Characterization and Evaluation of Materials; Charge efficiency; Charge transport; Chemistry and Materials Science; Classical Mechanics; Crystallography and Scattering Methods; electric current; electrodes; Energy Materials; Heterojunctions; hydrogen; light; Materials Science; nanosheets; Oxidation; Photoanodes; Photoelectric effect; Photoelectric emission; Polymer Sciences; Quantum efficiency; Solid Mechanics; Spin coating; Surface charge; tungsten oxide; Tungsten oxides; Valence band
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-020-05754-5

Tungsten trioxide (WO 3 ) has been conceived as a promising photoanode material for photoelectrochemical (PEC) water oxidation. Therefore, many efforts have been made to improve its PEC performances. Herein, a novel heterojunction is fabricated through combining rocksalt CoO (R-CoO) or blende CoO (B-CoO) nanosheets with WO 3 nanoplates using a spin-coating method. The typical type II heterojunctions, e.g., WO 3 /R-CoO and WO 3 /B-CoO, both have exhibited higher photocurrent densities than pristine WO 3 photoanode. The photocurrent densities of WO 3 /R-CoO, WO 3 /B-CoO and WO 3 are 0.53 mA cm −2 , 0.45 mA cm −2 and 0.31 mA cm −2 at 1.23 V vs. reversible hydrogen electrode, respectively. For the WO 3 /R-CoO photoanode, the surface charge separation efficiency is 50.95% and the photoconversion efficiency is 0.062%, which are both higher than the WO 3 and WO 3 /B-CoO photoanodes. The enhanced PEC performances are due to the type II heterojunction between WO 3 and R-CoO (or B-CoO), which facilitates the absorption of visible light and charge transport. The better performance of WO 3 /R-CoO than that of WO 3 /B-CoO may be due to the deeper valence band position of R-CoO. Our work demonstrates that R-CoO (or B-CoO) can couple with WO 3 to form a type II heterojunction to improve the PEC water oxidation performance.