Cobalt Aluminate Spinel as a Cocatalyst for Photocatalytic Oxidation of Water: Significant Hole-Trapping Effect
Tomoki Kanazawa, Kosaku Kato, Ryusei Yamaguchi, Tomoki Uchiyama, Daling Lu, Shunsuke Nozawa, Akira Yamakata, Yoshiharu Uchimoto, Kazuhiko Maeda
Abstract
Here we show that nanoparticulate CoAl2O4 spinel serves as an efficient cocatalyst for photocatalytic oxidation of water. The O2 evolution activity of CoAl2O4/g-C3N4 from an aqueous solution of AgNO3 under visible light irradiation was ∼10 times that of unmodified g-C3N4 and also exceeded that of an analogue modified with a well-known Co3O4 cocatalyst for each optimal preparation condition. Transient absorption spectroscopy indicated that the CoAl2O4 cocatalyst with Co2+ as the main cobalt species at the A site of the spinel possessed better hole-capturing properties than the Co3O4 cocatalyst, which was the main reason for the improved water-oxidation performance.