Applied Catalysis B: Environmental, Vol.209, 663-668, 2017
Silver-inserted heterojunction photocatalyst consisting of zinc rhodium oxide and silver antimony oxide for overall pure-water splitting under visible light
Overall pure-water splitting under visible-light irradiation at wavelengths up to 660 nm was accomplished utilizing a solid-state hetero-junction photocatalyst following the Z-scheme mechanism in which zinc rhodium oxide (ZnRh2O4) and silver antimony oxide (AgSbO3) as hydrogen (H-2)- and oxygen (O-2)-evolution photocatalysts, respectively, were connected with silver (Ag, ZnRh2O4/Ag/AgSbO3). In our previous paper (Kobayashi et al., J. Phys. Chem. C, 118 (2014) 22450-22456), nitric acid (HNO3) treatment of mixtures of AgSbO3, Ag2O, and ZnRh2O4 after calcination formed defective AgSbO3 (Ag1-xSbO3-y) and the resulting photocatalyst, ZnRh2O4/Ag/Ag1-xSbO3-y, exhibited reduced visible-light wavelength sensitivity (up to 545 nm) and overall water-splitting activity. To overcome this limitation, here, unnecessary Ag was removed by treatment with ammonium hydroxide (NH4OH) and hydrogen peroxide (H2O2), which resulted in the successful formation of ZnRh2O4/Ag/AgSbO3. This photocatalyst was capable of utilizing visible light at wavelengths up to 660 nm and exhibited enhanced overall water-splitting activity. The synthesis approach described in this study represents a novel and facile method for preparing visible-light sensitive heterojunction photocatalysts connected with Ag. (C) 2017 Elsevier B.V. All rights reserved.
Keywords:Two-step overall water-splitting;Zinc rhodium oxide;Silver antimony oxide;Silver;Ammonia treatment