A high-efficiency Z-scheme Er3+:YAlO3@(Au/SrTiO3)-Au-WO3 photocatalyst for solar light induced photocatalytic conversion of Cr(VI)

Abstract

• Er 3+ :YAlO 3 @(Au/SrTiO 3 )-Au-WO 3 can effectively convert Cr(VI) into Cr(III). • Er 3+ :YAlO 3 can enhance photocatalytic activity of SrTiO 3 /WO 3 in conversion of Cr(VI). • Z-scheme system can inhibit recombination of photo-induced electrons and holes. • Using Au as co-catalyst and mediator can boost separation of electrons and holes. • The mechanism on solar light photocatalytic conversion of Cr(VI) was clarified. A high-efficiency Z-scheme photocatalyst, Er 3+ :YAlO 3 @(Au/SrTiO 3 )-Au-WO 3 , is fabricated successfully via hydrothermal and photo-deposition methods. All as-prepared samples are characterized by XRD, SEM, TEM, FT-IR, EDX, XPS, Raman spectroscopy, PL and DRS. The activity of the prepared Z-scheme Er 3+ :YAlO 3 @(Au/SrTiO 3 )-Au-WO 3 photocatalyst is evaluated through photocatalytic conversion of Cr(VI) under simulated solar light irradiation. The meaningful influencing factors such as simulated solar light irradiation time, light intensity, sacrificial agents and cycling times are investigated. The results displayed that the existence of Er 3+ :YAlO 3 can improve the utilization ratio of solar light for wide band-gap SrTiO 3 . Moreover, the formation of Z-scheme SrTiO 3 /WO 3 photocatalytic system and the introduction of Au nanoparticles as electron mediator and co-catalyst can promote the separation of photo-induced electron and hole to obtain much high photocatalytic activity. Finally, the mechanism on conversion of Cr(VI) caused by Z-scheme Er 3+ :YAlO 3 @(Au/SrTiO 3 )-Au-WO 3 photocatalyst is put forward. © 2021 Elsevier B.V. All rights reserved.