Self doping promoted photocatalytic removal of no under visible light with Bi₂MoO₆: Indispensable role of superoxide ions

In this study, we demonstrated that the reactive species generation of Bi₂MoO₆ under visible light can be regulated by Bi self-doping via a simple soft-chemical method. Density functional theory calculations and systematical characterization results revealed that Bi self-doping could not only promote the separation and transfer of photogenerated electron-hole pairs of Bi₂MoO₆ but also alter the position of valence and conduction band without changing its preferential crystal orientations, morphology, visible light absorption as well as band gap energy. The photocatalytic removal of NO and products determination revealed that the enhanced generation of superoxide could improve the oxidation of NO to NO₂ while ‧OH and photogenerated holes mainly contributed to the further oxidation of NO₂ to NO₃⁻. Photostability and NO absorbtion tests demonstrated that NO₃⁻ on the surface of catalysts occupied the NO absorption sites and caused the deactivation of catalysts. This study provides new insight into the different effects of photogenerated reactive species on NO removal and sheds light on the design of highly efficient visible light-driven photocatalysts for NO removal. Copyright © 2015 Published by Elsevier B.V.