A novel strategy to promote photo-oxidative and reductive abilities via the construction of a bipolar Bi2WO6/N-SrTiO3 material

Abstract

Focusing on holistically promoting both photo-oxidative and reductive abilities, we constructed a novel Bi₂WO₆/N-SrTiO₃ composite, which was expected to have excellent properties for the removal of complicated contaminants from solution environments under visible light irradiation. The prepared Bi₂WO₆/N-SrTiO₃ was assembled from massive N-SrTiO₃ nanoballs segmented via 2D interlaced nanosheets of Bi₂WO₆. N-SrTiO₃ on its own has good reductive ability and can easily reduce Cr(VI) ions, while Bi₂WO₆ has been demonstrated to have good oxidative ability to oxidize tetracycline under visible light irradiation. Importantly, mixed contaminants (TC and Cr⁶⁺ ions) could be completely removed under visible light by the assembled Bi₂WO₆/N-SrTiO₃ material. It is proposed that the holes lying at the valence band of N-SrTiO₃ are the main active species for the oxidation of tetracycline, while the electrons located at the conduction band of Bi₂WO₆ are mainly responsible for the reduction of Cr(VI) ions. The matched band structures of Bi₂WO₆ and N-SrTiO₃ were beneficial for inhibiting the recombination of electron–hole pairs and maintaining the redox capacity through a Z-type n–n heterojunction. Such a bipolar design of photo-oxidative and photo-reductive semiconductor nanomaterials is concluded to be highly effective in remediating complicated toxic residual constituents of both unfixed pharmaceuticals and heavy metals in aquatic environments.