Novel photocatalyst, Bi2Sn2O7, for photooxidation of As(III) under visible-light irradiation

Nanocrystalline Bi2Sn2O7, a visible-light photocatalyst synthesized via a facile hydrothermal route, is used to remove arsenite from aqueous solution for the first time. The as-synthesized Bi2Sn2O7 product is characterized by X-ray diffraction, N2 sorption–desorption, UV–vis diffuse reflectance spectroscopy, transmission electron microscopy, electron spin resonance, X-ray photoelectron spectra, and electrochemistry technology. The results reveal that the sample has an average particle size of approximately 10 nm, a specific surface area of 51.3 m2/g, and a band gap of 2.88 eV. Moreover, the Bi2Sn2O7 nanoparticles exhibit a high photocatalytic activity in the oxidation of As(III) (up to 96.8%) under visible-light irradiation. O2− and h+ are recognized as the primary active species responsible for As(III) oxidation. Meanwhile, a possible mechanism for the photo-oxidation of As(III) over Bi2Sn2O7 is also proposed.

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► Bi2Sn2O7 is a promising photocatalyst for As(III) oxidation under visible-light.
► O2− and h+ are recognized to be the main active species in As(III) oxidization.
► A band-gap model is proposed to explain the generation mechanism of active species.