Photocatalytic Degradation and Mechanism of BiOI/Bi_2WO_6 toward Methyl Orange and Phenol

BiOI/Bi2 WO6 photocatalysts with various BiOI amounts were prepared by a simple deposition method and characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),high-resolution transmission electron microscopy(HR-TEM),UV-Vis diffuse reflectance spectroscopy(UV-Vis DRS) and low temperature nitrogen adsorption.The photocatalytic performance of BiOI/Bi2 WO6 catalysts was evaluated using the photodegradation of methyl orange(MO) and phenol in an aqueous solution under UV and visible light irradiation.The results indicate that compared with commercial Degussa P25 and pure Bi2 WO6,the 13.2% BiOI/Bi2 WO6 photocatalyst shows much higher UV and visible light photocatalytic performance.The obviously increased photocatalytic activity could be mainly attributed to the effective transfer of the photogenerated electrons and holes at the interface of Bi2 WO6 and BiOI,which reduces the recombination of electron-hole pairs.A transfer process of photogenerated carriers is proposed based on the band structures of BiOI and Bi2 WO6.Radical scavengers experiments demonstrate that ·OH,h+,·O2-and H2 O2,especially h+,together dominate the photodegradation process of MO and phenol.