Characterization and mechanism analysis of Mo–N-co-doped TiO2 nano-photocatalyst and its enhanced visible activity

In this study, Mo–N-co-doped TiO2 nano-photocatalysts have been synthesized through hydrolysis-precipitation method, combined with sonication posttreatment. The resulting materials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and UV–vis diffuse reflectance spectroscopy (UV–vis DRS). XRD showed that co-doping with Mo and N favored the formation of anatase and retarded the growth of crystallite size. XPS revealed that N was incorporated into the lattice of TiO2 through substituting oxygen atoms and coexisted in the forms of β-N and γ-N in co-doped TiO2. Meanwhile, Mo was also incorporated into the lattice of TiO2 through substituting titanium atoms and existed in the form of Mo6+. DRS indicated that the light absorbance in visible region was improved by co-doping with Mo and N, leading to a narrower band gap and higher visible light photocatalytic activity for the degradation of phenol than that of pure and N-doped TiO2. The enhanced visible light photocatalytic activity of Mo–N-co-doped TiO2 nano-photocatalyst was attributed to the small crystallite size, narrow band gap and intense light absorbance in visible region. This study provides a new method to synthesize visible light active TiO2-based photocatalyst.

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► Mo–N–TiO2 was synthesized through hydrolysis-precipitation and sonication methods.
► The light absorption edge of Mo–N-codoped TiO2 was shifted to visible light region.
► The activity enhanced mechanism was discussed in detail.
► This study provides a new way to synthesize visible light photocatalyst.