Ag-Loaded Bi5O7I/Sr2TiO4 p-n Junction Photocatalysts for Photocatalytic Degradation of Methyl Orange Under Visible Light Illumination

Abstract

Ag-loaded n-type Sr2TiO4 and p-type Bi5O7I heterostructure photocatalyst was prepared in this work. Scanning electron microscopy, UV-Vis optical absorption spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy were performed. Bismuth ions are easily to substitute on titanium sites by adjusting the pH value because Sr2TiO4 and Bi5O7I exhibit identical orthorhombic layered structure, thus shifting the optical absorption edge of the Bi5O7I/Sr2TiO4 composite toward long wavelength region and reducing the band gap energy. After Ag loading as a cocatalyst, Ag-Bi5O7I/Sr2TiO4 composite showed high photocatalytic activity to degrade methyl orange dye under visible light irradiation. This result can be attributed to the high electron-hole separation resulting from the strong electron-withdrawing ability of Ag and the p-n junction formed at the Bi5O7I/Sr2TiO4 interface. In summary, a facile Ag-loaded Bi5O7I/Sr2TiO4 heterojunction presented an improved photocatalytic activity and can be served as a promising photocatalyst.