Synthesis and Evaluation of Visible-Light Photocatalyst: Nitrogen-Doped TiO₂/Bi₂O₃ Heterojunction Structures

Abstract

N-TiO2/Bi2O3 composites have been successfully prepared by a simple coupling method and evaluated in detail. These composites represent a potential new class of heterojunction-structured photocatalysts wherein the enhanced light absorption properties of N-TiO2 are anticipated to couple with the observed benefits of composite TiO2/Bi2O3 systems. The composites were characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), N-2-adsorption desorption, diffuse reflectance spectroscopy (DRS), and scanning electron microscopy (SEM). It was found that composites with low Bi2O3 content display enhanced photocatalytic activity for decomposition of 2,4-dichlorophenol (2,4-DCP) under visible light irradiation, which is attributed to a synergistic effect between the two composite components and the flow of holes and electrons through the heterojunction. The PL spectroscopy was adopted to analyze the physical properties of the photogenerated carriers and it was found that the separation of photogenerated carriers of Bi2O3 has been largely promoted after being coupled with N-TiO2. Significantly, the enhanced performance demonstrated the importance of evaluating new composite photocatalysts. It would be helpful in designing and constructing high efficiency heterogeneous semiconductor photocatalyst with the purpose of enhancing activity by coupling suitable wide and narrow band-gap semiconductors, which is inspiring for the practical environmental purification.