Research On Modified Of Visible Light Response Environmental Purification Materials

Energy crisis and environmental pollution are two intractable problems facing the world. It is hopeful to simultaneously settle these puzzles by effectively transform solar energy to chemical energy or directly degrading environmental pollutants on semiconductor photocatalysts. Visible light possess the main component of the solar spectrum, and therefore exploring efficiency and stable photocatalysts with visible light response is the key point of photocatalysis. This thesis will focus on developing visible light response organic and inorganic photocatalytic materials.g-C3N4as an organic photocatalysts have a low cost and simple synthesis method, which lead to have a broad application potential, but the low photocatalytic activity and quantum efficiency constraints of its application. In this paper, a series of benzoic acid derivatives modified polymeric photocatalysts were synthesized based on the reaction of carboxylic acid and NH2groups in carbon nitride polymer. Their photocatalytic activity was also evaluated by the photodegradation of methyl orange, and the results show that the incorporation of benzoic acid derivatives into the skeleton of carbon nitride polymer could obviously enhance its photocatalytic activity. Furthermore, benzoic acid derivative with electron-donating group is more favorable than that with electron-withdrawing group to increase the photocatalytic activity. Theoretical calculation results demonstrated that the incorporated benzoic acid derivatives conjugated with the skeleton of carbon nitride polymer. It seems that the photogenerated hole was stabilized by the incorporated benzoic acid derivatives through conjugation, which could account well for the experimental observations.TiO2as an inorganic catalyst, have lots of advantages such as chemical stability, easy obtained and high activity under UV light irradiation. However, its photo-electronic transition efficiency and photocatalytic activities are limited by its inherent low utility to visible light. Many efforts have been recently devoted to improve the low visible light utility of TiO2by doping transitional metal. Molybdenum doped mesoporous titanium have positive effect to enhance the photoinduced electron transfer process. A novel mesoporous-structured photocatalyst MoO3/TiO2was synthesized through a modified sol-gel method by using P123as the template, and the resulting nano-photocatalysts were characterized by X-ray diffraction (XRD), N2adsorption measurements, transmission electron microscope (TEM), UV-vis spectroscopy, XPS and Raman techniques. The calcined meso-MoO3/TiO2materials exhibit the high photocatalytic activity for the degradation of MB (methylene blue) under visible light radiation. According to the results, the Ti4+was partially substituted by Mo6+, the electron density increase duo to charge equilibrium, Mo(VI) became the electron donor, increased the Fermi level of TiO2and thus the width of the band gap was narrowed correspondingly.