Modification Of Bismuth-based Materials By Conductive Polymers And Their Photocatalytic Applications

Photocatalytic technology driven by the abundant solar source can transform the light energy to chemical energy and has been applied in many aspects such as solar cells,water decomposition to H₂,CO₂ conversion,nitrogen fixation and environmental restoration.Especially in the environmental restoration,because of its green,efficient,without secondary pollution and other advantages,it has a great prospect for development and application.Semiconductor photocatalyst is the base and core of this technology.However,the traditional photocatalysts titanium dioxide?TiO₂?can only respond to UV light,the utilization of sunlight is less than 5%,which limit its practical applications in photocatalytic field.Therefore,it is significant to develop novel photocatalysts with wide spectral response and excellent light energy conversion.The bismuth-rich?dehalogenation?Bi_xO_yX_z?X=Cl,Br,I?photocatalysts have the response ability of visible light and its unique electronic and structural characteristics,thus it has been attracted more and more attention in this field.However,like most of the existing catalysts,Bi_xO_yX_z has a narrow absorption range of visible light,low utilization rate and easy recombination of photogenerated carries,which causes a poor photocatalytic performance.Therefore,this paper modified Bi_xO_yX_z with conductive polymer to improve the visible light absorption range and photogenerated carriers separation efficiency,so as to enhance photocatalytic degradation efficiency.The main research contents are as follows:1.Conducting polymer polyaniline?PANI?has a good charge migration and high photosensitive properties.So,using it to modify the Bi₁₂O₁₇Cl₂ to obtain PANI/Bi₁₂O₁₇Cl₂ composites.It was found that the introduction of PANI not only enhance the visible light response ability of Bi₁₂O₁₇Cl₂,but also improve the separation efficiency of its photogenerated carriers,thus realize the photocatalytic enhancement.The photocatalytic activity was evaluated by using CIP as a target water pollutant,and the degradation process was explored by mass spectrometry?MS?.The toxicity of degradation products was evaluated by a microbial experiment.The results showed that the toxicity was reduced obviously.Finally,a possible photocatalytic mechanism has been explored preliminarily.2.Bi₄O₅Br₂ was used as the main material to obtain different PANI/Bi₄O₅Br₂composites by loading PANI with different contents.CIP and tetracycline?TC?were used as the target water pollutants to investigate their photocatalytic performance.The results show that the introduction of PANI can also improve the optical response range of Bi₄O₅Br₂ and the separation of photogenerated carriers,thus enhance the photocatalytic activity of the material.Moreover,the degradation intermediates and degradation pathways of pollutants were analyzed by MS,and the toxicity of degradation products was evaluated via a microbial experiments.The photocatalytic mechanism has been further discussed,and the photocatalytic activity can be improved after the combination of PANI with semiconductor has been verfied.3.The conductive polymer polythiophene?PTh?has good stability and photosensitive properties,and is often used in combined with semiconductors to improve photocatalytic efficiency.Based on this,PTh/Bi₄O₅I₂ composite was prepared by using PTh to modify Bi₄O₅I₂ in this paper.Bisphenol A?BPA?was used as the degradation substrate to evaluate the photocatalytic performance.It was found that the introduction of PTh can broaden the absorption range of Bi₄O₅I₂,and promote the effective separation of photogenerated carriers,thus improve the efficiency of photocatalytic degradation of BPA.The reaction rate of the optimal activity is about3.7 times to Bi₄O₅I₂.In this paper,a photocatalytic system with both photocharge separation efficiency and visible light utilization efficiency increased was designed by a facile synthesis method,which provided a new idea for the design of photocatalyst system and the enhancement of photocatalytic degradation ability in future.