Heterojunctions Of PDI/BiOX Regulatory Synthesis And Their Photocatalytic Mechanism

In recent years,the issue of water pollution has become increasingly prominent due to the rapid development of urban construction in China.The accumulation of organic pollutants in surface water basins has resulted in sewage evolution and environmental pollution.This problem undoubtedly affects the sustainable development of society and has a serious negative impact on human health.Currently,photocatalytic technology,which utilizes semiconductors as the main catalyst,is considered a new and green method to alleviate the environmental crisis and is gaining popularity.By selecting the appropriate semiconductor material,a variety of active species can be produced under sunlight excitation,which can completely mineralize pollutant molecules into water and carbon dioxide.Numerous semiconductor materials,including the conventional narrow bandgap Bi OX,have been utilized in photocatalytic technology.However,these materials suffer from fast electron-holes recombination,low valence band,and difficulty in generating reactive free radicals.This paper presents the design and synthesis of several highly efficient S-scheme composites using a simple ionic liquid combustion method.The objective is to achieve spatial separation of photogenerated carriers,which can enhance the photocatalytic efficiency and effectively remove environmental pollutants.The specific research focuses on the following aspects:1)This paper reports on the preparation of PDI/Bi OI heterojunctions with varying proportions using a simple and rapid ionic liquid combustion and continuous ionic layer adsorption method.The results reveal that the samples prepared under visible light exhibit excellent photocatalytic activity.For instance,the removal rate of Rh B（10 mg/L）within 60min was 99.11%for the 1/4 PDI/Bi OI heterojunction,which was 31 times that of Bi OI.Similarly,the removal rate of MO（10 mg/L）reached 50.0%within 60 min of visible light irradiation,which was 16.7 times that of Bi OI and 4.4 times that of self-assembled PDI.The heterojunction also exhibited good stability after four experimental cycles.The built-in electric field in theπ-πof Bi OI pointing to PDI promotes electron-holes separation,which leads to higher contribution rates of active species·O₂^-and ¹O₂ than that of Bi OI.This study offers a promising approach for enhancing the photocatalytic activity of Bi OI through modification with PDI.2)In this chapter,the self-assembled PDI was modified on the surface of Bi OBr nanosheets by continuous ion layer adsorption method,and a S-scheme PDI/Bi OBr heterojunction was designed to further improve the degradation performance.To explore its microstructure,photoelectric properties and other characteristics,the electron transport channel constructed between self-assembled PDI and Bi OBr is to hinder photogenerated electron-holes recombination.Under visible light irradiation,when the Rh B was 50 mg/L,the removal rate of 1/3 PDI/Bi OBr reached 98%,which was 15.9 times that of self-assembled PDI and 13 times that of Bi OBr.After ESR testing,·O₂^-is the main active species of the reaction,and the structure of the recovered photocatalyst will not change.3)In this chapter,the wet impregnation method is used to achieve a low-cost and increase in the reactive sites,so that it can efficiently produce active species.A photocatalyst with S-scheme sheet PDI/Bi OCl heterojunction structure with oxygen vacancies on the surface was constructed.Under visible light,1/5 PDI/Bi OCl showed strong degradation performance,and the removal rate of Rh B（50 mg/L）reached 92.4%within 20 min and 100%within 60 min.Under the dual action of oxygen vacancies on the surface of Bi OCl and activated molecular oxygen,free radical chain reaction and mutual conversion reaction occur,and under the interaction of internal electric field and edge-bent coulomb,carriers can be transferred along theπ-πstack between PDI molecules,so charge recombination can be effectively inhibited.This work provides a direct case for the construction of S-scheme heterojunctions using simple methods for photocatalytic materials,and provides a reference for further study of the photocatalytic activity of Bi OCl materials.