Heterojunction Composite Modification Study Of Carbon Cloth Supported Silver Phosphate And Silver Carbonate Photocatalytic Materials

With the increasing seriousness of environmental pollution,Photocatalytic technology is widely welcomed as it can degrade organic pollutants in water and air and improve the environment.For traditional disposal techniques such as incineration and landfill,photocatalytic technology not only operates Simple,low energy consumption,and more importantly,it will not produce secondary pollution.In addition,solar energy is inexhaustible.For broadband gap photocatalysts that can only show activity under ultraviolet light（only 4%-6%of the solar spectrum）,this obviously reduces the utilization of visible light（about 43%-46%of the solar spectrum）.Therefore,it is of great significance to study the photocatalysts that can respond under visible light.Silver-based compounds such as silver phosphate（Ag₃PO₄）and silver carbonate（Ag₂CO₃）can respond to visible light and have narrow band gaps,high quantum efficiency,and unique crystal structures,and have been studied by major domestic and foreign research.sought after.However,there are still some problems in silver based photocatalytic materials:on the one hand,a single silver based photocatalytic material is prone to photochemical corrosion,which greatly reduces the photocatalytic activity and stability;On the other hand,when silver-based photocatalytic materials are used to purify wastewater in practical applications,they often encounter difficulties in separation and recovery.Supporting photocatalytic materials on a certain substrate is expected to solve the problem of separation and recycling.Carbon cloth has become an ideal carrier due to its good flexibility,high porosity and good electrical conductivity.In this thesis,commercial carbon cloth is used as the carrier to carry out a series of modification work on silver phosphate and silver carbonate photocatalytic materials.The specific research contents are as follows:1.Using zinc nitrate hexahydrate（Zn（NO₃）₂·6H₂O）and hexamethylenetetramine(C₆H₁₂N₄)as raw materials,ammonia（NH₃·H₂O）and deionized water as solvents,firstly,we prepared carbon fiber cloth supported zinc oxide（labeled as CC@Zn O）.Then Zn O/Ag₃PO₄ composites supported by carbon fiber cloth were prepared by impregnation method.In order to verify the photocatalytic activity of rhodamine（Rh B）solution.The activity test results showed that after 100 min irradiation,the degradation rate of Rh B solution was the highest,up to 87.1%.In contrast,the degradation rate of Rh B solution by CC/Ag₃PO₄ at the same time is relatively low,only 38.3%,while CC@Zn O The degradation rate of Rh B solution was only 14.7%.The first-order reaction rate constant of the carbon cloth-supported Zn O/Ag₃PO₄ composite photocatalytic material is 19.1×10^-3min^-1,which is 16 times that of CC@Zn O and 4.8 times that of CC/Ag₃PO₄,respectively.A series of tests show that a heterojunction is formed between Zn O and Ag₃PO₄,This can effectively reduce the recombination efficiency of photogenerated electron-hole pairs.In addition,due to the good electrical conductivity of carbon cloth,it can not only transport electrons,but also improve the separation efficiency of electron-hole pairs,but also solve the problems of separation and recovery as a substrate.This heterojunction composite photocatalytic material provides a new idea for the modification and loading of other photocatalytic materials.2.Using ammonium fluoride,urea and cobalt nitrate hexahydrate as raw materials,ethylene glycol and deionized water as solvents,Co₃O₄ supported carbon cloth was prepared by solvothermal calcination method,and then Co₃O₄/Ag₃PO₄ supported carbon cloth composite was synthesized by impregnation method.photocatalytic materials.Through a series of tests and characterization,the deposition of Ag₃PO₄ after Co₃O₄supported on carbon cloth will form a heterojunction,which can effectively improve the separation efficiency of e^--h⁺pairs,so as to improve the activity and stability.In the degradation experiment of Rh B solution,the degradation rate of Rh B solution reached 98.5%after illumination for 80 min,and its first-order reaction The rate constant is 47.1×10^-3 min^-1,which is 67.29 times that of CC@Co₃O₄(0.7×10^-3 min^-1)and 6.63 times that of CC/Ag₃PO₄(7.1×10^-3 min^-1)in the cycling experiments Among them,the carbon cloth supported Co₃O₄/Ag₃PO₄ composite photocatalytic material can show good stability.Therefore,we believe that this composite photocatalytic material is expected to play a good potential in practical wastewater purification.3.Using ammonium fluoride,urea and cobalt nitrate hexahydrate as raw materials,ethylene glycol and deionized water as solvents,Co₂（CO₃）（OH）₂ was grown on carbon cloth by solvothermal method,and then calcined to obtain carbon cloth supported tricobalt tetroxide（CC@Co₃O₄）,and then obtained the CC@Co₃O₄/Ag₂CO₃ composite photocatalytic material by impregnation method.The results show that the composite of Co₃O₄ and Ag₂CO₃ can effectively improve the activity.The degradation experiment shows that,CC@Co₃O₄/Ag₂CO₃ The degradation rate of Rh B solution reached 91.68%after 100min illumination,which was significantly better than CC,CC@Co₃O₄,and CC/Ag₂CO₃.The first-order reaction rate constant of CC@Co₃O₄/Ag₂CO₃ is 20.15×10^-3 min^-1,1007.5times that of CC@Co₃O₄(0.02×10^-3 min^-1)and 1.73 times that of CC/Ag₂CO₃(11.65×10^-3min^-1).