Preparation Of Attapulgite Composites And Their Photoelectrocatalytic Reduction Of Carbon Dioxide

The continuous consumption of traditional fossil fuels has led to the energy crisis and the rapid increase of greenhouse gas emissions,leading to global warming,rising sea levels and other ecological problems.In order to solve these problems,carbon dioxide elimination and further resource conversion are becoming increasingly important.photoelectrocatalytic reduction of carbon dioxide into high value-added hydrocarbon products is one of the high ways of CO₂ conversion.On the one hand,this method can effectively solve the environmental problem of greenhouse effect;on the other hand,it can reduce the pressure of energy crisis by using solar energy to convert CO₂ into hydrocarbon fuel.In recent years,the use of solar energy to reduce carbon dioxide to chemicals through photocatalysis has been a great challenge for scientists working in chemistry,materials and environmental sciences.Researchers have been working to develop efficient and stable catalysts.There are few applications in CO₂ reduction.At present,the application of porous materials in CO₂ utilization mainly focuses on CO₂ capture and storage,but is less used in CO₂ reduction.Attapulgite materials have attracted attention because of their advantages such as low toxicity,low cost,large surface area,high stability and strong adsorption.Based on the above comprehension,this thesis developed and synthesized attapulgite based composite material,and applied it to the photoelectrocatalytic reduction of CO₂.Through organic functionalization,surface light deposition,metal oxide loading and other methods to introduce catalytic active components,improve the catalytic activity,the preparation and synthesis of excellent catalysts of attapulgite-based materials were investigated with full characterization,and high efficiency of photoelectrocatalytic CO₂ reduction.（1）S-ATP-Cu-x material:In this part,APTES and salicylaldehyde were functionalized and grafted to ATP surface by heating reflow method,and Cu nanoparticles were deposited by photodeposition to obtain functionalized S-ATP-Cu-x photocathode.The structure of the functionalized mesoporous material was characterized by SEM,TEM,XRD,XPS,IR,UV-vis and BET,and its photocatalytic reduction performance of CO₂ was tested by LSV,EIS,etc.The results show that the catalytic activity of mesoporous materials can be improved by introducing the catalytic active components into the mesoporous materials ATP by organic functional assembly and deposition of Cu nanoparticles.The surface plasmon resonance effect caused by Cu nanoparticles promotes the generation of hot electrons.The functionalized mesoporous materials S-ATP-Cu-x with different Cu contents all show excellent catalytic activity for photoelectrocatalytic reduction of CO₂,effectively promoting C-C coupling and generating formic acid,ethanol,acetic acid and other products.When the applied voltage is-0.9V（vs.SCE）,the total hydrocarbon formation rate of the photocathode S-ATP-Cu-2 is the highest,with 98.9%faradaic efficiency.（2）Sn O₂-ATP-x-Cu-y material:In this part,rod-shaped attapulgite composite catalyst（Sn O₂-ATP）loaded with granular Sn O₂ was in-situ prepared by hydrothermal method.ATP was dispersed in the Sn O₂ precursor solution by ultrasonic,and the Sn O₂-ATP catalyst was obtained by hydrothermal synthesis,and copper nanoparticles were introduced by photodeposition.The structure of the functionalized mesoporous material was characterized by SEM,TEM,XRD,XPS,IR,UV-vis and BET,and its photocatalytic reduction performance of CO₂ was tested by LSV,EIS,etc.The introduction of ATP inhibited the aggregation of Sn O₂,improved its dispersity,and increased the CO₂ reduction active site.Meanwhile,the surface plasmon resonance effect of Cu enhances the material’s light absorption performance.The optimal SA-2-Cu-2 catalyst produced HCOOH,CH₃OH,CH₃CH₂OH and CH₃COOH in high yield.When the applied voltage is-1.0V（vs.SCE）,the total hydrocarbon formation rate of the photocathode SA-2-Cu-2 is the highest,with 102.1%faradaic efficiency.