Research Of Carbon Dioxide Capture And Electrochemical Reduction

Carbon dioxide capture and conversion is an effective approach to mitigate the greenhouse effect.The adsorption method for carbon dioxide capture has the advantages of low energy consumption,low cost,no corrosion and pollution.The electrochemical reduction of carbon dioxide into value-added compounds has the advantages of pollution-free,mild conditions,controllable reaction process.This paper made an intense research into carbon dioxide adsorption and electrochemical reduction collection to formate.(1)After sulfuric acid treatment,MCM-41/SGU-29-c microporous/mesoporous composite molecular sieves were synthesized with different mass SGU-29 copper silicalite as precursor,sodium silicate hydrate as inorganic source and CTAB as mesoporous templat.This composite had the advantages of microporous molecular sieve and mesoporous molecular sieve.The composite molecular sieve showed better CO2 adsorption capacity than pure microporous molecular sieve SGU-29 and pure mesoporous molecular sieve MCM-41.When SGU-29/CTAB mass ratio is 0.212,MCM-41/SGU-29-2 showed highest pure CO2 adsorption quantity which reached 1.68 mmol·g-1.(2)Indium oxide samples with different dimensions and oxygen vacancy contents were prepared by heat treatment from two-dimensional InOOH nanosheets and their performance of electrochemical CO2 reduction were researched.Benefit from a large number of oxygen defects,the two samples of Vo-rich InOOH nanosheets and In2O3 nanorod showed exceeding 90%Faraday efficiency of formate and the current density reached 12 mA·cm-2 at-0.9 V vs RHE.(3)Assisted by KOH,urea as nitrogen-rich raw material,nitrogen-deficient graphene phase carbon nitride c-g-C3N4-x were prepared by one-step method.The active nitrogen contents on the surface of carbon nitride could be regulated by the amount of KOH and 0.5-g-C3N4-x was the highest in three samples,which reached up to 0.889.A new type of non-metallic CO2 reduction electrocatalyst c-g-C3N4-x/CNTs were synthesized by loading c-g-C3N4-x onto carbon nanotubes(CNTs)through hydrothermal treatment.Among them,0.5-g-C3N4-x/CNTs showed highest Faraday efficiency to formate,which reached up to 89%at-0.75 V vs RHE.