Preparation And Electrocatalytic Performance Study Of Metal Polyaniline Composites For CO₂ Reduction

At present,the amount of CO₂ emissions in the atmosphere has exceeded 400 ppm,which has brought a great negative impact on the environment.Electroreduction CO₂technology is a promising technology.It can use the electricity generated by renewable energy sources（wind,electricity,tidal energy,etc.）to electrocatalytically reduce CO₂ to high value-added chemicals,such as CO,methane,methanol,ethanol,ethane and so on.These substances can also be used as fuel for automobiles,aircrafts,and other transportation vehicles,which is involved in people’s daily lives.It can not only reduce CO₂ emissions and protect the global environment,but also store unconventional renewable energy sources,alleviating the energy crisis.CO₂ electroreduction systems can be divided into aqueous and non-aqueous systems.Because the reaction conditions of the aqueous solution system are simple and can be carried out at normal temperature and pressure,we choose the aqueous solution system to analyse the performance of two different polyaniline-based catalyst materials on electrocatalytic reduction of CO₂,and the catalysts preparation also were disscused.Unless otherwise specified,the potential applied in this paper refers to the reversible hydrogen electrode（RHE）.And the main contents and conclusions of this thesis are as follows:（1）Polyaniline material was prepared on carbon paper substrate by electrochemical method,which was used as the base material for the following procedure.By in-situ reduction composite method,two types of Au/PANI/CP composites with different morphologies were obtained.And the Au/CP composites without polyaniline were also prepared by the same method latterly.The faraday efficiency,linear sweep voltammetry（LSV）and other properties of the electrocatalytic reduction of CO₂ from these three materials were compared,and the reaction mechanism was also discussed.All three catalysts can reduce CO₂ to carbon monoxide.At-0.7 V,the faraday efficiency of CO on Au/PANI-1/CP composites with low polyaniline content is the largest,which can reach99.4%,while the highest faraday efficiency of CO in Au/CP materials at-0.8 V potential is60.3%.Au/PANI-1/CP composites with high polyaniline content also reach the highest faraday efficiency of CO at a potential of-0.7 V,which is about 40%,lower than the other two catalysts.This difference in catalytic efficiency may be due to the synergy between Au and certain PANI films.（2）Based on Au/PANI-1/CP,a cuprous oxide（Cu₂O）particle with a cubic structure is prepared by an electrochemical deposition method to form a Cu₂O/Au/PANI/CP composite material.Among them,the Cu₂O particles prepared at 10 minutes of electrodeposition are more closely arranged.To obtain a Cu₂O/Au/PANI-α/CP composite material,the Cu₂O/Au/PANI/CP composite material is calcined in N₂ atmosphere.By comparing the performance of the two materials for electrocatalytic reduction of CO₂,we concluded that both materials have the highest selectivity to CO at-0.8 V.Among them,there are many kinds of catalytic products of Cu₂O/Au/PANI/CP materials,including hydrogen,CO,CH₄,C₂H₄,and C₂H₆.The maximum faraday efficiency of CO can reach 15%,while the yields of methane,ethane,and ethylene are less than 2%,mainly producing H₂.The gas phase products of Cu₂O/Au/PANI-α/CP materials are only CO and H₂,which CO faraday efficiency reaches a maximum of 8.4%.