Cu Based Electrocatalysts Studies For CO₂ Electro-reduction Reaction With Hydrocarbon Productions

CO₂ electro-reduction reaction?CO₂RR?can directly convert CO₂ into fuel and useful chemicals at atmospheric and near normal temperature,which is the key technology to achieve the“carbon cycle”in nature and alleviate many environmental problems.In this thesis,the internal relationship between the structure of Cu based electrocatalytic materials and the performance of CO₂RR was studied by transient electrochemical technology,plasma surface treatment technology,optical microscopy technology and numerical simulation analysis.First of all,plasma surface treatment technology was used to carry out ex-situ modulation of the surface morphology and oxidation state of the Cu foil.The effects of RF power,oxygen partial pressure and treatment time on the Cu surface structure and the conversion activity of C_xH_y prepared were investigated.Secondly,the periodic potential pulse method was used to adjust the surface structure and oxidation state of Cu foil in situ in CO₂RR.The effects of the pulse parameters of oxidation time Ta,reduction time Tc,reduction potential Ec and oxidation potential Ea on the conversion activity of CO₂ to C_xH_y were investigated.It was proposed that the periodic potential pulse method can realize the controllable preparation of the catalyst crystal surface and the crystal size.In turn,a controlled conversion of CO₂ to CH₄ could be achieved.Under this experimental condition?5?,Ta=5 s,Ea=1 V,Ec=-2.2 V,Tc=70 s?,the Faraday efficiency of CO₂RR to CH₄ on the surface of Cu foil could be as high as 76.66%.In addition,Under the condition of constant Ea and Ta,the regular relationship of Faraday efficiency of CH₄ was proposed.Finally,in order to further understand the mechanism of CO₂ to C_xH_y and electrode process dynamics,Cu was used as catalyst to carry out macro kinetic analysis and sensitivity analysis of kinetic parameters for CH₄.It aimed to understand the reaction mechanism from CO₂ to CH₄ and the key factors that affect the electrode process dynamics.The results showed that the formation of CO_adsds was a rate control step;in each model parameter,the sensitivity coefficient for the influence of the cathode potential on the parameter from large to small is in order of CO₂ dissolved concentration>limit coverage of active center>KHCO₃concentration>CO dissolved concentration.