Structure Design And Activity Studies Of The Molecular Catalysts For CO₂ Electroreduction Reaction

CO₂ is the main pollutant of industrial development,and also the available carbon resource under the background of energy crisis.The reduction and utilization of CO₂ has attracted worldwide attention,so China has put forward the dual carbon policy of carbon peak and carbon neutralization.CO₂ electrocatalytic reduction reaction（CO₂RR）is one of the ways to realize the resource conversion of CO₂.It refers to the use of renewable energy to convert CO₂ in the form of electrocatalytic into fuels with high added value such as carbon monoxide（CO）,methane（CH₄）and ethylene（C₂H₄）.The design of efficient cathode catalysts is the key to the development of CO₂RR.The emergence of molecular catalysts such as metal phthalocyanine and metal porphyrin has attracted the attention of researchers due to their excellent catalytic activity due to their unique electronic structure,and has attracted a series of studies on the structure-property relationship of molecular catalysts.The purpose of this paper is to solve the three scientific problems of metal center screening,microscopic mass transfer and intrinsic activity improvement in the research process of molecular catalysts.Firstly,the thermal-dynamic model was constructed based on the reaction element equation and the rate equation,and the thermal-dynamic simulation of the process of CO₂conversion to CO was realized based on the experimental data.The kinetic parameters and thermodynamic properties of the reaction were obtained,and the change trend of the coverage of the reaction intermediates was obtained.Based on this understanding of the reaction mechanism,the examples of CO₂RR reaction model construction of molecular catalysts were listed and the accuracy of the model construction was proved by electrochemical experiments.The scientific research problems on the intrinsic activity of molecular catalysts were put forward,including mass transfer control and electronic structure adjustment.Next,a series of nickel phthalocyanine/carbon-based support（NiPc/C）molecular catalysts with uniform dispersion and clear active sites were synthesized by wet chemical adsorption method.Nickel phthalocyanine was loaded on different carbon-based supports as an active center.The combination of nickel phthalocyanine and the support in the form ofπ-πinteraction was confirmed by structural characterization and density functional theory calculation to obtain its electrochemical performance.It was found that Ni-G had the highest conversion frequency of6089.53 h^-1,and the difference in electrocatalytic activity was due to mass transfer control.Further characterization showed that the microporous structure of carbon-based support promoted the mass transfer of CO₂ on the material surface.Finally,the effect of metal center of phthalocyanine on the CO₂RR of metal phthalocyanine/carbon nanotubes（MPc/CNT）molecular catalyst was studied.It was found that the metal center played a regulatory role in the binding of intermediates in the CO₂RR process.At the same time,the optimization of metal center can be realized by constructing the volcanic shape relationship with ^*COOH as the identifier.Based on this understanding of molecular catalysis.