Synthesis Of Flower-like Cobalt 2D Catalysts And The Electrocatalytic Investigation On Carbon Dioxide Reduction Reaction

With the continuous development of global economy,the demand of science and technology as well as industrial production and the human consumption of traditional fossil fuels lead to the global greenhouse effect.The concentration of carbon dioxide which has been known as the main“culprit”of“greenhouse gas”is increasing year by year.Severe global environmental problems force society to develop CO₂ conversion technology vigorously in order to convert it into available energy,and finally realize the carbon cycle.Electrocatalytic reduction of carbon dioxide has the advantages of simple reaction conditions,easy control of process,high conversion rate,effortless acquisition of materials,easy to scale up production and so on.Electrocatalytic reduction of carbon dioxide which has potential practical application value is considered as a promising energy conversion technology.At present,the electrocatalysts commonly used in electrocatalytic reduction of carbon dioxide are mainly copper,silver,gold and other metal materials with high cost.At the same time,two-dimensional catalysts have been widely studied because of their large specific surface area and dense active sites.Therefore,the synthesis of high-efficiency non-noble metal two-dimensional material catalyst with special morphology has important significance for improving the catalytic performance and reducing the reaction cost.In this thesis,a novel metal cobalt catalyst with special morphology was synthesized by facile solvothermal method.The morphology and particle size of the self-made catalyst were analyzed by a series of physical characterization methods,including scanning electron microscopy?SEM?,X-ray diffraction?XRD?.A series of electrochemical characterization methods?including cyclic voltammetry,linear sweep voltammetry,etc.?were used to study the electrochemical behavior.Nuclear magnetic resonance?NMR?technique was used to study the reduction products qualitatively and quantitatively so as to evaluate the catalytic performance of the materials accurately.Firstly,by adding n-butylamine as a capping agent and sodium hypophosphite as a reducing agent,a flower-like metal cobalt catalyst material was prepared by a solvothermal method.In addition,cobalt hydroxide and bulk metal cobalt material were prepared by changing reaction conditions for comparison.The flower-like cobalt material has higher catalytic activity for carbon dioxide reduction reaction due to the special morphology.Secondly,by scanning cyclic voltammetry in the different electrode potential ranges,the prepared flower-like cobalt material was applied to investigate the process of carbon dioxide reduction reaction.The results show that there exists interfacial catalysis between zero valence metal cobalt and partially oxidized divalent cobalt.The analysis of the causes of cathodic reduction current at more negative potential provides a basis for further understanding of the process of carbon dioxide electroreduction.Besides,the effect of electrolyte concentration on the reduction process was also studied.The Faraday efficiency and yield of formic acid were 63.4%and 136 mg/L,respectively.Finally,the nitrogen-doped mesoporous carbon two-dimensional material with a thickness of about 2 nm was synthesize by a double template method,and the electrochemical test result shows that the nitrogen-doped mesoporous carbon two-dimensional material has good catalytic activity on the electroreduction of carbon dioxide.