Design Of Metal-Based Catalysts And Their Performance In O₂ And CO₂ Electroreduction Reactions

Under the dual pressure of energy crisis and environmental problems,CO₂ resource utilization becomes an effective solution.Among them,it is a promising method to convert CO₂ into methanol by means of electrochemical reduction,but at the same time,it is faced with such problems as low selectivity and low yield.Based on this,a nitrogen-doped carbon black matrix supported Cu monatomic catalyst?named Cu-SA/NC?was reported.The catalyst achieved high activity and selectivity of CO₂ electroreduction to methanol.For example,at-1.4 V(vs RHE;The Faraday efficiency and yield of methanol production were63±3%and 304.2 mmol h^–1 g^–1,respectively,under the electrode potential of reversible hydrogen electrode,which were better than other electrocatalysts reported.In addition,the catalyst maintained stable current density and Faraday efficiency of methanol production in the continuous electrolysis process for 28 hours,indicating that it has good electrochemical stability.In addition,the data of synchrotron radiation showed that Cu was atomically dispersed and cu-n4 coordination was fitted,which was used as the active site of the catalyst.Through theoretical calculation,it can be concluded that Cu-SA/NC catalyst is favorable for the generation of*COOH and the desorption of*OCH₃ to generate methanol.Therefore,the reduction process of the catalyst is a process of reducing methanol by 6 electrons.This work proves for the first time that monatomic catalysts have high yield,selectivity and excellent stability in the process of CO₂ reduction to methanol,thus contributing to the field of monatomic electrocatalysis.CO can be used in industry to produce chemicals and synthetic fuels,so selective conversion of CO₂ into CO is a promising approach.In this article,we also reported a kind of manganese dioxide nano-sheet catalyst grown on the nickel foam substrate.This catalyst was first used in the electrocatalytic reduction of CO₂ reaction.Benefiting from the unique nano-sheet structure of manganese dioxide,it exposed a large number of active sites,thus achieving high selectivity for CO.For example,at-0.95 V,the Faraday efficiency of CO production reaches 71%.In addition,the catalyst has good electrochemical stability.Zinc-air battery has attracted extensive attention due to its advantages of safety,zero pollution,high energy,high power,low cost and renewable materials.How to prepare a kind of non-noble metal catalyst to replace the traditional Pt catalyst has become the current research hotspot.To solve this problem,this paper proposes a simple method to achieve in-situ coupling between Fe₃O₄ nanoparticles and nitrogen-doped graphite carbon by one-step pyrolysis of heme in an atmosphere of argon.Electrochemical tests showed that the half-wave potential of the catalyst was 0.875 V vs.RHE,close to that of commercial Pt/C catalyst,but its stability and methanol resistance were better than Pt/C.We then applied the catalyst to the cathode of the zinc-air battery.The maximum power density of the battery is 174.8 mW cm^-2,and the specific capacity is up to 708.9 mAh g_Zn^-1.