Synthesis Of Heteroatom-doped Three-dimensionally Ordered Macro-/Mesoporous Carbon Material And The Studied Of Electroc Atalytic CO₂ Reduction Reaction Performance

The issues of environmental and energy are hot topics of common concern to all mankind.The burning of fossil fuels leads to the transitional emission of CO2,and the resulting series of environmental problems such as global warming and melting glaciers need to be resolved urgently.Researchers in related fields are working hard to find a powerful way to solve the above problems.Among them,the conversion and utilization of CO2 can not only consume CO2 in the atmosphere to solve environmental problems,but also relieve energy pressure.Electrocatalytic CO2 reduction(ECR)technology that uses clean energy to convert CO2 into high value-added fuels and chemical products has attracted extensive research interest because of its mild operating conditions and high conversion efficiency.However,the activation of CO2-stabilized linear molecules requires high amounts of activation energy to act simultaneously with highly efficient catalysts,limiting the pace of its industrial application.Therefore,there is an urgent need to develop excellent electrocatalysts to promote the practical application of this process.After continuous research,precious metal electrocatalysts have excellent performance,but lack of resources and high cost hinder their large-scale application.Therefore,the design and development of efficient,inexpensive,and industrializable electrocatalysts is an effective method to promote CO2 conversion and alleviate environmental and energy problems.Based on this,the paper designs and develops a three-dimensionally(3D)ordered macro-/mesoporous carbon material co-doped with Ni and N(Ni-N-OMMC).At the same time,the physical characterizes and the electrocatalytic CO2 reduction performance were studied.The main work can be briefly summarized as follows:1.The three-dimensionally ordered Ni,N co-doped macro-/mesoporous carbon material(Ni-N-OMMC)was prepared by dual-templating technology.The macroporous hard template is SiO2 colloidal crystal.The mesoporous guiding agent is nonionic surfactant Pluronic F127.Take resol type phenolic resin prepolymer(Mw<500),dicyandiamide(DCDA)and Ni(NO3)2·6H2O as sources of C,N and Ni,respectively.A series of physical characterization shows that the synthesized materials exhibit a good 3D ordered hierarchical macropore and mesopore structure.The pore diameter of macropore is about 250 nm,and the average mesopore diameter is about 12 nm.The electrocatalytic CO2 reduction performance test shows that Ni-N-OMMC has excellent CO2 reduction to CO performance.2.Prepare three-dimensionally ordered nickel and nitrogen co-doped macro-/mesoporous carbon with different Ni and N ratios by changing the mass ratio of Ni and N sources(Ni-N-OMMC-x).The results show that:(1)Catalysts with different ratios have similar three-dimensionally ordered macro-/mesoporous structure.However,the difference is that as the Ni/N ratio increases,the order of the material becomes worse.(2)The Ni-N-OMMC-0.6 in the sample has a relatively ordered structure and a large specific surface area.Compared to other samples,Ni-N-OMMC-0.6 contains riched Ni-Nx and pyridinic-N sites with highest content of the total is 37.6%.(3)The ECR performance studies show that Ni-N-OMMC-0.6 exhibits the best CO2 reduction performance,and its current density reaches a maximum of-13.4 1A cm-2 within the test potential range CO Faraday efficiency is as high as 98%,and has good electrochemical stability.3.Using the catalyst Ni-N-OMMC-0.6 as the research object,to explore the effect of the electrolyte KHCO3 concentration on the CO2 reduction performance of the sample.The results show that the higher the electrolyte concentration lead to the lower the CO selectivity.The 0.1 M KHCO3 is the best electrolyte concentration for ECR to CO.In addition,the toxic substance KSCN was added to the reaction system to study its effect on the catalyst performance.The results showed that:Toxic ions can partially poison the catalyst and reduce its activity,but it is not completely deactivated,indicating that the catalyst has a certain anti-toxic stability.