Preparation And Electrocatalytic Properties Of Metal-Nitrogen Doped Carbon-Based Materials

The ecological problems caused by energy depletion and CO₂ need to be supported by clean energy.Therefore,proton exchange membrane fuel cell（PEMFC）and electroreduction CO₂ technology have aroused a scientific boom.Oxygen reduction reaction（ORR）is a restricted reaction（cathode reaction）of fuel cells.Due to its slow kinetics and high cost,its application development is limited.Therefore,it is necessary to explore new catalysts to solve the current situation.Hollow carbon sphere combines the advantages of porous carbon material,hollow and three-dimensional spherical shape,and has the advantages of high electrical conductivity and strong stability.Electro-reduction reaction CO₂（CO₂RR）technology converts chemically stable CO₂ into high value-added products,but it still faces problems such as high overpotential and serious side reactions.At present,the metal-N/S-doped carbon nanosphere catalyst has significant effects on the above applications.So in this paper,the effects of carbon sphere diameter,metal load,shell thickness,feed ratio and N/S element doping on the catalytic activity of oxygen reduction reaction（ORR）and CO₂ electroreduction reaction were studied by ICP-OES,XPS and Raman spectroscopy.This study is divided into two aspects:Catalytic activity of oxygen reduction reaction of hollow carbon spheres supported by Co:A Co supported,N/S co-doped hollow carbon spheres ORR monatomic catalyst was prepared by in-situ supporting of non-noble metal Co and using Si O₂ as hard template.The catalysts were induced to form hollow carbon nanospheres with a wall thickness of 10 nm and a uniform morphology by adjusting the loading amount and reaction temperature of metal Co in the catalyst.The ORR reaction of Co-N/S@HCS-1 with 0.42 wt%Co and reaction temperature of100℃was in accordance with the first order reaction kinetics principle,which was 4 electron transfer.Its half-wave potential and initial potential are similar to those of precious metal catalyst Pt/C,and its stability is better than that of commercial Pt/C.The excellent catalytic performance of Co-N/S@HCS-1 is attributed to the formation of non-noble metal Co-N_x active site,the introduction of S,high specific surface area and electron transport of mesoporous hollow carbon spheres.Catalytic activity of Ni supported mesoporous carbon nanoparticles in CO₂electroreduction:A Ni modified,N/S co-doped mesoporous carbon spheres CO₂electroreduction catalyst was prepared by one-pot method,using 3-aminophenol（N source）and formaldehyde generated phenolic resin nano-spheres as carbon precursors and 2,2,4,4-tetrahydroxy diphenyl sulfide as S source.By adjusting the synthesis time of carbon precursors,the addition amount of tetramethyl orthosilicate（TEOS）and the content ratio of N/S,the mesoporous carbon spheres with an average particle size of 65 nm were obtained.When Ni-N/S-C-24 was synthesized for 24 h,the amount of TEOS was 1 m L,and the ratio of N/S was1,the Faraday efficiency of CO was the highest,and the Faraday efficiency of side reaction was the lowest.The excellent CO selectivity of Ni-N/S-C-24 is attributed to the synergistic effect of non-noble metal Ni with N and S,high specific surface area and good electrical conductivity of the catalyst.