Preparation And Electrocatalytic Performance Of Nitrogen-doped And Defect-Rich Carbon-based Metal-free Catalysts

Along with the massive consumption of traditional fossil fuels,the energy and environmental crisis has become a huge challenge for human development in the 21 st century.The development of emerging renewable energy systems(e.g.,fuel cells,metal-air batteries,and water-splitting electrolysis devices)is critical to tackling above challenge.Oxygen reduction reaction(ORR),oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)are key for these energy storage and conversion devices.The highly efficient electrocatalysts are needed for catalyzing ORR/OER/HER,leading to highly efficient energy storage and conversion devices.Carbon-based metal-free catalysts have attracted more and more attention due to their abundant reserves,easy preparation,environmental friendliness,and high stability.Therefore,designing efficient carbon-based metal-free electrocatalysts is of great significance,and has become a common opportunity and challenge.In this paper,a series of novel carbon-based metal-free catalysts are designed and prepared through appropriate charge transfer modification,such as heteroatom doping and defect engineering.The main research results are as follows:1.A novel porous N-doped carbon material was synthesized by the reduction covalent cross-linking reaction of C60 with benzene-1,4-double nitrogen tetrafluoroborate(BBT),followed by carbonization in an ammonia atmosphere.N-doped porous carbon material has a high specific surface area and rich pores.In alkaline solution,the half-wave potential of it reached 0.82 V,so it is an efficient carbon-based metal-free electrocatalyst for ORR in alkaline solution.2.Using mesoporous silica SB A-15 as a hard template and C60 highly soluble in 1-chloronaphthalene solvent as a precursor,N-doped mesoporous carbon was successfully prepared.The N-doped mesoporous carbon possessed the pore structure,exposing more active sites,and promoting the transport of oxygen and electrons.The resulting N-doped mesoporous carbon had a half-wave potential of 0.857 V,exhibiting more excellent ORR catalytic activity than Pt/C catalyst in alkaline electrolyte.3.Using potassium steam to split multi-walled carbon nanotubes,a graphene nanoribbon and carbon nanotube composite material(N-GNR/CNT)with rich edges and N doping was developed.Due to high aspect ratio of graphene nanoribbons,edge defects and high pyridine nitrogen content of the composite,the resultant catalyst has rich active sites,leading to excellent ORR(E1/2=0.81 V)and OER performance(E10=0.496 V)in alkaline electrolytes,and good HER performance(E10=-0.4 V)in acid electrolytes.It is a good trifunctional carbon-based metal-free electrocatalyst for ORR,OER and HER.