Preparation Of Nitrogen/Fluorine And Transition Metals Co-doped Carbon Materials And Their Oxygen Reduction/Oxygen Evolution Properties

The energy crisis has spurred scientists to explore new energy materials,energy conservation and conversion technologies,such as fuel cell and water electrolysis technology.However,the development of fuel cell and water electrolysis has been severely limited by the slow reaction of oxygen electrodes.Oxygen electrode reaction includes oxygen reduction reaction and oxygen evolution reaction.Because their reaction rate is too slow,so they need to be accelerated by electrocatalysts.At present,precious metals platinum（Pt）,iridium（Ir）and ruthenium（Ru）related materials are mainly used for oxygen reduction reaction and oxygen evolution reaction.But precious metals are unfriendly in terms of poor stability,reserves,prices and so on.Therefore,it is necessary to develop non-noble metal catalysts with low cost,sufficient resources and stable performance.Carbon-based catalysts have become a hot research topic due to its large specific surface area,excellent electrical conductivity,easy doping heteroatom,supporting transition metal,adjusting porosity,low price,good stability and high catalytic efficiency.In this paper,the M-N-C type oxygen electrode catalysts formed by nitrogen（fluorine）heteroatom and transition metals co-doped carbon based materials were studied.The electrocatalytic properties and some characterization techniques were used to explore the impact of the morphology and structure of the catalysts and the interaction among the elements on the electrocatalytic properties.The main research contents are as follows:1.Fe-N-C non-noble metal catalysts were prepared by high temperature calcination of biomass carbon material derived from fermented bean curd with ferric chloride as iron source.When the activation temperature of 900℃,the BET specific surface area of the precursor after acidification and reheat treatment is as high as 5,876m²g^-1,and the material is rich in microporous,mesoporous and macroporous structures.Its half-wave potential is comparable to that of commercial Pt/C catalysts,it has good stability and methanol resistance ability.In the process of oxygen reduction catalytic reaction,both"direct 4 electron mechanism"and"2+2 electron mechanism"exist.2.We used polyaniline and melamine as carbon raw materials,iron and nickel metal materials combined to prepare the catalysts for oxygen reduction and oxygen evolution reaction.When the carbonization temperature is 900℃,The specific surface area of our precursor material shows 92 m²g^-1.In the case of simultaneous oxygen reduction,the initial potential is distributed at 0.898V,and the half-wave potential is distributed at 0.801V.Oxygen reduction reaction also has excellent methanol resistance durability.The initial potential of oxygen evolution reaction is 1.56V,which is better than RuO₂,showing good oxygen evolution performance.3.The mixed porous carbon materials of iron and copper bimetallic were synthesized by one step method using melamine,polytetrafluoroethylene,anhydrous ferric chloride and copper acetate monohydrate.When the ratio of iron to copper is increased by 1.5 times,the specific surface area of the catalyst is 625 m²g^-1.In alkaline environment,the initial potential is 0.98 V,and the half-wave potential is 0.85 V,the electrochemical activity is better than commercial Pt/C,the stability and methanol durability are quite superior.It also has good activity in acidic environment.