Preparation Of Co-doped Carbon Materials Of Fluorine,Nitrogen And Iron(Cobalt)and Study On Oxygen Reduction Properties

Fuel cell is a new way of energy conversion.Unlike traditional fossil fuels,it doesn’t becomes non-renewable with the continuous consumption of fuel.Fuel cell is an environmentally friendly and efficient way of energy conversion,and the traditional fossil energy can’t be supported for too long from the current use speed.There is an urgent need for a new renewable energy conversion approach to address the energy crisis that will soon be faced.Fuel cell are one of the most promising ways to convert energy.The cathode oxygen reduction reaction of fuel cell is a very slow process,and the cathode oxygen reduction catalyst used at this stage is mainly precious metal platinum.Pt-based catalysts are expensive and have few reserves,which also limits the process of extensive commercial application of fuel cells.In this paper,a series of carbon-doped oxygen reduction catalysts were prepared from melamine and PTFE.We studied the structure,morphology,elemental composition of the catalyst and the effect of the interaction between the various elements on the performance of the catalyst by rotating disk electrode,SEM,TEM,XRD and other equipments,and summarized the rule of the change of the activity of the catalyst.The main findings are as follows:1.Using melamine and polytetrafluoroethylene（PTFE）as raw materials,a high-performance co-doped oxygen reduction catalyst was prepared by one-pot method.When the heat treatment is 900℃,the material has a high degree of graphitization.The nitrogen and fluorine elements are evenly distributed in the material,and the catalyst shows the best catalytic performance of oxygen reduction.It’s half-wave potential reached 0.815 V at 0.1M KOH solution,very close to the commercial platinum-carbon electrode,and specific surface area also reached 379 m²g^-1.2.Using melamine,polytetrafluoroethylene（PTFE）and Ethanol solution of cobalt acetate,and the ethanol solution was ground into powder through a mortar.Then prepared by high temperature heat treatment a single metal cobalt,fluorine and nitrogen doped graphene structure oxygen reduction catalyst.The best performance when the calcination temperature is 950℃.The specific surface area of the oxygen reduction catalyst synthesized by this method reaches 642 m²g^-1.At high magnification,the catalyst was stacked in multiple layers with an average number of layers of seven.It’s half-wave potential also reached an excellent 0.86 V,under alkaline conditions.Through the 30,000 s stability test,the current retention rate is still 87.13%,and the cycle stability is also better than that of commercial platinum-carbon catalysts.3.A bimetallic iron,cobalt,and fluorine and nitrogen four-doped oxygen reduction catalyst were synthesized using melamine,polytetrafluoroethylene（PTFE）,the ethanol solution of ferric chloride and the ethanol solution of cobalt acetate as raw materials.Bimetallic doped catalysts exhibit better catalytic performance than single metal doped catalysts under both acidic and alkaline conditions.The half-wave potential reached 0.9 V under alkaline conditions.The cycling stability is more excellent than that of commercial platinum-carbon catalysts.After the stability test for 30,000 s,the current retention is 90.8%.The specific surface area of the bimetallic doped catalyst is up to 634 m²g^-1 and the catalyst still adopts the grapheme-like structure.