Preparation Of Co-N-C Catalyst Derived From Metal-organic Framework And Its Oxygen Reduction Performance

With the development of national strength,our economy is developing rapidly,the usage of fossil energy is increasing gradually,but the total output of global energy resources is limited,at the same time,the problems of environmental destruction left after the exploitation of energy can not be dealt with in time.Therefore,committed to the development of green new energy is the focus of attention all over the world.The development and mass production of fuel cell is the future of new energy.Based on the existing research of hydrogen oxygen proton exchange membrane fuel cells,this paper reviewed the current research and development status of fuel cells,and analyzed the mechanism of oxygen reduction reaction on the cathode,and explored the synthesis process and catalytic principle of non-noble metal catalysts.The details are as follows:（1）Firstly,the metal-organic skeleton（MOF）was synthesized by continuous stirring at room temperature using self-assembly method.Then,the metal organic skeleton derived Co-N-C catalyst was heated to 950℃under Ar atmosphere at a temperature rate of 20℃/min for 120min.The electrochemical test results showed that the half-wave potential of the catalyst was 0.775 V.In addition,after 10,000voltammetry cycles,the electrochemical performance was almost the same as before aging.At the same time,it was inferred from the H₂O₂ yield and the number of transferred electrons that the catalysis followed the four-electron reaction path and would not generate polluting intermediate peroxides.The performance advantage of the catalyst was analyzed from the dynamic influencing factors.A lot of physical characterization has proved that the active site of Co-N-C catalyst is Co-N_x,and excessive Co particles will interact with the active substance to improve the catalytic performance.Then,different heating temperature and heating rate were adjusted to explore the synthesis process of Co-N-C catalyst.（2）Using sodium chloride as the molten salt template,carbonization was achieved and pores were made successfully at 800℃for two hours.Then,gradient heating method was used to increase the heating rate to 950℃at 20℃/min,and the porous Co-N-C Ps catalyst was obtained at Ar atmosphere for two hours.The SCV results in HCl O₄ solution showed that the half-wave potential of the catalyst was 0.805 V,and the（3）electrochemical performance did not decrease significantly after 10,000voltammetry cycles.Meanwhile,combined with the analysis of the H₂O₂ yield and the number of transferred electrons,the catalyst followed the four-electron reaction path.The analysis of physical characterization results showed that the Na Cl template did play a role in pore-making,which provided defective structures for the growth of the active site.The gradient temperature rise made the active site grow on the surface of the catalyst pore structure dominated by micropore structure,the specific surface area of the catalyst is larger and more active sites are found Thus,it has better electrochemical activity.Then,the synthesis process of Co-N-C Ps catalyst was investigated by adjusting different feeding ratios and temperature gradients.