The Study Of ZIF-8 Derived Nitrogen-doped Non-precious Metal Catalyst For Oxygen Reduction Reaction

The worsening environment and the depletion of traditional energy resources are serious problems that people need to face and solve in the 21st century.As a clean and renewable energy,hydrogen energy has attracted wide attention,and proton exchange membrane fuel cell(PEMFC)is an efficient device to use hydrogen energy.However,because most of them use Pt as catalyst,the high cost of Pt hinders the commercialization of fuel cells.Therefore,the search for a non-noble metal catalyst to replace the traditional platinum-based catalyst has become an ideal solution.MOFs(Metal Organic Frameworks,MOFs)have attracted much attention in recent years due to their unique pore structure and high specific surface area.Among them,ZIFs(Zeolitic Imidazolate Frameworks,ZIFs)is one of the research hotspots,and ZIF-8,as a zinc-containing ZIFs,can escape zinc element through heat treatment at high temperature,so that the material produced has a very high specific surface area.Firstly,ZIF-8,a framework material of zeolite imidazole,was prepared by different methods.As a precursor,it was mixed with acetate ferrousby ball milling and calcined at high temperature to obtain Fe/N/C catalyst.It was found that the morphology of ZIF-8 prepared by hydrothermal method was uniform and its specific surface area was higher,and the final catalyst had a better performance.Next,the test conditions of semi-cell and full-cell of the catalyst were optimized.In the half-cell test,the half-wave potential in acid electrolyte is 0.773 V;in the full-cell test,the maximum power density can reach 810 mW/cm2,when the load is 3 mg/cm2 and the back pressure is 0.2 MPa.On the other hand,graphene oxide has been widely used in the preparation of electrochemical catalysts because of its special structure and abundant functional groups.Therefore,we doped graphene oxide on the basis of the above-mentioned Fe/N/C catalysts,combined with the related physical and electrochemical characterization,we found that the specific surface area of the material increased and the proportion of micro-porous mesoporous increased with the introduction of trace graphene oxide,but when the amount of graphene oxide was too large,the performance would decline significantly.Under the optimum raw material ratio,the half-wave potential of the catalyst increased by about 40 mV to 0.814 V after doping graphene oxide,and the stability also improved significantly.After 10000 cycles of scanning,the performance of the catalyst decreased by only 10 mV.In the whole battery test,the activity is basically the same as that before doping.The results show that graphene oxide can improve the performance of catalysts,but there is still a gap compared with traditional commercial platinum carbon catalyst.