Controllable Synthesis And Performance Research Of Carbon-based Non-noble Metal Oxygen Reduction Materials

Since the industrial revolution,fossil fuels have become the main energy to sustain social development.However,their limited reserves and serious pollution force people to develop green and efficient new energy storage and transformation technologies to meet the requirements of sustainable development of society.Fuel cell is considered to be the most ideal energy conversion device because of its advantages of quick start-up at low temperature,clean reaction products and high energy conversion efficiency.The cathode of fuel cell is oxygen reduction reaction?ORR?,which contains a complex four-electron process,and which is the speed-controlling step of the whole catalytic reaction.Although noble metal materials have excellent catalytic performance for ORR,their commercial applications are limited by many shortcomings.By studying non-noble metal cataly sts,the problem of high price and poor stability of noble metals in fuel cells can be solved,so as to solve the problems of energy shortage and environmental pollution faced by the current society.Therefore,the development of abundant an d cheap non-noble metal-based ORR catalysts has become a research hotspot.Based on the characteristics of hetero-atom carbon and transition metal-based catalysts,this paper designed and synthesized hetero-atom doped carbon and its complex with transition metal phosphating compound.By regulating the structure of the catalyst,the ORR performance of the material was optimized and its catalytic reaction mechanism was explored.The main research contents of this paper are as follows:1)The precursor of ZnO@ZIF8 was controllable synthesized by solvent heat method with hexagonal ZnO nano-sheet as sacrifice template and Zn source,urea as added carbon source and nitrogen source;Nitrogen doped porous carbon nanosheets?N-PCN?were obtained by gas pyrolysis of ZIF produced by urea pyrolysis during high temperature carbonization.The porous flake structure not only increases the specific surface area of the catalyst and exposes more active sites,but also helps the electrolyte permeate,thus improving the ORR performance of nitrogen-doped carbon nanosheets.2)A small amount of Fe source was added in the solvent thermal synthesis ZIF-8reaction to prepare Fe-doped ZIF8 precursor?Fe-ZIF?based on Fe-N coordination.Fe-N-C catalyst can be obtained by heat treatment.The size of Fe-ZIF8 can be effectively adjusted by controlling the feeding ratio of Zn and Fe in the synthesis process.Fe-Nx as the active site of ORR enhanced the ORR activity of Fe-N-C in acidic and alkaline electrolytes.3)With amino phosphonic acid chelating resin as carbon,nitrogen and phosphorus sources,the composite of metal Mo and Fe ions with the resin was achieved through coordination and adsorption;N and P co-doped graphitized carbon complexes?MoP-FeP/GC?were obtained by in-situ phosphating in N₂ atmosphere.The MoP-FeP/GC has high electrocatalytic properties due to the synergistic effect of transition metal phosphatides and N,P co-doped graphitized carbon.This work not only provides a new synthesis method for metal phosphors and graphite carbon compounds,but also expands the application of bimetallic phosphors in electrocatalytic oxygen reduction.