Study On Preparation And Catalytic Performance Of M-N-C Compound Catalysts For Oxygen Reduction/Oxygen Evolution Reaction

As the consumption of fossil energy increases year by year,traditional primary energy can no longer meet the needs of society.The development of new energy sources has become the direction of future energy development.Among them,fuel cells in electrocatalytic technology have received scholars’extensive attention.However,the most important oxygen reduction reaction in fuel cell is greatly limited due to its slow kinetics.It is necessary to develop highly efficient electrocatalysts.Among them,the commercial development of precious metal catalysts is limited due to their scarcity and high cost,while nonboble metal carbon-based materials have attracted ongoing attention owing to their low cost and high activity.The obtained carbon-based materials exhibit excellent performance after pyrolysis,but the structure will be disordered and the corresponding active sites will be not clear after high temperature process,which has hindered the further study on the catalytic mechanism.In this work,pyrolysis-free non-noble-metal catalysts were synthesized by microwaveassisted method,which presents efficient oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)performance.The main research results are as follows:(1)Covalent organic polymer(COPBTC-Fe)with homogeneously dispersed iron was prepared by microwave-assisted method,which has been comparable to commercial Pt/C in alkaline solution.In order to improve its ORR activity under acid condition,the COPBTc-Fe was modified with 3-pyridine sulfonic acid which contributes to improve the proton mobility.The half-wave potential of 700 mV(vs.RHE)in 0.1 mol L’1 perchloric acid solution can be reached.Although the current ORR performance is not up to the commercial Pt/C-based catalyst,it has better stability.The COPBTC-Fe still maintains 84%of primal catalytic activity after 25000 s test and presents better methanol poisoning resistance,compared with Pt/C-based catalyst.We believe that the ORR performance is expected to be further improved via reasonable molecular design and surface modification strategies.(2)The bimetallic based covalent organic polymer(COPBTC-Ni0.6Co0.4)was synthesized by microwave-assisted method.The consistency of the synthesized polymer and the designed structure was verified by infrared spectroscopy,solid state NMR carbon spectroscopy,XPS and other characterizations,which proved that the synthesis was controllable.At the same time,the synergistic effect of the bimetals benefits to optimize the electronic structure and adsorption energy,which was conducive to the electrochemical oxidation of water.In 0.1 mol L-1 KOH solution,the OER performance of the catalyst was 1.67 V(vs.RHE)vs RHE at the current density of 10 mA cm-2,which was comparable to the performance of 20%IrO2/C.It also maintains a voltage of 1.68 V(vs.RHE)(at a current density of 10 mA cm-2)after a stability test of 5000 s.