Study On Synthesis Of High Efficiency Oxygen Reduction Catalysts With Iron Based Metal Organic Framework Derivatives

With the exhaustion of fossil fuels and the aggravation of environmental pollution,it is urgent to develop green sustainable energy and corresponding new energy technology.Zinc-air battery has attracted extensive attention because of its high theoretical capacity,stable discharge safety,green and pollution-free characteristics.However,due to the slow oxygen reduction reaction(ORR)of its cathode,high efficiency catalyst is needed to speed up the reaction.At present,the commercially applied platinum carbon catalysts(Pt/C)have the problems of high cost,poor catalytic tolerance and easy to be poisoned.Therefore,the exploitation of cheap and efficient catalysts is the key to the further development of zinc-air batteries.Carbon-based ORR catalyst materials have attracted extensive attention because of their low price and large potential for performance improvement.In this thesis,we synthesized Fe/Fe3C composite nitrogen-doped carbon nanotubes(Fe/Fe3C@NCNTFs)as ORR catalyst material by multi-step self-template method.Subsequently carried out detailed material characterization and electrochemical characterization.(1)The Fe/Fe3C@NCNTFs catalyst was synthesized by a simple multistep self-template method.Then the morphology,structure,composition and element valence state of Fe/Fe3C@NCNTFs were characterized in detail.In the subsequent electrocatalytic performance test,Fe/Fe3C@NCNTFs catalyst also performed excellent:the ORR catalytic performance in 0.1 M KOH alkaline environment result in a half-wave potential of 0.863V,and at the same time,it had glorious catalytic tolerance and methanol toxicity resistance,which was better than Pt/C.It is found that the Fe/Fe3C@NCNTFs catalyst also has eminent catalytic activity of oxygen evolution reaction(OER):In 1 M KOH alkaline environment,the overpotential is 340 mV(10 mA cm-2),Tafel slope was 125 mV dec-1,showing wonderful bifunctional catalytic performance.(2)Toward further investigate the performance of Fe/Fe3C@NCNTFs catalyst in zinc-air battery,using Fe/Fe3C@NCNTFs as catalyst by two simple methods to build the air electrode to assemble the zinc-air battery,and the performance of the battery was subsequent tested.The zinc-air battery assembled with Fe/Fe3C@NCNTFs shows excellent battery performance with an open-circuit voltage of 1.52 V,a peak power density of 206 mW cm-2,and a charge-discharge voltage gap of only 0.83 V.It also has outstanding stability that can still run stably after 300 h charge and discharge when the current density is 5 mA cm-2.