Electrocatalytic Performance Regulation Of Transition Metal-based Composite Materials

Since the 21st century,people's demand for various types of energy has increased.Conventional fossil fuels not only difficult to regenerate but also pollute the environment,which makes people more interested in efficient,clean and sustainable development of new energy power technology.The energy conversion system based on the electrochemical device is expected to replace the status of traditional fossil fuel in the energy industry chain due to the good sustainability,efficiency and environmental friendliness.Among them,zinc-air battery and full water splitting involve electrocatalytic basic reactions including ORR,OER,HER,but the slow kinetics of these reactions hinders their wide application.At present,the widely used catalysts are still mainly made of precious metals such as platinum,iridium and ruthenium.However,precious metal materials have obvious disadvantages such as small reserves and high prices.Therefore,the development of low-cost,high-performance low precious metal-based or non-noble metal-based catalysts is essential.In this paper,non-noble metal-based nanocomposites are designed and synthesized on the basis of transition metals,which can be used as high-efficiency electrocatalysts for the electrocatalytic reactions of ORR,OER,and HER.The shape of the prepared nanomaterials was analyzed by scanning electron microscope(SEM),transmission electron microscope(TEM),XPS(X-ray diffraction method),XRD(X-ray diffraction energy spectrum)and Raman spectroscopy(Raman)techniques.Morphological structure,element valence,crystal phase composition,degree of graphitization and degree of defects.The electrochemical performance of the catalyst was characterized by linear sweep voltammetry(LSV),rotating disk electrode(RDE),rotating ring disk electrode(RRDE),chronoamperometry(i-t)and other electrochemical testing methods.A series of meaningful results have been obtained,which are summarized as follows:1.Through the liquid phase synthesis method and the subsequent pyrolysis,a carbon composite material(FeRu@NCNTs)embedded with FeRu alloy nanoparticles and supported by N-doped carbon nanotubes was successfully prepared.The catalyst after adjusting the material ratio for ORR,OER and HER has excellent electrocatalytic activity and durability.It shows that the onset potential of ORR is 0.95 V vs.RHE,the overpotential of OER at 10 m A cm^-2 is 417 m V and the overpotential of HER at 10 m A cm^-2 is 162 m V in alkaline media.The zinc-air battery assembled with FeRu@NCNTs as an air cathode exhibits a high power density of 148.59 mW cm^-2,excellent rate performance,and good long-term cycle stability(50 h).At the same time,take FeRu@NCNTs/NF as cathode and anode respectively also showed excellent all water cracking performance and durability.2.A Fe/Co-N-C electrocatalyst was successfully prepared by liquid phase synthesis method and subsequent pyrolysis treatment.The catalyst after adjustment shows good performance and long-term durability,with an onset potential of 0.98 V vs.RHE for ORR.The zinc-air battery with Fe/Co-N-C as an air cathode exhibits a high power density of 163.95 mW cm^-2,excellent rate performance and good charge-discharge cycle stability(66 h).