Preparation Of Fe/Co Doped 3D Honeycomb Like Multifunctional Catalyst And Application Of Rechargeable Zn-Air Battery

Developing high-performance and low-cost electrocatalysts to replace noble metal based catalysts is the key to achieve the goal of clean energy.Among them,non noble metal doped carbon based catalysts are considered to be promising electrocatalysts for industrial applications.It has low cost and good durability,and heteroatoms such as N and P can be doped in the carbon structure to further improve the overall performance of the catalyst.Therefore,a dual regulation method is proposed to prepare3D honeycomb like carbon based catalysts with stable Fe/Co doping.Through the study of its physical and chemical properties,its catalytic reaction mechanism is speculated,and it is actually tested in the application of electrocatalysis and Zn-air battery.In this synthesis method,polystyrene（PS）microspheres were used as hard template,polyaniline（PANI）layer was polymerized on the surface,and Fe atoms were highly dispersed and fixed on the shell of core-shell microspheres;In the process of pyrolysis,PS microspheres decompose at high temperature,which can etch and explode the microspheres,and make carbon based catalyst Fe₈Co_0.2-NC-800 with honeycomb like structure.The prepared catalyst contains a large number of Fe/Co nanoparticles.The characterization results show that the carbon based catalyst has the characteristics of large specific surface and mesoporous structure.The doped Fe/Co nanoparticles are mainly in Co crystal structure,and the Fe atoms are highly dispersed in Co nanocrystals.The change of free energy of corresponding structure in catalytic reaction is calculated by density functional theory（DFT）,so as to judge the source of activity and catalytic mechanism.The prepared Fe₈Co_0.2-NC-800 have excellent catalytic activity and durability in oxygen reduction reaction（ORR）,oxygen evolution reaction（OER）and hydrogen evolution reaction（HER）.In ORR test,the half wave potential（0.822 V）is equivalent to that of Pt/C catalyst（0.819 V）.In OER test,the over potential（397 m V）at E_{10 m A cm-2} is also equivalent to that of Ru O₂ catalyst（399 m V）.In HER test,the overpotential at E_{10 m A cm-2} is 297m V.The Zn-air battery（ZAB）assembled with the prepared catalyst as the air cathode has good charge and discharge performance,maintains a stable charge and discharge platform in 311 hours of cycle,and has an ultra long service life.It is speculated that the Fe/Co structure and a large number of exposed（111）crystal planes in the doped Fe/Co nanoparticles are the sources of excellent properties.