Preparation Of Prussian Blue Derived Transition Metal/Carbon Hybrid Materials And Their Application In Zinc-Air Battery

With the development of science and technology,the demand for energy is increasing rapidly,and sustainable development has become the focus of modern society.At present,lithium-ion batteries（LIBs）are dominant in the field of energy storage,but they have the problems of low energy density and high cost.Zinc-air battery（ZAB）is considered to be the most promising technology to replace lithium-ion batteries because of its high energy density,good safety,low cost and environmental protection.However,the slow reaction kinetics and different reaction mechanisms of oxygen evolution reaction（OER）and oxygen reduction reaction（ORR）in the charge-discharge process are the main factors limiting the development of zinc-air batteries.Therefore,the biggest challenge to develop high-performance rechargeable ZABs is to explore efficient and stable bifunctional oxygen electrocatalysts to catalyze both OER and ORR reactions simultaneously.Transition metals and their compounds have various oxidation states due to incomplete filling of electron orbitals,and the degree and mechanism of promoting catalyst activity by different oxidation states are also different.In view of the above considerations,the activity of the catalyst can be further improved by the synergistic effect of two or more transition metals.On this basis,a series of alloy-N-doped carbon hybrid materials are fabricated by using bimetallic or trimetallic Prussian blue analogue（PBA）as precursors through skillful alkali etching,the introduction of polydopamine layer（PDA）,the doping of metal ions,and finally pyrolysis at high temperature,and their electrochemical properties are studied.Its catalytic mechanism and application in zinc-air battery are preliminarily revealed.The specific research contents are as follows:（1）Based on the PBA precursor,a unique multi-core hollow cage nanoreactor is developed by using the spatial confined pyrolysis strategy,in which Fe-Co-Ni trimetallic alloy nanoparticles are embedded into porous nitrogen-doped carbon nanocages.Trimetallic alloys can optimize the electronic structure of the catalyst,thus inducing charge redistribution,and then adjust the adsorption and desorption energy barriers of intermediates in electrochemical reactions.The unique nanopore design provides a convenient and efficient channel for mass and charge transfer during ORR and OER.Therefore,the obtained electrocatalyst exhibits good reversible oxygen catalytic activity;The half-wave potential of ORR is 0.850 V,and the overpotential of OER is 355 m V at10 m A/cm² under alkaline conditions.Based on this multi-core hollow cage nanoreactor,an assembled zinc-air battery can provide a potential gap of 0.735 V,a power density of315 m W/cm²,a specific capacity of 754 m Ah/g _Zn,and a cycle stability of 165 hours continuous charge-discharge time.This unique catalyst design can provide new ideas for the design and synthesis of other heterogeneous electrocatalytic materials.（2）Nitrogen-doped carbon hollow nanobox catalyst embedded with Mn O and Fe Co alloys are prepared by pyrolysis of the Fe-Co-Mn trimetallic prussian blue analogue precursor.Benefiting from the unique electrocatalytic design,the obtained catalysts exhibit excellent electrochemical performance.In alkaline electrolyte,the half-wave potential of ORR is 0.88 V,the limiting current density is 5.62 m A/cm²,and the overpotential of OER is 271 m V at 10 m A/cm².Further studies show that the enhancement of catalytic activity can be attributed to the Mott Schottky heterojunction generated by the coupling of Fe Co alloy and semiconductor Mn O,which promotes the rapid transfer of charge at the interface,thus enhancing the charge separation of the catalytic process.At the same time,the maximum exposure of active sites in the catalyst model and the unique cavity design provide a convenient and efficient channel for mass transport in ORR and OER processes.The assembled Zn-air battery can provide a potential gap of 0.621 V,a power density of 253 m W/cm²,a specific capacity of 761m Ah/g _Zn,and a continuous charge-discharge cycle test of 336 hours.The composite catalyst model can provide a new reference and solution for the design of efficient and stable ORR-OER bifunctional oxygen electrode.Figure[60]Table[8]Reference[143]...