Layer And Interface Structure Regulation Of Nickel-iron Based Materials For Electrocatalyst And Zinc Air Battery

Zinc-air battery(ZAB)has attracted wide attention because of its high energy density,cost-effective and high safety.However,the sluggish kinetics of oxygen reduction and evolution reactions(ORR and OER),corresponding to the discharging and charging processes in the air cathode,respectively,significantly impedes the ZAB performance.It is the key point to explore air electrocatalyst with cost-effectively and high activity for achieving high performance of ZAB.Nickel-iron based catalysts have great development potential in catalyzing ORR and OER,due to their advantages of abundant reserves,low cost,strong synergistic effect and high catalytic activity.However,some shortages of low conductivity and low instrinic activity limit the development of nickel-iron based catalysts.Therefore,it is the research focus in this thesis that explores the variation of electronic structure,active sites and adsorption-desorption energy for enhancing catalytic perfoamance by regulating layer structure and interface structure of nickel-iron based materials.The content of this thesis includes four parts primarily:1.Highly conductive few-layer ferric and nickel chloride co-intercalated graphite intercalation compounds(Fe Cl₃-Ni Cl₂-GIC)are designed as bifunctional oxygen catalysts for ZAB.The optimized few-layer Fe Cl₃-Ni Cl₂-GIC catalyst exhibits a small overpotential of OER and achieves a high onset potential of ORR.The theoretical analysis demonstrates the electron-rich state on the carbon layers of Fe Cl₃-Ni Cl₂-GIC during the catalytic process favors the kinetics of electron transfer and lowers the absorption energy barriers for intermediates.Impressively,the ZAB assembled with few-layer Fe Cl₃-Ni Cl₂-GIC catalyst displays outstanding performance.2.Fe Ni PS₃/graphite layers(Fe Ni PS₃/GL)sandwich-structure was designed and prepared by in-situ transforming ferric and nickel chloride-based graphite intercalation compounds(GIC)through solid-state reaction for catalyzing OER.The obtained sandwich-structured Fe Ni PS₃/GL catalyst exhibits excellent catalytic performance,which may be caused by the coupling effect,the sandwich-structure and the active Ni doping that facilitates the electrons transfer,suppresses the aggregation of Fe Ni PS₃ and exposes massive edge active sites.The Fe Ni PS₃/GL assembled ZAB also presents durable stability and stable energy efficiency which further exhibits the promising potential for practical application.3.According to the influence of different components intercalating layered metal phosphorus trisulfides,Ni PS₃ intercalated by tetraethyl ammonium hydroxide was designed and prepared under 100?hydrothermal condition(Ni PS₃-TEA-100)as effective OER catalyst.The Ni PS₃-TEA-100 catalyst exhibits great OER performance with small overpotential and durable stability,which may be caused by the variation of Ni PS₃ electronic structure affected by the intercalation of tetraethyl ammonium hydroxide into Ni PS₃ layer.The optimized electrochemical active area and charge transfer improve the OER catalytic activity of Ni PS₃-TEA-100.In addition,Ni PS₃-TEA-100 assembled ZAB exhibited durable cycling stability and high energy efficiency.4.Cost-effective OER catalyst composing of nickel-iron Prussian blue analogue and iron oxyhydroxide(Ni Fe PBA-Fe OOH)was successfully prepared by facile hydrothermal method.Designed Ni Fe PBA-Fe OOH catalyst exhibits superior OER performance with low overpotential,small Tafel slope and stable durability.Systematic investigations with in-situ Raman and Transmission electron microscope reveal that the as-prepared catalyst has undergone in-situ electrochemical transformation to generate real catalytic active species of nickel and iron oxyhydroxides.Particularly,the assembled ZAB with Ni Fe PBA-Fe OOH catalyst also displays a long-term lifetime only presenting a slight increase in voltage gap.Additionally,the successful exploration of cobalt-iron PBAs with iron oxyhydroxides further demonstrates the universality of PBAs-oxyhydroxides composites for energy storage and conversion applications.