Synthesized Of Oxide Supported Cobalt-Based Oxygen Electrocataltsy For Zinc-Air Batteries

Zinc-air batteries have attracted huge attention due to their high theoretical energy density(1086 Wh kg^-1),eco-friendliness and inherent safety.Oxygen reduction reaction（ORR）and oxygen precipitation reaction（OER）are the key factors that determine the performance of zinc-air batteries.Precious metal Pt/Ir materials are greatest electrocatalysts for ORR/OER.However,various of disadvantages of precious metals hinders their practical applications.Conventional,carbon support transition metals catalyst was expected to substitute precious metal due to their cost-effective and excellent catalytic performance.While,carbon support will occur collapse and agglomeration under the operating conditions of zinc-air batteries,resulting in performance degradation.N-doped titanium monoxide（N-TiO）have electrochemical stability and good electrical conductivity.In addition,the three-dimensional macroporous structure can provide good mass transfer efficiency which is also vital for the three-phase electrocatalytic reactions.In this paper,Co-based transition metal composites supported by three-dimensional N-TiO was developed and optimized by various method.The catalyst performance was test and analyzed reaction mechanism by density functional theory.Finally,it was used as cathode electrocatalyst for zinc-air batterues.The main contents of this paper are as follows:（1）The polystyrene as template,Ti（OBu）₄,Co（OAc）₂ and WCl₆as metal sources,the ORR catalyst 3DOM Co/W@N-TiO was prepared by high temperature carbonization and NH₃ treatment.The half-wave potential of 3DOM Co/W@N-TiO is 0.84 V vs.RHE competitive with Pt/C（0.85 V vs RHE）,and exhibiting the better methanol resistance and stability than Pt/C.From the experimental and theoretical calculation results,3DOM N-TiO support with rich oxygen vacancies not only offers a high surface area and conductivity but also facilitates the anchoring of Co/W nanoclusters via strong metal-support interaction,endowing the catalysts with excellent catalytic activity and durability performance.An electron synthetic effect between the binary Co/W nanocluster,promoting the ORR kinetics and thermodynamics.The 3DOM Co/W@N-TiO powered zinc-air batteries achieve high power density of 168 mW cm^-2and specific capacity of 792 mAh g^-1,suggesting its potential for wide applications.（2）In order to synthesized the bifunctional catalyst.Based on the advantages of support in the previous chapter.In this work,by introducing another heteroatom sulfur to form Co-NSC active component that synthesized efficient bifunctional electrocatalyst3DOM Co-NSC@N-TiO.Benefit from binary heteroatom synergistic effect.The half-wave potential of 3DOM Co-NSC@N-TiO is 0.85 V vs.RHE competitive to Pt/C,and the over-potential at 10 mA cm^-2is 440 mV.According to the experiment and theoretical calculation results,Co-NSC is the active site of ORR reaction,and the in-situ formation of CoOOH on the surface of metal Co nanoparticles is the real active site of OER.The zinc-air batteries achieve high power density of 123 mW cm^-2,specific capacity of 776 mAh g^-1and long-term stability over 300 h under current density of 10 mA cm^-2.This work provides an effective strategy for the development of efficient and durable ORR catalysts through conductive oxide support design and the synergistic engineering of binary metals and heteroatom,demonstrating its promising potentials in energy conversion systems.