Preparation Of Mof-derived Catalyst And Its Application In Zinc-air Batteries

Zinc-air batteries(ZABs)have become a very promising battery system with their outstanding advantages.Nowadays,the extensive application of ZABs in the commercialization process is hindered by the excessively high overpotential during the oxygen evolution reaction(OER)process and the slow kinetics during the oxygen reduction reaction(ORR)process.Metal organic frameworks(MOFs)have attracted widespread attention as support and precursors of novel carbon nanocomposites.In this paper,based on the special advantages of MOFs materials,two new types of non-noble metal catalysts were prepared.(1)A new type of bifunctional electrocatalyst(ZnCo-Te@NC)was prepared,which is composed of carbon nanotubes decorated with ZnTe and CoTe nanoparticles.The structure of the derived carbon nanotubes is obtained by using Te nanotubes as a sacrificial template during the high-temperature pyrolysis process after being coated with ZnCo-MOF.The volatilization of Zn during pyrolysis can increase the specific surface area of the catalyst.Owing to the combined effect of CoTe nanoparticles and N-doped C,ZnCo-Te@NC exhibits good electrocatalytic activity.More significantly,the rechargable ZAB with ZnCo-Te@NC air cathode exhibits notable reversibility and stability during long-term charge and discharge cycles.The emergence of this new type of catalytic material is expected to provide new ideas for other main electrocatalytic reactions and open up a new path for the development of energy storage and catalytic technology.(2)Herein,a bifunctional non-noble metal catalyst(ZIF-L-0.5-900℃)was simply constructed.By using two-dimensional template,hydrothermal reaction and programmed temperature control,a fragmented MOF-derived metal cobalt-nitrogen co-doped carbon structure is obtained.ZIF-L-0.5-900℃ has a large specific surface area(1028.9 m2 g-1),which is conducive to the mass transfer process in the electrocatalytic process.In addition,the material has high content of pyridine N and graphitized N,which is beneficial to ORR process.The study found that ZIF-L-0.5-900℃(△E=0.806 V)in alkaline electrolyte solution has dual-functional characteristics which are equivalent to Pt/C+IrO2(△E=0.809 V).ZIF-L-0.5-900℃ is used as a cathode catalyst for rechargable ZAB,which shows higher power density(237.06 mW cm-2)and charge-discharge performance than Pt/C+IrO2(211.21 mW cm-2).This work provides a good method for the design of non-noble metal dual-function catalysts and has a good application prospect.