Preparation Of Transition Metal Doped Carbon Material And Its Application In Zinc-air Battery

Renewable clean energy to replace traditional fossil energy is a historical choice.At present,there are still some problems with the use of clean energy,including low conversion efficiency,difficulty in storage and transportation,and safety.Therefore,additional energy storage equipment is required.Among many energy storage devices,electrochemical storage devices,such as fuel cells,metal-air batteries,and supercapacitors,which utilizes the conversion between chemical energy and electrical energy,has potential practical value.Among them,metal-air batteries have many advantages such as high power density,no pollution,simple preparation,safety and reliability,etc.,which have been extensively studied.However,the slow kinetics of oxygen reduction(ORR)and oxygen evolution reaction(OER)in the negative electrode limit practical applications.Currently,noble metal-based Pt and Ir O2/Ru O2 catalysts are the most effective ORR and OER catalysts.Nevertheless,high prices,scarce resources,poor stability,single performance and other shortcomings limit the large-scale application of precious metal catalysts.Therefore,the development of efficient and stable nonnoble metal-based ORR and OER catalysts is the key to breaking the bottleneck of metal-air battery applications.In this paper,we use cheap and abundant transition metals to compound with highly conductive carbon carriers to prepare highly efficient catalysts.By combining with the carbon support,the morphology and electronic structure of the transition metal compound can be adjusted to improve its poor conductivity and single catalytic performance.It is hoped that a highly efficient dual-functional oxygen electrocatalyst can be prepared through this low-cost,environmentally-friendly,easy-to-operate and economic-friendly method.And through the analysis of its morphology,structure and composition to explore its possible electrocatalytic mechanism.The main results are as follows:(1)A simple in-situ growth method was used to composite ZnCo-ZIF on graphene oxide nanosheets to prepare a composite material(ZnCo-ZIF@GO),which was used as a low-cost and high-efficiency bifunctional oxygen electrocatalyst.SEM and TEM were used to analyze the morphology and structure of hybrid materials.FTIR、Raman and XRD were used to verify the successful preparation of ZnCo-ZIF on the surface of graphene oxide.XPS analyzed the composition and valence state of ZnCo-ZIF after compounding GO.The electrochemical performance show that the hybrid catalyst has outstanding ORR performance,initial potential and half-wave potential(0.89,0.76V),and it also has a lower overpotential in the OER test.When used as a cathode material for zinc-air batteries,rechargeable zinc-air batteries have excellent energy density and outstanding long-term cycle stability.(2)A facile pyrolysis of cobalt salt,phytic acid,and k-carrageenan aerogel was carried out on Co2 P nanoparticles within P-doped porous carbon(Co2P-PCA-800).The effects of different doping ratios on the structure morphology and catalytic performance of the obtained materials were compared.SEM and TEM were used to compare the morphology and structure of different doped materials.And it was found that Co2P-PCA-800 has a more complete hole structure.The N2 adsorption and desorption test compared the specific surface area and pore volume of different samples.The sample annealed at 800 ℃ has the largest specific surface area.X-ray photoelectron spectroscopy found that there is a charge transfer between P and Co.The electrocatalytic test show that the catalyst has outstanding oxygen reduction performance,initial potential and half-wave potential(0.96,0.85V),which are significantly better than Co2 P nanoparticles.What`s more,the catalyst has outstanding OER performance.When used as an air cathode catalyst,the ZABs assembled by the catalyst show good charge and discharge performance and energy density,as well as outstanding specific capacity and stability.