The Fabrication And Electrocatalytic Performance Investigations On Transition Metals/Oxides@ Carbon Composites

Metal-air batteries have attracted great attentions because of their extremely high theoretical energy densities,environmental friendliness,and low cost.However,many challenging tasks still exist for the practical application of metal-air batteries.Especially,without the use of catalyst,the reaction kinetics on the air electrodes are extremely slow,which is one of the main reasons why the metal-air batteries couldn't be commercialized extensively.In this thesis,we mainly focus on the exploring and electrocatalytic performance investigations on the transition metals/oxieds@carbon composites as oxygen catalysts of metal-air batteries.All the work in this thesis could be divided into three parts.Part I,?-Fe₂O₃ pseudo-nanocubes are prepared by solvothermal method,and a layer of conductive polymer PPy is coated on the surface of the?-Fe₂O₃ pseudo-nanocubes,and then PPy is transformed into N-doped carbon material by calcination.The ORR electrocatalytic performances of the composites have been studied and compared in alkaline solution.Part II,metal oxide Fe₂O₃ coated on the surface of the N-doped carbon nanofibers have been achieved by using electrospinning technology,and then Fe₂O₃ has been transformed into transition metal Fe by calcination,which could increase the conductivity of the hybrid material further.In addition,we changed the proportion of the precursors and calcination procedures to optimize the size and distribution of Fe on the surface of the carbon nanofibers.Moreover,the composites of metal Ni and Co decorated on N-doped carbon nanofibers have also been fabricated and studied separately.The electrocatalytic performance differences between the above several materials in alkaline solutions have been explored and discussed.Part III,NiCo alloy nanoparticles embedded within N-doped carbon nanofibers as efficient and stable dual-function oxygen catalysts have been synthesized by electrospinning,and then the effect of NiCo alloy nanoparticles loading weight on electrocatalytic performance has been studied systematically.Finally,the cell performances of the NiCo alloy nanoparticels@N-doped carbon nanofibers as the catalysts in zinc-air and lithium-air batteries have been studied thoroughly.