Synthesis,Characterization And Electrochemical Performance Study Of Nanostructured Electroactive Materials

The rapid increase in the energy consumption and the environment impact of traditional fossil fuel pose a series of serious challenges to energy security and environmental protection.Developing next generation renewable energy to replace traditional fossil fuel becomes the currently hot spot.New conversion and energy storage devices become the key technologies of using clean energy.Fuel cells are clean and efficient energy conversion devices that can directly convert the chemical energy of fuels to electricity.Supercapacitors are energy storage devices which have high power density and long cycle life.Using fuel cells and supercapacitors in energy storage devices,electric vehicles and portable electronic devices can effciently relieve the energy crisis and environmetal pollution.Cost and performace are the major issues that restrict the large-scale applications of fuel cells and supercapacitors.The electrode materials are the key factors that limit the cost and performace.Direct methanol fuel cells(DMFC)has aroused wide attention due to the advantages of low operating temperature,ease of transport and storage of methanol.Pt catalytis had great development in the commercialization of DMFC,but its development was restricted due to the high cost and CO poison issues.So the development and utilization of non-noble metal to replace Pt becomes the main research contents of the current.Conducting polymer has attracted great attention due to high energy storage,low cost and easy preparation.The main defects are the low self-discharge rate and cycle performace.So it urges to develop low cost,high performance electrode materials.Nickel Oxide(NiO)possesses high methanol catalytic activity and low cost,which can replace Pt catalytis and reduce the cost of DMFC.Using novel support materials(such as carbon nanotubes and graphene)which have high electric conductivity,high surface area and chemical stability can defeat the defects of low electric conductivity and improve the methanol catalytic activity of NiO.Polypyrrole(PPy)has excellent electrochemical performance,but the relatively dense structure limits the electrolyte into the internal polymer.In order to understand the electrochemical properties of PPy and improve its capacity and cycle performance,studying the effect of nano particle size on the capacitor performance provides a certain value.Based on this,the main innovations of this study lie in the introduction of carbon nanotubes and graphene as NiO support materials and nitrogen doping for the support materials which can optimize the NiO catalyst of methanol catalytic properties,sceondly analyzes the PPy nano size effect on the performance of supercapacitor and put forward the model of the relationship between the size and capacity.The main results are as follows:(1)Uniformly dispersed NiO nanoparticles supported on N-doped carbon nanotubes(NCNTs)are successfully synthesized.Doping carbon nanotubes can imporve the dispersity and reduce the size of NiO nanoparticles.Treatment temperature and NiO loading contet have great influence on the catalytic performace of catalyst in alkaline conditions.NiO/NCNT catalyst calcined at the temperature of 400 oC and optimized catalyst loadings displays the highest methanol oxidation electrocatalytic activity and stability.Using N-doped graphene as the support materials,the catalysts calcined at the temperature of 200 oC and loaded on NG which is heated at 1000 oC achieve superior methanol electrocatalytic oxidation performance and stability.(2)PPy nanoparticles with precisely controlled diameters have been synthesized by an effective chemical oxidation polymerization method.The effects of PPy nanoparticles size on the capacitance behavior are systematically studied.The highest capacitance performance is obtained at 80 nm,and the capacitance properties of PPy nanomaterials are synergistically affected by the charge carrier,band gap and the surface area.This paper optimize the electrochemical performance of NiO and PPy used as catalyst for the direct methanol fuel cells and supercapacitor electrode materials.And provides a new opportunity for DMFC and supercapacitor.