Preparation And Propeties Of Pyrolytic Carbon Materials For Supercapacitor And ORR Catalysis

Novel energy storage devices,such as supercapacitors,zinc-air batteries and fuel cells,became hot research topic recently.Porous doped carbon materials exhibited large specific surface area,high conductivity and abundant active sites,considered to be ideal electrode materials for supercapacitors and zinc-air batteries.The structure of precursors significantly influenced the properties of porous carbon materials.However,casein and polyphosphazenes were seldom investigated as the procursor of carbon materials.In this thesis,porous doped carbon materials were prepared using casein and polyphosphazene as precursors,displaying excellent performances as the electrode material of supercapacitor and catalysis of oxygen reduction reaction.Casein,a facile and cheap protein,was used as carbon precursor and phytic acid as pore-forming agent,then doped porous carbon materials were prepared by pre-carbonization.Subsequently,hierarchically porous doped carbon materials were fabricated by activation with KOH,indicative of a high surface area of 3560 m² g^-1.They showed a specific capacitance of 411 F g^-1 at 1 A g^-1,and a specific capacitance of 230 F g^-1at 20 A g^-1.At a current density of 10 A g^-1,the specific capacitance could maintain at 208 F g^-1 after 10,000 cycles.The results suggested that the porous carbon materials by pyrolysis of casein were excellent electrode materials for supercapacitor.Polyphosphazenes,with phosphorus-nitrogen double bonds in the main chains,showed high content of phosphorus and nitrogen and were considered as an excellent carbon precursor.Polyphosphazene nanotubes were initiallly synthesized,then carbonized and activated by KOH,achieving the hierarchically porous and doped nanotubes.After impregnating with Hemin and further carbonization,Fe,N co-doped porous carbon materials were obtained,displaying outstanding ORR performances and great potential application prospect.Its half-wave potential and limiting current density are 0.90 V and 5.6 m A cm^-2,respectively,higher than those of commercial Pt/C and most metal/non-metal codoped porous carbon catalyst.Moreover,its half-wave potential almost remained unchanged,thus ita cyclic stability was outstanding.Its resistance to methanol was also superior.