Preparation Of Nitrogen-doped Carbon Nanomaterials Using Biomass As Carbon Source And Its Electrochemical Properties

Energy crisis and the use of fossil fuels in increasingly caused serious environmental pollution. Developing the most efficient energy storage and conversion devices becomes more and more important. Carbon materials can be the sources of a lot of chemical power,such as fuel cells, lithium-ion batteries and supercapacitor electrode materials. At present,there are many ways to produce carbon materials, such as vapor deposition method, high temperature pyrolysis method and hydrothermal method, etc. Oil cracking products and biomass are major carbon source.Soybeans mainly contain fat, protein, a small amount of sugar and trace inorganic salt.Food oil is extracted from the soybean in the food industry and its residue ?bean curd? is rich in protein. This thesis we use bean dregs, which are rich in nitrogen after oil squeezed, as the precursor and nickel nitrate as the source of metal to prepare nitrogen-doped carbon supported transition metal electro-catalyst through gel high temperature pyrolysis. Then nitrogen-doped carbon supported transition metal electro-catalysts were activated to prepare the nitrogen doped nanoporous carbon materials. The main results are displayed as follows:?1? Using bean dregs as precursor and nickel nitrate as the curing agent. We prepare the nitrogen-doped and transition metal nano carbon materials by special gel method, which is also called Chinese traditional tofu halide technology. We apply this material to the fuel cell cathode catalyst and explore the influence of carbonization temperature on the catalytic performance. The result fully shows that sample which heated at the temperature of 900 ?is the best. it's starting voltage is 0.86 V ?vs RHE? and half wave potential is 0.72 V ?vs RHE?. After 1000 cycles of CV scanne in air saturated electrolyte, potential attenuation is only 47 mV; After the chronoamperometry, current remains 72% of the initial current. These results show this material has high stability.?2? Nitrogen-doped carbon supported transition metal electro-catalyst is activated through K₂C₂O₄, KOH and K2CO₃ to get the nitrogen-doped nanoporous carbon materials,which were applied to the supercapacitor. At the current density of 1 A/g,their capacity are 126.5,96.6,109.6 F/g ,respectively. After constant current loop 1000 times, it's capacity still can maintain about 90%. Compared with activated carbon prepared by other methods, this material used metal nickel on carbon materials in catalysis, not only formed a large number of graphite carbon,but also maked the high electrical conductivity. Freeze drying, Ni doping,Ni dissolution and activation are beneficial to form the different multilevel pore structure and high specific surface area. The high nitrogen content in the bean dregs is also good for increasing the pseudocapacitance.