Study Of Non-precious Metal-Nitrogen-Doped Carbon(M-N-C) Catalyst For Oxygen Reduction Reaction Of Fuel Cells

As a new energy technology,fuel cells have changed the way of energy storage and conversion,and provided a new solution to the problem of global warming and environmental pollution caused by traditional fossil energy consumption.However,limited by the slow cathode reaction process of the fuel cell,it is inevitable to use a catalyst to improve the energy conversion efficiency of the novel energy storage device.Metal-nitrogen-doped Carbon(M-N-C)catalysts,which are carbon-supported and metal-nitrogen co-doped,are widely studied as a candidate that have the potential to replace traditional catalysts such as Pt due to their outstanding performance under alkaline conditions.However,the usual M-N-C materials generally have problems such as expensive synthetic raw materials,harsh reaction conditions,complicated reaction system,low yield,limited defects and load sites,that objectively hinder the deep development and application of fuel cells.In this study,different forms of carbon-supported metal nitrogen-doped catalytic materials were synthesized by simple chemical vapor deposition and the principle of the active center has been studied.This article mainly tested the following parts:1.The metal cobalt salt is used as the catalyst,and the dicyandiamide is used as the carbon source and the nitrogen source.The cobalt and nitrogen co-doped carbon nanotubes can be obtained by simple high-temperature pyrolysis.The catalyst was characterized by scanning electron microscopy and X-ray diffraction spectroscopy.Uniform and intact morphology and comparable catalytic performance with good stability to Pt/C was found due to the loading of metals and nitrogen.2.Iron salt and the small molecule carbon source are thoroughly mixed and further pyrolyzed to obtain a porous carbon material with a large specific surface area by evaporating the solvent which contains a moderate amount of template slowly.The porous property effectively enhances the mass transfer efficiency of the reaction process which plays an active role in the diffusion of oxygen from the liquid phase to the electrode surface and reflected in the higher limiting diffusion current.3.In order to further improve the doping efficiency of iron and nitrogen,melamine was introduced as a nitrogen source to synthesize the Fe-NMPC@CNT by a hydrothermal method.The close binding of the active sites to the carbon support is achieved by pyrolysis and the performance exceeding Pt/C of material is obtained.The half-wave potential of the Fe-CNT@NMPC is 0.86v,which is higher than the 0.84v of the 20% commercial Pt/C.Compared with other types of carbon-supported metal-nitrogen-doped catalysts,the product has more activity sites,prominent methanol tolerance and cycle stability.