Preparation Of Nitrogen-containing Carbon Materials From Pyrolyse Okara And Its Application In Electrocatalysis

Direct methanol fuel cells have been extensively studied owing to its environmentfriendly and high energy conversion efficiency. However, their dependence onexpensive Pt-based catalysts for both the anode and the cathode hinder the large-scaleapplication of such fuel cells. Recent studies show that excellent support material cangive a favor to the noble metal nanostructure and morphology control, thereby obtaina high performance catalyst. Therefore, it is essential to select the appropriate supportmaterials and reasonably preparation route for DMFC technologies. Althoughnitrogen-doped carbon materials have excellent efficacy, the raw materials useconventional nitrogen-doped with organic compounds as the source of carbon andnitrogen, which were expensive and the synthesis process were needing complex steps,so makes it difficult to be commercialized. Hence, with the concept of greenchemistry and sustainable development, many researches set out to use cheap rawmaterials (such as biomass) for synthesize novel nitrogen-doped carbon materials viaa simple green methods and this type of methods has been focused.In this paper, nitrogen-containing carbon materials were successfully preparedvia carbonization and post-processing by using high protein content natural polymerokara as nitrogen and carbon sources. Furthermore, it was applied to the electrode inthe catalytic reaction that use methanol oxidation (MOR) and oxygen reduction(ORR). Meanwhile, its structure and catalytic properties were systematicallyevaluated by test methods of physical characterization and electrochemical,respectively.This thesis consists of the following three parts:Part I: Preparation of Nitrogen-containing Carbon Materials from PyrolyseOkara as oxygen reduction electrocatalystNitrogen-containing carbon materials (OC) was prepared by ball milling andcarbonization the natural polymer okara twice to obtain the ORR catalyst.Experimental results show that: OC catalyst compared with XC-72carbon, its onsetpotential and half-wave potential were positive shift60mV and133mV(vs.Ag/AgCl), respectively; While, compared with commercial Pt/C catalyst, the onsetpotential and the half-wave potential, a difference of only80mV and73mV(vs. Ag/AgCl), respectively, indicate the OC catalyst has high ORR activity in alkalinesolutionsPart â…¡: Okara derived Nitrogen-containing Carbon Materials as oxygenreduction electrocatalystFe+O and O+Fe catalysts were prepared by using high protein content naturalpolymer okara as nitrogen and carbon sources via adding to ferric chloride for beforeand after. At the same time, the effect of the carbonization process and the effect onthe oxygen-reduction of ferric chloride in the catalyst were studied. Results show that:After adding iron carbide carbide again obtained O+Fe catalyst half-wave potentialthan commercial Pt/C catalysts are shifted10mV (vs. Ag/AgCl), indicates O+Fecatalyst has good electrocatalytic ORR activity. Meanwhile, the diffusion currentwhich is almost the same as commercial platinum on carbon, which may be attributedto the carbon material after the addition of iron carbide to better promote theformation of the active site structure of CNx, which is more conducive electrocatalyticoxygen reduction.Part â…¢: Preparation of Nitrogen-containing Carbon Materials from Okaraand Application as Electrocatalyst SupportPt/ODC catalyst was successfully prepared by using ODC carbon material as acarrier. Experimental results show that: Pt/ODC methanol catalyst oxidation peakcurrent density up to12.2mA cm-2(vs. Ag/AgCl),1.74times of the same process forpreparing the catalyst of Pt/XC-72, and a strong resistance to CO poisoning.