N, S Co-Doped Porous Carbon Materials Derived From Animal Hair And Their Electrocatalytic Performance For Oxygen Reduction Reaction

Biomass as a renewable resources has some advantages of large storage capacity and environmental friendly, which is considered to be ideal and suitable raw materials for synthesis of carbons. In addition to carbon, many of biomass contain abundant nitrogen and sulfur, therefore, recently biomass has widely used as precursor to synthesize doped carbon materials for fuel cells’ catalyst, which exhibited good catalytic performance for oxygen reduction reaction(ORR). In this thesis, several kinds of animal hairs have been used as raw materials to prepare porous carbons via hard template method and hydrothermal method. The effects of the doping amount, specific surface area and pore structures on the performances have been investigated. The main contents and conclusions of this thesis are follows:(1) N, S co-doped carbon materials were obtained by pyrolysis of polypeptides as precursor degraded from three kinds of animal hairs(pig bristles, chicken feather, hair) and Mg O as template. The experimental results showed that the specific surface areas and catalytic activity of bio-carbon materials increased with the dosage of template increasing.With the increase of pyrolysis temperature, the amount of nitrogen doping decreased, the amount of sulfur doping increased and the graphitization degree increased. By analyzing and comparing, the carbons derived from chicken feather have the most excellent performance for ORR. The optimal dosage ratio of template(polypeptides / Mg O) is 1:2 and the optimal pyrolysis temperature is 900 o C. The as-prepared bio-carbon materials have large specific surface areas of 493.0 m2 g-1. In alkaline medium, the prepared carbons as a cathode catalyst has the most positive onset potential, half-wave potential and peak potential, which are nearly close to those of Pt/C catalyst. The kinetic current density of ORR reached to 3.83 m A cm-2, the current retention still stayed 89.8 % after 3000 cycles, which is superior to that of Pt/C catalyst(76.5 %).(2) N, S co-doped porous carbon materials(NSC) obtained via pyrolysis of zinc-based metal-organic coordination polymer(MOCP-Zn) which was synthesized through a hydrothermal reaction between zinc salt and polypeptides. The results showed the as-prepared carbon materials(NSC-3.5) by optimization possess large BET surface areas of 828.9 m2 g-1.NSC-3.5 exhibited a superior electrocatalytic activity and excellent stability towards ORRboth in alkaline and acid media. Especially, NSC-3.5 could be comparative to Pt/C in acid media, the peak potential was 0.34 V, transferred electron number was 3.98, the current retention still stayed 100 % after 3000 cycles, exhibiting a promising application in the acidic environment of the proton exchange membrane fuel cell. It is proven that the enhanced ORR activities aroused by the high content of pyridinic- and graphitic-type nitrogen and large surface areas with abundant porous structures. Moreover, the growth mechanism of nitrogen and sulfur co-doped bio-carbon materials from chicken feather via coordination reaction and bio-mineralization process is investigated. This study develops a new method to prepare nonmetal-doped bio-carbon materials with large surface areas from waste biomass.