Preparation Of Nitrogen Doped Ordered Mesoporous Carbon Materials For Oxygen Reduction Reaction

Developing a potential substitute for the platinum-based catalysts with low cost, high activity and durability, particularly at the cathode, is a central issue of catalysts research in proton-exchange membrane fuel cells (PEMFC). In this work, the novel nitrogen doped ordered mesoporous carbon derived from conjugated polymer poly (pyrrole-co-furfural)(MPF-x) is successfully prepared. Then, the MPF-xs are used as supports for the fabrication of cobalt oxide based oxygen reduction reaction catalysts (nCoMPF-x).The p-toluenesulfonic acid (PTSA) covered SBA-15is used template. In-situ copolymerization of pyrrole and furfural is carried out into the channel of template through solution phase reaction. The as-prepared MPF-xs possess a direction parallel to the pore channels of the CMK-3type carbons and narrow pore size distributions. The maximum values of specific surface area (1812m2·g-1) and pore volume (1.56m3g-1) are obtained in the sample calcined at800℃(MPF-800). The content of nitrogen (3.3-5.9at.%) can be controlled by different feeding proportion of polymer monomer and temperature. The cyclic voltammetry (CV) and rotating disk electrode (RDE) tests show that the MPF-800sample has more positive onset potential (Eonset=-0.116V vs. Ag/AgCl) and half-wave potential (E1/2=-0.220V vs. Ag/AgCl) than other samples as a metal-free catalyst in alkaline media. Besides, the Koutecky-Levich plots of MPF-800at-0.4V (vs. Ag/AgCl) is3.78, which is close to four-electron ORR process. And the value of kinetic-limited current density (JK) at-0.4V is8.95mA·cm-2, which is closer to the commercial Pt/C electrocatalyst than corresponding samples, but it exhibits superior stability.The MPF-xs are used as supports to fabricate CoMPF-x catalysts by ultrasonic-assisted wetness impregnation. The as-prepared CoMPF-x catalysts retain ordered mesopores of supports with well-dispersed cobalt oxide particles. The cobalt atoms are uniformly distributed over the N-doped supports. The optimized10CoMPF-800sample has a positive onset potential (Eonset=-0.06V vs. Ag/AgCl), which is fairly close to commercial Pt/C in alkaline media. Furthermore,10CoMPF-800exhibits higher kinetic current density (JK=22.29mA·cm-2) with a nearly complete four-electron (n=3.98) ORR process at-0.4V (vs. Ag/AgCl) and superior stability to the commercial Pt/C electrocatalyst.