高氮掺杂多孔炭材料的制备及其氧化还原性能研究

Preparation of high nitrogen-doped porous carbons for oxygen reduction reaction

催化剂是影响燃料电池阴极氧化还原反应(ORR)的重要因素。铂等贵金属可以作为有效的ORR催化剂,但其资源有限,价格高昂。氮掺杂多孔炭材料(NPC)具有价格低、导电性高等突出优点,使其成为当前金属铂催化剂的重要替代材料。本研究采用细乳液聚合合成聚丙烯腈(PAN)微球,然后浸渍挥发性电解质ZnCl_2溶液,经预氧化、炭化制得高氮掺杂多孔炭材料(NPC)。ZnCl_2作为活化剂兼具溶剂和活化扩孔双重作用,炭化时ZnCl_2的挥发增加了NPC的孔隙率,制备出的NPC比表面积大(1 776 m^2/g),含氮量高(>10%)。用于ORR,起始电位为0.9 V vs RHE,电子转移数约为4,说明NPC具有良好的氧化还原性能。

The catalyst was a very important factor affecting the oxygen reduction reaction （ORR） of fuel cell cathode. To substitute the active but expensive Pt-based ORR catalyst, low-cost alternatives such as nitrogen-doped porous carbons （NPC） have been explored with promising advances. In this study, polyacrylonitrile （PAN） microspheres were used as templates for the preparation of NPC via miniemulsion polymerization, impregnation with volatile electrolyte ZnC12 solution and followed by pre-oxidation and carbonization. Activator ZnC12 acted as a volatile porogen during PAN pyrolysis to form porous structures with significantly increased specific surface area （1 776 m2/g） and high nitrogen content （〉10%）. The onset potential was about 0.9 V vs RHE and the electrode proceeds mainly through a 4e reduction pathway, indicating that NPC had good oxygen reduction performance.