Iron promoted nitrogen doped porous graphite for efficient oxygen reduction reaction in alkaline and acidic media

Nitrogen doped porous graphite with trace iron and hollow spherical shape is synthesized by using glucose as carbon source, dopamine hydrochloride as N source, Fe(NO3)(3) as Fe source and solid core mesoporous shell silica sphere as template. The glucose and dopamine is carbonized to N-doped carbon; the silica template produces porous and hollow shape with much edges or intrinsic defects; and the addition of Fe increases pore diameter, graphitization degree, total N and pyridinic N content. The characterizations confirm that the doping N leads to active sites for oxygen reduction reaction; the Fe forms active N-Fe species yet electrochemically unstable, which is removed at last. The intrinsic graphite defect and its synergistic effect with doping N are also believed to favor ORR. The material with the above features corresponds to superior oxygen reduction activity in both alkaline and acidic media to commercial Pt/C. The as-synthesized material with few Fe also shows excellent stability due to the graphitized matrix and little metal with excellent anti-methanol and anti-CO performances. The durability of catalysts is also confirmed by using graphite as counter electrode to exclude the impact of dissolution of Pt counter electrode and its re-deposition on the working electrode. (C) 2018 Elsevier B.V. All rights reserved.