Hexamethylenetetramine-derived pyridinic N abundant porous carbon-supported Co/Co-Nx nanoparticles as highly efficient oxygen reduction catalyst and zinc-air battery cathode

Fuel cells and metal-air batteries attracted extensive research attention owing to high power density, renewability, and environmental friendliness. Hence, developing heteroatom-doped pyridinic N abundant porous carbon materials with large surface area have an extensive effect on oxygen reduction reaction (ORR) for fuel cell and metal-air battery. Herein, high content of pyridinic N porous carbon-supported Co/Co-N x nanoparticles were synthesized as ORR catalysts by carbonizing complexes of hexamethylenetetramine (HMT) and Co(NO 3 ) 2 ·6H 2 O with silica template. The HMT-Co@SiO 2 -900 with high content of pyridinic N, large specific surface area, and porous structure exhibits a more positive half-wave potential (0.85 V) than 20% Pt/C and the outstanding performance oxygen evolution reaction  behavior. The low Tafel slope of HMT-Co@SiO 2 -900 revealed the faster reaction kinetics during ORR. The HMT-Co@SiO 2 -900 zinc-air battery showed a high excellent cyclic stability in continuous charge/discharge cycles for 420 times at 10 mA/cm 2 . This research provides an efficient strategy for the preparation of pyridinic N porous electrocatalyst by the reduction of diffusion restriction and exposure of active sites.