Highly Active Fe-N-doped Porous Hollow Carbon Nanospheres as Oxygen Reduction Electrocatalysts in Both Acidic and Alkaline Media
Hierarchical iron-nitrogen-codoped porous hollow carbon spheres have been synthesized by using melamine-formaldehyde (MF) resin spheres as templates, nitrogen sources and pore-forming agent. FeCl3, 1,10-phenanthorline and carbon black as iron, nitrogen and carbon sources. The as-obtained porous hollow carbon spheres possess a high specific surface area of 807 m2g-1, as well as exhibited excellent electrocatalytic activity for oxygen reduction reaction (ORR) in both acidic and alkaline media. In 0.1 M HClO4 solution, the onset potential of 0.857 V (vs RHE) and the half-wave potential of 0.715 V, which are only 78 and 80 mV less than 20% Pt/C catalyst, respectively. In addition, in 0.1 M KOH solution, the onset potential of 1.017 V and the half-wave potential of 0.871 V for ORR, which are 22 and 28 mV more positive than Pt/C catalyst, respectively. Meanwhile, the catalyst also exhibited excellent methanol tolerance and long-term durability with a more effective four-electron pathway compared to the 20% Pt/C in both acidic and alkaline media. When used as an air-cathode catalyst for a Zn-air battery, the maximum power density for a Zn-air battery with the MF-C-Fe-Phen-800 cathode was 235 mW cm-2 under the high current density of 371 mA cm-2, and a high open-circuit potential of 1.654 V, superior to that of Pt/C (199 mW cm-2, 300 mA cm-2, 1.457 V). A series of designed experiments suggested that the remarkable performance was attributed to high specific area, hollow carbon spheres, unique hierarchical micro-mesoporous structures, high contents of pyridinic-N and graphitic-N. The superiority of the as-prepared catalyst makes it promising for use in practical applications.
- This article is part of the themed collection: 2020 Nanoscale HOT Article Collection