Cobalt- and iron-containing nitrogen-doped carbon aerogels as non-precious metal catalysts for electrochemical reduction of oxygen

• Carbon aerogels were prepared by pyrolysis of metal- and N-containing organic aerogels.
• ORR activity of the catalysts was tested by RDE and RRDE in alkaline solution.
• Co-containing aerogel was slightly more active than Fe-containing material.
• N-doped carbon aerogels are possible cathode materials for alkaline membrane fuel cells.

Nitrogen-doped carbon aerogels containing transition metals have been used as non-precious metal catalysts for oxygen reduction reaction (ORR). The electrocatalysts were prepared by sol–gel polymerisation of organic precursors, followed by insertion of Co or Fe by ion exchange and subsequent carbonisation. The resulting materials were characterised by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Electrochemical testing of the catalysts by thin-film rotating disk and ring-disk electrode technique revealed their high activity and stability in alkaline solution. Cobalt-containing aerogel showed slightly better performance than iron-containing material and the aerogel not containing transition metals was considerably less active. The Koutecky–Levich analysis indicated nearly four-electron reduction of O2 on metal-containing nitrogen-doped carbon aerogels. The non-precious metal catalysts studied could be used as cathode materials for alkaline membrane fuel cells.