Nitrogen-Doped Carbon Foam as a Highly Durable Metal-Free Electrocatalyst for the Oxygen Reduction Reaction in Alkaline Solution

Nitrogen-doped carbon foam (CFN) with large surface area is synthesized via a template-free, scalable combustion technique using diethanolamine as a nitrogen source. The resulting macroporous, open-cell foam has micron-scale hollow cells, surrounded by thin, graphene-like walls. This material is applied as a metal-free electrocatalyst for the oxygen reduction reaction (ORR) in alkaline KOH solution. The activity of this metal-free electrocatalyst at the half-wave potential is just 43 mV lower than that of platinum decorated carbon (Pt/CB), but 87 mV lower than a commercially available Fe-containing non-precious electrocatalyst (Pajarito Powder, PP), suggesting that iron is important in achieving the highest activities. In durability tests measured over 60,000 potential cycles, Pt/CB and PP undergo significant degradation, whilst the non-precious CFN electrocatalyst shows negligible change, indicating high stability of the electrochemical active sites compared with platinum or iron. Such metal-free catalysts therefore show great promise as electrocatalysts for specific alkaline ion exchange membrane fuel cell (AEMFC) applications where long lifetimes are most important. (C) 2016 Elsevier Ltd. All rights reserved.