Credit: © 2009 AAAS

Highly active electrocatalytic electrodes used to reduce oxygen are important components of fuel cells but most are platinum-based. The scarcity and cost of this and other potentially useful noble metals has driven researchers to look for non-metal alternatives. Now, Liming Dai of the University of Dayton and colleagues from the University of Akron and the Air Force Research Laboratory, Ohio, have developed1 an electrode using carbon nanotubes (CNTs) that does not require a noble metal.

An array of vertically aligned, nitrogen-doped carbon nanotubes (VA-NCNTs) was created by pyrolysis of iron(II) phthalocyanine, electrochemically purified to remove all iron and attached to a glassy carbon electrode. The electrocatalytic performance of the VA-NCNT electrodes for the reduction of oxygen in an alkaline solution was superior to that of a commercially available platinum-loaded carbon electrode.

The performance was also superior to that of doped non-aligned CNT electrodes — attributed to the well-defined large surface area of the VA-NCNT electrode — and that of undoped CNT electrodes, which was attributed to the electron-accepting ability of the nitrogen heteroatoms that disrupt the carbon framework. The electrode was also shown to be highly stable and tolerant to both CO and fuel poisoning.