Hierarchically porous Fe-N-doped carbon nanotubes as efficient electrocatalyst for oxygen reduction

A hierarchically meso/micro-porous Fe-N-doped carbon nanotube electrocatalyst (meso/micro-Fe-N-CNT), for the first time, was synthesized. Anodic aluminum oxide (AAO) was used as a template to cast the CNT framework and Fe(NO)3 was filled in the AAO nanochannels as both a mesopore template in CNT walls and the iron source to form Fe-N-C active sites. Subsequent NH3 activation was carried out to create abundant micropores and active sites to produce the meso/micro-Fe-N-CNT. This hybrid material has a unique characteristic of a high-conductivity CNT framework, an ultrahigh surface area of 2137 m2 g−1, a high density of Fe-N-C catalytic active sites, and abundant meso- and micropores for efficient mass transport channels. As a consequence, excellent oxygen reduction reaction performance under acidic conditions and even better performance under alkaline conditions were demonstrated that are comparable to that of Pt/C.