Facile synthesis of one-dimensional iron-oxide/carbon hybrid nanostructures as electrocatalysts for oxygen reduction reaction in alkaline media.

One-dimensional iron-oxide/carbon hybrid nano tubular structures were synthesized via anodic aluminium oxide (AAO) template method. Highly unform iron oxide nanoparticles and carbon structures were formed simultaneously on the wall surface of the AAO template from an iron-oleate precursor by solventless thermal decomposition method. The 1D iron-oxide/carbon nanostructures were obtained after removing the AAO template. The typical size of the iron oxide nanoparticles was - 6 nm, and the nanoparticles had a crystalline structure of maghemite (γ-Fe2O3), which was determined from the HRTEM and X-ray diffraction (XRD). This nanocrystalline spinel structure could provide more active sites for oxygen reduction reaction (ORR) catalysis due to the higher specific surface area and numerous defects. As an ORR catalyst, the hybrid nanotubes showed higher limiting mass activity (8.8 A/g) and a more positive onset potential (-0.241 V, vs. Hg/HgCl) than iron oxide nanoparticles in alkaline media. This electrocatalytic activity of the nanocomposites is mainly attributed to the synergetic effects of the iron oxide nanoparticles and carbon matrix in the one-dimensional nanostructure.