Iron-nitrogen co-doped hierarchically mesoporous carbon spheres as highly efficient electrocatalysts for the oxygen reduction reaction

By using hierarchically mesoporous silica spheres as hard template, 2-aminopyridine and FeCl3 as carbon, nitrogen and iron sources, respectively, iron and nitrogen co-doped hierarchically mesoporous carbon spheres (Fe-N-CS) were successfully prepared. The sample Fe-N-CS- 900 obtained at a carbonization temperature of 900 degrees C exhibited a highly efficient electrocatalytic activity with positive half-wave potential (-0.11 V), high limiting current density (-4.79 mA cm(-2)) and high selectivity (electron transfer number around 4) for the oxygen reduction reaction (ORR) in alkaline media. Moreover, Fe-N-CS- 900 shows higher stability and better methanol tolerance in comparison to commercial Pt/C catalyst in both alkaline and acidic media. Its highly efficient ORR activity could be ascribed to its high specific surface area, unique porous structure and homogeneous distribution of Fe-N-x active sites formed during pyrolysis.