Interrelations between sulfur, iron, nitrogen, pore and graphite matrix for oxygen reduction reaction

Abstract Nitrogen doped lotus-stem carbon and that being promoted by sulfur or iron (N-LC, NS-LC, NFe-LG and NSFe-LG) are synthesized. The interrelations between pore size, graphitization degree, N content, Fe–N content, S doping, and their effects on oxygen reduction reaction (ORR) activity and stability in alkaline media are studied. The NSFe-LG shows the most excellent performances for ORR. The Fe-free NS-LC shows close ORR activity and comparable stability to the NSFe-LG, which may make metal-free catalyst attractive.