Synergy between isolated-Fe3O4 nanoparticles and CNx layers derived from lysine to improve the catalytic activity for oxygen reduction reaction

In order to seek heterogeneous electrocatalyst with efficient catalytic activity for oxygen reduction reaction (ORR), Fe3O4-CNx composite reported in our previous work was studied as electrocatalyst for ORR and showed poor catalytic activity. To improve the catalytic activity, Fe3O4-CNx composite is modified by the CNx layers derived from lysine through pyrolysis. The physical characterization show that the coral-shaped morphology of the resultant composite (Fe3O4-CNx-Lys) is still retained, while the degree of its graphitic crystalline increases. Besides, Fe3O4-CNx-Lys has 364.7 m2 g−1 of surface area with hierarchical porous structure. Electrochemical tests show that the catalytic activity Fe3O4-CNx-Lys for ORR is not only higher than those Fe3O4-CNx, XC-72-Lys derived from lysine and XC-72 Vulcan carbon but also comparable to that of commercial Pt/C (20 wt%).