Facile synthesis of magnesium ferrite nanoparticles supported on nitrogen and sulfur co-doped carbon black as an efficient electrocatalyst for oxygen reduction reaction

Novel nanohybrid MgFe2O4 (MFO) supported on carbon black co-doped by nitrogen and sulfur (CNS) was facilely synthesized as an efficient electrocatalyst (namely, MFO/CNS) for oxygen reduction reaction (ORR) in alkaline medium. Structural analysis by X-ray diffraction revealed the formation of MFO and confirmed its spinel structure in MFO/CNS nanocomposite. Transmission electron microscope images showed that the products synthesized by different annealing temperature displayed a diverse particle size and dispersion of active component. Electrochemical results indicated that the MFO/CNS hybrid with the controllable N, S-co-doping shows an enhanced ORR catalytic activity and desired direct four-electron reaction pathway, which is better than MFO and CNS synthesized under the same conditions. The excellent electrochemical performance of MFO/CNS should be attributed to the synergistic effect of MFO and CNS to form a conductive network structure, which offers the increased electrochemical active surface area, the facilitated electron transfer, and effective mass transport between oxygen molecules and active sites. The results demonstrated that the MFO/CNS nanohybrid in this study appears to be a promising cathodic electrocatalyst in alkaline fuel cells.