Enhancing oxygen reduction activity by Mn-pyridinic N bonding in SmMn2O5/nitrogen-doped carbon black hybrid catalysts

Abstract

In order to overcome the poor conductivity of transition metal oxides, design of hybrid catalyst with carbonaceous materials is an effective strategy to improve oxygen reduction reaction (ORR) performance. Here, the hybrid catalysts composed of SmMn2O5 and nitrogen-doped carbon black (SMO/NC-x) were synthesized in situ by hydrothermal method. When SMO content is about 21.6 wt%, SMO/NC-2.5 exhibits excellent ORR performance, the half-wave potential increases from 0.69 V for pure SMO to 0.77 V for SMO/NC-2.5, the diffusion-limited current density of SMO/NC-2.5 is 4.9 mA cm−2, higher than 3.8 mA cm−2 for pure SMO. Combining with X-ray photoelectron spectroscopy and Raman analysis, it is confirmed that the efficient ORR activity of the hybrid catalyst is mainly attributed to the synergic effect generated by Mn and pyridinic N Bonding, which is conducive to the storage and transfer of electrons at the interface. In addition, the detailed mechanism of synergic effect was well discussed.