FeC cluster-promoted single-atom Fe, N doped carbon for oxygen-reduction reaction

A key challenge in carrying out an efficient oxygen reduction reaction (ORR) is the design of a highly efficient electrocatalyst that must have fast kinetics, low cost and high stability for use in an energy-conversion device ( e.g. metal-air batteries). Herein, we developed a platinum-free ORR electrocatalyst with a high surface area and pore volume via a molten salt method along with subsequent KOH activation. The activation treatment not only increases the surface area to 940.8 m 2 g −1 by generating lots of pores, but also promotes the formation of uniform Fe 3 C nanoclusters within the atomic dispersed Fe-N x carbon matrix in the final material (A-FeNC). A-FeNC displays excellent activity and long-term stability for the ORR in alkaline media, and shows a greater half-wave potential (0.85 V) and faster kinetics toward four-electron ORR as compared to those of 20 wt% Pt/C (0.83 V). As a cathode catalyst for the Zn-air battery, A-FeNC presents a peak power density of 102.2 mW cm −2 , higher than that of the Pt/C constructed Zn-air battery (57.2 mW cm −2 ). The superior ORR catalytic performance of A-FeNC is ascribed to the increased exposure of active sites, active single-atom Fe-N-C centers, and enhancement by Fe 3 C nanoclusters. An Fe 3 C nanocluster is successfully introduced to an Fe-N-C catalyst via a KOH active process. And the electronic effect of Fe 3 C enhances the activity towards oxygen reduction reaction.