Simultaneously Engineering the Synergistic-Effects and Coordination-Environment of Dual-Single-Atomic Iron/Cobalt-sites as a Bifunctional Oxygen Electrocatalyst for Rechargeable Zinc-Air Batteries

Single-atom introduced carbon nanomaterials show favorable oxygen-reduction reaction (ORR) and oxygen-evolution reaction (OER) performance for renewable energy applications. Nevertheless, the electronic-structure regulation by decorating heterogeneous single-metal-atoms and the engineering of a single-atom active-sites' microenvironment need to be optimized simultaneously, which is challenging. Herein, we develop an atomic-interfacial-regulation approach to fabricate dual single Fe/Co atoms synchronized with both nitrogen/sulfur atoms on defective/graphitic/porous carbon nanosheets (Fe,Co/DSA-NSC). The unsymmetrically organized N and S coordinated Fe/Co bridged atomic-sites [Fe-(N2S)/Co-(N2S) moiety] are established to prompt charge-transfer, lowering the energy barrier of oxygenated reaction-intermediates and leading to boost the reaction-kinetics. As estimated, the Fe,Co/DSA-NSC exhibits an improved ORR/OER activity with higher half-wave potential and lower overpotential (E1/2 = 879 mV and η10 = 210 mV, respectively) and also good cycling stability toward zinc-air batteries. This discovery hence provides a widespread scheme for the synergistic-principles of dual-single-atom catalysts and controlled regulation of an active-sites' microenvironment toward energy applications.