Atomically Dispersed Fe/N4and Ni/N4Sites on Separate‐Sides of Porous Carbon Nanosheets with Janus Structure for Selective Oxygen Electrocatalysis

Abstract

AbstractDual single atoms catalysts have promising application in bifunctional electrocatalysis due to their synergistic effect. However, how to balance the competition between rate‐limiting steps (RDSs) of reversible oxygen reduction and oxygen evolution reaction (OER) and fully expose the active centers by reasonable structure design remain enormous challenges. Herein, Fe/N4and Ni/N4sites separated on different sides of the carbon nanosheets with Janus structure (FeNijns/NC) is synthesized by layer‐by‐layer assembly method. Experiments and calculations reveal that the side of Fe/N4is beneficial to oxygen reduction reaction (ORR) and the Ni/N4side is preferred to OER. Such Janus structure can take full advantage of two separate‐sides of carbon nanosheets and balance the competition of RDSs during ORR and OER. FeNijns/NC possesses superior ORR and OER activity with ORR half‐wave potential of 0.92 V and OER overpotential of 440 mV atJ = 10 mA cm−2. Benefiting from the excellent bifunctional activities, FeNijns/NC assembled aqueous Zn–air battery (ZAB) demonstrates better maximum power density, and long‐term stability (140 h) than Pt/C+RuO2catalyst. It also reveals superior flexibility and stability in solid‐state ZAB. This work brings a novel perspective for rational design and understanding of the catalytic mechanisms of dual single atom catalysts.