In situ surface-confined fabrication of single atomic Fe-N4 on N-doped carbon nanoleaves for oxygen reduction reaction

Controllable fabrication of Fe-N-C based single-atom catalysts(SACs) for enhanced electrocatalytic performance is highly desirable but still challenging. Here, an in situ surface-confined strategy was demonstrated for the synthesis of single atomic Fe-Non N-doped carbon nanoleaves(L-Fe NC). The in situ generated Zn[Fe(CN)]could not only serve as a protection layer against collapse of nanoleaves but also provide abundant Fe source for the formation of Fe-N moieties during pyrolysis, leading to high surface area and high graphitization degree of L-Fe NC simultaneously. Benefiting from abundant Fe-Nactive sites, enhanced mass and charge transfer, the as-prepared L-Fe NC manifested a half-wave potential of 0.89 V for oxygen reduction reaction(ORR) in 0.1 M KOH. A maximum power density of 140 m W cmand stable discharge voltage even after operation for 50,000 s have been demonstrated when the L-Fe NC was used as air cathode for Zn-air battery. This work not only provided a unique surfaceconfined strategy for the synthesis of two-dimensional nanocarbons, but also demonstrated the significant benefit from rational design and engineering of Fe-N-C SACs, thus offering great opportunities for fabrication of efficient energy conversion and storage devices.