Porous carbon layers wrapped CoFe alloy for ultrastable Zn-Air batteries exceeding 20,000 charging-discharging cycles

Developing high active and stable bifunctional electrocatalysts towards oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is essential for the development of rechargeable Zn-air batteries.Herein,a facile strategy to synthesize the porous carbon layers wrapped CoFe alloy(C/CoFe)through the pyrolysis of a homogeneous mixture containing Co,Fe ions and N-doped carbon quantum dots(Ndoped CQDs)was reported.The prepared carbon layers with multi-level pore structures provides more active sites and optimizes the homogeneity of the electron and mass transport.In addition,the carbon layers,which is doped by Co/Fe/N atoms,is responsible for high ORR activity,while the CoFe alloy plays a vital role in OER performance.The as-synthesized catalyst exhibits an excellent bifunctionality for electrochemical oxygen reactions,which is comparable to the commercial Pt/C and IrO2 benchmarks.Owing to the carbon layers protects CoFe alloy nanoparticles from the harsh environment,the rechargeable Znair battery with the C/CoFe catalyst delivers excellent stability during 20,000 charging-discharging cycles.