Molecular Scissor Tailoring Hierarchical Architecture of Zif-Derived Fe/N/C Catalysts for Acidic Oxygen Reduction Reaction

Iron and nitrogen co-doped carbon (Fe-N-C) electrocatalysts have great potential to catalyze the kinetically slow oxygen reduction reaction (ORR). Unfortunately, the ORR performances of existing Fe/N/C catalysts is seriously hindered by the poor accessibility and inherent activity of the atomic Fe-Nx moieties. Herein, a carboxylate (OAc) molecular scissor is proposed to tailor Fe doped zeolitic-imidazolate-framework-8 (ZIF-8) at atomic scale and construct hierarchical architecture. This molecular scissoring strategy imparts Fe/N/C-OAc with dense accessible active sites, multidimensional mass transfer pathways, hierarchical porous structure and entangled carbon nanotubes network. Therefore, the tailored Fe/N/C-OAc electrocatalyst exhibits excellent ORR activity in acidic media with a half-wave potential of 0.838V, which is comparable to state-of-the-art non-precious metal catalysts. When assembled as cathode catalyst in a H2-O 2 proton exchange membrane fuel cell, it delivers a peak power density of 0.74Wcm-2 . This work provides a new approach for tailoring catalyst architecture and accessibility of active sites.