ZnO@zeolitic imidazolate frameworks derived porous hybrid hollow carbon shell as an efficient electrocatalyst for oxygen reduction

Designing reasonable MOFs-derived carbon materials to further effectively improve the catalytic activity toward ORR in the practical application of fuel cells is very necessary but remains a great challenge. Herein, a new facile yet robust strategy, self-sacrifice template approach combined with a variety of MOFs, to achieve core–shell ZnO@zeolitic imidazolate frameworks precursor (ZnO@ZIF-8@ZIF-67) is developed. Subsequently, the porous hybrid hollow carbon shell (Zn/Co-NC) can be obtained by calcinating the precursor. Impressively, the Zn/Co-NC-800 prepared by pyrolysis at 800 °C manifests excellent ORR performances with a positive onset potential of 1.03 V (vs. reversible hydrogen electrode) (vs. RHE), a more positive half-wave potential at 0.856 V (vs. RHE, a positive shift of 28 mV compared with the Pt/C) and 4-electron pathway (n = 3.80). Also, it performs higher long-term stability (only a 7.9% decay of initial current density after 20000 s) and better methanol tolerance in comparison with the traditional Pt/C in alkaline media. In our current work, the synthesis strategy of the self-sacrificing template combined with ZIFs opens up a new route for the preparation of highly efficient non-precious metal electrocatalysts for ORR.