Bimetallic dispersion zeolitic imidazolate framework derived spherical porous bifunctional catalysts for liquid/solid Zn-Air batteries

In recent years, bifunctional electrocatalysts derived from zeolite imidazole framework (ZIF) as a carbon substrate have been a hot research topic. In addition, one-component catalyst cannot achieve the efficient catalysis of oxygen reduction reaction(ORR) and oxygen evolution reaction( OER). At the same time, this paper reports a bifunctional catalyst with a bimetallic three-dimensional porous structure using silicon spheres as a hard template and ZIF as a carbon substrate. The inherent porosity of pie-shaped ZIF, the use of silica templates to generate an ordered macroporous structure, and the synergy between metal activity sites, which together promote the mass transfer and electrocatalytic activity of the battery. The synthesized catalyst showed excellent electrocatalytic activity toward ORR and OER including a half-wave potential (E1/2 =0.80 V) which is 20 mv less than Pt/C, and its overpotential (0.321 V) and voltage gap (ΔE=0.751 V) surpasses commercial Pt/C+RuO2 catalyst (0.368 V, ΔE=0.778 V). Moreover, primary and rechargeable Zn-air battery is assembled based on this catalyst delivered preferable performance, including a high power density (98.7 mw cm-2),batter charge/discharge cycling stability (220 h) exceeds commercial Pt/C+RuO2 catalyst (160 h）. Given its unique pore structure and good electrical conductivity, this derived material has scope for expansion in bifunctional catalysis and other energy technologies for rechargeable Zn-air batteries.