Abstract:
and Debaprasad Mandal *
Oxygen electrochemistry plays an imperative role in renewable energy systems. Development of nonprecious metals and efficient bifunctional catalysts for the oxygen reduction reaction and oxygen
evolution reaction (ORR & OER) is highly demanded for metal–air batteries. Herein, a conjugate of tetracobalt sandwich polyoxometalate [Co4(H2O)2(PW9O34)2]
10 (CoPOM) and polyvinyl butyl imidazolium
(PVIM) (PVIM–CoPOM) supported on carbonaceous materials was explored as an oxygen bifunctional
catalyst in alkaline media. The PVIM–CoPOM/NCNT composite is highly active towards ORR and OER.
The novel composite exhibits a low overpotential (hj10) of 0.28 V vs. RHE for OER, outperforming the
state-of-the-art RuO2 catalyst (0.35 V), and a comparable ORR activity to Pt/C with similar overall
oxygen electrode activity to the benchmark precious metal catalyst. A conventional Zn–air battery with
the PVIM–CoPOM/NCNT air cathode shows high energy density and a low charge–discharge potential gap.
