Strongly coupled Co, N co-doped carbon nanotubes/graphene-like carbon nanosheets as efficient oxygen reduction electrocatalysts for primary Zinc-air battery

Abstract

Rational design and feasible synthesis strategy for the construction of carbon-based non-precious metal electrocatalysts for oxygen reduction reaction (ORR), which is the core electrode reaction of fuel cells or metal-air batteries, is of paramount importance for the renewable energy conversion and storage applications. Herein, Co, N encapsulated nanocarbon hybrid of carbon nanotubes in situ grown between the graphene-like carbon nanosheets (Co-NCNT/Ng) are fabricated via a one-pot pyrolysis of the mixture of Co precursor, dicyandiamide and glucose. The optimized Co-NCNT/Ng catalyst with a 3-dimensional (3D) interconnected framework possesses a high specific surface area, hierarchical porous structure and effective doping of Co and N. Due to the synergistic utilization of active sites and effective mass transfer, the 3D hybrid delivers comparable ORR catalytic activity to commercial 20 wt% Pt/C catalyst as evidenced by the half-cell potential of 0.825 V, long-term stability as well as strong methanol tolerance in alkaline medium. Notably, the real validations for the Co-NCNT/Ng as the cathode catalyst can be carried out by an assembled primary Zinc-air battery, which surpasses the Pt/C catalyst in terms of power density and long-term stability.