Cobalt-based multicomponent nanoparticles supported on N-doped graphene as advanced cathodic catalyst for zinc-air batteries

To improve the efficiency of cathodic oxygen reduction reaction (ORR) in zinc-air batteries (ZABs), an adsorption-complexation-calcination method is proposed to generate cobalt-based multicomponent nanoparticles comprising Co, Co₃O₄ and CoN, as well as numerous N heteroatoms, on graphene nanosheets (Co/Co₃O₄/CoN/NG). The Co/Co₃O₄/CoN nanoparticles with the size of less than 50 nm are homogeneously dispersed on N-doped graphene (NG) substrate, which greatly improve the catalytic behaviors for ORR. The results exhibit that the half-wave potential is high to 0.80 V vs. RHE and the limiting current density is 4.60 mA cm^-2, which verge on those of commercially available platinum/carbon (Pt/C) catalysts. Investigating as cathodic catalyst for ZABs, the battery shows large specific capacity and open circuit voltage of 843.0 mAh g_Zn^-1 and 1.41 V, respectively. The excellent performance is attributed to the efficient two-dimensional structure with high accessible surface area and the numerous multiple active sites provided by highly scattered Co/Co₃O₄/CoN particles and doped nitrogen on the carbon matrix.