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 was 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 show that the half-wave potential is as high as 0.80 V vs. RHE and the limiting current density is 4.60 mA∙cm⁻², which are close to those of commercially available platinum/carbon (Pt/C) catalysts. Applying as cathodic catalyst for ZABs, the battery shows large specific capacity and open circuit voltage of 843.0 mAh∙g⁻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.