An architecture of dandelion-type Ni-Co3O4 microspheres on carbon nanotube films toward an efficient catalyst for oxygen reduction in zinc-air batteries

Abstract Sluggish kinetics of oxygen reduction reaction (ORR) at an air cathode of a rechargeable zinc-air battery (ZAB) is a serious obstacle hindering the development of the ZAB. In the present work, hierarchical Co3O4 nanowires doped with Ni atoms (Ni-Co3O4) were fabricated and self-assembled into dandelion-type microspheres on CNT films (Ni-Co3O4/CNTs) by a hydrothermal method. X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and high resolution transmission electron microscope (HRTEM) results verified the successful incorporation of Ni atoms into the Co3O4 lattice. Electrochemical measurements, such as cyclic voltammetry (CV) and linear sweep voltammetry (LSV) techniques, revealed that the dandelion-type Ni-Co3O4/CNT composite could greatly enhance the catalytic activity and ORR durability of the air cathode in the O2-saturated 0.1 M KOH electrolyte. Here, we report that the synergistic effect between Ni-Co3O4 nanowires and CNTs could greatly improve the stability and electrochemical performance of Co3O4 catalysts. Especially, the Ni-Co3O4/CNTs prepared at 160 °C exhibited the best catalytic capability and long-term durability (93.34% after 8.3 h) in the present work, which are better in comparison with the performance of the 20 wt% commercial Pt/C electrode in ZABs.