LAUSR

Abstract In this study, both morphology-related factors and catalytic activity factors were taken into account simultaneously and sea urchin-like Co3O4 nanoneedles grown on nickel foam were synthesized via a facile hydrothermal strategy (grass-like Co3O4 were also prepared for comparison). Most noteworthy is that 3D open-structured sea urchin-like Co3O4 exposing more Co3+ sites with large specific surface area and abundant mesoporous structure exhibited superior electrocatalytic performance as compared to 1D structured grass-like Co3O4 and former reported 3D structured electrodes (i.e., urchin shaped, flower shaped). Pd decorated sea urchin-like Co3O4 was also prepared through a simple impregnation method. When served as binder/carbon-free catalytic cathode for Li-O2 batteries, the problems about limited capacity, large overpotential and poor cycle life were effectively improved. The catalytic electrode displayed a low overpotential of 1.12 V, high specific capacity (8819.2 mA h g−1) at a current density of 200 mA g−1 and long cycle life with the capacity limited at 500, 1500, 2500, even 3500 mA h g−1, overmatching most of the transition-metal-oxides based catalytic electrodes, which are intrinsically dependent on the characteristic design in both morphology and catalytic active sites of the electrodes.