Facile hydrothermal synthesis of urchin-like NiCo2O4 spheres as efficient electrocatalysts for oxygen reduction reaction

In this work, we have successfully prepared urchin-like NiCo2O4 spheres via a facile hydrothermal method without any templates or surfactants. The as-prepared urchin-like NiCo2O4 spheres have uniform diameters of 6 μm with numerous small nanorods radially-grown from the center. Typical nanorods have diameters of 20–50 nm and lengths of 2–3 μm. Remarkably, urchin-like NiCo2O4 nanostructure as an alternative non-precious metal electrocatalyst for ORR exhibits catalytic performance and excellent cycling stability in alkaline environment.