Two-step growth mechanism of supported Co3O4-based sea-urchin like hierarchical nanostructures

The formation mechanism of Co3O4-based sea-urchin like nanostructures from Co-O-B layers is unveiled. In this process, promoted by oxidizing annealing, B plays a major role, inducing first a chemical reduction of Co and the formation of a metallic particle core. The growth of nano-needles from the particle surface occurs through outdiffusion and oxidation of Co from the metallic reservoir