Synthesis of CoOOH hierarchically hollow spheres by nanorod self-assembly through bubble templating

CoOOH hierarchically hollow spheres consisting of nanorods by self-assembly coupled with bubble templating through a facile one-step hydrothermal route have been demonstrated. An energy-minimizing-driven self-assembly of CoOOH nanorods on the base Of 02 bubbles induced by CTAC is responsible for the formation of hierarchically hollow structure. The effects of H2O2 concentrations and CTAC during the crystallization and self-assembly process of CoOOH nanorods have been studied. It is found that H2O2 concentration is a key factor that affects not only the crystallinity, shape, and size but also the further self-assembly process of CoOOH nanorods, determining the final formations of hollow spheres or solid aggregates of nanorod self-assemblies, while CTAC can probably induce the CoOOH nanorods to get more ordered self-assembly. This is the first synthesis of complex hollow structure of CoOOH crystals with hierarchy.