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 O 2 bubbles induced by CTAC is responsible for the formation of hierarchically hollow structure. The effects of H 2 O 2 concentrations and CTAC during the crystallization and self-assembly process of CoOOH nanorods have been studied. It is found that H 2 O 2 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.