Synthesis of CoOOH Hierarchically Hollow Spheres by Nanorod Self-Assembly through Bubble Templating

Abstract

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 O₂ 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.