Soft template-assisted synthesis of single crystalline β-cobalt hydroxide with distinct morphologies

Abstract

In this work, a facile soft template-assisted water-bath method was adopted to synthesize pure phase single-crystalline β-cobalt hydroxide. Using polyvinyl pyrrolidone (PVP), polyethylene glycol (PEG) and cetyltrimethyl ammonium bromide (CTAB) as soft templates, β-Co(OH)₂ with hexagonal, disc-like and flower-like morphologies was successfully fabricated. It was found that all of the nanostructures exhibited preferentially oriented crystal growth along the (001) plane. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that the soft templates had an important role in guiding the crystal growth and determining the final structure of β-Co(OH)₂. Cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) measurements indicated that the flower-like structures had superior electrochemical properties over hexagonal and disc-like β-Co(OH)₂. A four-step growth mechanism of β-Co(OH)₂ was proposed based on time-dependent morphological evolution results. The results reveal the potentiality of soft templates in fine-tuning the morphology of single crystal β-Co(OH)₂ nanomaterials.