Dandelion-like cobalt hydroxide nanostructures: morphological evolution, soft template effect and supercapacitive application

Abstract

A facile one-pot water bath method has been proposed to synthesize cobalt hydroxide (Co(OH)₂) nanodandelions with polyvinyl pyrrolidone (PVP) as soft template. Morphological evolution has been investigated to reveal the crystal growth process of Co(OH)₂ and understand the relationship between microstructure and capacitive properties by changing the reaction time and amounts of soft template. The results demonstrate that by rational design of the morphology, the electrochemical performance of Co(OH)₂ can be dramatically enhanced. The unique dandelion-like structure can facilitate both ion and electron diffusion and improve the reaction kinetics, thus offering suitable characteristics for electrode materials of high performance supercapacitors. A high specific capacitance of 407 F g⁻¹ is obtained, and after 5000 charge–discharge cycles at 10 A g⁻¹, the capacitance retention is still as high as 92%. This work provides an effective method to synthesize hierarchical nanomaterials with high electrochemical capability.