One-step synthesis of low defect density carbon nanotube-doped Ni(OH)2nanosheets with improved electrochemical performances

Abstract

A facile soft chemistry route is described to fabricate a composite of α-Ni(OH)₂ nanosheets doped with low defect density carbon nanotubes (CNTs) via one step. As a result of the hydrolysis of nickel nitrate in a water/N-methyl-pyrrolidone (NMP) system, the as-produced H⁺ and NO₃⁻ species can react with carbon atoms of CNTs, yielding a small amount of oxygen-containing functional groups which may serve as the anchor sites. It is interesting to find that CNTs simultaneously act as both nucleation centers and templates, eventually leading to the formation of smooth and micro-scale α-Ni(OH)₂ nanosheets–CNTs hybrids. Because of the soft oxidation nature of as-proposed synthetic pathway, the conjugation of carbon atoms in the framework is less disrupted and the CNT backbones in the composite have a characteristically low defect density; thereby, the physical properties of CNTs are well preserved in the composite material. As expected, a high specific capacitance of 1302.5 F g⁻¹ of the composite are obtained in comparison with its individual components (372.1 F g⁻¹ for Ni(OH)₂ and 101.4 F g⁻¹ for CNTs), highlighting the importance of rational design and synthesis of hybrid nanostructures for high-performance energy storage applications.