Decoration of Spongelike Ni(OH)2 Nanoparticles onto MWCNTs Using an Easily Manipulated Chemical Protocol for Supercapacitors

Abstract

This study uses a "bottom-up" approach chemical method to coat nanocrystalline Ni(OH)2 onto multiwalled carbon nanotubes (MWCNTs) for flexible supercapacitor electrodes, where the higher electronic conductivity of MWCNTs permits their use as the supporting backbone onto which Ni(OH)2 can be deposited. The paper portrays the advantages of the facile successive ionic layer adsorption and reaction (SILAR) method for depositing Ni(OH)2/MWCNT thin films onto large area flexible substrates. We demonstrate that these Ni(OH)2/MWCNT films consist of a uniform coating of sponge-like Ni(OH)2 on the MWCNT network structure using scanning electron micrographs and transmission electron micrographs; this structure is promising for supercapacitor applications. Ni(OH)2/MWCNT films exhibit a specific capacitance of 1487 F g(-1) at a scan rate of 5 mV s(-1) in a 2 M KOH aqueous solution. The electrodes are generated using a simple three-beaker SILAR system at ambient conditions, thus providing an easy approach to fabricate high-power and high-energy flexible supercapacitors. Ni(OH)2/MWCNTs demonstrate a good rate capability and excellent long-term cyclic stability (96% capacity retention after 1000 cycles). Such high-performance capacitive behavior indicates that Ni(OH)2/MWCNT composites are promising electrode materials for the fabrication of supercapacitors. Thus, the method described in this paper provides a generalized route for the production of a wide range of Ni(OH)2/MWCNT-based materials for applications beyond electrochemical energy storage. These encouraging results promote interest in developing such devices, including nontoxic and greener components, compared with current organic-based devices.