Multiwall carbon nanotube/nickel oxide nanocompositecoatings: Sol-gel deposition and characterization

Abstract

Due to their unique electronic and optical properties nanocomposite materials have wide range of applications in solar energy conversion. In this study, multiwalled carbon nanotubes (MWCNTs)/Nickel oxide (NiO) nanocomposites were successfully prepared by a sol-gel process and coated on aluminium substrate. The MWCNTs were chemically functionalized and then added into NiO alcogels which is followed by magnetic stirring in order to homogeneously disperse in the NiO matrix solution. The morphology of the nanocomposite thin films showed that the MWCNTs were embedded in NiO nano-particle matrix. HRTEM confirmed the fact that the MWCNTs were decorated by the NiO nano-particles. Raman spectra for functionalized MWCNTs displayed a red shift from the pristine MWCNTs phonons suggesting successful purification/functionalization. The spectrum for the MWCNTs/NiO nanocomposite presented both the TO and LO phonons of NiO, and the D and G bands of the MWCNTs. Redshifts and blue shifts of the NiO phonons and the MWCNT phonons suggested that the vibrational properties of both materials were changed to form new nonocomposite vibrational properties. The solar absorptance of pure NiO was found to be 0.35 and that of nitrogenated NiO to be 0.55. However, the absorptance for the functionalized MWCNTs/NiO nanocomposite films gave 0.84. The thermal emittance was about 0.1. These preliminary results suggest that MWCNTs/NiO nanocomposite material is suitable for solar thermal applications.