Growth of carbon nanotube based zinc oxide nanowires and investigation of their optoelectronic properties

The integration of carbon nanotubes (CNTs) with zinc oxide (ZnO) has shown significant promise in improving the efficiency of materials for various applications. This thesis presents the synthesis and characterization of CNT/ZnO nanowires by growing ZnO on CNT using hydrothermal method. The fabricated nanowires were analyzed using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray spectrometry (EDX), Fourier Transform Infrared spectroscopy (FTIR), Thermogravimetric Analysis (TGA) and X-Ray Diffraction (XRD). SEM images show that the nanowires are long and thin and dense nanowire structures with high aspect ratio are grown. SEM results show that ZnO nanowires were successfully grown homogeneously on the CNT substrate. The nanowires have an average diameter of 20-50 nm and a length of 5-10 μm. The EDX spectrum of ZnO confirms the presence of ZnO by showing prominent peaks corresponding to zinc (Zn) and oxygen (O). Comparing the spectra of pure ZnO and CNT/ZnO, additional carbon peaks and possible changes in Zn and O peak intensities indicate the successful formation of nanostructures. FTIR spectroscopy provided information on the chemical bonds and functional groups present in the samples. The presence of alkyne (C≡C) and aromatic (C=C) vibrations is consistent with the graphitic structure and possible defects or functional groups in the CNT. Moreover, the peaks at 971.12 cm-¹ and 666.87 cm-¹ are characteristic of Zn-O bond vibrations, confirming the presence of ZnO. TGA/DTG was used to evaluate the thermal stability. The significant weight loss at high temperatures indicated the complete oxidation of CNTs and potential changes in ZnO. XRD data confirmed the crystal structure and phases of the synthesized nanostructures. XRD analysis revealed that the average crystal size was 25-30 nm. The sharpness of the diffraction peaks indicates that ZnO was grown in high quality and homogeneously.