Understanding the thermal decomposition effects in TOPO capped ZnO nanocrystals

Abstract

Different shapes and sizes of TOPO-capped ZnO nanostructures have been obtained by the decomposition of the cupferron complex in the presence of tri-n-octylphosphine oxide (TOPO) under different conditions. The precursor : TOPO ratio, the order of reactants and thermal decomposition temperature play important roles in determining of the shape and size of nanoparticles. Particle size was evaluated using TEM images and effective mass approximation method from UV-vis spectroscopy to be about 1–80 nm. Changes in luminescence intensities have been measured for ZnO capped by TOPO after different growth temperatures. FT-IR, ¹H-NMR and {¹H}³⁵P-NMR results confirm the contribution of coordinated TOPO persists longer, but at a high temperature only the broad background peaks remain. FE-SEM images of ZnO samples obtained by hydrothermal treatment have been shown to have nano-leaf like and nanorod morphology. The morphology of the ZnO nanorod and nano-leaf are related to the crystal structure and the velocities of crystal growth in different directions. XRD patterns were shown with increasing thermal decomposition temperature, the diffraction peak intensity of faces [0002] and [101] were obviously lower and the peak intensity of polar face [100] increases. EDX analysis was indicated ZnO nanocrystal without impurity at 600 °C.