ZnO nanoparticles with tunable bandgap obtained by modified Pechini method

Abstract

Zinc oxide nanoparticles (N–ZnO) obtained by the Pechini method and calcined using a closed clay container are the focus of the present work. The synthetic route includes a modification in the calcination process (modified Pechini method), that is, without the change in the calcination process. The modified calcination process carried out in a clay container allows for the tunability of the ZnO bandgap. To characterize the materials, X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV–visible (UV–Vis) spectroscopy have been performed. The analysis of UV–Vis absorption measurements allows us to conclude that the bandgap of N–ZnO can be tuned from 2.8 to 3.04 eV for ZnO–CC:400 and ZnO–CC:600 (samples of carbon-doped N–ZnO or C–N–ZnO), respectively, which are smaller than the ZnO bulk value of 3.37 eV. This gives rise to new possibilities of adaptation for the N–ZnO to new applications by shifting the bandgap from the UV to the visible region. The XRD and TEM measurements show that all samples are highly crystalline and have small grain sizes, confirming that the ethylene glycol seems to be a useful polymerizing agent for the preparation of C–N–ZnO.