A facile one pot flash combustion synthesis of ZnO nanoparticles and their characterizations for photocatalytic applications

Herein, we have facilely synthesized high purity ZnO nanoparticles by flash combustion technique in presence of different citric acid (CA) content. X-ray diffraction study rules out the existence of any extra phase except single hexagonal phase of ZnO. Further, crystallite size, dislocation density and strain values were estimated, and the crystallite size was found to be reduced from 20to 10 nm with rising the concentration of CA. Vibrational study also confirm the single phase in accordance with XRD results and revealed that the modes of vibration are slightly shifted owing to quantum size effect and relaxed nanostructure formation. To confirm the purity of synthesized ZnO the energy dispersive X-ray spectroscopy was carried out which confirm the high purity of synthesized products. Spherical nanoparticles (SNPs) morphology was confirmed through scanning electron microscopy and the size is reduced with raising the concentration of CA. TEM study was also carried out which clearly shows the formation of spherical nanoparticles (SNPs) and the mean size is around 10 nm for 1 g CA:ZnO and < 6 nm for 10 g CA:ZnO samples. The blue shift in absorption edge was noticed in DR spectra with raising the CA concentrations and the energy gap was estimated using Kubelka-Munk theory. The estimated direct energy gap of ZnO SNPs was noticed to be increased from 3.25 to 3.28 eV. An enhancement in dielectric constant from 14 to 17 and ac conductivity was observed with raising the CA content. Furthermore, the prepared SNPs of ZnO were subjected to photocatalytic study from application point of view. The photocatalytic performance of the prepared materials is found to be improved several times. All results displayed that the CA is playing the vital role in improving the optoelectronic and photocatalytic performance of ZnO and hence will be more applicable. (C) 2019 Elsevier B.V. All rights reserved.