Shape Control Synthesis, Characterizations, Mechanisms And Optical Properties Of Larg Scaled Metal oxide Nanostructures Of ZnO And TiO2

National Physical Laboratory, Council of Scientific and Industrial Research, Dr. K. S. Krishnan Road, New Delhi 110012, India

Adv. Mater. Lett., 2015, 6 (4), pp 324-333

DOI: 10.5185/amlett.2015.5661

Publication Date (Web): Mar 21, 2015

Copyright © IAAM-VBRI Press

E-mail: aks@nplindia, avanish.aks@gmail.com

Abstract

In the present study, ZnO and TiO₂ nanostructures of different size have been synthesized in high yield with excellent repeatability by simple, economical and environmentally benign chemical route. ZnO quantum dots and nanorods of tuned aspect ratio were evolved by optimising the reaction conditions such as by varying solvent composition, precursor concentration and by using different additives. On the other hand, the synthesis of brookite, the rare phase, anatase and rutile, the stable phases of TiO₂ were also achieved by just varying the annealing temperature from 400 to 615 °C.  The obtained nanostructures were rationalized by various characterization techniques such as XRD, FTIR, Raman, SEM, HR- TEM, UV-Vis and PL. The Phase formation and structure determination were identified by using XRD, FTIR and Raman Spectra, SEM and HR-TEM were performed to determine the morphology and particle size. The aspect ratio was calculated to be in the range of 3.2-9.4 in case of ZnO NRs, and particle size was found to be 2-5 nm for ZnO QDs of wurtzite phase and ~ 10 nm for TiO₂ (anatase phase) NPs, respectively. The UV-Vis optical absorption spectrum demonstrates the band gap value of 3.60, 4.02 and 3.40 eV for ZnO NRs, QDs and TiO₂ NPs respectively. The UV-Vis optical absorption spectrum demonstrates the band gap and room temperature PL spectra illustrates about the various defects present in the sample. Various chemical reactions and mechanism involved in producing these nanostructures are dealt in detail. The future prospective of these metal oxide nanostructures lie in photocatalysis, sensors and biomedical applications.

Keywords

Nanostructures, structural analysis, electron microscopy, spectroscopy.