Aqueous chemical growth of ZnO/CdO nanocomposite thin films: effect of volume ratio and annealing on structural, morphol
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Aqueous chemical growth of ZnO/CdO nanocomposite thin films: effect of volume ratio and annealing on structural, morphological and optical properties M. D. Tyona1,* F. I. Ezema3
, G. E. Akpen1,3, Itodo Anejo1, Kaana Asemave2, P. U. Asogwa3, and
1
Department of Physics, Benue State University, P.M.B. 102119, Makurdi, Nigeria Department of Chemistry, Benue State University, P.M.B. 102119, Makurdi, Nigeria 3 Department of Physics and Astronomy, University of Nigeria, P.O. Box 2201, Nsukka, Nigeria 2
Received: 22 June 2020
ABSTRACT
Accepted: 8 October 2020
Structural, morphological and optical characteristics of ZnO/CdO nanocomposite films synthesized via successive ionic layer adsorption and reaction (SILAR) technique with different ratios of ZnO/CdO: 30:50 ml, 40:40 ml and 50:30 ml has been investigated. Structural studies indicated a mixed phase of hexagonal ZnO and cubic CdO with low intensities. Variation of identified crystal phases, crystallinity and crystallites sizes responded strongly with varying precursor ratios and thermal annealing. SEM micrographs show nanoparticles of varying particle sizes in the range of 32.9–57.7 nm, governed by CdO content in the film and thermal annealing. Optical studies indicated that the synthesized materials have predominantly ultraviolet (UV) absorption which was significantly enhanced into the visible spectrum due to annealing. Bandgap shrinked from 3.80 to 2.72 eV as a result of annealing and variation of precursor ratio. The materials demonstrated very low reflectance, which confirmed their good absorption quality. The refractive index of the material indicated abnormal and normal dispersion regions with uniform peaks, which were slightly blue-shifted upon annealing. High optical conductivity in the order of 1011 S-1 were measured, which confirmed the good photoresponse of the films. The absorption and extinction coefficients of the materials were in good agreement with the high ultraviolet–visible (UV–Vis) absorption observed. Finally, the synthesized materials were adjudged to be suitable for photovoltaic (PV) application, photocatalysis, thermoelectrics, photo diodes, disinfectants, antibacterial activity, gas sensing and optical communication.
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https://doi.org/10.1007/s10854-020-04635-6
J Mater Sci: Mater Electron
1 Introduction Emerging nanostructures of different materials or composite materials at various nanoscales are found with many fascinating applications in different fields [1–3]. There has been increasingly high research attraction on biocompatible, biodegradable, and functionalized nanomaterials applications in the last two decades due to their excellent performance [4]. Hexagonal wurzite zinc oxide (ZnO) and cubic cadmium oxide (CdO) semiconductor nanomaterials has been widely researched consequent upon the outstanding properties they exhibit independently or as composite [5]. Hexagonal wurzite ZnO is classified as a II–VI com
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