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Author(s) |
Gawai, U. P.; Kamble, S. D.; Gurav, S. K.; Yadav, A. K.; Jha, S. N.; and others (A&MPD)
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Source |
ACS Omega, 2022. Vol. 7 (8): pp. 6700-6709 |
ABSTRACT
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Developing the most straightforward, cheapest, and eco-friendly approaches for synthesizing nanostructures with well-defined morphology having the highest possible surface area to volume ratio is challenging for design and process. In the present work, nanosheets of NiO and β-Ni(OH)2/Co3O4, and nanorods of Co3O4 have been synthesized at a large scale via the microwaveassisted chemical coprecipitation method under low temperature and atmospheric pressure. X-ray absorption spectroscopy (XAS) measurements, which comprises both X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) techniques, have been carried out at Co and Ni K-edges to probe the electronic structure of the samples. Also, the local atomic structural, chemical bonding, morphological, and optical properties of the sample were systematically investigated using XAS, synchrotron X-ray diffraction (SXRD), Raman spectroscopy, FTIR, transmission electron microscopy (TEM), and UV−visible spectroscopy. The normalized XANES spectra of the β-Ni(OH)2/Co3O4 nanosheets show the presence of Ni2+ and a mixed oxidation state of Co. The disorder factor decreases from β-Ni(OH)2/Co3O4 to Co3O4 with increasing Co−O bond length. The SXRD pattern analyzed using Rietveld refinement reveals that NiO has a face-centered cubic phase, Co3O4 has the standard spinal structure, and β-Ni(OH)2/Co3O4 has a mixed phase of hexagonal and cubic structures. TEM images revealed the formation of nanosheets for NiO and β-Ni(OH)2/Co3O4 samples and nanorods for Co3O4 samples. FTIR and Raman spectra show the formation of β-Ni(OH)2/Co3O4, which reveals the fingerprints of Ni−O and Co−O. |
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