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Opis: The paper reports the thermal-induced order fuctuations, in a carbon nanosystem with carbon nanotubes (CNTs) synthesized by the incomplete combustion of gingelly oil. The sample annealed at diferent temperatures (30–400 °C) is subjected to various morphological and spectroscopic characterizations. The ultraviolet–visible spectroscopic and thermogravimetric analyses reveal the CNTs in the sample. The high-resolution transmission electron microscopy (HR-TEM) also confrms the formation of CNTs in the sample. The Raman spectrum and X-ray difraction pattern show the signature of multi-walled to single-walled CNT transformation and thus an order fuctuation on annealing. The quantum yield of the sample, measured by integrating sphere method, yields 46.15% at an emission wavelength of 575 nm. When the excitation wavelength is varied from 350 to 510 nm, the CIE coordinate moves from the white region to the yellowish-green region. The varying amount of CNTs in the soot, upon annealing is found to vary the luminescence emission from the sample. The study reveals the thermal-induced oscillatory order in carbon nanosystem with carbon nanotubes (CNTs) leading to tunable excitation/ thermal-dependent luminescence emission and thereby suggesting the possibility of converting the futile soot for fruitful applications in photonics and nanoelectronics.
Ključne besede: Carbon nanosystem, Single-walled carbon nanotubes, Multi-walled carbon nanotubes, Raman spectroscopy, Thermogravimetric analysis, CIE plot, Quantum yield, gingelly oil
Objavljeno v RUNG: 05.07.2022; Ogledov: 2032; Prenosov: 0
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Opis: X-ray Raman spectroscopy (XRS) is an emerging spectroscopic technique that utilizes inelastic scattering of hard Xrays to study X-ray absorption edges of low Z elements in bulk material. It was used to identify and quantify the amount of carbonyl bonds in a cathode sample, in order to track the redox reaction inside metal−organic batteries during the charge/ discharge cycle. XRS was used to record the oxygen K-edge absorption spectra of organic polymer cathodes from different multivalent metal−organic batteries. The amount of carbonyl bond in each sample was determined by modeling the oxygen K-edge XRS spectra with the linear combination of two reference compounds that mimicked the fully charged and the fully discharged phases of the battery. To interpret experimental XRS spectra, theoretical calculations of oxygen K-edge absorption spectra based on density functional theory were performed. Overall, a good agreement between the amount of carbonyl bond present during different stages of battery cycle, calculated from linear combination of standards, and the amount obtained from electrochemical characterization based on measured capacity was achieved. The electrochemical mechanism in all studied batteries was confirmed to be a reduction of double carbonyl bond and the intermediate anion was identified with the help of theoretical calculations. X-ray Raman spectroscopy of the oxygen K-edge was shown to be a viable characterization technique for accurate tracking of the redox reaction inside metal−organic batteries.
Ključne besede: X-ray Raman spectroscopy, meta-organic batteries, oxygen K-edge XANES, electrochemical processes
Objavljeno v RUNG: 24.03.2022; Ogledov: 2437; Prenosov: 21
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