Structural and electrochemical investigation of nanostructured C:TiO2–TiOF2 composite synthesized in plasma by an original method of pulsed high-voltage discharge
“…To confirm that interpolations from Figure 10 are meaningful, the Ti 2p BE value of TiOF 2 [54,55] is calculated from the grey curve and found to be 459.6 eV, which matches quite well with the experimental BE of 459.5 eV (blue star in Fig. 10), found in the literature.…”
Section: Separations Between the C-ti-o/oh C-ti-f Peaks And Other Component Peakssupporting
Since their discovery in 2011, the 2D transition metal carbide, nitrides, and carbonitridesdubbed MXenes -have garnered a lot of worldwide interest. Given their 2D structure, surface, or termination, chemistries play a vital role in most applications. X-ray photoelectron spectroscopy, XPS, is one of the most common characterization tools for quantifying surface terminations and overall chemistry. Herein we critically review the XPS fitting models proposed for Ti 3 C 2 T z MXene in the literature and make the case that they are at best incomplete and at worst contradictory. We propose a new fitting algorithm based on all the data obtained from previously published studies. In our approach, we assign the Ti 2p peak at 455.0 eV, to the C-Ti-O\O\O and C-Ti-C octahedra. The peaks at 456.0, 457.0, 457.9, and 459.6 eV are assigned to C-Ti-O\O\F, C-Ti-O\F\F, C-Ti-F\F\F, and TiO 2-x F 2x , respectively. The first four represent possible Ti atom terminations; the last is an oxyfluoride. In our proposed model we do not distinguish between O and OH terminations in the Ti 2p spectra; we only do so in the O spectra. Lastly, we propose and recommend a method for quantifying the surface terminations in Ti 3 C 2 T z .
“…To confirm that interpolations from Figure 10 are meaningful, the Ti 2p BE value of TiOF 2 [54,55] is calculated from the grey curve and found to be 459.6 eV, which matches quite well with the experimental BE of 459.5 eV (blue star in Fig. 10), found in the literature.…”
Section: Separations Between the C-ti-o/oh C-ti-f Peaks And Other Component Peakssupporting
Since their discovery in 2011, the 2D transition metal carbide, nitrides, and carbonitridesdubbed MXenes -have garnered a lot of worldwide interest. Given their 2D structure, surface, or termination, chemistries play a vital role in most applications. X-ray photoelectron spectroscopy, XPS, is one of the most common characterization tools for quantifying surface terminations and overall chemistry. Herein we critically review the XPS fitting models proposed for Ti 3 C 2 T z MXene in the literature and make the case that they are at best incomplete and at worst contradictory. We propose a new fitting algorithm based on all the data obtained from previously published studies. In our approach, we assign the Ti 2p peak at 455.0 eV, to the C-Ti-O\O\O and C-Ti-C octahedra. The peaks at 456.0, 457.0, 457.9, and 459.6 eV are assigned to C-Ti-O\O\F, C-Ti-O\F\F, C-Ti-F\F\F, and TiO 2-x F 2x , respectively. The first four represent possible Ti atom terminations; the last is an oxyfluoride. In our proposed model we do not distinguish between O and OH terminations in the Ti 2p spectra; we only do so in the O spectra. Lastly, we propose and recommend a method for quantifying the surface terminations in Ti 3 C 2 T z .
“…The XPS data processing shows the multicomponent character of the high-resolution C 1 s spectrum (electronic supplementary material, figure S2d). The binding energies of 287.3 and 289.5 eV are associated with the C─O and O═C─O groups [ 34 ], respectively, while the value of 285.0 eV was related to the C─C or/and C─H bonds [ 36 ]. Figure 3.…”
Hafnium-doped titania (Hf/Ti = 0.01; 0.03; 0.05) had been facilely synthesized via a template sol–gel method on carbon fibre. Physico-chemical properties of the as-synthesized materials were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis, scanning transmission electron microscopy, X-ray photoelectron spectroscopy, thermogravimetry analysis and Brunauer–Emmett–Teller measurements. It was confirmed that Hf4+ substitute in the Ti4+ sites, forming Ti1–xHfxO2 (x = 0.01; 0.03; 0.05) solid solutions with an anatase crystal structure. The Ti1–xHfxO2 materials are hollow microtubes (length of 10–100 µm, outer diameter of 1–5 µm) composed of nanoparticles (average size of 15–20 nm) with a surface area of 80–90 m2 g–1 and pore volume of 0.294–0.372 cm3 g–1. The effect of Hf ion incorporation on the electrochemical behaviour of anatase TiO2 in the Li-ion battery anode was investigated by galvanostatic charge/discharge and electrochemical impedance spectroscopy. It was established that Ti0.95Hf0.05O2 shows significantly higher reversibility (154.2 mAh g–1) after 35-fold cycling at a C/10 rate in comparison with undoped titania (55.9 mAh g–1). The better performance offered by Hf4+ substitution of the Ti4+ into anatase TiO2 mainly results from a more open crystal structure, which has been achieved via the difference in ionic radius values of Ti4+ (0.604 Å) and Hf4+ (0.71 Å). The obtained results are in good accord with those for anatase TiO2 doped with Zr4+ (0.72 Å), published earlier. Furthermore, improved electrical conductivity of Hf-doped anatase TiO2 materials owing to charge redistribution in the lattice and enhanced interfacial lithium storage owing to increased surface area directly depending on the Hf/Ti atomic ratio have a beneficial effect on electrochemical properties.
“…Moreover, characteristic planes of TiOF 2 are also obtained at 23.6°, 48.1°, 54.2°, 70.5°, 75.2°, which are indicative planes of the (100), (200), (210), (220) and (215) [25,26,27] (PDF-2 Release 2015 RDB). It could be concluded that a small part of the precursor transformed into TiOF 2 crystals after F ion modifcation and these TiOF 2 dangling on the surface of TiO 2 nanospheres, which supplies an adequate number of Ti ions to anchor Aphen through coordination interactions (Scheme 1).…”
Developing sensing materials for military explosives and improvised explosive precursors is of great significance to maintaining homeland security. 5-Nitro-1,10-phenanthroline (Aphen)-modified TiO2 nanospheres are prepared though coordination interactions, which broaden the absorption band edge of TiO2 and shift it to the visible region. A sensor array based on an individual TiO2/Aphen sensor is constructed by regulating the excitation wavelength (365 nm, 450 nm, 550 nm). TiO2/Aphen shows significant response to nitroaromatic explosives since the Aphen capped on the surface of TiO2 can chemically recognize and absorb nitroaromatic explosives by the formation of the corresponding Meisenheimer complex. The photocatalytic mechanism is proved to be the primary sensing mechanism after anchoring nitroaromatic explosives to TiO2. The fingerprint patterns obtained by combining kinetics and thermodynamics validated that the single TiO2/Aphen sensor can identify at least six nitroaromatic explosives and improvised explosives within 8 s and the biggest response reaches 80%. Furthermore, the TiO2/Aphen may allow the contactless detection of various explosives, which is of great significance to maintaining homeland security.
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