TiO₂–multi-walled carbon nanotube nanocomposites: hydrothermal synthesis and temporally-dependent optical properties

Abstract

MWCNTs/TiO2 nanocomposites have been prepared by a hydrothermal method and characterized by various spectroscopic techniques, and an enhanced optical nonlinearity was observed for M1.00 due to a combination of mechanisms.

Effects of Different TiO2 Particle Sizes on the Microstructure and Optical Limiting Properties of TiO2/Reduced Graphene Oxide Nanocomposites

“…21-1272, all XRD patterns of the two series of TiO 2 /rGO nanocomposites and bare TiO 2 could be indexed to anatase, which indicated the spontaneous product of TiO 2 during the hydrothermal process. Moreover, it displayed no characteristic diffraction peaks related to rutiles and brookites in Figure 1, which indicated the TiO 2 was free of rutiles and brookites [29,30]. Although the Ti-source materials of the two samples were different, 0.1 g P25 and 0.25 g TBT samples exhibited similar patterns from Figure 1a.…”

“…Compared to bare TiO 2 , all TiO 2 /rGO nanocomposites, whether TBT series samples or P25 series samples, exhibited enhanced light absorption in the visible region and a smaller band gap. Moreover, the absorption edge of TiO 2 /rGO nanocomposites showed different degrees of red shift, which probably was due to the decreased band gap of TiO 2 and the oxygen vacancies existing on the surface of TiO 2 [29,30,52,53,54], corresponding to the results of FTIR spectra and XPS spectra. The decreased band gap indicated a larger possibility for photon-generated carriers to transfer, which increased the kinetic energy of the carriers to disperse the laser energy.…”

“…Figure 6 displays the UV-Vis absorption spectra of TiO 2 , TBT samples (a) and P25 samples (b). Bare TiO 2 showed a characteristic absorption edge at about 390 nm, which was associated with a charge transfer from the valence band to the conduction band [29]. Absorption wavelength threshold (λ g ) and corresponding band gap (E g ) were calculated and shown in Table 3 according to reference [51].…”

CNTs based improved chlorine sensor from non-covalently anchored multi-walled carbon nanotubes with hexa-decafluorinated cobalt phthalocyanines

“…36,37 Raman spectra of MWCNTs-COOH exhibit the characteristic G-band (related to C-C vibration of the carbon material with a sp 2 orbital structure) around 1593 cm À1 and D band (associated with sp 2 C with defects) around 1360 cm À1 . 38,39 Comparison of Raman spectra of the hybrid with F 16 CoPc and MWCNTs-COOH shows a combination of their individual characteristic Raman peaks with a change in peak positions and their intensities. The intensity ratio of D band to the G band (I D /I G ), known as a ratio of sp 3hybridized carbon atom relative to sp 2 -bonded carbon atom, is found to be 1.16 and 1.31 for MWCNTs-COOH and hybrid sample, respectively.…”

“…On Cl 2 exposure, the peak corresponding to cobalt-nitrogen bond 51 at 175 cm À1 is found to shi by 7 cm À1 and peaks of macro-cyclic vibrations 52 (206, 285, 468, 587, 738, 961 and 1192 cm À1 ) are shied by 5 cm À1 , whereas D and G band corresponding to MWCNTs-COOH at 1342 and 1593 cm À1 are shied by 2 and 1 cm À1 , respectively. 38,39 The signicant shi of 9 cm À1 is observed for the Raman peak at 1542 cm À1 , which is due to displacement of C-N-C bridge bond, closely linked to the central metal ion of phthalocyanine molecule. 53 This observation is concomitant with the predominant interaction of Cl 2 with the cobalt ions of the hybrid sensor.…”