A novel route for the synthesis of CNT-TiO 2 hybrid nanostructures is reported based on a combination of sol-gel and arc discharge methods in a liquid. The CNT-TiO 2 nanocomposites were prepared using an arc discharge between graphitic electrodes in a TiO 2 solution and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and ultra violet-visible absorption spectroscopy (UV-Vis). The photocatalytic performance in visible light and antibacterial activity of the CNT-TiO 2 nanocomposites demonstrated degradation of Rhodamine B (Rh. B) and inactivation of Escherichia coli (E. coli) bacteria. It was observed that the absorption spectrum of the CNT-TiO 2 nanocomposites extended into the visible region, and considerably improved photocatalytic efficiency and antibacterial properties under visible light irradiation. The amount of CNTs formed in the TiO 2 solution was controlled by the arc duration time and the optimum value for the best possible photocatalytic performance of each specific arc current was also probed. We found that the prepared samples have high photocatalytic activity and antibacterial efficiency.The significant enhancement in the photocatalytic properties and antibacterial activity of CNT-TiO 2 nanocomposites under visible light irradiation can be attributed to the effect of doped CNTs acting as electron traps in the TiO 2 band gap.
Here in this paper, synthesis of WO3 nanoparticles (NPs) by laser ablation of a pure tungsten plate immersed in water is reported. For this purpose, the first harmonic of an acousto-optically Q-Switched Nd:YAG laser is utilized at 13, 18 and 23 J/cm2 laser fluences. X-ray diffraction (XRD) and transmission electron microscopy (TEM) associated with dynamic light scattering (DLS) techniques show that while the laser fluence increases from 13 to 23 J/cm2, the crystallinity, length of particle chains and average particle size of the products increase, respectively. UV–Vis spectra indicate a red shift on the absorption edge towards the visible region for the samples produced at higher laser fluences attributed to the particle size increment and energy band gap decrement, subsequently. Also other linear optical parameters including Urbach energy, refractive index dispersion, relaxation time, complex dielectric and conductivity functions are derived and discussed. Z-scan analysis is carried out to determine the nonlinear refraction index, nonlinear absorption coefficient and third-order nonlinear susceptibility. It is found that WO3 NPs can be considered for optical limiting performance because of the high nonlinear absorption. Furthermore, the specimens prepared at higher laser fluences are more applicable due to the larger particle size and higher nonlinear absorption, consequently.
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