Enhancement of the photocatalytic activity of modified TiO2 nanoparticles with Zn2+. correlation between structure and properties

Abstract

Zinc doped and undoped TiO 2 photocatalysts were synthesized via sol-gel techniques. Doping of TiO 2 with M 2+ (M-Zn) was intended to create tail states within the band gap of TiO 2 . These can subsequently be employed as efficient photocatalysts which can effectively decompose organic contaminants only with vis ible light activation. The structure, physico chemical and optical properties of the products were character ized by using the X ray diffraction (XRD), Raman spectra, UV vis diffuse reflectance spectroscopy (DRS) and electrochemical impedance spectroscopy (EIS) techniques. Doping shifts the optical absorption edge to the visible region and decreases the charge transfer resistance. Under visible light, the composite nanoparti cles very efficiently catalyze the MB dye. Results implied that Zn doping increased photoinduced charge transfer rate, and the use of described methods is a powerful tool toward predicting and understanding the photocatalytic processes and behaviors. ENHANCEMENT OF THE PHOTOCATALYTIC ACTIVITY 491 390 455 520 585 650 715 λ, nm Absorbance 1 2 Fig. 3. UV vis diffuse reflectance spectra of (1) the bare and (2) Zn doped TiO 2 materials.

Impact of the Precursor on the Physicochemical Properties and Photoactivity of TiO2 Nanoparticles Produced in Supercritical CO2

“…Crystallite sizes displayed an improvement compared to other studies [ 14 , 19 , 41 , 42 ], since all catalysts prepared in this work range from 9 to 14 nm, showing a smaller crystal size than in other studies, in which they vary between 16–17 nm, and even bigger in the case of commercial catalyst P-25 (20 nm). In this work, the crystallite size is smaller than that of the catalysts obtained by Zhang et al [ 40 ] with traditional methods, which range between 12–15 nm. This decrease in crystal size points towards an increase in the surface area, which could reduce the path length of diffuse light and transport of the charge carriers, thus enhancing the photocatalytic activity.…”

“…With XRD data, it is possible to calculate the percentage of the different crystal phases, as well as crystallite sizes, which are presented in Figure 6 . These characteristics were obtained from the Debye–Scherrer Equation detailed elsewhere [ 40 ]. As no rutile nor brookite peaks have been detected, all the catalysts synthetized only possess anatase as crystal phase.…”

Effects of Various Semiconducting Oxides as Photoanode and Counter Electrode for Dye Sensitized Solar Cell Application - A Review

“…The ZnO nanorods usually grown on seeded catalyst that used to reduce the thermodynamic barrier [78]. The materials were usually used as seeded catalyst such as aluminium (Al) [79], magnesium (Mg) [7], magnesium oxide (MgO) [80], silicon dioxide (SiO2) and aurum (Au) [81].…”

Effect of molarity on sol–gel routed nano TiO2thin films

“…where D is the crystallite size (nm), is the wavelength of X-ray radiation ( ¼ 0:154 nm) for Cu K , K is the coefficient (0.89), is full width half maximum FWHM intensity (radian) and is the corresponding diffraction angle. 21,22 From XRD analysis, the crystallite size of TiO 2 nanoparticles gradually decreases with increase of molarity. The thickness of TiO 2 film increases with the increase in molarity as in Table 1.…”