Sol-gel TiO2 nanostructures single doped with copper and nickel as nanocatalysts for enhanced performance for the Liebeskind–Srogl reaction (original) (raw)
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2015
Rare earth (RE) ion (RE = La, Ce, Y) doped TiO 2 catalysts were successfully synthesized by the sol-gel method. The particle size were reducing while increasing doping concentration (x= 0.2, 0.4, 0.6) in the 2 nd order reaction and it was strongly reflected inX-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy(TEM). The resulted images indicated that the particles were binded. While increasing the concentration of dopents particle size also increases. The average particle size of TiO 2 with dopant said to 70±2 nm. In FTIR spectrum comparing all compositions peak between 400-4000 cm -1 were shifted and also Ti-O-RE stretching band, which attributed to formed pure and doped TiO 2 nanoparticles. The reflectance spectra reveal that the RE-doped TiO2resulted in red shifts. Optical band gap (Eg) was reducedin high doping concentration (0.6) due to highadsorptionon the surface of RE-doped TiO2 (3.02 eV) and pristine TiO2 (3.2 eV). It causes that...
Journal of Water and Environmental Nanotechnology, 2022
TiO2-based nanomaterials are very effective for water and air purification and act as good antibacterial agents due to their unique physicochemical properties. TiO2 is a promising nanocatalyst because of its non-toxicity, chemical stability, and low cost. The wide band gap and rapid electron-hole recombination limit its performance which can be overcome by doping with metals and non-metal ions. Metal doping improves the trapping of electrons to inhibit electron-hole recombination and non-metal doping reduces the bandgap of TiO2. These doped TiO2 materials can be synthesized by different routes like the Sol-gel method, hydrothermal method, precipitation method, impregnation method, etc. Among these, the Sol-gel method is reported as the best and most accurate for the synthesis of TiO2 particles in the nano scale range. Because it allows the incorporation of dopant ions at the molecular level with homogeneity and high chemical purity. The structural, morphological, and optical properties of as-synthesized TiO2 nanocatalysts can be well characterized by XRD, SEM, EDX, FT-IR, UV Vis-DRS, TEM, BET, and PL. In this review article, we would like to discuss the advantage of the Sol-gel method over other preparative methods of TiO2 nanomaterials and experimental techniques related to their characterization.
Sol–gel doped TiO 2 nanomaterials: a comparative study
Journal of Sol-gel Science and Technology, 2009
Among the great number of sol–gel prepared nanomaterials, TiO2 has attracted significant interest due to its high photocatalytic activity, excellent functionality, thermal stability and non-toxicity. The photocatalytic degradation of pollutants using un-doped and doped TiO2 nanopowders or thin films is very attractive for applications in environmental protection, as a possible solution for water purification. The present work describes a comparative structural and chemical study of un-doped TiO2 and the corresponding S- and Ag-doped materials. The photocatalytic activity was established by testing the degradation of organic chloride compounds from aqueous solutions. Sol–gel Ag-doped TiO2 coatings, prepared by co-gelation and sol–gel Ag-doped TiO2 coatings obtained from nanopowders were also compared. Their structural evolution and crystallization behaviour (lattice parameters, crystallite sizes, internal strains) with thermal treatment were followed by thermal analysis, X-ray diffraction, transmission electron microscopy, atomic force microscopy and specific surface areas measurements. X-ray photoelectron spectroscopy analyses were performed to characterize the surface composition and S or Ag speciation, which was used to interpret the catalytic data.
Springer Berlin Heidelberg, 2019
In the present work, Ni 2+ and Cu 2+ ions are doped with TiO 2 using sol-gel technique. The effects of Ni and Cu doping in TiO 2 matrix are characterized by XRD, Micro-Raman, FTIR, UV-DRS, PL, and FESEM with EDS. Furthermore, it is analyzed for photocatalytic activity and magnetic applications. From XRD analysis, it is observed that the peaks corresponding to the planes match with the JCPDS data [anatase: 89-4203] of TiO 2. The crystallite size of the doped samples is found to be greater than that of TiO 2. Micro-Raman analysis shows the confirmation of anatase phase of TiO 2. FTIR analysis confirms the presence of functional groups which are presented in the prepared samples. From UV-DRS, the band-gap values of TiO 2 and doped TiO 2 (Ni 2+ , Cu 2+) are found to be 3.25, 2.48, and 1.25 eV. Photoluminescence (PL) results show an emission edge of Ni-and Cu-doped TiO 2 is red shifted which is due to the vacancies of titanium and oxygen imported subsequently during doping. The surface morphology and the elemental composition of Ni-and Cu-doped TiO 2 nanoparticles are also analyzed. The photocatalytic activity of all the prepared samples are assessed by methylene blue dye as testing pollutant and visible radiation. The test reveals that Cu-TiO 2 , Ni-TiO 2 , and TiO 2 show the degradation efficiency of 68.14, 61.04, and 33.32%, thereby showing that the doped TiO 2 are more efficient in degrading the pollutant and can be applied for future photocatalytic applications. From VSM analysis, the saturation magnetization of Ni-TiO 2 and Cu-TiO 2 is found to be weak and can be improved by the synthesis process and the proportion of dopant.
The advancements in sol–gel method of doped-TiO 2 photocatalysts
A critical review on the advancements in sol-gel method of doping TiO2 photocatalysts is provided. Various sol-gel and related systems of doping were considered, ranging from co-doping, transition metal ions doping, rare earth metal ions doping to other metals and non-metals ions doping of TiO2. The results available showed that doping TiO2 with transition metal ions usually resulted in a hampered efficiency of the TiO2 photocatalyst, though in some few cases, enhancements of the photocatalytic activity of TiO2 were recorded by doping it with some transition metal ions. In most cases, co-doping of TiO2 increases the efficiency of its photocatalytic activity. The review reveals that there are some elemental ions that cannot be used to dope TiO2 because of their negative effects on the photocatalytic activity of the catalyst, while others must be used with caution as their doping will create minimal or no impacts on the TiO2 photocatalytic efficiency.
Applied catalysis. B, …, 2011
In recent years, significant effort has been focused on the production of visible-light activated photocatalysts such as N-doped TiO 2 for advanced oxidation processes. Thus, this paper describes a facile and simple route to produce N-doped TiO 2 nanoparticles by a modified polymeric precursor method using urea. In addition, the paper describes the characterization and photocatalytic activity evaluation of N-doped TiO 2 nanoparticles. The predominance of the anatase phase and the modification of band-gap energies in N-TiO 2 indicate that the doping process is effective; Raman spectroscopy shows bands related to TiO x N 1−x . The presence of N in higher amounts in the doped nanoparticles confirms the doping process which was also confirmed by X-ray photonelectron spectroscopy (XPS). Unmodified TiO 2 nanoparticles indicate higher UV-C photocatalytic activity, and the N-doped TiO 2 nanoparticles show better visible photocatalytic activity, suggesting a useful way to operate those catalysts under visible light and/or sunlight.
Desalination, 2011
In the present study, titanium dioxide nanoparticles were synthesized by sol-gel method, from various precursors in some solvents under different synthesis conditions such as solvent percent, water percent, reflux temperature, reflux time, sol drying method and calcination temperature. Structure, size, band gap and specific surface area of nanoparticles were determined by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-Vis reflectance spectroscopy (DRS) and BET analysis methods. The photocatalytic activity of TiO 2 was evaluated in the photodegradation of C.I. Acid Red 27 as a model contaminant from textile industry under UV-C light irradiation. Results indicate that structure and photocatalytic activities are functions of precursor type, solvent type and other synthesis conditions. TiO 2 nanoparticles synthesized in the presence of methanol as solvent and titanium (IV) isopropoxide as precursor under 3 h reflux at 80°C with sol thermal drying and calcination temperature of 450°C indicate high photocatalytic activity in comparison with TiO 2 -P25 (Degussa Co.).
Copper-/Zinc-Doped TiO2 Nanopowders Synthesized by Microwave-Assisted Sol–Gel Method
Gels
Using the microwave-assisted sol–gel method, Zn- and Cu-doped TiO2 nanoparticles with an anatase crystalline structure were prepared. Titanium (IV) butoxide was used as a TiO2 precursor, with parental alcohol as a solvent and ammonia water as a catalyst. Based on the TG/DTA results, the powders were thermally treated at 500 °C. XRD and XRF revealed the presence of a single-phase anatase and dopants in the thermally treated nanoparticles. The surface of the nanoparticles and the oxidation states of the elements were studied using XPS, which confirmed the presence of Ti, O, Zn, and Cu. The photocatalytic activity of the doped TiO2 nanopowders was tested for the degradation of methyl-orange (MO) dye. The results indicate that Cu doping increases the photoactivity of TiO2 in the visible-light range by narrowing the band-gap energy.