Sol-gel TiO2 nanostructures single doped with copper and nickel as nanocatalysts for enhanced performance for the Liebeskind–Srogl reaction (original) (raw)
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.
Revista de Chimie
Selenium-doped titania nanoparticles were prepared and characterized from physico-chemical and morphological point of view, with the aim possible applications in photocatalysis. DLS measurement indicated that TiO2 particles presents two different components: the first one, with low concentration and maximum size distribution at about 20 nm, and second one, with high concentration and size distribution ranging from 40 to 250 nm (maximum at 100 nm). After doping procedure and thermal treatment at 800 ͦ C, the size distribution reveals the formation of nanoparticles with wide range of diameters, from 20 nm to 500 nm, with good stability, as demonstrated by Zeta potential values: -19 mV for TiO2 and -25 mV for Se/TiO2 particles. Ti-O-Ti and Se-O vibrational modes were identified in ATR FTIR spectra. As a consequence of thermal treatment at 800 ͦ C, morphological changes of titania particles from nanorodes to nanowires were observed. The XRD spectrum of TiO2 starting material shows the t...
Carbon letters, 2017
This study synthesized pure anatase carbon doped TiO 2 photocatalysts supported on a stainless steel mesh using a sol-gel solution of 8% polyacrylonitrile (PAN)/dimethylformamide (DMF)/TiCl 4. The influence of the pyrolysis temperature and holding time on the morphological characteristics, particle sizes and surface area of the prepared catalyst was investigated. The prepared catalysts were characterized by several analytical methods: high resolution scanning electron microscopy (HRSEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), and X-ray photoelectron spectroscopy (XPS). The XRD patterns showed that the supported TiO 2 nanocrystals are typically anatase, polycrystalline and body-centered tetragonal in structure. The EDS and XPS results complemented one another and confirmed the presence of carbon species in or on the TiO 2 layer, and the XPS data suggested the substitution of titanium in TiO 2 by carbon. Instead of using calcination, PAN pyrolysis was used to control the carbon content, and the mesoporosity was tailored by the applied temperature. The supported TiO 2 nanocrystals prepared by pyrolysis at 300, 350, and 400ºC for 3 h on a stainless steel mesh were actual supported carbon doped TiO 2 nanocrystals. Thus, PAN/DMF/TiCl 4 offers a facile, robust sol-gel related route for preparing supported carbon doped TiO 2 nanocomposites.
Applied Nanoscience, 2015
Mesoporous, nanocrystalline, Zinc-doped TiO 2 nanoparticles were synthesized by surfactant-assisted solgel method. The X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), and UV-VIS spectrometer techniques were used to characterize the synthesized products. XRD results confirm the formation of the anatase phase for the TiO 2 nanoparticles, with crystallite sizes in the range of 12.6-18.1 nm. The small crystallite size and doping with Zinc ion inhibit phase transformation and promote the growth of the TiO 2 anatase phase. The SEM and TEM micrographs revealed the spherical-like morphology with average diameter of about 12-18 nm which is in agreement with XRD results. The optical study shows that doping ions lead to an increase in the absorption edge wavelength and a decrease in the band gap energy of titania. Photocatalytic activity of the synthesized nanomaterials was successfully tested for photodegradation of methyl red as model pollutant under UV light. The photocatalytic activity results confirm that the doped nanoparticles show higher activity than undoped titania. The small grain size, high crystallinity, high specific surface area and decrease in the band gap energy of doped titania may be responsible for the high photocatalytic activity.
Oriental Journal of Chemistry, 2017
The present study addresses a tailored preparation method of different structures of TiO 2 nanoparticles over narrow ranges of varying parameters. In this work, titanium-n-butoxide was used to prepare TiO 2 nanoparticles via sol gel method. The influence of the experimental preparation conditions: pH, drying and calcination temperatures were studied at ranges 5-9, 70-110°C, and 450-650 o C, respectively. Slight changes through these mentioned ranges lead to drastically change in the phase transformation, degrees of crystallinity and crystal systems of the prepared TiO 2. Pure anatase and rutile forms as well as different ratios of mixed phases were obtained. X-ray diffraction and transmitting electron microscope TEM techniques were used for the characterization of the prepared samples. The photocatalytic performance of TiO 2 samples were evaluated according to their abilities toward the generation of the highly active hydroxyl radicals. Results indicate that the photocatalytic activities of TiO 2 samples are dependent on their preparation experimental conditions. The maximal photocatalytic activities were noticed at high pH and drying temperature values.