Search results for "Catalysis"
showing 10 items of 5944 documents
BN/GdxTi(1-x)O(4-x)/2 nanofibers for enhanced photocatalytic hydrogen production under visible light
2019
Abstract BN/GdxTi(1-x)O(4-x)/2 nanofibers were elaborated via electrospinning technique. The properties of the prepared nanofibers were controlled using different ratios of gadolinium. All the prepared nanofibers exhibit the tetragonal structure of anatase TiO2 phase. An increase in the unit cell volume and a decrease in the crystallite size were observed with increasing the doping amount of Gd3+ as revealed by Rietveld refinement analysis. The defect in TiO2 lattice was observed by Raman. The Gd3+ incorporation inside TiO2 lattice, which is accompanied by the creation of Ti-O-Gd bond, was characterized by the X-ray photoelectron spectra. Scanning electron microscopy demonstrates that the a…
Preparation and photoactivity of samarium loaded anatase, brookite and rutile catalysts
2011
Abstract Pure and samarium loaded anatase, brookite and rutile nanopowders were synthesized by thermohydrolysis of TiCl 4 . The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), specific surface area (SSA) determination, UV–vis diffuse reflectance spectroscopy (DRS), atomic force microscopy (AFM), contact angle (CA) measurements and photoluminescence (PL) spectroscopy. The photocatalytic activity of pure and Sm-loaded TiO 2 polymorphs was investigated by employing the photodegradation of 4-nitrophenol as probe reaction in a liquid-solid system. Loading with Sm resulted in an improvement of the photoreactivity of the three TiO 2 polymorphs. The benefi…
Photocatalytic Degradation of 4-nitrophenol in aqueous suspension by using polycristalline TiO2 samples impregnated with a Cu(II)-phthalocyanine
2002
In this paper, the preparation of polycrystalline TiO2 samples impregnated with a modified Cu(II)-phthalocyanine (TiO2–CuPc) is reported along with an investigation on the photocatalytic behavior of this system compared with bare TiO2 (both in the anatase and rutile form) and with TiO2 samples impregnated with not functionalized commercial phthalocyanine (TiO2–CuPc) or with metal free phthalocyanine (TiO2–Pc). The photocatalytic degradation of 4-nitrophenol (4-NP) was studied as a probe reaction. The presence of modified CuPc showed to be beneficial only for TiO2 (anatase) while the commercial not functionalized CuPc also slightly for both TiO2 (anatase) and TiO2 (rutile). The metal free Pc…
Nanostructured Solids from Freeze-Dried Precursors: Multigram Scale Synthesis of TiO2 -Based Powders
2012
Nanocrystalline TiO2 and Ti1−xVxO2 (x = 0.01) powders have been prepared by thermal decomposition, in air, of amorphous precursors resulting from the freeze-drying of appropriate solutions. In addition, TiO2−xNy (anatase and rutile) and TiOxNy (rock-salt) have been prepared by thermal treatment in ammonia of a crystalline precursor (TiO2 obtained at 673 K). TEM and SEM images, as well as the analysis of the X-ray diffraction (XRD) patterns, show the nanoparticulated character of those solids obtained at low temperatures, with typical particle sizes in the 10–20 nm range when prepared at 673 K. The UV–Vis results indicate both the insertion of V in the anatase lattice and the feasibility of …
Hydrothermal synthesis of well-dispersed ultrafine N-doped TiO2 nanoparticles with enhanced photocatalytic activity under visible light
2010
Abstract Ultrafine nitrogen-doped TiO 2 nanoparticles with narrow particle size distribution, good dispersion, and high surface area were synthesized in the presence of urea and PEG-4000 via a hydrothermal procedure. TEM observation, N 2 adsorption, XRD, UV–vis spectroscopy, the Raman spectroscopy and XPS analysis were conducted to characterize the synthesized TiO 2 particles. The synthesized TiO 2 particles were a mixture of 49.5% anatase and 50.5% rutile with a size of around 5 nm. The photocatalytic activities were tested in the degradation of an aqueous solution of a reactive Brilliant Blue KN-R under both UV and visible light. The synthesized TiO 2 particles showed much higher photocat…
Effect of Reynolds number on TiO2 nanosponges doped with Li+ cations
2018
[EN] Anatase TiO2 nanosponges have been synthesized by anodization of Ti, and Li+ cations have been inserted in these nanostructures. The influence of hydrodynamic conditions (Reynolds number, Re = 0 to Re = 600) during anodization has been studied. Li-Doped TiO2 nanosponges were characterized by field emission scanning electron microscopy (FE-SEM), Raman confocal microscopy, electrochemical impedance spectroscopy (EIS) and Mott¿Schottky analysis (M¿S). The photoelectrochemical performance and resistance to photocorrosion were also measured. Li¿TiO2 nanosponges proved to be better photocatalysts for water splitting than Li¿TiO2 nanotubes. Moreover, the photoelectrochemical behavior of the L…
TiO2 nanostructures prepared by ferrocene/cobalt catalyst agents
2008
We present the growth and characterization of TiO2 nanocrystals. Nanostructured growth is obtained in a low-pressure CVD system by using an organometallic precursor Ti(OC3H7)4 as both the Ti and O source catalyzed by both ferrocene (an organometallic precursor) and cobalt metallic clusters prepared by the microwave-assisted polyol method. Two kinds of TiO2 structures were obtained in the cobalt clusters: a) pine-tree like (with short-leaf structure) and b) long-leaf structures as large as a few micrometers in size and both under 10 nm in thickness. Long-leaf TiO2 structures were grown at cobalt grain boundaries. For the growth conditions utilized, the TiO2 structures are composed of both an…
Partial photoelectrocatalytic oxidation of 3-pyridinemethanol by Pt, Au and Pd loaded TiO2 nanotubes on Ti plate
2021
Abstract The photoelectrocatalytic (PEC) oxidation of 3-pyridinemethanol to 3-pyridinemethanal and vitamin B3 was investigated by using Pt, Au and Pd loaded (as single or bimetallic) nanotube structured TiO2 on Ti plate in water under UVA irradiation. Nanotube structured TiO2 on Ti plate samples were prepared as anode by anodic oxidation method in ethylene glycol solution in different times, and then they were calcined at 500 °C to be obtained in crystalline form. The anodes were loaded with noble metals by electrochemical reduction method and characterized by XRD, XPS, SEM, and photocurrent techniques. The TiO2 on the plates was in the anatase phase. The loaded metals were in metallic form…
Ab initiomodeling of sulphur doped TiO2nanotubular photocatalyst for water-splitting hydrogen generation
2012
In order to construct an efficient visible-light-driven TiO2 photocatalyst for water splitting applications, one has to perform improvements of its electronic structure. In this theoretical study we consider single-walled anatase TiO2 nanotubes having following morphologies: (101) 3-layered wall with chirality indexes (n,0) and (n,n), (101) 6-layered wall with (n,0) and (0,n), (001) 6-layered wall with (n,0) and (0,n), and (001) 9-layered wall with (n,0) and (0,n). The latter configuration occurs to be the most energetically stable, due to possessing negative strain energy. In our study the most stable 9-layered anatase (001) (0,n) nanotube has been doped with sulphur. According to obtained…
Influence of pH on the degradation kinetics of nitrophenol isomers in a heterogeneous photocatalytic system
1993
Abstract The kinetics of photocatalytic degradation of 2-, 3- and 4-nitrophenol in aqueousdispersions containing TiO2 (anatase) has been investigated at different initial values of pH and concentrations of substrate. A pseudo-first order kinetics with respect to the nitrophenol concentration was found to hold; an increase of the substrate concentration and the initial pH was detrimental on the degradation rate.