Search results for "I.2"
showing 10 items of 662 documents
TiO2/ORMOSIL Thin Films Doped with Phthalocyanine Dyes: New Photocatalytic Devices Activated by Solar Light
2008
WOS: 000253222200065
Preparation of Sm-loaded brookite TiO2 photocatalysts
2011
Abstract Pure and Sm-loaded brookite nanoparticles and thin films were prepared using TiCl4 as precursor of TiO2. The samples were characterized by X-ray diffraction (XRD), specific surface area (SSA) determination, diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) measurements. The photocatalytic activity of the powders was investigated by employing the photodegradation of 4-nitrophenol in a liquid–solid system whilst the photoreactivity of the films was tested by evaluating the rate of degradation of 2-propanol in a gas–solid system. Loading with Sm resulted in a significant improvement of the photoreactivity of brookite and the beneficial effect was attributed to an incre…
Photoactivity under visible light of metal loaded TiO2 catalysts prepared by low frequency ultrasound treatment
2017
Abstract Visible-light responsive bare and metal loaded (Pt, Ag, Rh, Pd) TiO 2 photocatalysts were prepared by using a simple ultrasound treatment. This method induced bulk oxygen deficiency resulting in a narrowing bandgap (from 3.18 to 3.04 eV) and in visible light absorption. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), BET specific surface area (SSA) and pore size distribution (PSD), UV–vis diffuse reflectance spectroscopy (DRS), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity of the samples was evaluated by using the 4-nitrophenol oxidation reaction and the photocatalytic oxidation of glucose w…
Enhanced Solar Light Photocatalytic Activity of Ag Doped TiO2–Ag3PO4 Composites
2020
Composites comprised of Ag3PO4 and bare TiO2 (TiO2@Ag3PO4) or silver doped TiO2 (Ag@TiO2&ndash
Doped TiO2 Nanomaterials and Applications
2008
This special issue brieflyreviews some trends and factors that have impacted heterogeneous photocatalysis with next generation TiO2 nanophotocatalysts that could absorband make use of both UV (290–400 nm) and visible (400–700 nm) sunlight to enhance process efficiencies, along with some issues of current debate in the fundamental understanding of the science that underpins the field. Preparative methods and some characteristics features of doped TiO2 as well as its environmental applications are presented and described. The next generation of doped TiO2 photocatalysts should enhance overall process photoefficiencies in many cases, since doped TiO2s absorb a greater quantity of solar radiati…
Heterogeneous photocatalytic materials for sustainable formation of high-value chemicals in green solvents
2021
Abstract The most investigated materials used as heterogeneous photocatalysts for the formation of high-value chemicals under mild experimental conditions are presented in this survey. Only papers reporting reactions carried out in harmless solvents such as water, the green solvent par excellence, are reported. Metal oxides have been used often, but carbon-based materials such as carbon nitride and graphene, metal nanoparticles, sulphides and selenides also have received a great attention mainly due to their good performances both in partial oxidations and reductions. The results presented indicate that an appropriate choice of the photocatalytic material is the main problem to be faced to …
Effect of oxygen deficiency on the radiation sensitivity of sol-gel Ge-doped amorphous SiO2
2008
We report experimental investigation by electron paramagnetic resonance (EPR) measurements of room temperature γ-ray irradiation effects in sol-gel Ge doped amorphous SiO2. We used materials with Ge content from 10 up to 104 part per million (ppm) mol obtained with different preparations. These latter gave rise to samples characterized by different extents of oxygen deficiency, estimated from the absorption band at ~5.15 eV of the Ge oxygen deficient centers (GeODC(II)). The irradiation at doses up to ~400 kGy induces the E'-Ge, Ge(1) and Ge(2) paramagnetic centers around g ~ 2 with concentrations depending on Ge and on GeODC(II) content. We found correlation between Ge(2) and GeODC(II) con…
Near-Infrared Emission of O2 Embedded in Amorphous SiO2 Nanoparticles
2011
We report an experimental study on the emission properties of O2 molecules loaded by a thermal diffusion process at 200 °C into high-purity silica nanoparticles with mean diameters of 7 and 40 nm. The embedded O 2 features a singlet to triplet emission band peaked at 1272 nm in agreement with the band observed for bulk silica materials. The photoluminescence excitation spectra have been determined in the visible and in the infrared range and are characterized by narrow bands peaked at 691, 764, and 1069 nm, respectively. By comparison of the transition energies, the vibrational quanta have been determined for the ground and for both the excited states; the values found are lower than the co…
Charge Transport Layers Limiting the Efficiency of Perovskite Solar Cells: How To Optimize Conductivity, Doping, and Thickness
2019
Perovskite solar cells (PSCs) are one of the main research topics of the photovoltaic community; with efficiencies now reaching up to 24%, PSCs are on the way to catching up with classical inorganic solar cells. However, PSCs have not yet reached their full potential. In fact, their efficiency is still limited by nonradiative recombination, mainly via trap-states and by losses due to the poor transport properties of the commonly used transport layers (TLs). Indeed, state-of-the-art TLs (especially if organic) suffer from rather low mobilities, typically within 10(-5) and 10(-2) cm(-2) V-1 s(-1), when compared to the high mobilities, 1-10 cm(-2) V-1 s(-1), measured for perovskites. This work…
Photoelectrochemical characterization of Cu2O-nanowire arrays electrodeposited into anodic alumina membranes
2007
Perfectly aligned nanowire arrays of polycrystalline Cu2O were grown by template-pulsed electrodeposition from a cupric acetate-sodium acetate bath into anodic alumina membranes (AAM). The photoelectrochemical behavior of arrays with different nanowire lengths (0.5 mu m and 2 mu m) was investigated in neutral solution, and the results compared to those pertaining to Cu2O films grown with the same procedure. Although all samples displayed the same indirect bandgap (similar to 1.9 eV), differences were observed both in photocurrent intensity and sign. The latter changed with potential and wavelength in different ways for nanowires and films, revealing a different defect concentration in the t…