Search results for "PHOTOCHEMISTRY"
showing 10 items of 2034 documents
TiO2/ORMOSIL Thin Films Doped with Phthalocyanine Dyes: New Photocatalytic Devices Activated by Solar Light
2008
WOS: 000253222200065
Self-organization of porphyrin units induced by magnetic field during sol-gel polymerization
2007
The use of a magnetic field as a controlling factor during the hydrolysis-polycondensation of porphyrin precursors substituted by Si(OR)(3) groups, induces a self-organization of porphyrin moieties due to the stacking of these units in the hybrid material and this study also confirms the effect of the magnetic field in the nano- and micrometric organization during the kinetically controlled polycondensation process.
A novel 2D coordination network built from hexacopper(i)-iodide clusters and cagelike aminophosphine blocks for reversible “turn-on” sensing of anili…
2018
A new copper(I) coordination polymer [Cu6(μ3-I)6(μ3-PTAO)2]n (1) was prepared from copper(I) iodide and 1,3,5-triaza-7-phosphaadamantane-7-oxide (PTAO). The crystal structure of 1 reveals an intricate 2D coordination network constructed from the hexacopper(I)-iodide [Cu6(μ3-I)6] cluster units with the 4M6-1 topology interlinked by the μ3-PTAO spacers. An overall 2D layer network can be simplified to a binodal 3,6-connected net with the kgd topology. A derived 1@paper material was prepared by impregnating compound 1 onto a filter paper. Detailed investigation of the luminescence properties for 1 and 1@paper in the solid state revealed a remarkable ability of both materials to sense aniline m…
Heterogeneous photo-assisted catalytic hydration/dehydration reactions based on Keggin and Wells-Dawson type heteropolytungstates
2021
Polyoxometalates (POMs) are a wide class of metal-oxygen clusters that can be applied in acid and oxidation catalysis, medicine, electrochemistry, materials design, or models for self-assembling nanoscale systems as long as green and cheap photocatalysts. Heteropolyacids (HPAs) are a POM subclass extensively used as homogeneous photocatalysts for the oxidation of organic substrates. Dispersing HPAs onto solid supports with a high surface area increases their specific surface area and hence (photo)catalytic activity. This chapter reports the use of selected HPAs, heteropolytungstates, immobilized on different supports as heterogeneous photocatalysts.
Electron transfer in ZnO–Fe2O3 aqueous slurry systems and its effects on visible light photocatalytic activity
2017
ZnFex (x = 0.025, 0.05, and 0.1) nanocomposites and pure ZnO and Fe2O3 photocatalysts were synthesized by a simple sol–gel route and characterized by means of specific surface area (SSA) analysis, X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), and transmission electron microscopy/energy dispersive X-ray spectroscopy (TEM/EDS). Their photocatalytic activity was investigated under visible light by using methylene blue (MB) and benzoic acid (BA) as model compounds. Coupling ZnO and Fe2O3 results in higher photocatalytic activity with respect to the pure materials. Photoelectrochemical characterization performed in slurry systems allowed the elucidation of the electronic struc…
Electrochemical and Spectroelectrochemical Behavior of a Tetracyanotriphenodioxazine in Solution and Thin-Films
2018
International audience; We report the electrochemical behavior of a tetracyano triphenodioxazine bearing two triisopropylsilylethynyl moieties (TiPS‐TPDO‐tetraCN) during its reduction studied either in solution or after vacuum evaporation deposition on indium tin oxide (ITO) support. While in dichloromethane, it typically proceeds in two successive monoelectronic reactions, in acetonitrile, the mechanism appears more complex. Fine analysis of the spectroelectrochemical results combined with simulation of the voltammograms with various amount of water suggest the involvement of water and of a restructured dianion in the electrochemical process. In the solid‐state, the formation of the diprot…
Strong, Rapid and Reversible Photochromic Response of Nb doped TiO2 Nanocrystal Colloids in Hole Scavenging Media
2020
Understanding photochromicity is essential for developing new means of modulating the optical properties and optical response of materials. Here, we report on the synthesis and exciting new photochromic behavior of Nb5+ doped TiO2 nanoparticle colloids (NCs). We find that in hole scavenging media, Nb5+ doping significantly improves the photochromic response time of TiO2 nanoparticles. In the infrared regime, Nb-doped TiO2 NCs exhibit an order of magnitude faster photoresponse kinetics than the pristine TiO2. Enhanced photochromic response is observed in the visible light regime as well. The transmittance of Nb-doped TiO2 NCs drops to 10% in less than 2 minutes when irradiated by UV light in…
Double D–π–A branched dyes – a new class of metal-free organic dyes for efficient dye-sensitized solar cells
2017
Double branched donor acceptor compounds (D–π–A)2L, whose separate branches are linked by saturated chains or ring systems, are highly promising sensitizers for dye-sensitized solar cells (DSSCs). Their photovoltaic performance η (power conversion efficiency PCE) is higher than the η value of the corresponding single branched sensitizers D–π–A. This advantage can be attributed to the lower aggregation tendency and to the higher loading density of the chromophores on the semi-conductor surface (TiO2). Moreover, the intramolecular transfer of the excitation energy can enhance the contact time of the adsorbed dye molecules in the excited state S1 and thus reduce the unwanted charge recombinati…
Photoinduced Electron Transfer Reactions in a Porphyrin−Viologen Complex: Observation of S2 to S1 Relaxation and Electron Transfer from the S2 State
1999
Photoinduced Energy Transfer Reactions in a Porphyrin-Viologen Complex: Observation of S2 to S1 Relaxation and Electron Transfer from the S2 state
Photophysics and photochemistry with Earth-abundant metals - fundamentals and concepts.
2020
Recent exciting developments in the area of mononuclear photoactive complexes with Earth-abundant metal ions (Cu, Zr, Fe, Cr) for potential eco-friendly applications in (phosphorescent) organic light emitting diodes, in imaging and sensing systems, in dye-sensitized solar cells and as photocatalysts are presented. Challenges, in particular the extension of excited state lifetimes, and recent conceptual breakthroughs in substituting precious and rare-Earth metal ions (e.g. Ru, Ir, Pt, Au, Eu) in these applications by abundant ions are outlined with selected examples. Relevant fundamentals of photophysics and photochemistry are discussed first, followed by conceptual and instructive case stud…