Search results for "PHOTOCATALYSIS"
showing 10 items of 606 documents
Reversible oxidation of WOx and MoOx nano phases
2012
International audience; WOx and MoOx nano phases were prepared on TiO2(1 1 0) surfaces by a CVD procedure consisting of adsorption and decomposition of W(CO)(6) or Mo(CO)(6) precursors followed by annealing under UHV. Metal amount involved in each elaborated sample is in the fractional range from 0.1 to 0.35 equivalent monolayer (eqML) of W or Mo. Evolution of sample stoichiometry as a function of subsequent treatment is followed by valence band and core level photoemission as well as work function measurement. In each case, exposure of samples to molecular oxygen at room temperature induces an increase of sample work function in a range of several tenth of eV. Such a work function change i…
Photocatalytic printing of inorganic nanopatterns via poly(styrene-block-carbosilane) copolymer thin films on titania substrates.
2009
Well-defined, ordered arrays of nanoscale depressions were obtained in linear-brush-type polystyrene-block-polycarbosilane (PS-b-PCS) diblock copolymer thin films by acetone vapor annealing and silica nanodot arrays were directly obtained from such thin films deposited on a titania substrate by one-step exposure to UV light as a result of transformation of the PCS units to silica, driven by the photocatalytic activity of titania concurrent with removal of the organic matrix.
Studies on various reactor configurations for coupling photocatalysis and membrane processes in water purification
2002
General aspects and perspectives of heterogeneous photocatalysis for the treatment of polluted aqueous effluents are presented. Some experimental results obtained by using various configurations of photocatalytic membrane reactors (PMRs) are reported. The configurations studied were: (i) irradiation of the cell containing the membrane, with three sub-cases: (i1) catalyst deposited on the membrane; (i2) catalyst in suspension, confined by means of the membrane; (i3) entrapment of the photocatalyst in a PSF membrane; (ii) irradiation of the re-circulation tank and catalyst in suspension confined by means of the membrane. In the case “(i)”, a preliminary investigation of membrane stability und…
Development of photocatalytically active heterostructured MnO/ZnO and CuO/ZnO films via solution precursor plasma spray process
2019
Abstract Heterostructured ZnO photocatalysts for the degradation of organic pollutant are mainly synthesized by conventional chemical methods, suffering from long duration, multi-steps, and post-treatment of the powder-formed catalysts after usage. In this paper, Solution Precursor Plasma Spray (SPPS) process is demonstrated to be a fast and efficient method for the one-step preparation of MnO/ZnO and CuO/ZnO heterostructured films for photocatalytic applications. The ratios between MnO or CuO and ZnO materials in the films were easily adjusted by varying the molar ratio of Mn(OAc)2 or Cu(OAc)2 relative to Zn(OAc)2 during the SPPS synthesis. To optimize the microstructure of selected CuO/Zn…
Sol-gel auto-combustion synthesis of Ca2Fe2O5 brownmillerite nanopowders and thin films for advanced oxidation photoelectrochemical water treatment i…
2019
Abstract This study describes a straightforward Ca2Fe2O5 brownmillerite nanopowder and thin film synthesis by the water-based sol-gel auto-combustion method. The material characterization results confirmed the phase pure narrow bandgap Ca2Fe2O5 nanoparticle formation. The surface area of synthesized nanopowder was 13.55 m2/g. Powders at loading 1 g/l exhibit high visible light photocatalytic activity by degrading 10 mg/l methylene blue in water in 120 min confirmed by total organic carbon studies. The high visible light photocatalytic activity is related to Ca2Fe2O5 narrow band gap and high reduction potential of its conduction band which triggers the formation of superoxide radical ∙ O 2 -…
Brookite, the Least Known TiO2 Photocatalyst
2013
Brookite is the least studied TiO2 photocatalyst due to the difficulties usually encountered in order to obtain it as a pure phase. In this review, a comprehensive survey of the different methods available for preparing brookite powders and films is reported. Attention has been paid both to the most traditional methods, such as hydrothermal processes at high temperatures and pressures, and to environmentally benign syntheses using water soluble compounds and water as the solvent. Papers reporting the photocatalytic activity of pure and brookite-based samples have been reviewed.
An Investigation into the Stability of Graphitic C 3 N 4 as a Photocatalyst for CO 2 Reduction
2018
The increasing CO 2 concentration in the atmosphere exerts a significant influence on global warming and climate change. The capture and utilization of CO 2 by conversion to useful products is an area of active research. In this work, the photodriven reduction of CO 2 was investigated using graphitic carbon nitride (g-C 3 N 4 ) as a potential photocatalyst. The photocatalytic reduction of CO 2 was investigated with g-C 3 N 4 powder immobilized on a glass support in a batch gas-phase photoreactor. The experiments were carried out under UV-vis irradiation at 70 °C and an initial pressure of 2.5 bar. The only gas-phase product detected during the irradiation of the g-C 3 N 4 in the presence of…
Polymeric carbon nitride (C3N4) as heterogeneous photocatalyst for selective oxidation of alcohols to aldehydes
2018
Abstract Polymeric carbon nitride (C3N4) is a semiconductor material which is a very promising green photocatalyst with good physico-chemical properties and stability. It is a metal-free carbon based non-toxic material which can be easily obtained from earth-abundant components. The robustness and versatility of C3N4 as a photo-redox catalyst allows its use for selective oxidations by heterogeneous photocatalysis. This paper reviews the state of art in the application of C3N4 as heterogeneous photocatalyst for selective oxidation of alcohols to the corresponding aldehydes.
Cathodoluminescence characterization of ZnO/ZnS nanostructures anodized under hydrodynamic conditions
2018
[EN] ZnO/ZnS nanostructures were successfully synthesized by a simple electrochemical anodization of zinc in a glycerol based electrolyte containing sulfide-ammonium fluoride. The influence of different hydrodynamic conditions and anodization potentials during anodization on the morphological and electronic properties of the obtained ZnO/ZnS nanostructures was studied. The anodized samples were characterized using confocal Raman microscopy, X-Ray Diffraction (XRD), Field Emission Scanning Electronic Microscopy (FE-SEM), cathodoluminescence (CL), and photoelectrochemical water splitting tests under standard AM 1.5 conditions. The results showed that hydrodynamic conditions and higher potenti…
Junction Effect on the Photocatalytic Activity of Mixed-Phase TiO2 Nanoparticles
2010
Active TiO2 photocatalysts were prepared under mild experimental conditions by thermohydrolysis of TiCl4 in pure water at 100 {degree sign}C. The preparation method is very simple and does not require the use of expensive thermal or hydrothermal treatments. Depending on the TiCl4/H2O ratio, pure rutile, binary mixtures of anatase and rutile or anatase and brookite, or ternary mixtures of anatase, brookite and rutile, can be obtained. 4-nitrophenol photodegradation was used to evaluate the photoactivity of the various powders. The high photocatalytic activity of the mixed samples was explained by the presence of junctions among different polymorphic TiO2 phases that allows an improved charge…