scholarly journals Photocatalytic Liquid-Phase Selective Hydrogenation of 3-Nitrostyrene to 3-vinylaniline of Various Treated-TiO2 Without Use of Reducing Gas

Catalysts ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 329 ◽  
Author(s):  
Okorn Mekasuwandumrong ◽  
Saknarin Chaitaworn ◽  
Joongjai Panpranot ◽  
Piyasan Praserthdam
Keyword(s):  
Selective Hydrogenation ◽  
Consumption Rate ◽  
Rutile Phase ◽  
Optimum Amount ◽  
Electron Hole ◽  
Tio2 Photocatalysts ◽  
Reducing Gas ◽  
Pl Intensity ◽  
Different Gases ◽  
Hole Recombination

In this work, we investigate the effect of TiO2 properties on the photocatalytic selective hydrogenation of 3-nitrostyrene (3-NS) to 3-vinylaniline (3-VA). The P25-TiO2 photocatalysts were calcined at 600–900 °C using different gases (Air, N2, and H2) and characterized by XRD, N2 physisorption, XPS, UV-Vis, and PL spectroscopy. In the photocatalytic hydrogenation of 3-nitrostyrene in isopropanol, the selectivity of 3-vinylaniline of the treated TiO2 was almost 100%. A linear correlation between the 3-NS consumption rate and PL intensity was observed. Among the catalysts studied, P25-700-air, which possessed the lowest PL intensity, exhibited the highest photocatalytic activity due to the synergistic effect that resulted from its high crystallinity and the optimum amount of anatase/rutile phase content, leading to the reduction of the electron-hole recombination process.

Anomalous Temperature dependence of Fermi-edge Singularity in Modulation-doped AlGaAs/InGaAs/GaAs hetero-structures

2005 ◽  
Vol 872 ◽  
Author(s):  
K. Gopalakrishna Naik ◽  
K.S.R.K. Rao ◽  
T. Srinivasan ◽  
R. Muralidharan ◽  
S. K. Mehta
Keyword(s):  
Excitation Power ◽  
Anomalous Behavior ◽  
Electron Hole ◽  
Edge Singularity ◽  
Fermi Edge ◽  
Fermi Edge Singularity ◽  
Pl Intensity ◽  
Dimensional Electron Gas ◽  
Increasing Temperature ◽  
Hole Recombination

AbstractThe temperature and power dependence of Fermi-edge singularity (FES) in high-density two-dimensional electron gas, specific to pseudomorphic AlxGa1-xAs/InyGa1-yAs/GaAs heterostructures is studied by photoluminescence (PL). In all these structures, there are two prominent transitions E11and E21considered to be the result of electron-hole recombination from first and second electron sub-bands with that of first heavy-hole sub-band. FES is observed approximately 5 -10 meV below the E21transition. At 4.2 K, FES appears as a lower energy shoulder to the E21transition. The PL intensity of all the three transitions E11, FES and E21grows linearly with excitation power. However, we observe anomalous behavior of FES with temperature. While PL intensity of E11and E21decrease with increasing temperature, FES transition becomes stronger initially and then quenches-off slowly (till 40K). Though it appears as a distinct peak at about 20 K, its maximum is around 7 - 13 K.

Preparation and Photocatalytic Performance of RGO/TiO2 Photocatalyst

2017 ◽  
Vol 728 ◽  
pp. 359-363
Author(s):  
Voranuch Thongpool ◽  
Akapong Phunpueok
Keyword(s):  
Visible Light ◽  
Photocatalytic Performance ◽  
Photocatalytic Process ◽  
X Ray Diffraction ◽  
Electron Hole ◽  
Tio2 Photocatalysts ◽  
X Ray ◽  
Reduced Graphene ◽  
Uv Visible ◽  
Hole Recombination

In this study, reduced graphene oxide and Titanium dioxide (RGO/TiO2) photocatalysts were synthesized by ultrasonic mixing. The prepared RGO/TiO2 photocatalysts were characterized by scanning electron microscopy, X-ray diffraction spectroscopy and UV-visible spectrophotometry. The performance of the RGO/TiO2 photocatalysts was studied under UV and visible light evaluated by the degradation of the methylene blue (MB). In the photocatalytic process, all the RGO/TiO2 photocatalysts showed better photocatalytic activity than commercial TiO2 nanopowder (P25) under visible light, which showed that RGO could reduce electron-hole recombination on the TiO2, led to the improvement of the photocatalytic performance under visible light

scholarly journals Correlation of fluorescence and photocatalytic activity of Co-doped TiO2

2015 ◽  
Vol 11 (3) ◽  
Author(s):  
Koh Pei Wen ◽  
Leny Yuliati ◽  
Lee Siew Ling
Keyword(s):  
Photocatalytic Activity ◽  
Sol Gel ◽  
Chemical Properties ◽  
Rutile Phase ◽  
Band Gap Energy ◽  
Electron Hole ◽  
Doped Tio2 ◽  
Physical And Chemical ◽  
Hole Recombination ◽  
Co Doped

Co-doped TiO2 (0.5-4 mol%) photocatalysts were synthesized via sol-gel method and their physical and chemical properties were investigated. Addition of Co oxide dopant induced anatase to rutile phase transition and reduced the band gap energy of TiO2. The fluorescence result indicated that the electron-hole recombination rate was reduced with the presence of Co oxide dopant. The best photocatalyst obtained was 3Co-TiO2 which enhanced the photocatalytic activity of TiO2 by 12 folds to 26.6%. The importance of fluorescence properties of Co-doped TiO2 towards its photodegradation of Congo Red was presented.

Optically Detected Magnetic Resonance and Double Beam Photoluminescence of CdS/HgS/CdS Nanoparticles

1998 ◽  
Vol 536 ◽  
Author(s):  
H. Porteanu ◽  
A. Glozman ◽  
E. Lifshitz ◽  
A. Eychmüller ◽  
H. Weller
Keyword(s):  
Optical Properties ◽  
Magnetic Resonance ◽  
Cds Nanoparticles ◽  
Electron Hole ◽  
Cladding Layer ◽  
Double Beam ◽  
Optically Detected Magnetic Resonance ◽  
Optically Detected ◽  
Cladding Layers ◽  
Hole Recombination

AbstractCdS/HgS/CdS nanoparticles consist of a CdS core, epitaxially covered by one or two monolayers of HgS and additional cladding layers of CdS. The present paper describes our efforts to identify the influence of CdS/HgS/CdS interfaces on the localization of the photogenerated carriers deduced from the magneto-optical properties of the materials. These were investigated by the utilization of optically detected magnetic resonance (ODMR) and double-beam photoluminescence spectroscopy. A photoluminescence (PL) spectrum of the studied material, consists of a dominant exciton located at the HgS layer, and additional non-excitonic band, presumably corresponding to the recombination of trapped carriers at the interface. The latter band can be attenuated using an additional red excitation. The ODMR measurements show the existence of two kinds of electron-hole recombination. These electron-hole pairs maybe trapped either at a twin packing of a CdS/HgS interface, or at an edge dislocation of an epitaxial HgS or a CdS cladding layer.

Pre-Industrial Experience in Solar Photocatalytic Mineralization of Real Wastewaters. Application to Pesticide Container Recycling

1999 ◽  
Vol 40 (4-5) ◽  
pp. 123-130 ◽  
Author(s):  
S. Malato ◽  
J. Blanco ◽  
C. Richter ◽  
B. Milow ◽  
M. I. Maldonado
Keyword(s):  
Organic Contaminants ◽  
Toxic Waste ◽  
Experimental Plant ◽  
Electron Hole ◽  
Particulate Suspensions ◽  
Photocatalytic System ◽  
Commercial Pesticide ◽  
Pesticide Container ◽  
By Products ◽  
Hole Recombination

Particulate suspensions of TiO2 irradiated with natural solar tight in a large experimental plant catalyse the oxidation of organic contaminants. The problem in using TiO2 as a photocatalyst is electron/hole recombination. One strategy for inhibiting e−/h+ recombination is to add other (irreversible) electron acceptors to the reaction. In many highly toxic waste waters where degradation of organic pollutants is the major concern, the addition of an inorganic anion to enhance the organic degradation rate may be justified. For better results, these additives should fulfil the following criteria: dissociate into harmless by-products and lead to the formation of ·OH or other oxidising agents. In this paper, we attempt to demonstrate the optimum conditions for the treatment of commercial pesticide rinsates found in the wastewater produced by a pesticide container recycling plant. The experiments were performed in one of the pilot plants of the largest solar photocatalytic system in Europe, the Detoxification Plants of the Plataforma Solar de Almería (PSA), in Spain. After testing ten different commercial pesticides, results show that peroxydisulphate enhances the photocatalytic miniralization of all of them. This study is part of an extensive project focused on the design of a solar photocatalytic plant for decontamination of agricultural rinsates in Almería (Spain).

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