scholarly journals Carbon modified TiO2 photocatalysts for water purification

2009 ◽  
Vol 11 (2) ◽  
pp. 46-50 ◽  
Author(s):  
Antoni Morawski ◽  
Magdalena Janus ◽  
Beata Tryba ◽  
Masahiro Toyoda ◽  
Tomoki Tsumura ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Water Purification ◽  
Visible Region ◽  
Carbon Layer ◽  
Photocatalytic Decomposition ◽  
Visible Range ◽  
Tio2 Photocatalysts ◽  
Carbon Doped ◽  
Carbon Coated

Carbon modified TiO2 photocatalysts for water purification Carbon can form different structures with TiO2: carbon-doped TiO2, carbon coated TiO2 and composites of TiO2 and carbon. The presence of carbon layer on the surface of TiO2 as well as the presence of porous carbon in the composites with TiO2 can increase the concentration of organic pollutants on the surface of TiO2, facilitating the contact of the reactive species with the organic molecules. Carbon-doped TiO2 can extend the absorption of the light to the visible region by the narrowing of the band gap and makes the photocatalysts active under visible light irradiation. TiO2 loaded carbon can also work as a photocatalyst, on which the molecules are adsorbed in the pores of carbon and then they undergo the photocatalytic decomposition with UV irradiation. Enhanced photocatalytic activity for the destruction of some organic compounds in water was noticed on the carbon coated TiO2 and TiO2 loaded activated carbon, mostly because of the adsorptive role of carbon. However, in carbon-doped TiO2, the role of carbon is somewhat different, the replacement of carbon atom with Ti or oxygen and formation of oxygen vacancies are responsible for extending its photocatalytic activity towards the visible range.

scholarly journals Increase of the Photocatalytic Activity of by Carbon and Iron Modifications

2008 ◽  
Vol 2008 ◽  
pp. 1-15 ◽  
Author(s):  
Beata Tryba
Keyword(s):  
Photocatalytic Activity ◽  
Organic Compounds ◽  
Visible Light Irradiation ◽  
Organic Molecules ◽  
Visible Region ◽  
Photocatalytic Decomposition ◽  
Oh Radicals ◽  
Carbon Doped ◽  
Free Carriers ◽  
Hole Scavenger

Modification of by doping of a residue carbon and iron can give enhanced photoactivity of . Iron adsorbed on the surface of can be an electron or hole scavenger and results in the improvement of the separation of free carriers. The presence of carbon can increase the concentration of organic pollutants on the surface of facilitating the contact of the reactive species with the organic molecules. Carbon-doped can extend the absorption of the light to the visible region and makes the photocatalysts active under visible-light irradiation. It was proved that modified by carbon and iron can work in both photocatalysis and photo-Fenton processes, when is used, enhancing markedly the rate of the organic compounds decomposition such as phenol, humic acids and dyes. The photocatalytic decomposition of organic compounds on modified by iron and carbon is going by the complex reactions of iron with the intermediates, what significantly accelerate the process of their decomposition. The presence of carbon in such photocatalyst retards the inconvenient reaction of OH radicals scavenging by , which occurs when Fe- photocatalyst is used.

Carbon-Coated TiO2 - Hybridization between Photoactivity and Adsorptivity

2006 ◽  
Vol 46 ◽  
pp. 180-187 ◽  
Author(s):  
Masahiro Toyoda ◽  
Beata Tryba ◽  
Fumi Koujin ◽  
Tomoki Tsumura ◽  
Michio Inagaki
Keyword(s):  
Surface Area ◽  
Rate Constant ◽  
Carbon Layer ◽  
Bet Surface Area ◽  
Tio2 Photocatalysts ◽  
Carbon Coated ◽  
Water Rate ◽  
Coated Carbon ◽  
Tio2 Phase

Carbon-coated TiO2 photocatalysts were prepared by a simple heat treatment of the powder mixtures of anatase-type TiO2 with PVA at a temperature of 700 and 900 oC in a N2 atomosphere. Diffuse optical reflectance spectra for carbon-coated TiO2 showed the absorption edge for anatase structure clearly, overlapping with absorption due to coated carbon over whole range of wavelegth. These carbon-coated TiO2 photocatalysts had relatively high apparent BET surface area, from 50 to 170 m2/g, which suggested the formation of porous carbon layers, and showed relatively high adsorption of various pollutants, methylene blue (MB), reactive black (RB-5), phenol (Ph) and iminoctadine triacetate (IT), in water. Photocatalytic activity of carbon-coated TiO2 thus prepared was evaluated through the determination of the rate constant for the decomposition of different pollutants in water. Rate constant values were strongly depend on the pollutants, but their dependence on the crystallinity of TiO2 phase. The relations between adsorptivity and rate constant for four pollutants looked similar with each other, and the pollutants adsorbed in the larger amount was decomposed with the higher rate. Adsorptivity of carbon-coated TiO2 photocatlysts was determined and discussed on the relations to BET surface area, amount of carbon coated and also rate constant k for the decomposition of MB, RB5, Ph and IT. Adsorptivity of carbon-coated catalysts depends strongly on the adsorbate (pollutant) but also on the surface nature of carbon layer on TiO2 particles. The relations between adsorptivity and rate constant k for four pollutants looked similar, suggesting that the pollutant adsorbed in the larger amount being decomposed with the higher rate.

Carbon-coated anatase: the role of the carbon layer for photocatalytic performance

Carbon ◽  
2005 ◽  
Vol 43 (8) ◽  
pp. 1652-1659 ◽  
Author(s):  
Michio Inagaki ◽  
Fumi Kojin ◽  
Beata Tryba ◽  
Masahiro Toyoda
Keyword(s):  
Photocatalytic Performance ◽  
Carbon Layer ◽  
Carbon Coated

Carbon Coated N-Doping of TiO2 Nanotube Films with Enhanced Visible-Light Photocatalytic Activity

2012 ◽  
Vol 512-515 ◽  
pp. 1564-1567 ◽  
Author(s):  
Fang Zhou Jia ◽  
Zhong Ping Yao ◽  
Zhao Hua Jiang
Keyword(s):  
Raman Spectroscopy ◽  
Photocatalytic Activity ◽  
Visible Light ◽  
Visible Region ◽  
Step Process ◽  
Graphitized Carbon ◽  
N Doping ◽  
Carbon Coated ◽  
Visible Light Photocatalytic ◽  
Nanotube Films

Carbon coated N-doping of TiO2 nanotube films were successfully prepared by a two-step process of anodization and gas thermal penetration. The morphologies and structures of composites were characterized by SEM, XRD, XPS and Raman spectroscopy analyses, respectively. The results show that graphitized carbon deposited on the surface of TiO2NTs nanotubes under gas thermal penetration conditions, by which N atoms are incorporated into the lattice of TiO2NTs through substituting the site of oxygen atoms. Such Carbon coated N-doping of TiO2 nanotube films presents the enhance absorption in visible region. The photo catalytic tests show that the prepared films at 600°C reveal higher photocatalytic activity for splitting of water than other samples.

scholarly journals MoS2/Cu/TiO2 nanoparticles: synthesis, characterization and effect on photocatalytic decomposition of methylene blue in water under visible light

2018 ◽  
Vol 2017 (1) ◽  
pp. 184-193 ◽  
Author(s):  
Desireé M. de los Santos ◽  
Sara Chahid ◽  
Rodrigo Alcántara ◽  
Javier Navas ◽  
Teresa Aguilar ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Photocatalytic Activity ◽  
Visible Light ◽  
Tio2 Nanoparticles ◽  
Visible Region ◽  
Pure Tio2 ◽  
Photocatalytic Decomposition ◽  
Tio2 Sample ◽  
X Ray ◽  
Vis Spectroscopy

Abstract Photodegradation processes are of great interest in a range of applications, one of which is the photodecomposition of pollutants. For this reason, analysing nanoparticles that improve the efficiency of these processes under solar radiation are very necessary. Thus, in this study, TiO2 was doped with Mo and Cu using low-temperature hydrolysis as the method of synthesis. Pure TiO2 and x%MoS2/Cu/TiO2 nanoparticles were prepared, where x is the theoretical quantity of MoS2 added (0.0%, 1.0%, 5.5%, 10.0%), setting the nominal quantity of Cu at 0.5 wt.%. The samples obtained were characterized by X-ray diffraction, Raman spectroscopy, X-ray electron spectroscopy and UV-Vis spectroscopy in diffuse reflectance mode. The results suggest that the TiO2 structure was doped with the Mo6+ and Cu2+ ions in the position of the Ti4+. The x%MoS2/Cu/TiO2 samples presented lower band gap energy values and greater optical absorption in the visible region than the pure TiO2 sample. Lastly, the photocatalytic activity of the samples was assessed by means of the photodegradation of methylene blue under visible light. The results show that when the quantity of Mo in the co-doped samples increased (x%MoS2/Cu/TiO2) there were significant increases of up to 93% in the photocatalytic activity.

scholarly journals The Role of Fluorine in F-La/TiO2 Photocatalysts on Photocatalytic Decomposition of Methanol-Water Solution

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 2867 ◽  
Author(s):  
Miroslava Edelmannová ◽  
Lada Dubnová ◽  
Martin Reli ◽  
Vendula Meinhardová ◽  
Pengwei Huo ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Diffuse Reflectance Spectroscopy ◽  
Water Solution ◽  
Pure Tio2 ◽  
Photocatalytic Decomposition ◽  
Tio2 Photocatalysts ◽  
X Ray ◽  
Optical And Electronic Properties ◽  
Production Of Hydrogen

F-La/TiO2 photocatalysts were studied in photocatalytic decomposition water-methanol solution. The structural, textural, optical, and electronic properties of F-La/TiO2 photocatalysts were studied by combination of X-ray powder diffraction (XRD), nitrogen physisorption, Ultraviolet–visible diffuse reflectance spectroscopy (UV-Vis DRS), Electrochemical impedance spectroscopy (EIS), and X-ray fluorescence (XPS). The production of hydrogen in the presence of 2.8F-La/TiO2 was nearly up to 3 times higher than in the presence of pure TiO2. The photocatalytic performance of F-La/TiO2 increased with increasing photocurrent response and conductivity originating from the higher amount of fluorine presented in the lattice of TiO2.

Nano Gold Doped Nano TiO2 – An Efficient Solar Photocatalyst for the Degradation of Persistent Organic Pollutants

2014 ◽  
Vol 938 ◽  
pp. 292-296 ◽  
Author(s):  
Jesty Thomas ◽  
K.R. Chitra
Keyword(s):  
Gold Nanoparticles ◽  
Photocatalytic Activity ◽  
Organic Pollutants ◽  
Chemical Reduction ◽  
Organic Pollutant ◽  
Visible Region ◽  
Titania Nanoparticles ◽  
Visible Range ◽  
Hydrothermal Route ◽  
Nano Gold

Novel nanogold doped TiO2nanoparticles are found to be highly efficient for the photocatalytic degradation of organic pollutants. TiO2nanoparticles were synthesized from titanium (IV) isopropoxide through hydrothermal route. Gold nanoparticles were prepared by chemical reduction and stabilization employing D-glucosamine, and were doped in TiO2nanoparticles. The analysis revealed that the diameter of gold nanoparticles used for doping is around 5 nm. Undoped and gold doped samples were characterized by X-ray diffraction (XRD), Raman spectroscopy, UV-Vis diffuse reflectance spectra (DRS) and field emission scanning electron microscopy (SEM). DRS study showed that nanogold doping in titania nanoparticles induces a shift of absorption edge to the visible range and reduces the band gap. Complementing our earlier finding that noble metal doping in titania nanoparticles enable photocatalytic activity in the visible region, it is showed that gold doping enhances photocatalytic activity of the titania nanoparticles. This was confirmed by the degradation of the dye methylene blue repeatedly using gold doped nanoparticles under direct sunlight. Further, the nanoparticles were used to study the degradation of the persistent organic pollutant, β endosulfan, and near complete degradation were observed in an hour. Regenerated nanoparticles were found effective for the degradation of the pesticide for more than three cycles.

scholarly journals Activation Treatments and SiO2/Pd Modification of Sol–Gel TiO2 Photocatalysts for Enhanced Photoactivity under UV Radiation

Catalysts ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1184
Author(s):  
Julien Mahy ◽  
Valériane Sotrez ◽  
Ludivine Tasseroul ◽  
Sophie Hermans ◽  
Stéphanie Lambert
Keyword(s):  
Photocatalytic Activity ◽  
Band Gap ◽  
Uv Radiation ◽  
Diffuse Reflectance Spectroscopy ◽  
Sol Gel ◽  
Pure Tio2 ◽  
Visible Range ◽  
Crystallographic Structure ◽  
Tio2 Sample ◽  
Tio2 Photocatalysts

The objective of this work is to improve the efficiency of TiO2 photocatalysts by activation treatments and by modification with palladium nanoparticles and doping with SiO2. The influence of the additive loading was explored, and two activation treatments were performed: UV exposition and H2 reduction. TiO2/SiO2/Pd photocatalysts were synthesized by an original cogelation method: a modified silicon alkoxide, i.e., [3-(2-aminoethyl)aminopropyl]trimethoxysilane (EDAS), was used to complex the palladium ions, thanks to the ethylenediamine group, while the alkoxide groups reacted with TiO2 precursors. Pure TiO2 was also synthesized by the sol–gel process for comparison. X-ray diffraction evidenced that the crystallographic structure of TiO2 was anatase and that Pd was present, either in its oxidized form after calcination, or in its reduced form after reduction. The specific surface area of the samples varied from 5 to 145 m2 g-1. Transmission electron microscopy allowed us to observe the homogeneous dispersion and nanometric size of Pd particles in the reduced samples. The width of the band gap for pure TiO2 sample, measured by UV/Visible diffuse reflectance spectroscopy at approximately 3.2 eV, corresponded to that of anatase. The band gap for the TiO2/SiO2/Pd composite samples could not be calculated, due to their high absorption in visible range. The photocatalytic activity of the various catalysts was evaluated by the degradation of a methylene blue solution under UV radiation. The results showed that the photocatalytic activity of the catalysts was inversely proportional to the content of silica present in the matrix. A small amount of silica improved the photocatalytic activity, as compared to the pure TiO2 sample. By contrast, a high amount of silica delayed the crystallization of TiO2 in its anatase form. The activation treatment under UV had little influence on photocatalytic efficiency. The introduction of Pd species increased the photocatalytic activity of the samples because it allowed for a decrease in the rate of electron–hole recombinations in TiO2. The reduction treatment improved the activity of photocatalysts, whatever the palladium content, thanks to the reduction of Ti4+ into Ti3+, and the formation of defects in the crystallographic structure of anatase.

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