Nano-Ag particles doped TiO2 for efficient photodegradation of Direct azo dyes

Sobana, N.; Muruganadham, M.; Swaminathan, M.

doi:10.1016/j.molcata.2006.05.013

Cited by 448 publications

(193 citation statements)

References 56 publications

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“…[5][6][7] There are mainly two beneficial effects ascribed to Pt decoration: (i) changes in surface band bending in TiO 2 induced by the metal contact (Fermi level pinning) which leads to a faster transport of electrons, and (ii) its role as a hydrogen recombination catalyst that promotes H 2 formation from reduced atomic hydrogen. [8][9][10][11][12][13] In order to modify TiO 2 surfaces with noble metal nanoparticles, several methods are commonly used such as photoassisted deposition, impregnation, and physical mixing. [14][15][16][17] In the present work, we demonstrate that a very facile and straightforward Pt self-decoration of TiO 2 nanotube walls can be achieved in situ, that is during tube growth, by using Ti-Pt alloys with a small amount of Pt (in our case 0.2 at%) for the anodization process.…”

mentioning

confidence: 99%

Self-decoration of Pt metal particles on TiO₂ nanotubes used for highly efficient photocatalytic H₂ production

et al. 2014

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Pt decorated TiO 2 has, over the past decades, been a key material for photocatalytic hydrogen production. The present work shows that growing anodic self-organized TiO 2 nanotubes from Ti-Pt alloy with a low Pt content of 0.2 at% leads to oxide nanotube layers that are self-decorated with Pt nanoparticles of 4-5 nm in diameter. The average particle spacing is in the range of~50 nm and is partially adjustable by the anodization conditions. This intrinsic decoration of TiO 2 nanotubes with Pt leads to a highly active photocatalyst for the production of H 2 under UV or visible light conditions.Since Fujishima and Honda in 1972 showed the feasibility to produce hydrogen, the fuel of the future, by photoelectrochemical water splitting using a TiO 2 electrode, vast efforts have been dedicated to optimize systems to enhance the hydrogen yield. 1 The principle of this pathway to hydrogen is based on using a semiconductor for light absorption and formation of excited electron-hole pairs that then on the semiconductor surface react with an environmental H-source. A key requirement of the semiconductor is that it has suitable band-edge positions to allow generation of H 2 (namely a conduction band edge with a negative potential to the H 2 /H + redox potential). If the goal is to achieve a photocatalytic hydrogen production system that operates without external bias (i.e., under open circuit conditions), then also the transfer of holes from the valence band to the environment should be not only thermodynamically possible but also kinetically fast. 2,3 In the case of TiO 2 , most measures to enhance the kinetics are the use of sacrificial agents such as methanol, ethanol and decorating the surface with suitable charge transfer co-catalysts.Other key parameters for an effective hydrogen evolution from TiO 2 are a large surface area and an optimized geometry of the photocatalyst. For the latter reason, one-dimensional nanostructures have attracted wide interest in this field, as they provide a high aspect ratio with an optimized light absorption path and an orthogonal carrier separation. A most straightforward approach towards directional structures is self-organized TiO 2 nanotube arrays. To produce these nanotube structures a Ti metal substrate can be anodized under self-organizing electrochemical conditions. 4 The advantage of an anodic formation is not only simplicity of the process but also the easiness of geometry control (length, diameter, wall thickness) via the selection of suitable anodization parameters. 4 In the context of H 2 production from TiO 2 , as co-catalysts most active are noble metal nanoparticles (mainly Pt) that act very efficiently on TiO 2 nanostructures -in fact in order to obtain measurable contents of H 2 from TiO 2 under non-biased conditions (without the use of a counter electrode and by applying a potential difference) co-catalyst decoration is mandatory. [5][6][7] There are mainly two beneficial effects ascribed to Pt decoration: (i) changes in surface band bending in TiO 2 induced by the meta...

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confidence: 99%

Self-decoration of Pt metal particles on TiO₂ nanotubes used for highly efficient photocatalytic H₂ production

et al. 2014

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“…Then the required amount of AgNO 3 for doping was added to the TiO 2 suspension, where the silver concentration was of 0.5, 1.0, 1.5, 2.0 and 2.5% (mole ratio) versus TiO 2 . The mixtures were then irradiated with UV light (30 W, UV-C, λ max = 254 nm, manufactured by Philips, Holland) for 3 h and then dried in an air oven at 100 o C for 12 h. The dried solids were ground in an agate mortar and calcined at 400 o C for 6 h in a furnace (Sobana et al, 2006).…”

Section: Photodeposition Methodsmentioning

confidence: 99%

“…In this case, the metal deposits become recombination centers (Carp et al, 2004). -The probability of the hole capture is increased by the large number of silver particles at high silver loadings, which decrease the probability of holes reacting with adsorbed species at the TiO 2 surface (Sobana et al, 2006).…”

Section: The Effect Of Doping Content Of Silvermentioning

confidence: 99%

Enhancement of photocatalytic activity of TiO2 nanoparticles by silver doping: photodeposition versus liquid impregnation methods

Behnajady

Modirshahla²,

Shokri³

et al. 2013

Issue 1

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Silver doped TiO 2 nanoparticles have been prepared by liquid impregnation (LI) and photodeposition (PD) methods and characterized by surface analytical methods such as scanning electron micrographs (SEM) and X-ray diffraction (XRD). The photocatalytic activity of silver doped TiO 2 was tested by photocatalytic degradation of C.I. Acid Red 88 (AR88) as a model compound from monoazo textile dyes. Results show silver doped TiO 2 is more efficient than undoped TiO 2 at photocatalytic degradation of AR88. The positive effect of silver on the photoactivity of TiO 2 at degradation of AR88 may be explained by its ability to trap electrons. This process reduces the recombination of light generated electron-hole pairs at TiO 2 surface. Silver content has an optimum value 2% in LI and 0.5% in PD methods for achieving high photocatalytic activity. The AR88 decomposition with Ag-photodeposited method was much higher than that of deposited with LI method.

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“…The superiority of photocatalytic degradation by nanoparticles in wastewater treatment is due to its advantages over the conventional methods, such as quick oxidation, no formation of polycyclic products and oxidation of pollutants. It is an effective and rapid technique in the removal of pollutants from wastewater [3]. In the recent years, numerous metal oxides including TiO 2 [4], ZnO [5], and other oxides have attracted growing attentions for photodegradation of organic dyes; TiO 2 is of particular interests due to its low cost and high stability.…”

Section: Introductionmentioning

confidence: 99%

Catalytic Degradation of Organic Dyes using Synthesized Silver Nanoparticles: A Green Approach

S¹,

M²,

MV³

2015

J Bioremed Biodeg

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The scientific community is search in for new methods for the synthesis of metallic nanoparticles. Green synthesis has now become a vast developing area of new research groups. Here we report a green method to the synthesis of silver nanoparticles (AgNPs) using the different parts of Vishanika or Indian screw tree, an ayurvedic medicinal tree. This is nontoxic, eco-friendly and low cost method. The reduction and stabilization capability of the plant extracts of different parts are described. The size and structure of the silver can be characterized by varying the plant parts of the vishanika. The biosynthesized nanoparticles are characterized by using UV-VIS spectroscopy, TEM, XRD, DLS and FTIR. The size and extract dependent catalytic activity of the biosynthesized nanoparticles is established in the degradation of organic dyes.plant products represent excellent platforms for this purpose [6][7][8]13]. The compounds present in plants that have different potential biological activities; phytochemicals are important natural resource for the synthesis of metal nanoparticles. They play important roles in both stabilization and reduction of nanoparticles. The focus of the present work is to apply the accurate principles of green chemistry for the synthesis of silver nanoparticles by using stem bark, root and leaf of Helicteres isora extracts as stand-alone reducing and capping agent. H. isora plant extracts possess anticancer properties [14]. Usually, the bark and root juice were used against diabetes and emphysema. In traditional medicine, the bark and root juice is claimed to be useful in snake bite, diabetes, blood disorder, cough, colic, diarrhoea, astringent, etc., [15], expectorant and astringent [16], hypolipidemic [17], antihyperglycemic activity and glibenclamide [18]. In the present study, we have investigated the extracts and size dependent catalytic degradation of organic dyes-methyl violet, safranin, eosin methylene blue and methyl orange by in the presence of silver colloids. Materials and MethodsSilver nitrate (99.99%), methyl violet, safranin, eosin methylene blue and methyl orange, were purchased from sigma Aldrich. All glassware's were cleaned with sterile distilled water and rinsed with deionized water. Preparation of extractDifferent parts of (stem bark, root and leaf) H. isora were collected from Western Ghats of Tamil Nadu, washed with sterile distilled water and dried, then make it powder. 1 g of each explants powder was mixed with 100 mL of water and kept on orbital shaker at 120 rpm for 12 h. After that, the extracts were filtered with filter paper and stored at 4 0 C in refrigerator until further use. Journal of Bior emediation & Biodegradation Synthesis of silver nanoparticlesSilver nanoparticles (stem bark (S), root (R) and leaf (L)) have been synthesized by Bhakya et al. [19] method with slight modification. The formation of AgNPs is indicated by the appearance of dark brown color within 5 min. CharacterizationUV-visible spectra analysis was performed for all samples and the abs...

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Nano-Ag particles doped TiO2 for efficient photodegradation of Direct azo dyes

Cited by 448 publications

References 56 publications

Self-decoration of Pt metal particles on TiO₂ nanotubes used for highly efficient photocatalytic H₂ production

Self-decoration of Pt metal particles on TiO₂ nanotubes used for highly efficient photocatalytic H₂ production

Enhancement of photocatalytic activity of TiO2 nanoparticles by silver doping: photodeposition versus liquid impregnation methods

Catalytic Degradation of Organic Dyes using Synthesized Silver Nanoparticles: A Green Approach

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Nano-Ag particles doped TiO2 for efficient photodegradation of Direct azo dyes

Cited by 448 publications

References 56 publications

Self-decoration of Pt metal particles on TiO2 nanotubes used for highly efficient photocatalytic H2 production

Self-decoration of Pt metal particles on TiO2 nanotubes used for highly efficient photocatalytic H2 production

Enhancement of photocatalytic activity of TiO2 nanoparticles by silver doping: photodeposition versus liquid impregnation methods

Catalytic Degradation of Organic Dyes using Synthesized Silver Nanoparticles: A Green Approach

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Self-decoration of Pt metal particles on TiO₂ nanotubes used for highly efficient photocatalytic H₂ production

Self-decoration of Pt metal particles on TiO₂ nanotubes used for highly efficient photocatalytic H₂ production