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101.
Gold nanoparticle-decorated keggin ions/TiO2 photococatalyst for improved solar light photocatalysis
Pearson A Jani H Kalantar-zadeh K Bhargava SK Bansal V 《Langmuir : the ACS journal of surfaces and colloids》2011,27(11):6661-6667
We demonstrate a facile localized reduction approach to synthesizing a Au nanoparticle-decorated Keggin ion/TiO(2) photococatalyst for improved solar light photocatalysis application. This has been achieved by exploiting the ability of TiO(2)-bound Keggin ions to act as a UV-switchable, highly localized reducing agent. Notably, the approach proposed here does not lead to contamination of the resultant cocatalyst with free metal nanoparticles during aqueous solution-based synthesis. The study shows that for Keggin ions (phosphotungstic acid, PTA), being photoactive molecules, the presence of both Au nanoparticles and PTA on the TiO(2) surface in a cocatalytic system can have a dramatic effect on increasing the photocatalytic performance of the composite system, as opposed to a TiO(2) surface directly decorated with metal nanoparticles without a sandwiched PTA layer. The remarkable increase in the photocatalytic performance of these materials toward the degradation of a model organic Congo red dye correlates to an increase of 2.7-fold over that of anatase TiO(2) after adding Au to it and 4.3-fold after introducing PTA along with Au to it. The generalized localized reduction approach to preparing TiO(2)-PTA-Au cocatalysts reported here can be further extended to other similar systems, wherein a range of metal nanoparticles in the presence of different Keggin ions can be utilized. The composites reported here may have wide potential implications toward the degradation of organic species and solar cell applications. 相似文献
102.
Uppamoochikkal P Tristram-Nagle S Nagle JF 《Langmuir : the ACS journal of surfaces and colloids》2010,26(22):17363-17368
We report the direction of tie-lines of coexisting phases in a ternary diagram of DOPC/DPPC/cholesterol lipid bilayers, which has been a system of interest in the discussion of biological rafts. For coexisting Ld and Lo phases, we find that the orientation angle α of the tie-lines increases as the cholesterol concentration increases and it also increases as temperature increases from T = 15 °C to T = 30 °C. Results at lower cholesterol concentrations support the existence of a different two-phase coexistence region of Ld and So phases and the existence of a three-phase region separating the two two-phase regions. Our method uses the X-ray lamellar D-spacings observed in oriented bilayers as a function of varying hydration. Although this method does not obtain the ends of the tie-lines, it gives precise values (±1°) of their angles α in the ternary phase diagram. 相似文献
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105.
Madathumpady Abubaker Habeeb Muhammed Pramod Kumar Verma Samir Kumar Pal Dr. R. C. Arun Kumar Soumya Paul Ramakrishnapillai Vyomakesannair Omkumar Dr. Thalappil Pradeep Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(39):10110-10120
A novel interfacial route has been developed for the synthesis of a bright‐red‐emitting new subnanocluster, Au23, by the core etching of a widely explored and more stable cluster, Au25SG18 (in which SG is glutathione thiolate). A slight modification of this procedure results in the formation of two other known subnanoclusters, Au22 and Au33. Whereas Au22 and Au23 are water soluble and brightly fluorescent with quantum yields of 2.5 and 1.3 %, respectively, Au33 is organic soluble and less fluorescent, with a quantum yield of 0.1 %. Au23 exhibits quenching of fluorescence selectively in the presence of Cu2+ ions and it can therefore be used as a metal‐ion sensor. Aqueous‐ to organic‐phase transfer of Au23 has been carried out with fluorescence enhancement. Solvent dependency on the fluorescence of Au23 before and after phase transfer has been studied extensively and the quantum yield of the cluster varies with the solvent used. The temperature response of Au23 emission has been demonstrated. The inherent fluorescence of Au23 was used for imaging human hepatoma cells by employing the avidin–biotin interaction. 相似文献
106.
We report the synthesis of platinum telluride nanoparticles (Pt(3)Te(4) NPs) in the solution phase at room temperature using a template-assisted method. The dendrimeric aggregates formed are composed of several small units of Pt(3)Te(4) NPs of ~4 nm diameter. Tellurium nanowires (Te NWs) are used as the template and the reducing agent in the growth of NPs which occurs due to the galvanic replacement reaction between Te NWs and PtCl(6)(2-). Surface-enhanced Raman scattering (SERS) of the dispersed Pt(3)Te(4) NPs was studied using crystal violet (CV) as the analyte. SERS sensitivity up to 10(-8) M of CV was observed. The Raman enhancement factor (EF) of adsorbed CV on NP aggregates was calculated to be 1.74 × 10(5). The catalytic ability of the as-synthesized Pt(3)Te(4) NPs for the reduction of 4-nitrophenol (4-NP) was studied. 相似文献
107.
Prashant Singh Pradeep Kumar Anju Katyal Rashmi Kalra Sujata K. Dass Satya Prakash Ramesh Chandra 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2010,75(3):983-991
In the present work, we report the synthesis and characterization of novel charge-transfer complexes of thiazolidine-2,4-dione (TZD) with sigma acceptor (iodine) and pi acceptors (chloranil, dichlorodicyanoquinone, picric acid and duraquinone). We also evaluated their thermal and electrochemical properties and we conclude that these complexes are frequency dependent. Charge-transfer complex between thiazolidine-2,4-dione and iodine give best conductivity. In conclusion, complex with sigma acceptors are more conducting than with pi acceptors. 相似文献
108.
109.
Ciprofloxacin-protected gold nanoparticles 总被引:3,自引:0,他引:3
Tom RT Suryanarayanan V Reddy PG Baskaran S Pradeep T 《Langmuir : the ACS journal of surfaces and colloids》2004,20(5):1909-1914
The antibacterial drug ciprofloxacin (cfH) has been used to protect gold nanoparticles of two different mean diameters, 4 and 20 nm. The protection is complete with about 65 and 585 cfH molecules covering 4 and 15 nm particles, respectively. The nature of binding has been investigated by several analytical techniques. The nitrogen atom of the NH moiety of piperazine group binds on the gold surface, as revealed by voltammetric and spectroscopic studies. The cfH-adsorbed particles are stable in the dry state as well as at room temperature, and as a result, redispersion is possible. The rate of release of the drug molecule from the nanoparticles is more in the basic medium than in pure water, and the kinetics depend on the size of the particle; faster desorption is seen in smaller particles. The bound cfH is fluorescent, and this property could be used in biological investigations. This study shows that metal nanoparticles could be useful carriers for cfH and fluoroquinolone molecules. Most of the bound molecules could be released over an extended period of time. 相似文献
110.
Nagarajan K Joshi HK Chaudhury PK Pal K Cooney JJ Enemark JH Sarkar S 《Inorganic chemistry》2004,43(15):4532-4533
Synthesis of [PPh4]2[Mo(SPh)2(S2C2(CN)2)2] (2) from [PPh4]2[MoO(S2C2(CN)2)2] (1) has been achieved to mimic the postulated [Mo(S)6] core of polysulfide reductase with two thiolates and two bis(ene-dithiolate) ligands. Compound 2 reacts with polysulfide to yield H2S, modeling the function of polysulfide reductase. The facile conversion of 2 back to 1 in moist solvent suggests that the interconversion of the [MoIV = O] and [MoIV - X] (X = O-Ser, S-Cys, Se-Cys) moieties might occur in the DMSO reductase class of enzymes under appropriate hydrophobic/hydrophilic conditions. 相似文献