Mesoporous Carbon and Poly(3,4-ethylenedioxythiophene) Composite as Catalyst Support for Polymer Electrolyte Fuel Cells

In situ polymerization of 3,4-ethylenedioxythiophene with sol-gel-derived mesoporous carbon (MC) leading to a new composite and its subsequent impregnation with Pt nanoparticles for application in polymer electrolyte fuel cells (PEFCs) is reported. The composite exhibits good dispersion and utilization of platinum nanoparticles akin to other commonly used microporous carbon materials, such as carbon black. Pt-supported MC-poly(3,4-ethylenedioxythiophene) (PEDOT) composite also exhibits promising electrocatalytic activity toward oxygen reduction reaction, which is central to PEFCs. The PEFC with Pt-loaded MC-PEDOT support exhibits 75% of enhancement in its power density in relation to the PEFC with Pt-loaded pristine MC support while operating under identical conditions. It is conjectured that Pt-supported MC-PEDOT composite ameliorates PEFC performance/durability on repetitive potential cycling. (C) 2010 The Electrochemical Society. DOI: 10.1149/1.3486172] All rights reserved.

Hydrazine carboxylate precursors to fine particle titania, zirconia and zirconium titanate

Titanyl hydrazine carboxylate dihydrate, TiO(N2H3COO)2.2H2O, zirconyl hydrazine carboxylate dihydrate, ZrO(N2H3COO)2.2H2O and their solid solution, ZrTiO2(N2H3COO)4.4H2O have been prepared for the first time and investigated as precursors to fine particle TiO2, ZrO2 and ZrTiO4 respectively. Titania(anatase) formed has a very high surface area of 110 m2/g and zirconium titanate showed very low dielectric loss (4 x 10(-4)).

Properties of ion assisted deposited titania films

Thin films of titanium dioxide have been deposited using ion assisted deposition with oxygen ions in the energy range 100�500 eV and current densities up to 100 ?A/cm2. It has been observed that the refractive index of the films increases up to 300 eV and the extinction coefficient increased only nominally up to 300 eV. Optical band gap calculations have shown a strong dependence of the gap on the energy of incident ions. Beyond a critical energy and current density of the ions the refractive index and extinction coefficient of the films start deteriorating. It has also been found that beyond the critical values the optical band gap value decreases. The maximum refractive index obtained was 2.49 at an energy of 300 eV and 50 ?A/cm2 current density. Post?deposition annealing of the films at 500?°C resulted in a slight increase in refractive index without affecting the extinction coefficient. X?ray diffraction studies revealed a monophasic anatase structure in these films. ?

Amorphous Mesoporous Iron Aluminophosphate Catalyst for the Synthesis of 1,5-Benzodiazepines

A simple and versatile method for the synthesis of 1,5-benzodiazepines from o-phenylenediamine and ketones in the presence of solvents and under solvent-free conditions that used an amorphous mesoporous iron aluminophosphate as catalyst was developed. High yields with excellent selectivity were obtained with a wide variety of ketones under mild reaction conditions. The catalyst had the advantages of ease of preparation, ease of handling, simple recovery, reusability, non toxicity, and being inexpensive.

Evidence for supramolecular organization of alkane and surfactant molecules in the process of forming mesoporous silica

Investigations of the pore expansion in mesoporous silica in the presence of n-alkanes suggest a cooperative organization of the surfactant and alkane molecules, involving additivity of chain lengths.

Mesoporous phases based on SnO2 and TiO2

A hexagonal mesoporous phase based on SnO2 is synthesized for the first time by using an anionic surfactant; hexagonal phases of TiO2 are prepared with neutral amine surfactants.

Improved lithium cyclability and storage in a multi-sized pore (''differential spacers'') mesoporous SnO2

A wide pore distribution mesoporous morphology stabilizes SnO2 structure during lithium insertion and removal and in the process remarkably enhances the lithium storage and cyclability.

Effect of TiO2 electrode thickness on photovoltaic properties of dye sensitized solar cell based on randomly oriented Titania nanotubes

Anatase titania nanotubes (TNTs) have been synthesized from P25 TiO2 powder by alkali hydrothermal method followed by post annealing. The microstructure analysis by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) revealed the formation of anatase nanotubes with a diameter of 9-10 nm. These NTs are used to make photo anode in dye-sensitized solar cells (DSSCs). Layer by layer deposition with curing of each layer at 350 C is employed to realize films of desired thickness. The performance of these cells is studied using photovoltaic measurements. Electrochemical impedance spectroscopy (EIS) is used to quantitatively analyze the effect of thickness on the performance of these cells. These studies revealed that the thickness of TiO2 has a pronounced impact on the cell performance and the optimum thickness lies in the range of 10-14 mu m. In comparison to dye solar cells made of P25, TNTs based cells exhibit an improved open circuit voltage and fill factor (FF) due to an increased electron lifetime, as revealed by EIS analysis. (C) 2011 Elsevier B.V. All rights reserved.

Synthesis and catalytic properties of cobalt- and molybdenum-containing mesoporous MCM-41 molecular sieves

Mesoporous MCM-41 type silicas containing molybdenum and cobalt have been prepared with pore sizes in the range 30-38 Angstrom and 54-59 Angstrom. Catalytic properties of these materials have been examined with respect to the oxidation of cyclooctene and aniline.

Structure and composition related properties of titania thin films

The dependence of optical constants, structure and composition of titania thin films on the process parameters has been investigated. Films were deposited using both reactive electron beam evaporation and ion Assisted Deposition(IAD). If has been observed that the refractive index of IAD films is higher than that for the reactively deposited films, without much difference in the extinction coefficient. Electron paramagnetic resonance has been used to estimate qualitatively the presence of non-stoichiometry in the films. It has been found that these spectra correlate very well the optical behaviour of the films. X-ray diffraction studies revealed that the neutral oxygen deposited films were stress free, while the IAD films showed tensile stress. The lattice parameters showed anisotropic change with ion beam parameters.

Mesoporous aluminoborates

Hexagonal, cubic and lamellar aluminoborate mesophases containing octahedral aluminium and tetrahedral boson are prepared and characterized for the first time.

Mesoporous MnO2 synthesized by using a tri-block copolymer for electrochemical supercapacitor studies

Mesoporous MnO2 is prepared from KMnO4 by using a tri-block copolymer, namely, poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEG-PPG-PEG) as a reducing as well as a structure-directing agent. The as synthesized MnO2 samples are poorly crystalline with mesoporosity having pore diameter between 8 and 40 nm. BET surface area as high as 273 m(2) g(-1) is obtained. By heating, the poorly crystalline MnO2 turns into a well crystalline form at 400 degrees C with nanorod morphology. However, the surface area decreases for the heated samples. Samples of MnO2 prepared by varying the ratio of KMnO4 and the copolymer, and also the heated samples are subjected to electrochemical characterization for supercapacitor studies. High specific capacitance values on mass basis are obtained for the as prepared mesoporous MnO2 samples. (C) 2011 Elsevier Inc. All rights reserved.

Electrochemical performance of mixed crystallographic phase nanotubes and nanosheets of titania and titania-carbon/silver composites for lithium-ion batteries

The role of homogeneity in ex situ grown conductive coatings and dimensionality in the lithium storage properties of TiO(2) is discussed here. TiO(2) nanotube and nanosheet comprising of mixed crystallographic phases of anatase and TiO(2) (B) have been synthesized by an optimized hydrothermal method. Surface modifications of TiO(2) nanotube are realized via coating the nanotube with Ag nanoparticles and amorphous carbon. The first discharge cycle capacity (at current rate = 10 mA g(-1)) for TiO(2) nanotube and nanosheet were 355 mAh g(-1) and 225 mAhg(-1), respectively. The conductive surface coating stabilized the titania crystallographic structure during lithium insertion-deinsertion processes via reduction in the accessibility of lithium ions to the trapping sites. The irreversible capacity is beneficially minimized from 110 mAh g(-1) for TiO(2) nanotubes to 96 mAh g(-1) and 57 mAhg(-1) respectively for Ag and carbon modified TiO(2) nanotubes. The homogeneously coated amorphous carbon over TiO(2) renders better lithium battery performance than randomly distributed Ag nanoparticles coated TiO(2) due to efficient hopping of electrons. (C) 2011 Elsevier B.V. All rights reserved.