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Abstract : Absorption Wavelength Extension for Dye-Sensitized Solar Cells by Varying the Substituents of Chiral Salen Cu(II) Complexes
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Abstract: New chiral salen-type Cu(II) complexes (1-9) were prepared, and the effects of different substituent groups on their absorption spectra were evaluated using time-dependent density functional theory (TD-DFT). Electron withdrawing groups resulted in a red-shift and an increase in the peak intensity. According to cyclic voltammetry analyses, the introduction of electron withdrawing groups brought the redox potentials (E0) in agreement with the orbital level energies determined via TD-DFT. The reduction potentials for 1-9 are less than −0.500 V, and therefore, it is electrochemically possible to dope electrons in TiO2. In addition, the oxidation potentials are greater than +0.200 V, indicating that it is electrochemically possible to regenerate the dyes. Preproduction dye-sensitized solar cells (DSSCs) fabricated using compounds 1-9 generated electricity. In particular, the DSSC prepared using 2 (which has electron withdrawing groups and the largest maximum absorption) exceeded the power conversion efficiency of DSSC fabricated using N3, which is a commonly used Ru(II) complex. Keywords: DSSC, Copper(II), Schiff base, Chirality, Crystal structure.Download Full Article |
Abstract : Synthesis of Stable Sols of Layered Titanate Nanoparticles using Dialysis and Applications for Thin Film Preparation
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Abstract: Sols with stable dispersion of layered titanate nanoparticles were prepared at 298 K using dialysis of a mixed solution of ethylene glycol, TiCl3, ammonium carbonate, and H2O2. Raman spectra of the particles in the obtained sols showed Raman scattering peaks which can be assigned to a layered titanate structure. The stability of the obtained sols depended on the molar ratio of [ammonium carbonate] / [Ti ion]. The molar ratios of 3, 4, and 5 produced transparent yellow stable sols. Peptization of titanium hydroxide precipitate with H2O2 formed stable sols with dispersion of layered titanate nanoparticles, which had plate - shaped morphology. The obtained sols formed layered titanate thin films on glass substrates easily by drying the sols. Furthermore, when the layered titanate thin films were heated at 773 K for 1 h, anatase TiO2 thin films were obtained with (101) orientation of crystallites and optical transparency. Keywords: Nanostructures, Oxides, Thin films, Sol-gel, Peptization, Coatings.Download Full Article |
Abstract : Thermodynamic Investigation of NaClO3 Solubility in the Mixed Solvent Medium and the Related Ion – Pair Formation at Different Temperatures
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Abstract: Using the evaporating method, the solubility of sodium chlorate was determined in the various mixed solvents (water + ethanol + propanol) at various temperatures. The results showed that the solubility of NaClO3 decreases with increasing the mass percent of ethanol and propanol. On the other hand, the solubility of NaClO3 increases with increasing the temperature .In addition, the equilibrium constant of ion pair formation, KIP, for the reaction Na+(aq) + ClO3-(aq) Na+ClO3- (Ion Pair) was estimated upon Fuoss contact ion pair model and then, the values of ion-pair concentrations were determined by using the extended Debye-Hückel model and iteration calculations in various mixed solvents and various temperatures . Finally the value of thermodynamic solubility product constant, Ksp(th), and the values ΔH°, ΔS° and ΔG° of and of ion-pair formation were estimated in the mixed solvent media. Keywords: Mixed solvent, The extended Debye-Hückel model, Ion- pair, Thermodynamic function.Download Full Article |
Abstract : Volumetric Study of the Binary Mixtures Containing a Branched Hexane and an Isomeric Chlorobutane
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Abstract: This paper reports densities at atmospheric pressure and at three temperatures T = (283.15, 298.15, and 313.15) K of eight binary mixtures involving a branched hexane (3-methylpentane or 2,2-dimethylbutane) and each one of the isomeric chlorobutanes (1-chlorobutane, 2-chlorobutane, 1-chloro-2-methylpropane or 2-chloro-2-methylpropane). Excess volumes were calculated from experimental densities and correlated with the Redlich-Kister equation. Moreover, the excess volumes were analysed using the Prigogine-Flory-Patterson theory. Keywords: Branched hexane, Isomeric chlorobutane, Prigogine-Flory-Patterson theory, Volumetric behaviour.Download Full Article |
