Highly efficient photodegradation of 4-nitrophenol over the nano-TiO2 obtained from chemical bath deposition technique

Research on Chemical Intermediates - Herein, we report the collection of TiO2 nanopowder after successful thin film deposition. The obtained TiO2 nanopowder was utilized for photodegradation of...     

Evaluation of cerium–zirconium mixed oxides for separation of 125Sb from radioactive liquid waste

Journal of Radioanalytical and Nuclear Chemistry - Low level radioactive liquid waste (LLW) contains various radioisotopes like 125Sb, 106Ru, 99Tc and traces of 137Cs, 134Cs, 90Sr. Chemical...     

Discrete transfer method with the concept of blocked-off region for irregular geometries

The discrete transfer method (DTM) is applied to irregular geometries with a concept of blocked-off region previously applied in the problems of computational fluid dynamics. This gives a new alternative to the DTM for its implementation to irregular structures. The Cartesian coordinate-based ray-tracing algorithm can be applied to the geometries with inclined or curved boundaries. Some test problems are considered and results are validated with the available results in the literature. Both radiative and non-radiative equilibrium situations are considered. The medium is assumed to be both participating and non-participating. Results are found to be accurate for all kinds of situations.     

Entropy of water in the hydration layer of major and minor grooves of DNA

Transport properties (translational and rotational) of water in the two grooves of the B-DNA duplex are known to be different from those in the bulk. Here, we use a recently developed theoretical scheme to compute the entropies of water molecules in both of the grooves of DNA and compare them with that in the bulk. The scheme requires as input both translational and rotational velocity autocorrelation function (C(V)(t) and C(omega)(t), respectively) data. These velocity autocorrelation functions were computed from an atomistic MD simulation of a B-DNA duplex (36 base pairs long) in explicit water (TIP3P). The average values of the entropy of water at 300 K in both of the grooves of DNA (the TS value in the major groove is 6.71 kcal/mol and that in the minor groove is 6.41 kcal/mol) are found to be significantly lower than that in bulk water (the TS value is 7.27 kcal/mol). Thus, the entropic contribution to the free energy change (TDeltaS) of transferring a minor groove water molecule to the bulk is 0.86 kcal/mol and of transferring a major groove water to the bulk is 0.56 kcal/mol at 300 K, which is to be compared with 1.44 kcal/mol for melting of ice at 273 K. We also calculate the energy of interaction of each water molecule with the rest of the atoms in the system and hence calculate the chemical potential (Helmholtz free energy per water molecule, A = E - TS) in the different domains. The identical free energy value of water molecules in the different domains proves the robustness of the scheme. We propose that the configurational entropy of water in the grooves can be used as a measure of the mobility (or microviscosity) of water molecules in a given domain.     

Photoelectrochemical characterization of annealed cadmium selenide photoelectrode using sulphide–polysulphide electrolyte

Cadmium selenide films have been synthesized by dip method. Cadmium selenide acts as photoanode in photoelectrochemical (PEC) cells. The photoanode was annealed upto 473 K. The cell configuration is n-CdSe∣NaOH (1 M) +S (1 M) +Na₂S (1 M) ∣C_(graphite). Various performance parameters were examined with respect to annealed temperature. It is found that the fill factor and efficiency are maximum for photoelectrode annealed at 473 K. This is due to low resistance, high flat-band potential, maximum open-circuit voltage as well as maximum short-circuit current. The barrier height was examined from the temperature dependence of the reverse saturation current. The lighted ideality factor was found to be minimum for photoelectrode annealed at 473 K. A cell utilizing annealed photoelectrode showed a wider spectral response. The utility of this work is in improving the efficiency of PEC cells.     

Effect of indium doping on photoelectrochemical properties of Cd0.9Zn0.1Se photosensitive films

Indium doped Cd_0.9Zn_0.1Se films have been synthesized by chemical bath deposition method. The deposited films act as photoanode in photoelectrochemical (PEC) cells. The varying concentration of indium from 0.01 to 1.0 mol% was used. The film thickness increases from 0.72 to 0.80 μm as doping concentration increases up to 0.1 mol%, thereafter it decreases. The cell configuration is n-Cd_0.9Zn_0.1Se:In|NaOH (1 M)+S (1 M)+Na₂S (1 M)|C_(graphite). The various performance parameters were examined with respect to doping concentration of indium. It is found that fill factor and efficiency is maximum for 0.1 mol% indium photosensitive films. This is due to low resistance, high flat band potential, maximum open circuit voltage as well as maximum short-circuit current. The barrier height was examined from the temperature dependence of the reverse saturation current. The lighted ideality factor was found to be minimum for 0.1 mol% indium photosensitive films. A cell utilizing doping photosensitive films showed a wider spectral response. The utility of this work is in improving efficiency of the PEC cell.     

Structure, surface morphological and opto-electronic properties of zinc sulphide thin films deposited by dip method

ZnS thin films have been deposited by dip technique using succinic acid as a complexing agent. The structural and morphological characterizations of films have been investigated by X-ray diffraction, scanning electron microscope. X-ray pattern shows crystalline has hexagonal structure. The films show that good optical properties high absorption and band gap value was found to be 3.7 eV. The specific conductivity of the film was found to be in order of 10⁻⁵ (Ω cm)⁻¹ and showing n-type conduction.