P.P. Hankare

A novel route to synthesize Cd1-xPbxse thin films from solution phase

Chemosynthesis of technologically important Cd1−xPbxSe thin films with varying lead concentrations (0 ≤ x ≤ 1) has been developed with the objective of studies related to growth kinetics, physical, microscopic, compositional, structural, optical and electrical characteristics, and the related alteration in these, due to the incorporation of Pb in CdSe. The developed method is based on the reaction between tartarate complexes of Cd2+ and Pb2+ with sodium selenosulphate in an aqueous alkaline medium at 278 K. The optimum preparative parameters, such as reactant concentration, pH, deposition temperature and rate of substrate agitation, have found to influence quality and thickness of films significantly. Attempts were made to optimize the parameters to obtain good quality films. The as deposited films were characterized by XRD, AAS, EDAX, SEM, and optical and thermoelectric techniques. The XRD study indicates polycrystalline nature in hexagonal (for 0 ≤ x ≤ 0.5) and cubic (for 0.6 ≤ x ≤ 1) phases. The effect of lead composition x on properties such as optical band gap, absorption coefficient and dark dc electrical conductivity has also been studied. It has been observed that the films constitute solid solutions with hexagonal and cubic structures in low lead composition and high lead composition, respectively.

Sol–gel synthesized TiO2–CeO2 nanocomposite: an efficient photocatalyst for degradation of methyl orange under sunlight

The nanocomposites of TiO2–CeO2 are synthesized by a simple and cost-effective sol–gel method with cetyl trimethyl ammonium bromide (cationic surfactant) as capping agent at 500xa0°C. The X-ray diffraction analysis revealed phase purity of synthesized product. The X-ray photoelectron spectroscopy showed Ti4+ oxidation state of Ti element while Ce element was exist as a mixture of Ce3+ and Ce4+ oxidation state. The UV–Vis diffuse reflectance spectra clearly indicate the positive alteration in the optical response of TiO2 nanoparticles by the introduction of CeO2 nanoparticles. Scanning electron microscopic study revealed the formation of nanoclusters of spherical particles with uniform size distribution. Energy dispersive X-ray analysis confirmed the elemental composition. Fourier transform infrared spectroscopy analysis confirmed the presence of Ti–O–Ti stretching modes in the range of 900–400xa0cm−1. Photoluminescence spectroscopy was used to study the rate of recombination and transfer behaviors of photoexcited electron–hole pairs in the nanocomposites. Further, the photocatalytic activity of pure TiO2 nanoparticles and nanocomposite of TiO2 was studied using methyl orange. The TiO2:CeO2 nanocomposites exhibit high dye degradation compare with pure TiO2 nanoparticles. The composite TiO2:CeO2 (7:3) shows highest photocatalytic degradation of methyl orange dye in UV (60xa0min) and sunlight (90xa0min).

Photocatalytic degradation of phosphamidon using Ag-doped ZnO nanorods

The photocatalytic degradation of the organo-phosphorous pesticide phosphamidon at low concentration in aqueous solution on Ag-doped ZnO nanorods was investigated. Nanosized Ag-doped ZnO rods were synthesized by using a microwave assisted aqueous method. High molecular weight polyvinyl alcohol was used as a stabilizing agent. Composition and structure were investigated using energy-dispersive X-ray spectroscopy (EDAX) and X-ray diffraction (XRD). The XRD pattern reveals that ZnO nanorods are of hexagonal wurtzite structure. The average crystallite size calculated from Scherrers relation was found to be 30u2009nm. The effects of catalyst loading, pH value, and initial concentration of phosphamidon on the photocatalytic degradation efficiency using Ag-doped ZnO nanorods as a photocatalyst have been discussed. The results revealed that Ag-doped ZnO nanorods with a diameter of 30u2009nm showed highest photocatalytic activity at a surface density of 1u2009gu2009dm−3. The catalyst doped with 0.2u2009mol% Ag is effective for the degradation of phosphamidon with visible light. This opens a new possibility to decompose pesticides that are present in wastewater.