Showing papers by "Chhagan Lal published in 2015"

Engineering high-performance Pd core–MgO porous shell nanocatalysts via heterogeneous gas-phase synthesis

Abstract: We report on the design and synthesis of high performance catalytic nanoparticles with a robust geometry via magnetron-sputter inert-gas condensation. Sputtering of Pd and Mg from two independent neighbouring targets enabled heterogeneous condensation and growth of nanoparticles with controlled Pd core–MgO porous shell structure. The thickness of the shell and the number of cores within each nanoparticle could be tailored by adjusting the respective sputtering powers. The nanoparticles were directly deposited on glassy carbon electrodes, and their catalytic activity towards methanol oxidation was examined by cyclic voltammetry. The measurements indicated that the catalytic activity was superior to conventional bare Pd nanoparticles. As confirmed by electron microscopy imaging and supported by density-functional theory (DFT) calculations, we attribute the improved catalytic performance primarily to inhibition of Pd core sintering during the catalytic process by the metal-oxide shell.

Effect of thickness on structural and optical properties of CdSe thin films

Abstract: This paper presents the effect of thickness on the structural and optical properties of thermally evaporated CdSe thin films The thin films of thickness 445nm, 631nm and 810nm are deposited on glass substrate and annealed at a temperature of 100°C The results show that the thin films are nanocrystalline in nature and having cubic phase with preferred orientation (111) The calculated structural parameters are in agreement with the standard data The optical band gap varies from 165eV to 171eV and decreases with thickness

Effect of annealing on structural and optical properties of thermally evaporated CdSe thin films

Abstract: In this study, the structural and optical properties of CdSe thin films are undertaken. These thin films were deposited on glass substrate employing thermal evaporation technique and subjected to air annealing at temperature 100°C, 200°C and 300°C. The thickness was verified by ellipsometry and was found to be 445 nm. The results show that the thin films are nanocrystalline in nature and having cubic phase with preferred orientation (111). The calculated crystallographic parameters like inter planner spacing, lattice constant and grain size are in agreement with the standard data. The strain and dislocation density are observed to be varied with annealing while the optical band gap is found to be varied from 1.72eV to 1.89eV.