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The activation and adsorption of CO2 over Cun clusters have been investigated by first principle calculations. Results of these calculations are compared with the previous studies of adsorption of CO2 on Cu (hkl) surfaces [Wang et al. Surface Science 570 (2004) 205-217]. We find that CO2 is preferentially adsorbed over the clusters in comparison with Cu (hkl) surfaces. The Cu13 cluster in particular dissociates the CO2 molecule adsorbed on the one of the caps of the icosahedron into CO and atomic oxygen. This activated configuration can act as a precursor to reactions leading to hydrocarbon fuels from CO2. [ABSTRACT FROM AUTHOR]

The electronic and optical properties of gold clusters Aun of size n = 1 = 15 were examined using a) Gaussian Software (GS) b) Siesta Code (SC). The structural properties were analyzed using GS and SC as well as Gupta Potential. Electronic properties like binding energy per atom (Eb/n), Homo-Lumo Gap (Eg), ionization potentials, (Adiabatic (AIP)), Chemical Potential(μ), hardness(η) and Softness(S) were investigated using GS and SC within the frame work of DFT formalism. Optical properties like static dipole polarizability of Aun were examined using GS only. Geometry optimization starting from a number of initial geometries were performed for each cluster size and obtained confirmed global minima till size n = 12. Interestingly, for cluster size n, at which 2D to 3D occurs in Aun, different in all different meanslike GS, SC and GP. [ABSTRACT FROM AUTHOR]

Structure, stability and electronic properties of medium sized neutral and cationic lithium clusters Lin (n = 2, 8, 10, 20, 30) have been investigated within the framework of Density-Functional Theory at B3LYP level using 6-311G* basis se. The results show that cationic clusters are energetically favorable compared to neutral ones. At magic-number sizes (n = 2, 8, 10, 20), Lin clusters posses relatively large HOMO-LUMO gaps and higher ionization potentials, corresponding to closure of the electronic shell. For Li20 all three diagonal elements of the polarizability tensor are equal (αxx = 1159.038, αyy = 1171.054, αzz = 1187.068) and found to be significantly isotropic. The structure of Li20 shows a remarkable symmetry. Whenever possible, results have been compared with available data. A good agreement between experimental and theoretical results suggests a good prediction of lowest energy structure for all clusters calculated in the present study. [ABSTRACT FROM AUTHOR]

Single walled carbon nanotubes (SWNTs) films are prepared by dispersing SWNTs in DMF solution which is filtered over flexible polycarbonate membrane by vacuum filtration method. SWNTs film has been functionalized with different amounts (0.1 mg, 0.2 mg and 1 mg) of SnO2 nanoparticles of size 20-30 nm. Sensor is made by mounting a piece of CNT and different CNT/SnO2 films on PCB headers and contacts are taken by using Au wire. The sensing behavior of CNT/SnO2 towards NO2 and NH3 in the concentration range of 0.5 to 100 ppm has been studied. The sensing response has been compared to that obtained from pristine SWNTs. SWNTs with 0.1 mg of SnO2 has given the maximum improvement of 1.6-8.5% and 0.8-1.75 times in response for NH3 and NO2 respectively, as compared to pristine CNTs.. [ABSTRACT FROM AUTHOR]