S. Harel

Novel soft-chemistry route of Ag2Mo3O10·2H2O nanowires and in situ photogeneration of a Ag@Ag2Mo3O10·2H2O plasmonic heterostructure.

Ultrathin Ag2Mo3O10·2H2O nanowires (NWs) were synthesized by soft chemistry under atmospheric pressure from a hybrid organic-inorganic polyoxometalate (CH3NH3)2[Mo7O22] and characterized by powder X-ray diffraction, DSC/TGA analyses, FT-IR and FT-Raman spectroscopies, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Their diameters are a few tens of nanometers and hence much thinner than that found for silver molybdates commonly obtained under hydrothermal conditions. The optical properties of Ag2Mo3O10·2H2O NWs before and after UV irradiation were investigated by UV-vis-NIR diffuse reflectance spectroscopy revealing, in addition to photoreduction of Mo(6+) to Mo(5+) cations, in situ photogeneration of well-dispersed silver Ag(0) nanoparticles on the surface of the NWs. The resulting Ag@Ag2Mo3O10·2H2O heterostructure was confirmed by electron energy-loss spectroscopy (EELS), X-ray photoelectron spectroscopy (XPS), and Auger spectroscopy. Concomitant reduction of Mo(6+) and Ag(+) cations under UV excitation was discussed on the basis of electronic band structure calculations. The Ag@Ag2Mo3O10·2H2O nanocomposite is an efficient visible-light-driven plasmonic photocatalyst for degradation of Rhodamine B dye in aqueous solution.

Impact of Mo density on Mo/CIGSe interfaces: An XPS study

We have investigated the impact of Mo density onto Mo/CIGSe interfaces. In this study, CIGSe layers have been simultaneously co-evaporated onto different Mo/soda-lime glass (SLG) substrates. Varying the Mo layer density allows to tune the amount of sodium available during CIGSe growth. The chemical composition of the Mo/CIGSe interfaces has been investigated by X-ray photoelectron spectroscopy (XPS) after lift the CIGSe layer off the molybdenum. Na and Ga amount on the Mo side are correlated to the Mo density. The CIGSe morphology is also impacted by Na amount. Two different chemical environments of sodium are distinguished for the fine-grained CIGSe.

Electronic structure of Na{sub x}Cu{sub 1-x}In{sub 5}S{sub 8} compounds: X-ray photoemission spectroscopy study and band structure calculations

The aim of the present work is to complete a preliminary study concerning the electronic band structure investigations of Na{sub x}Cu{sub 1-x}In{sub 5}S{sub 8} compounds with 0{<=}x{<=}1, which are expected to be formed at the Cu(In,Ga)Se{sub 2}/In{sub 2}S{sub 3} interface. The band structure calculations demonstrate that for the compounds containing both Na and Cu, as the Cu content increases the band gap tends to decrease, and x-ray photoemission spectroscopy measurements show that this variation is mainly due to valence-band-maximum shift along the solid solution. The band gap strongly depends on the nature of the monovalent cation, and the band structure calculations demonstrate that the d electrons of copper are responsible for the shift of the valence band. In addition, it is worth noting that the Cu-containing compounds have indirect gaps.