Electrochemical kinetics of nanosized Ag and Ag2O thin films prepared by radio frequency magnetron sputtering

Ag and Ag₂O thin films have been prepared by radio frequency magnetron sputtering on Cu substrates and have been characterized by X-ray diffraction, scanning electron microscope and atomic force microscope. The electrochemical performance of the thin films has been studied by galvanostatic cycling and cyclic voltammetry. The potential dependence of Li-ion chemical diffusion coefficients, [(D)\tilde]_\textLi {\widetilde{D}_{\text{Li}}} , of the films has been determined by galvanostatic intermittent titration technique and electrochemical impedance spectroscopy. It is found that Li-ion chemical diffusion coefficients of the Ag film range from 10⁻¹⁶ to 3 × 10⁻¹⁴ cm² s⁻¹. The Ag/Li₂O composite that is formed from Ag₂O after the first cycle exhibits higher [(D)\tilde]_\textLi {\widetilde{D}_{\text{Li}}} values than the Ag film, especially at a low Li-intercalation content. The phase transitions in the two-phase region cause a significant decrease of chemical diffusion coefficients.     

Synthesis of molybdenum(V) and molybdenum(VI) derivatives of 5,15-diphenyl-2,8,12,18-tetra-n-butyl-3,7,13,17-tetramethylporphyrin

The methoxo-oxomolybdenum(V), diperoxomolybdenum(VI) and cis-dioxomolybdenum(VI) derivatives of 5,15-diphenyl-2,8,12,18-tetra-n-butyl-3,7,13,17-tetramethylporphyrin ( 4a, 5c, 6a ) have been prepared and characterized by uv, ir, pmr, mass and esr spectra. The structure of the molybdenum(V) porphyrin was confirmed by X-ray analysis.