Single-step electrodeposition of superhydrophobic black NiO thin films

International audienceBlack finished surfaces have extensive applications in many domains, such as optics, solar cells, and aerospace. The single step electrodeposition of superhydrophobic black NiO films from a dimethyl sulfoxide based electrolyte is described in this paper. The physicochemical properties of the obtained film were characterized using Scanning Electron Microscopy, X-ray Diffraction, and electrochemical tests (Electrochemical Impedance Spectroscopy and potentiodynamic polarization). A rough surface with a low reflection of light was formed after the deposition process that increased the contact angle of water from about 87º (for bare Cu) to 163º (in presence of the black coating), which improved the corrosion resistance of the Cu substrate by about 30%. The formed black NiO film revealed a notably high stability and kept its appearance even after corrosion tests

Detection of Rhodamine 6G at low concentrations using Raman Spectroscopy: A comparison between Ag and Au-based nanoporous substrates

International audienceThe detection of R6G on nanoporous susbtrates at low concentrations (10(-4) M 1.10(-6) M, it was evidenced that R6G Raman response does not depend on metal chemical nature. It is linearly correlated to R6G adsorbed amounts, evidencing the pre-concentration property of the substrates. For lower concentrations, differences were observed in Raman responses. For C = 1.10(-6) M, the Raman bands of R6G adsorbed on SiO2 and Au@SiO2 are similar to those found at higher concentrations. For Ag@SiO2, two new bands, corresponding to bending modes of ethylamine groups, are present as well as the band related to Ag-N stretching mode. This was explained by the specific interaction developed between R6G and Ag@SiO2. For C = 1.10(-7) M, only the two bands related to R6G ethylamine groups are present for all substrates and a Raman signal enhancement was found for Ag-based substrate

Metal-organic framework MIL-101(Fe)–NH2 as an efficient host for sulphur storage in long-cycle Li–S batteries

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Dielectric relaxation in tetragonal tungsten bronze ceramics

Ferroelectric tantalates with the tetragonal tungsten bronze (TTB) type structure were studied over a wide frequency range from 102 to 109 Hz. Complementary microwave measurements at 36 GHz and micro-Raman experiments were performed in order to extend the dielectric study. A high frequency relaxation was observed above 108 Hz and fitted to the Cole–Cole formula. Different qualitative models are proposed to explain the understanding of the origin of the high frequency relaxation in ferroelectrics. Among these, polar clusters of ferroelectric active off-centred Ta5+ ions are considered