The ion conductivity of two series of porous ceramic diaphragms impregnated with caustic potash was investigated by electrochemical impedance spectroscopy. To understand the impact of the pore structure on ion conductivity, the threedimensional (3-D) pore geometry of the diaphragms was characterized with synchrotron x-ray absorption tomography. Ion migration was calculated based on an extended pore structure model, which includes the electrolyte conductivity and geometric pore parameters, for example, tortuosity (s) and constriction factor (b), but no fitting parameters. The calculated ion conductivities are in agreement with the data obtained from electrochemical measurements on the Correspondence concerning this article should be addressed to D. Wiedenmann at daniel.wiedenmann@gmail.com.Published in " " which should be cited to refer to this work.http://doc.rero.ch diaphragms. The geometric tortuosity was found to be nearly independent of porosity. Pore path constrictions diminish with increasing porosity. The lower constrictivity provides more pore space that can effectively be used for mass transport. Direct measurements from tomographs of tortuosity and constrictivity opens new possibilities to study pore structures and transport properties of porous materials.

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The performance of optical devices is dependent on their optical transparency (OT). This is evident when such devices are exposed to environmental conditions that can reduce OT. The development of a robust, transparent and self-cleaning coating is highly desirable, for applications likeoptical windows and solar panels. This work reports the design of such coatings based on a hydrophobic thin film fabricated using a sol-gel process. Coating properties were optimised by modification of the surface topography of the coatings, achieved by the incorporation of silica nanoparticles(NPs). The coating was characterised by water contact angle(WCA), scanning electron microscopy(SEM) and white light interferometry (WLI). The efficacy and robustness of the coating foroptical application was assessed.

b s t r a c tThe photocatalytic activity, mechanism and characterization of polyethylene-TiO 2 films (PE-TiO 2 ) during the discoloration/degradation of methylene blue (MB) are reported in this study. PE-TiO 2 films were prepared at moderate temperatures (∼90 • C). TiO 2 did not leach out during discoloration/degradation of MB. This is a significant finding for a low temperature catalyst-polymer preparation leading to a stable repetitive MB degradation kinetics. MB discoloration on PE-TiO 2 films proceeded showing a quantum yield of 0.25%. Band-gap irradiation of TiO 2 was applied by way of a mercury medium pressure lamp to excite only TiO 2 and avoid MB photosensitization. The nature of the oxidative radicals intervening in MB discoloration was investigated by scavenging experiments. The relative importance of the oxidative species during MB discoloration is: TiO 2 vbh + > HO 2Evidence is presented for the superoxide anion-radical O 2• − at pH 6, as the main radical species leading to MB-discoloration. The MB-discoloration kinetic trend on PE-TiO 2 followed the behavior observed for diffusion-controlled reactions. The diffusion distance of the HO 2 • and OH • radicals during the discoloration of a solution MB 1 × 10were estimated as 71 and 2.2 m respectively. The OH • formation was assessed quantitatively during MB degradation by fluorescence measurements. The PE-TiO 2 film at time zero presented a contact angle (CA) of ∼92• , decreasing within the five hour MB discoloration period to <5• . Reversibility from the hydrophilic nature of the film to the initial hydrophobic state proceeded in the dark within few days. The implications of the reversibility time on the MB-discoloration performance are discussed. Evidence for redox catalysis during MB-discoloration was found by XPS measurements. The surface properties of the (PE-TiO 2 ) films were characterized by X-ray fluorescence (XRF), UV-vis spectroscopy, X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma mass-spectrometry (ICP-MS).

a b s t r a c tThis study reports an innovative preparation polyethylene-FeOx (PE-FeOx films) leading to the degradation of the methylene blue (MB) dye under low intensity sunlight/visible light (>400 nm). The intermediate highly oxidative radicals generated by PE-FeOx leading to MB discoloration/degradation in the presence of H 2 O 2 were identified. The relative contribution to the MB discoloration by the Feions leached from the PE-FeOx films into solution was determined quantitatively. This allows estimating the contribution of the heterogeneous and of the homogeneous leading to MB-degradation. The shift in the peak binding energy (BE) for Fe was detected by photoelectron spectroscopy (XPS) after the MBdegradation providing the evidence for redox catalysis occurring during MB-degradation at the PE-FeOx surface. The particle size and roughness of the PE-FeOx surfaces were determined by atomic force spectroscopy (AFM). The spectral properties of PE-FeOx films are reported and insight is provided for the mechanism of MB-degradation.