departure from the theoretical current density distribution close to a point current source is observed in both Scanning Reference Electrode Technique (SRET) and Scanning Vibrating Electrode Technique (SVET) measurements. Here we report the use of a general multi-ion transport and reaction model, which accounts for micro-convection to point out the origin of the deviations that are experimentally observed. The validity of the model is proven by comparison against both analytical and measured (SRET and SVET) distributions of the current density in a typical calibration setup. Solutions with different conductivities and different impressed currents are considered. (c) 2014 Elsevier Ltd. All rights reserved.

A Zn,Al layered double hydroxide (LDH) intercalated by cis-[Mo(CO)(4)(bpdc)](2-) anions (bpdc - 2,2'-bipyridine-5,5'-dicarboxylate) has been prepared by ion exchange of a Zn,Al-NO3 LDH precursor, and characterized by powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), FT-IR, FT-Raman and UV-Vis spectroscopies. The ion exchange method gives rise to a highly organized intercalate with up to six (00l) basal reflections in the powder XRD pattern. The interlayer spacing of 18.0 angstrom indicates that the material contains a monolayer of guest anions positioned in such a way that the bpdc ligands are arranged with their longest dimension roughly perpendicular to the hydroxide layers of the host. Spectroscopic studies confirm the presence of structurally intact cis-[Mo(CO)(4)(bpdc)](2-) anions in the freshly prepared material, while also showing that the guest anions undergo slow decarbonylation over a period of several days, which is accelerated upon exposure of the material to light and air. The oxidative decarbonylation can be performed rapidly by reaction of the LDH containing intercalated tetracarbonyl complexes with tert-butylhydroperoxide, leading to intercalated molybdenum oxide/bipyridine species, which may be polymeric species of the type [MoO3(bpdc)](2-). Catalytic tests for the epoxidation of olefins and the oxidative dehydrogenation of alcohols were carried out for this material. (C) 2013 Elsevier B.V. All rights reserved.