Synthesis and Crystal Structure of a Copper(II) Benzoate Complex Bearing a Bis-2,2′-Tetrahydrofuryl Peroxide Moiety

Complex [Cu2(ben)4·2THF−(η1–O2)]∞ (2) (ben=C6H5CO2− benzoate; THF=tetrahydrofuran) was isolated when a solution of Cu2(ben)4·2THF (1) in THF upon natural sunlight irradiation yields crystals suitable for single-crystal X-ray diffraction analysis. 2, crystallized in the C2/c monoclinic space group, Z=8, V=3394.2 (4) Å3, and the unit cell parameters a=9.7935(7) Å, b=19.0055 (13) Å, c=18.2997 (13) Å, α=90°, β=94.7996 (11)º and γ=90°. This is the first example of a polymeric copper(II) carboxylate compound stabilizing a peroxo group via its apical ligand (THF molecule). Additionally, 2 was also characterized by elemental analysis, Fourier-transformed infrared spectroscopy (FTIR) and Raman spectroscopyUniversidad de Costa Rica/[804-B7-279]/UCR/Costa RicaUniversidad de Costa Rica/[804-B0-650]/UCR/Costa RicaUCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de QuímicaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Electroquímica y Energía Química (CELEQ

Evolution of the microstructure of disperse ZnO powders obtained by the freeze-drying method

Freeze-drying, as a cryochemical powder processing method is applied in the synthesis of ZnO submicrometer to narrosized powders. The process involves rapid freezing of the sprayed precursor solution, drying under vacuum by sublimation of the Solvent and salt decomposition to oxide by thermal treatment. Calcination of dehydrated Zn(NO3)(2) was performed through destruction of the primary crystal structure, i.e. through accumulation of different defect complexes and based on this, the formation of a new state of the ZnO crystal lattice. An analysis of the microstructure evolution of zinc oxide particles in the temperature range from 548 to 898 K is described. The research was performed using differential scanning calorimetry (DSC), scanning electron microscopy (SEM), X-ray powder diffraction (XRPD), electronic paramagnetic resonance (EPR) and infrared spectroscopy (IR). It was shown that the least ("primary") coherent scattering region (580 Angstrom) and the most defective state were ZnO obtained at the lowest calcination temperature (T-c = 548 K). Increase of the calcination temperature (T-c > 548 K) favors uniting of eight closest "primary" domains into "secondary" ones. Unification is accompanied by a pronounced increase in microstrainin "secondary" domains, whose size practically does not depend on the calcination temperature in the region 573-898 K

A New Approach to the Understanding of the Mechanism of Lead Electrodeposition

The most important applications of lead include the production of high purity active materials for acid battery, for semiconductors, and for the fabrication of electrochromic devices. In the form of powder, lead is widely used in industries of gas and oil exploration, radiological medical protective clothing, as an industrial X-ray shield, golf club manufacture, and antifriction products. The electrodeposition technique is a very suitable way to obtain lead in the form suitable for the application in the above-mentioned technologies. For example, the advantage of use of electrodeposition technique in the production of lead in the powder form lies in the fact that lead powder is produced at low overpotentials and hence with small spent of energy. The open porous structures of lead with the extremely high surface area (the honeycomb-like ones), which are ideally situated for electrodes in electrochemical devices such as fuel cells, batteries, and sensors, are also possible to get by the electrodeposition techniques

Influences of synthesis methods and modifier addition on the properties of Ni-based catalysts supported on reticulated ceramic foams

A method of synthesizing Ni-based catalysts supported on alpha-Al2O3-based foams was developed. The foams were impregnated with aqueous solutions of metal chlorides under an air atmosphere using an aerosol route. Separate procedures involved calcination to form oxides and drying to obtain chlorides on the foam surface. The synthesized samples were subsequently reduced with hydrogen. With respect to the Ni/Al2O3 catalysts, the chloride reduction route enabled the formation of a Ni coating without agglomerates or cracks. Further research included catalyst modification by the addition of Pd, Cu, and Fe. The influences of the additives on the degree of reduction and on the low-temperature reduction effectiveness (533 and 633 K) were examined and compared for the catalysts obtained from oxides and chlorides. Greater degrees of reduction were achieved with chlorides, whereas Pd was the most effective modifier among those investigated. The reduction process was nearly complete at 533 K in the sample that contained 0.1wt% Pd. A lower reduction temperature was utilized, and the calcination step was avoided, which may enhance the economical and technological aspects of the developed catalyst production method