The structural and electrocatalytic characteristics of composite materials based on non-precious metals were studied. Precursors of metallic phase (Ni, Co or CoNi) and oxide phase (TiO2) were grafted on a carbon substrate (Vulcan XC-72) by the sol-gel procedure and thermally treated at 250 ?C. Ni and CoNi crystals of 10-20 nm were produced, in contrast the Co and TiO2 were amorphous. The dissimilar electronic character of the components gives rise to a significant electrocatalytic activity for the hydrogen evolution reaction (HER), even in the basic series of prepared materials. Further improvement of the catalysts was achieved by modification of all three components. Hence, Mo was added into the metallic phase, TiO2 was converted into the crystalline form and multiwall carbon nanotubes (MWCNTs) were used instead of carbon particles. The improvement, expressed in terms of the lowering the hydrogen evolution overpotential at 60 mA cm-2, was the most pronounced in the Ni-based systems grafted on MWCNTs (120 mV lower HER overpotential) compared to 60 mV in case of Ni-based systems grafted on crystalline TiO2 (TiO2 prepared at 450 ?C) and of Ni-based systems containing 25 at.% Mo. Nevertheless, even with the realized enhancement, of all the tested materials, the Co-based systems remained superior HER catalysts.

This work is concerned with development of sol–gel method for preparation of nanoscaled TiO₂ using organometallic precursor—titanium tetraisopropoxide (TTIP) and determination of the present crystalline phases depending on the temperature of further thermal treatment. The characteristic processes and transformations during the thermal treatment were determined by means of thermal gravimetric analysis and/or differential thermal analysis (TGA/DTA) method. The crystalline structure and size of the TiO₂ crystallites were analyzed by means of Raman spectroscopy and X-ray powder diffraction (XRPD) method. At 250 °C, cryptocrystalline structure was detected, where amorphous TiO₂ is accompanied with crystalline anatase. The anatase crystallite phase is stable up to 650 °C, whereas at higher temperature rutile transformation begins. It was observed that at 800 °C, almost the whole TiO₂ is transformed to rutile phase. According to XRPD analysis, the increase of the temperature influences on the increase of the size of the crystalline particles ranging from 6 nm at 250 °C to less than 100 nm at 800 °C. The size and shape of the TiO₂ crystalline particles were observed by transmission electron microscopy (TEM). The shape of the studied samples changes from nanospheres (250, 380, and 550 °C) to nanorods (650 and 800 °C). Morphology of the formed TiO₂ aggregates was observed by scanning electron microscopy (SEM).

This paper is concerned with electrolysis processes aimed for production and refining of metals. This engineering field is named electrometallurgy. The main aspects of electrometallurgy such as electrochemical, energetic/economic and environmental ones are given. The peculiarity of electrorefining and electrowining in both aqueous electrolytes and molten salts are shown. The impact of energetic parameters, such as cell voltage and current efficiency on the economic justification of the electrolysis process is analyzed. It is emphasized that electrolysis is considerably cleaner technology than the pyrometallurgical production and refining of metals.

The subject of research was to monitor and evaluatethe changes in the structure and properties of nanoscaled TiO₂ exposed to the X-ray and e-beam irradiation. The studied nanoscaled TiO₂ was synthesized using sol-gel method and subsequently exposed to thermal treatment to obtain anatase crystalline structure. Powder diffraction (XRPD) and Raman spectroscopy revealed the following changes in the structure as result of the e-beam and X-ray irradiation: decrease of the crystallite size of TiO₂, increase of the distance between the crystalline planes and the lattice parameters as well as achieving a certain degree of amorphization. As a consequence of the structural changes, thermal stability decreased. Also, the shift of the light absorption towards the visible light was detected and the energy of the band gap was reduced, indicating a better photocatalytic activity, i.e. photocatalytic action can be shifted to the region of the visible light.