Solid-state composites based on sodium borohydride (NaBH₄) were studied for applications as hydrogen generation materials. Hydrates of cobalt and nickel chlorides subjected to a thermal treatment were added to the composites as catalyst precursors. Using thermal analysis and FTIR spectroscopy, it was shown that the amount of water removed increases with the increasing temperature. Herewith, the water molecules that remained in the samples were strongly bound to the metal and isolated from each other. According to the ultraviolet–visible (UV-vis) spectroscopy data, with the increasing temperature of the thermal pretreatment there took place a substitution of a portion of water molecules by chloride ions in the nearest environment of the metal. It appeared that it was the resulting weakening of the electrostatic field on metal that was mainly responsible for the formation of a more finely dispersed catalytic phase of amorphous cobalt boride in the reaction medium under the action of sodium borohydride. The smaller particles of the active components led to a faster rate of gas generation when water was added to the solid-state NaBH₄ composites. This trend remained for both the cobalt and the nickel catalytic systems even when the activity was calculated per gram of the metal. Thus, for the preparation of solid-state NaBH₄ composites, hydrates of cobalt and nickel chlorides with a low content of water should be used.

The development of solvent-free methods for the synthesis of catalysts is one of the main tasks of green chemistry. A nickel–alumina catalyst for CO₂ methanation was synthesized by solid-state combustion method using hexakis-(imidazole) nickel (II) nitrate complex. Using X-ray Powder Diffraction (XRD), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Hydrogen temperature-programmed reduction (H₂-TPR), it was shown that the synthesized catalyst is characterized by the localization of easily reduced nickel oxide on alumina surface. This provided low-temperature activation of the catalyst in the reaction mixture containing 4 vol% CO₂. In addition, the synthesized catalyst had higher activity in low-temperature CO₂ methanation compared to industrial NIAP-07-01 catalyst, which contained almost three times more hard-to-reduce nickel–aluminum spinel. Thus, the proposed approaches to the synthesis and activation of the catalyst make it possible to simplify the catalyst preparation procedure and to abandon the use of solvents, which must be disposed of later on.

The Mn-Ce oxide catalysts active in the oxidation of CO were studied by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR), transition electron microscopy (TEM), energy dispersive X-Ray (EDX), and a differential dissolution technique. The Mn-Ce catalysts were prepared by thermal decomposition of oxalates by varying the Mn:Ce ratio. The nanocrystalline oxides with a fluorite structure and particle sizes of 4–6 nm were formed. The introduction of manganese led to a reduction of the oxide particle size, a decrease in the surface area, and the formation of a Mn_yCe_1−yO_2−δ solid solution. An increase in the manganese content resulted in the formation of manganese oxides such as Mn₂O₃, Mn₃O₄, and Mn₅O₈. The catalytic activity as a function of the manganese content had a volcano-like shape. The best catalytic performance was exhibited by the catalyst containing ca. 50 at.% Mn due to the high specific surface area, the formation of the solid solution, and the maximum content of the solid solution.

Doping process is widely used to improving emission performance of MgO films thicker than 10 nm via assisting the surface recharge and changing in electron structure. The present paper briefly reviews this strategy in a search for the new materials and structures being effective for secondary electron emission (SEE) and their diagnostics. Then, Metal-Organic Chemical Vapor Deposition (MOCVD) coupled with the specially selected precursor is suggested here as a new technique that transforms the refractory oxides to nanoscale, defect-disordered materials able to solid-solid interaction at 450 °C. Primary experiments have been performed for demanded mixed films based on MgO with ZrO₂ and CeO₂ additions. A dopant impact on facilitating the formation of oxygen vacancies in the host oxide and on the features of new mixed phases have been studied by new diagnostic means, based primarily on chemical method of differential dissolution. The method brought out the effective solvents that were the probes for identifying the nanoscale and amorphous phases possessing by the different defects on the surface of MgO films and determining contents of these phases. This approach allowed us to explain the origin of mixed phases and to estimate contribution of each from them in the macroscopic SEE properties.

In this work two approaches to the synthesis of energetic complex compound Ni(Im)₆(NO₃)₂ from imidazole and nicklel (II) nitrate were applied: a traditional synthesis from solution and a solvent-free melting-assisted method. According to infrared spectroscopy, X-ray diffraction, elemental and thermal analysis data, it was shown that the solvent-free melt synthesis is a faster, simpler and environmentally friendly method of Ni(Im)₆(NO₃)₂ preparation. The results show that this compound is a promising precursor for the production of nanocrystalline Ni-NiO materials by air-assisted combustion method. The combustion of this complex together with inorganic supports makes it possible to synthesize supported nickel catalysts for different catalytic processes.

In this paper, structural features of the NiO-SiO₂ nanocrystalline catalyst synthesized by the sol-gel method were studied by X-ray diffraction (XRD), high-resolution transmission electron microscopy (TEM), and differential dissolution (DD). The XRD pattern of NiO-SiO₂ significantly differs from the “ideal” NiO pattern: the peaks of the NiO-like phase are asymmetric, especially the 111 diffraction peak. The NiO-SiO₂ nanocrystalline catalyst was investigated by means of XRD simulations based on two approaches: conventional Rietveld analysis and statistical models of 1D disordered crystals. Through a direct simulation of XRD profiles, structural information is extracted from both the Bragg and diffuse scattering. XRD simulations showed that the asymmetry of all the diffraction peaks is due to the presence of two NiO-like oxides with different lattice constants and different average sizes: ~90 wt% of mixed Ni-Si oxide (Ni:Si = 0.14:0.86) with average crystallite sizes (D ~ 27.5 Å) and ~10 wt% of pure NiO (D ~ 50 Å). The high asymmetry of the 111 diffraction peak is due to the appearance of diffuse scattering caused by the inclusion of tetrahedral SiO₂ layers between octahedral NiO layers. Such methods as TEM and DD were applied as independent criteria to prove the structural model, and the results obtained confirm the formation of mixed Ni-Si oxide.