Деградация человеческого потенциала как фактор латентной составляющей деятельности высшей школы Украины

Рассмотрены проблемы тенизации и коррупционности функционирования украин-ской высшей школы на фоне вектора развития показателей потенциала населения страны.Розглянуті проблеми тінізації і коррупційності функціонування української вищої школи на тлі вектору розвитку показників потенціалу населення країни

All-solid-state lithium-sulfur battery based on a nanoconfined LiBH₄ electrolyte

In this work we characterize all-solid-state lithium-sulfur batteries based on nano-confined LiBH4in mesoporous silica as solid electrolytes. The nano-confined LiBH4has fast ionic lithium conductivity at room temperature, 0.1 mScm-1, negligible electronic conductivity and its cationic transport number (t+= 0.96), close to unity, demonstrates a purely cationic conductor. The electrolyte has an excellent stability against lithium metal. The behavior of the batteries is studied by cyclic voltammetry and repeated charge/discharge cycles in galvanostatic conditions. The batteries show very good performance, delivering high capacities versus sulfur mass, typically 1220 mAhg-1after 40 cycles at moderate temperature (55°C), 0.03 C rates and working voltage of 2 V. © The Author(s) 2016

In Situ Transmission Electron Microscopy to Study the Location and Distribution Effect of Pt on the Reduction of Co3O4–SiO2

The addition of Pt generally promotes the reduction of Co3O4 in supported catalysts, which further improves their activity and selectivity. However, due to the limited spatial resolution, how Pt and its location and distribution affect the reduction of Co3O4 remains unclear. Using ex situ and in situ ambient pressure scanning transmission electron microscopy, combined with temperature-programmed reduction, the reduction of silica-supported Co3O4 without Pt and with different location and distribution of Pt is studied. Shrinkage of Co3O4 nanoparticles is directly observed during their reduction, and Pt greatly lowers the reduction temperature. For the first time, the initial reduction of Co3O4 with and without Pt is studied at the nanoscale. The initial reduction of Co3O4 changes from surface to interface between Co3O4 and SiO2. Small Pt nanoparticles located at the interface between Co3O4 and SiO2 promote the reduction of Co3O4 by the detachment of Co3O4/CoO from SiO2. After reduction, the Pt and part of the Co form an alloy with Pt well dispersed. This study for the first time unravels the effects of Pt location and distribution on the reduction of Co3O4 nanoparticles, and helps to design cobalt-based catalysts with efficient use of Pt as a reduction promoter

Carbon supported lithium hydride nanoparticles: Impact of preparation conditions on particle size and hydrogen sorption

Nanosizing of light metal hydrides has yielded significant improvements to their hydrogen storage properties. We explored for the first time a procedure for preparing supported LiH nanoparticles. Impregnation of a carbon framework with a butyllithium solution, followed by reaction with gaseous hydrogen yielded LiH particles ranging in size from 2 nm to the micrometer scale. Reducing the reaction temperature from 300 C to 100 C, as well as the use of a t-butyllithium precursor instead of an n-butyllithium precursor, gave significant improvements on the degree of confinement of the LiH particles. The particle size of the LiH has a significant impact on the hydrogen release profile, 11 nm crystallites begin to release hydrogen as low as 100 C under argon flow, a reduction of roughly 400 C on the macrocrystalline system. The hydrogen release is reversible, with hydrogen uptake after desorption as high as 7.0 wt% w.r.t. LiH (0.8 wt% w.r.t the sample) under 0.1 bar of hydrogen at 200 C and full uptake takes place within 5 min at 26 bar. This new preparation procedure for supported light metal hydrides is particularly relevant for the field of hydrogen storage

Ionic conductivity in complex metal hydride-based nanocomposite materials: The impact of nanostructuring and nanocomposite formation

Complex metal hydrides have recently gained interest as solid electrolytes for all-solid-state batteries due to their light weight, easy deformability, and fast ion mobility at elevated temperatures. However, increasing their low conductivity at room temperature is a prerequisite for application. In this review, two strategies to enhance room temperature conductivity in complex metal hydrides, nanostructuring and nanocomposite formation, are highlighted. First, the recent achievements in nanostructured complex metal hydride-based ion conductors and complex metal hydride/metal oxide nanocomposite ion conductors are summarized, and the trends and challenges in their preparation are discussed. Then, the reported all-solid-state batteries based on complex metal hydride nanocomposite electrolytes are highlighted. Finally, future research directions and perspectives are proposed, both for the preparation of improved metal hydride ion conductors, as well as metal hydride-based all-solid-state batteries

Particle Size Effects in the Selective Hydrogenation of Alkadienes over Supported Cu Nanoparticles

Copper is considered an excellent alternative to noble-metal selective hydrogenation catalysts. Herein, we systematically studied the effect of Cu nanoparticle size (2–10 nm) in the selective hydrogenation of 1,3-butadiene in excess of propene. The catalysts exhibited particle size-dependent activity, with particles above 4 nm being 3 to 4 times more active than the 2 nm ones, and at the same time more selective (up to 99 % at almost full butadiene conversion for 7–10 nm particles). The higher activity of larger particles was ascribed to a higher fraction of kinks and step sites, essential to activate hydrogen. The high selectivity of nanoparticulate Cu catalysts was explained by a very strong preferential adsorption of 1,3-butadiene compared to mono-olefin adsorption on the Cu surface (in particular on larger particles), as proven via adsorption measurements. These findings may guide both testing and catalyst design for reactions where hydrogen surface availability and selectivity play a key role

Surface-modified carbon materials for CO2 electroreduction

The electrochemical reduction of CO2 to produce sustainable fuels and chemicals has attracted great attention in recent years. It is shown that surface-modified carbons catalyze the CO2RR. This study reports a strategy to modify the surface of commercially available carbon materials by adding oxygen and nitrogen surface groups without modifying its graphitic structure. Clear differences in CO2RR activity, selectivity and the turnover frequency between the surface-modified carbons were observed, and these differences were ascribed to the nature of the surface groups chemistry and the point of zero charge (PZC). The results show that nitrogen-containing surface groups are highly selective towards the formation of CO from the electroreduction of CO2 in comparison with the oxygen-containing surface groups, and the carbon without surface groups. This demonstrates that the selectivity of carbon for CO2RR can be rationally tuned by simply altering the surface chemistry via surface functionalization

Carbon Nanofiber Growth Rates on NiCu Catalysts: Quantitative Coupling of Macroscopic and Nanoscale In Situ Studies

Since recently, gas-cell transmission electron microscopy allows for direct, nanoscale imaging of catalysts during reaction. However, often systems are too perturbed by the imaging conditions to be relevant for real-life catalyzed conversions. We followed carbon nanofiber growth from NiCu-catalyzed methane decomposition under working conditions (550 °C, 1 bar of 5% H2, 45% CH4, and 50% Ar), directly comparing the time-resolved overall carbon growth rates in a reactor (measured gravimetrically) and nanometer-scale carbon growth observations (by electron microscopy). Good quantitative agreement in time-dependent growth rates allowed for validation of the electron microscopy measurements and detailed insight into the contribution of individual catalyst nanoparticles in these inherently heterogeneous catalysts to the overall carbon growth. The smallest particles did not contribute significantly to carbon growth, while larger particles (8-16 nm) exhibited high carbon growth rates but deactivated quickly. Even larger particles grew carbon slowly without significant deactivation. This methodology paves the way to understanding macroscopic rates of catalyzed reactions based on nanoscale in situ observations

Influence of atmosphere, interparticle distance and support on the stability of silver on α-alumina for ethylene epoxidation

The stability of supported metal particles is an important parameter in heterogenous catalysis. For silver catalysts supported on α-alumina, industrially used in ethylene epoxidation, the loss of silver surface area as result of particle growth is one of the most important deactivation mechanisms. In this work, the growth of silver particles was investigated by exposing catalysts to thermal treatments. The presence of oxygen during heating strongly enhanced particle growth, and the interparticle distance was a crucial parameter. However, restricting movement of complete silver particles using cage-like α-alumina did not limit particle growth. These findings indicate that Ostwald ripening was the dominant mechanism behind particle growth, with the diffusion of oxidized silver species being a rate limiting factor. Finally, higher surface area α-alumina provided better silver stability during ethylene epoxidation, with only limited decrease in selectivity. This makes silver supported on high surface area α-alumina promising candidates for ethylene epoxidation catalysis