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

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

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

Influence of the Support on Propene Oxidation over Gold Catalysts

The epoxidation of propene without forming a substantial amount of byproducts is one of the holy grails of catalysis. Supported Cu, Ag and Au catalysts are studied for this reaction and the activity of the supported metals is generally well understood. On the contrary, limited information is available on the influence of the support on the epoxide selectivity. The reaction of propene with equal amounts of hydrogen and oxygen was tested over gold nanoparticles deposited onto CeO2, TiO2, WO3, γ‐Al2O3, SiO2, TiO2‐SiO2 and titanosilicate‐1. Several metal oxide supports caused further conversion of the synthesized propene oxide. Strongly acidic supports, such as WO3 and titanosilicate‐1, catalyzed the isomerization of propene oxide towards propanal and acetone. Key factors for achieving high PO selectivity are having inert or neutralized surface sites, a low specific surface and/or a low density of surface ‐OH groups. This work provides insights and practical guidelines to which metal oxide support properties lead to which products in the reaction of propene in the presence of oxygen and hydrogen over supported gold catalysts