Size-Dependent Kinetics of Hydriding and Dehydriding of Pd Nanoparticles

Using a new indirect nanoplasmonic sensing method with subsecond resolution, we have studied hydriding and dehydriding kinetics of Pd nanoparticles in the size range 1.8-5.4 nm. Strong particle-size effects are observed. The scaling of the hydriding and dehydriding time scales satisfies power and power-exponential laws. The former (with an exponent of 2.9) is in perfect agreement with Monte Carlo simulations of diffusion-controlled hydriding kinetics. The latter is explained by the effect of surface tension on hydrogen desorption from the surface layer. The approach is generalizable to other reactant-nanoparticle systems

Thermodynamics of hydride formation and decomposition in supported sub-10 nm Pd nanoparticles of different sizes

Hydrogen storage properties of supported Pd nanoparticles with average sizes in the range 2.7-7.6 nm were studied using indirect nanoplasmonic sensing. For each particle size, a series of isotherms was measured and, through Van't Hoff analysis, the changes in enthalpy upon hydride formation/decomposition were determined. Contrary to the expected decrease of the enthalpy, due to increasing importance of surface tension in smaller particles, we observe a very weak size dependence in the size range under consideration. We attribute this to a compensation effect due to an increased fraction of hydrogen atoms occupying energetically favorable subsurface sites in smaller nanoparticles

Geochemical features of the elemental composition of meadowsweet (Filipendula ulmaria (L).Maxim) in Kemerovo Oblast

Biogeochemical sampling of the aboveground part of meadowsweet (Fillipendula Ulmaria (L). Maxim) allowed us to study ecological and geochemical features of 10 regions in Kemerovo Oblast, including both natural and man-made landscapes. The content of 55 elements in the plant is determined by ICP-MS. Statistical analysis of the results allowed us to establish the effect of the soil mineral composition and the mining region specificity on the elemental composition of meadowsweet, to reveal significant positive correlations of the elements and to establish a statistically significant difference in the studied areas on the basis of the content of some elements. Sample reference to one of the clusters, followed by an assessment of their geochemical features is determined by the K-average method