Molecular Volumes and the Stokes-Einstein Equation.
TL;DR: In this article, a simple notion of the volume of a molecule was adopted to produce an empirical correction factor for the Stokes equation to enable one to apply it to molecules down to two angstroms in radius.
Abstract: By adopting a simple notion of the volume of a molecule it has been possible to produce an empirical correction factor for the Stokes equation to enable one to apply it to molecules down to two angstroms in radius.
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TL;DR: In this paper, a probe molecule coumarin 153 (Cu153) and picosecond spectroscopic techniques were used to examine the solvation dynamics in polar liquids and showed that the frequency of the electronic spectrum of this probe provides a convenient measure of solvation energetics.
Abstract: Solvation dynamics in polar liquids have been examined using the probe molecule coumarin 153 (Cu153) and picosecond spectroscopic techniques. Steady‐state absorption and fluorescence spectra of Cu153 as a function of solvent show that the frequency of the electronic spectrum of this probe provides a convenient measure of solvation energetics. Both nonspecific dipolar and to a smaller degree H‐bonding solute–solvent interactions are involved. Time‐correlated single photon counting was used to observe time‐dependent shifts of the fluorescence spectrum of Cu153 in a variety of alcohols, propylene carbonate, and N‐methylpropionamide solvents as a function of temperature. These time‐dependent spectral shifts provide a direct measure of the time dependence of the solvation process. Theoretical models that treat the solvent as a dielectric continuum do not adequately account for the observed solvation dynamics. In the solvents studied, such theories predict a single exponential shift of the fluorescence spectrum...
1,127 citations
TL;DR: Molybdenum disulphide is identified as a promising cost-effective substitute for noble metal catalysts and shows superior carbon dioxide reduction performance compared with the noble metals with a high current density and low overpotential in an ionic liquid.
Abstract: Electrochemical reduction is one process to produce higher value chemicals from carbon dioxide, and it is typically catalysed by noble metals. Here, the authors demonstrate that molybdenum disulphide is also capable of efficiently catalysing the reaction in the presence of an ionic liquid.
616 citations
485 citations
TL;DR: The methodological procedures that can be used to obtain accurate molecular sizes in solution from diffusion NMR spectroscopy, and how to take into account the size of the solute with respect to that of the solvent and its non-spherical shape using the appropriate correction factors in the frictional coefficient are reviewed.
Abstract: This tutorial review deals with the methodological procedures that can be used to obtain accurate molecular sizes in solution from diffusion NMR spectroscopy. The critical aspects associated with the estimation of the size of molecules from the measured translational self-diffusion coefficient, using the Stokes–Einstein equation, are highlighted and discussed. From a theoretical point of view, it is shown how to take into account the size of the solute with respect to that of the solvent and its non-spherical shape using the appropriate correction factors in the frictional coefficient. From a practical point of view, the advantages of introducing an internal standard in the sample are presented. Initially, non-aggregating systems are considered in an attempt to clarify what hydrodynamic dimensions mean. Successively, aggregating systems are addressed showing how it is possible to understand the aggregation level and derive the thermodynamic parameters for some illustrative aggregation processes.
462 citations
TL;DR: In this paper, a review of various innovative strategies used in material development, as well as the electrochemical properties of possible anode, cathode and electrolyte combinations are unravelled.
Abstract: The demand for electrochemical energy storage technologies is rapidly increasing due to the proliferation of renewable energy sources and the emerging markets of grid- scale battery applications. The properties of batteries and electrochemical energy storage (EES) technologies ideal for most of these applications, yet, faced with resource constraints, the ability of current lithium-ion batteries (LIB) to match this overwhelming demand is uncertain. Sodium-ion batteries (SIB) are a novel class of batteries with similar performance characteristics to LIB. Since they are composed of earth abundant elements, cheaper and utility scale battery modules can be assembled. As a result of the learning curve in LIB technology, a phenomenal progression in material development has been realised in the SIB concept. In this SIB review, various innovative strategies used in material development, as well as the electrochemical properties of possible anode, cathode and electrolyte combinations are unravelled. Attractive performance characteristics are herein evidenced, based on comparative gravimetric and volumetric energy densities to state-of-the-art LIB. Furthermore, opportunities and challenges towards commercialization are herein discussed. Combined with more industrial adaptations, the commercial prospects of SIB look promising and this challenging new technology is set to play a major role in grid-scale EES applications.
426 citations
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