1,721,013 research outputs found
G.W. Russell - A.E. : The Descent of the Gods - The Mystical Writings of G.W. Russell - A.E., edited and introduced by Raghavan and Nandini Iyer
No full textFierobe Claude. G.W. Russell - A.E. : The Descent of the Gods - The Mystical Writings of G.W. Russell - A.E., edited and introduced by Raghavan and Nandini Iyer. In: Études irlandaises, n°14-1, 1989. pp. 218-220
XAS of carbon supported platinum fuel cell electrocatalysts: advances towards real time investigations
No full textThe utility of XAS to provide detailed information regarding the structure of supported electrocatalysts has previously been demonstrated. A review of the literature relating to carbon supported Pt fuel cell electrocatalysts is presented. Improvements in the time resolution of the data collection which have become possible with the introduction of energy dispersive monochromators are discussed and a critical analysis of the effect of these improvements is presented
Dataset for: Evaluation of existing methods to extract microplastics from bivalve tissue: adapted KOH digestion protocol improves filtration at single-digit pore size
No full textDataset supporting: Thiele, C.J., Hudson, M. D. & Russell, A. E. (2019). Evaluation of existing methods to extract microplastics from bivalve tissue: adapted KOH digestion protocol improves filtration at single-digit pore size. Marine Pollution Bulletin.</span
Ethanol, O, and CO adsorption on Pt nanoparticles: effects of nanoparticle size and graphene support
No full textPt nanoparticles dispersed over carbonaceous supports are widely used as catalysts for different applications, making studies on the interplay between size and support effects indispensable for rational catalyst design. Here, we use DFT calculations to simulate the interaction between O, CO, and ethanol with free platinum cuboctahedral nanoparticles with up to 147 atoms and with the same Pt nanoparticles supported on a single layer of graphene with up to 720 carbon atoms. We compute adsorption energies for each adsorbate on different adsorption sites for supported and unsupported Pt nanoparticles. We show that as the Pt nanoparticle grows the adsorption energy decreases, and that the size effect is more important for O and CO adsorption than for ethanol. We observe that the generalized coordination number of each adsorption site controls the interaction strength for O and CO to a much larger extent than for ethanol. Electronic charge redistributions and density of states projected on the d band of the interacting Pt facets are used to obtain a better understanding of the differences between the electronic interactions for each adsorbate. For Pt nanoparticles supported on graphene, the support effects weaken the adsorption energies for all the adsorbates, but this effect rapidly decreases with larger nanoparticles, and it is only significant for our smallest nanoparticle Pt13. By demonstrating that the effects of nanoparticle size and support are different for ethanol as compared with O and CO, we conclude that it should be possible to modify different parameters in the catalyst design in order to tune the Pt nanoparticle to interact with specific adsorbates
EXAFS of carbon monoxide oxidation on supported Pt fuel cell electrocatalysts
No full textThe potential dependence of the extended X-ray absorption fine structure (EXAFS) obtained at the Pt LIII absorption edge for a carbon supported Pt electrocatalyst exposed to carbon monoxide is presented. The data have been analyzed using the difference file method to separate the dominant contributions of the Pt neighbors from contributions to the EXAFS from the adsorbed species. The presence of adsorbed CO is clearly observed with a Pt-C distance of 1.85 Å at potentials less than 0.5 V vs RHE. Increasing the potential above 0.5 V resulted first in the removal of the adsorbed CO and at more positive potentials, e.g., 1.05 V, in the formation of an oxide layer, as evidenced by the presence of a Pt-O coordination shell at 2.00 Å. These results demonstrate that in situ EXAFS of supported Pt electrocatalysts may be used to probe adsorbate structures
Microscopic infrared mapping of chloromethylated polystyrene resin beads
No full textIn solid-phase combinatorial chemistry, analyses are performed using a wide range of analytical techniques ranging from gel-phase nuclear magnetic resonance (NMR) to colorimetric tests to elemental analysis. However, these techniques cannot be used to interrogate functional group distribution at the single-bead level. This paper explores the feasibility of using Fourier transform infrared (FTIR) microscopy to examine site distribution on chloromethylated polystyrene resin beads and to quantify the loading after coupling with 4-cyanophenol, an IR tagging agent. FT-IR microscopy also provides a unique opportunity to better understand the reactivity of highly cross-linked polymer beads
under a range of chemical conditions
A parallel optical screen for the rapid combinatorial electrochromic analysis of electrochemical materials
No full textA high-throughput optical screen designed to reduce costs and accelerate the screening of libraries of electroactive materials, in particular fuel-cell electrocatalysts and battery materials, is presented. The methodology uses an electrochromic film as a counter electrode, and makes use of spatially varying color change across this screening counter electrode as differing amounts of charge are passed across the array during a test reaction
AMnO<sub>3</sub> (A = Sr, La, Ca, Y) perovskite oxides as oxygen reduction electrocatalysts
No full textA series of perovskite-type manganites AMnO3 (A = Sr, La, Ca and Y) particles were investigated as electrocatalysts for the oxygen reduction reaction. AMnO3 materials were synthesized by means of an ionic-liquid method, yielding phase pure particles at different temperatures. Depending on the calcination temperature, particles with mean diameter between 20 and 150 nm were obtained. Bulk versus surface composition and structure are probed by X-ray photoelectron spectroscopy and extended X-ray absorption fine structure. Electrochemical studies were performed on composite carbon-oxide electrodes in alkaline environment. The electrocatalytic activity is discussed in terms of the effective Mn oxidation state, A:Mn particle surface ratio and the Mn–O distances.</p
Combinatorial arrays and parallel screening for positive electrode discovery
No full textCombinatorial techniques have been applied to the preparation and screening of positive electrode candidates for lithium batteries. This work describes the automated parallel synthesis of 64-electrode arrays using a Packard Multiprobe II liquid handling system. A cell was constructed with a single lithium reference–counter electrode and 64, three-millimeter-diameter working electrodes containing LixMn2O4 active material, PVdF–HFP binder and carbon black as a conducting additive. Eight duplicate electrodes, each of eight respective compositions, were deposited on the array and the mass fraction of carbon was varied in steps from 1 to 25%. The results showed a rapid increase in capacity at the percolation limit of 3% for most cells. Some groups of nominally identical cells showed random variations in capacity, especially at low carbon loadings. The overall result is a demonstration of advantages of the combinatorial concept, which were time-saving and an improved statistical significance of the results compared with on–off experiments
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