scholarly journals Tuning the electronic structure of Ag-Pd alloys to enhance performance for alkaline oxygen reduction

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
José A. Zamora Zeledón ◽  
Michaela Burke Stevens ◽  
G. T. Kasun Kalhara Gunasooriya ◽  
Alessandro Gallo ◽  
Alan T. Landers ◽  
...  
Keyword(s):  
Metal Binding ◽  
Precious Metal ◽  
Metal Content ◽  
Density Functional ◽  
Binding Energies ◽  
Intrinsic Activity ◽  
Energy Technologies ◽  
Highly Active ◽  
Wide Range ◽  
Precious Metal Content

AbstractAlloying is a powerful tool that can improve the electrocatalytic performance and viability of diverse electrochemical renewable energy technologies. Herein, we enhance the activity of Pd-based electrocatalysts via Ag-Pd alloying while simultaneously lowering precious metal content in a broad-range compositional study focusing on highly comparable Ag-Pd thin films synthesized systematically via electron-beam physical vapor co-deposition. Cyclic voltammetry in 0.1 M KOH shows enhancements across a wide range of alloys; even slight alloying with Ag (e.g. Ag0.1Pd0.9) leads to intrinsic activity enhancements up to 5-fold at 0.9 V vs. RHE compared to pure Pd. Based on density functional theory and x-ray absorption, we hypothesize that these enhancements arise mainly from ligand effects that optimize adsorbate–metal binding energies with enhanced Ag-Pd hybridization. This work shows the versatility of coupled experimental-theoretical methods in designing materials with specific and tunable properties and aids the development of highly active electrocatalysts with decreased precious-metal content.

Money and Flows of Coinage in the Red Sea Trade

2017 ◽  
Author(s):  
Dario Nappo
Keyword(s):  
Red Sea ◽  
Precious Metal ◽  
Metal Content ◽  
Silver Content ◽  
Second Century ◽  
Roman Coins ◽  
Precious Metal Content ◽  
The Face ◽  
Over Time

This chapter considers the financial scale of Indo-Roman trade via the Red Sea, comparing the large sums mentioned by Pliny with the evidence of customs dues, ostraca from the Red Sea port of Berenike, and hoards of Roman coins found in India. Analysis of the finds of Roman coins in India by value rather than number over time suggests that, contrary to prevailing opinion, there was not a major diminution in the value of the trade after the reign of Tiberius. Although there was apparently some decline in the Flavian period, the face value of coin finds recovers in the second century until the reign of Antoninus Pius. Coins for export to India were specially selected for their higher precious metal content, and older issues with a higher silver content continued to be exported to India long after they had largely ceased to circulate within the Roman Mediterranean.

The Fiery Test of Critique

2021 ◽  
Author(s):  
Ian Proops
Keyword(s):  
Natural Science ◽  
Precious Metal ◽  
Metal Content ◽  
Philosophical Method ◽  
Indirect Proof ◽  
Precious Metal Content ◽  
Self Knowledge ◽  
Justification Of Faith ◽  
Comprehensive Study

The book aims to provide a comprehensive study of the ‘Transcendental Dialectic’ of Kant’s first Critique. It argues that Kant conceives of ‘critique’ as a kind of winnowing exercise, aimed to separate the wheat of good metaphysics from the chaff of bad. However, he uses a less familiar metaphor to make this point, namely, that of ‘the fiery test of critique’. This turns out to be, not a medieval ordeal (a trial by fire), but rather a metallurgical assay: so-called ‘cupellation’—a procedure in which ore samples are tested for their precious-metal content. The upshot is that critique has a positive, investigatory side: it seeks not merely to eliminate the dross of bad ‘dogmatic’ metaphysics but also to uncover any hidden nuggets of value that might be contained in traditional speculative metaphysics. There are both gold and silver to be found. The gold is the indirect proof of Transcendental Idealism afforded by the resolution of the Antinomies, the silver Kant’s defence of theoretically grounded ‘doctrinal beliefs’ in a wise and great originator and in an afterlife. In the course of making these points, the book engages with Kant’s views on a number of central problems in philosophy and meta-philosophy, including: the explanation of the enduring human impulse towards metaphysics, correct philosophical method, the limits of self-knowledge, the possibility of human freedom, the resolution of metaphysical paradox (‘Antinomy’), the justification of faith, the nature of scepticism, and the role of ‘as if’ reasoning in natural science.

Assessment of Hazardous and Precious Metal Content in E-Waste

2021 ◽  
pp. 65-72
Author(s):  
T. T. Meem ◽  
M. S. Khan ◽  
M. M. Hassan ◽  
R. Mamtaz
Keyword(s):  
Precious Metal ◽  
Metal Content ◽  
Precious Metal Content

scholarly journals A self-adjusting platinum surface for acetone hydrogenation

2020 ◽  
Vol 117 (7) ◽  
pp. 3446-3450 ◽  
Author(s):  
Benginur Demir ◽  
Thomas Kropp ◽  
Keishla R. Rivera-Dones ◽  
Elise B. Gilcher ◽  
George W. Huber ◽  
...  
Keyword(s):  
Reaction Kinetics ◽  
Density Functional ◽  
Surface Coverage ◽  
Binding Energies ◽  
Microkinetic Modeling ◽  
Reaction Conditions ◽  
Platinum Surface ◽  
Kinetics Parameters ◽  
Supported Platinum Catalysts ◽  
Wide Range

We show that platinum displays a self-adjusting surface that is active for the hydrogenation of acetone over a wide range of reaction conditions. Reaction kinetics measurements under steady-state and transient conditions at temperatures near 350 K, electronic structure calculations employing density-functional theory, and microkinetic modeling were employed to study this behavior over supported platinum catalysts. The importance of surface coverage effects was highlighted by evaluating the transient response of isopropanol formation following either removal of the reactant ketone from the feed, or its substitution with a similarly structured species. The extent to which adsorbed intermediates that lead to the formation of isopropanol were removed from the catalytic surface was observed to be higher following ketone substitution in comparison to its removal, indicating that surface species leading to isopropanol become more strongly adsorbed on the surface as the coverage decreases during the desorption experiment. This phenomenon occurs as a result of adsorbate–adsorbate repulsive interactions on the catalyst surface which adjust with respect to the reaction conditions. Reaction kinetics parameters obtained experimentally were in agreement with those predicted by microkinetic modeling when the binding energies, activation energies, and entropies of adsorbed species and transition states were expressed as a function of surface coverage of the most abundant surface intermediate (MASI, C3H6OH*). It is important that these effects of surface coverage be incorporated dynamically in the microkinetic model (e.g., using the Bragg–Williams approximation) to describe the experimental data over a wide range of acetone partial pressures.

Computational study of Mg insertion into amorphous silicon: advantageous energetics over crystalline silicon for Mg storage

2013 ◽  
Vol 1540 ◽  
Author(s):  
Fleur Legrain ◽  
Oleksandr I. Malyi ◽  
Teck L. Tan ◽  
Sergei Manzhos
Keyword(s):  
Density Functional ◽  
Nearest Neighbor ◽  
Defect Formation ◽  
Crystalline Silicon ◽  
Computational Study ◽  
Binding Energies ◽  
Functional Theory ◽  
Wide Range ◽  
Insertion Sites ◽  
Formation Energies

ABSTRACTWe show in a theoretical density functional theory study that amorphous Si (a-Si) has more favorable energetics for Mg storage compared to crystalline Si (c-Si). Specifically, Mg and Li insertion is compared in a model a-Si simulation cell. Multiple sites for Mg insertion with a wide range of binding energies are identified. For many sites, Mg defect formation energies are negative, whereas they are positive in c-Si. Moreover, while clustering in c-Si destabilizes the insertion sites (by about 0.1/0.2 eV per atom for nearest-neighbor Li/Mg), it is found to stabilize some of the insertion sites for both Li (by up to 0.27 eV) and Mg (by up to 0.35 eV) in a-Si. This could have significant implications on the performance of Si anodes in Mg batteries.

Geochemical systematics and precious metal content of the sedimentary horizons of Lower Gondwanas from the Sattupalli coal field, Godavari Valley, India

2011 ◽  
Vol 88 (2-3) ◽  
pp. 83-100 ◽  
Author(s):  
P.K. Prachiti ◽  
C. Manikyamba ◽  
Prakash K. Singh ◽  
V. Balaram ◽  
G. Lakshminarayana ◽  
...  
Keyword(s):  
Precious Metal ◽  
Metal Content ◽  
Coal Field ◽  
Precious Metal Content ◽  
Godavari Valley

Interaction mechanisms and structural properties of B-, Si-doped C60 fullerenes with 1-formylpiperazine

2016 ◽  
Vol 39 (5-6) ◽  
Author(s):  
Cemal Parlak ◽  
Özgür Alver ◽  
Ponnadurai Ramasami
Keyword(s):  
Electronic Properties ◽  
Density Functional ◽  
Interaction Mechanism ◽  
Potential Interaction ◽  
Binding Energies ◽  
Molecular Structures ◽  
Interaction Mechanisms ◽  
Wide Range ◽  
Si Doped ◽  
Physical And Chemical

AbstractPiperazines and fullerene nanocages are versatile compounds. These are discussed in a wide range of academic work, especially in the field of medicine, and considered for various applications by the pharmaceutical industry. In the present research, the potential interaction mechanisms between B-, Si-doped C60 and 1-formylpiperazine (1-fp) were examined within the framework of density functional theory, along with their optimized molecular structures and electronic properties. The calculated binding energies and various other physical and chemical parameters of 1-fp found in this work in comparison with the Si- and B-doped fullerenes suggest that doping of fullerene nanocage leads to a strong interaction mechanism that alters the chemical and electronic properties of the investigated compounds. This finding can be used as a guide for their further applications.

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