scholarly journals Development of a PtSn bimetallic catalyst for direct fuel cells using bio-butanol fuel

2015 ◽  
Vol 51 (69) ◽  
pp. 13412-13415 ◽  
Author(s):  
V. K. Puthiyapura ◽  
D. J. L. Brett ◽  
A. E. Russell ◽  
W. F. Lin ◽  
C. Hardacre
Keyword(s):  
Activation Energy ◽  
Fuel Cells ◽  
Bimetallic Catalyst ◽  
Lower Activation ◽  
Lower Activation Energy

PtSn showed a higher activity and lower activation energy towards butanol electrooxidation compared to pure Pt.

The diffusion of Fe2+ ions in spinels with relevance to the process of maghemitization

1980 ◽  
Vol 43 (331) ◽  
pp. 889-899 ◽  
Author(s):  
W. Freer ◽  
R. O'Reilly
Keyword(s):  
Activation Energy ◽  
Spinel Structure ◽  
Single Phase ◽  
Sea Water ◽  
Magnetic Minerals ◽  
Magnetic Studies ◽  
Water Leaching ◽  
Lower Activation ◽  
Diffusion Activation ◽  
Lower Activation Energy

SummaryThe maghemitization process, by which magnetic minerals with spinel structure become progressively oxidized but remain single phase spinels, seems to be an important feature of submarine weathering. Whether the process takes place by the minerals acquiring oxygen from the sea-water or by the sea-water leaching out iron, the controlling process is the diffusion of Fe2+ in the spinel structure. Magnetic studies have suggested that during maghemitization the availability for oxidation of Fe2+ in the tetrahedral (A) sites of the spinel structure is much less than that in octahedral (B) sites. In this study the Fe2+-containing spinels FeAl2O4, FeCr2O4, FeGa2O4, and Fe2GeO4, in which Fe2+ is predominantly in either A or B sites were prepared, and the diffusion of Fe2+ was studied by (1) interdiffusion experiments with the Mg2+ counterparts and (2) oxidation experiments in air. Fe2GeO4 (Fe2+ in B sites) was found to be associated with a higher interdiffusion coefficient and lower activation energy than FeAl2O4 (75% Fe2+ in A sites). Oxidation/diffusion activation energies of 0.27 and 0.71 eV were assigned to Fe2+ in B and A sites respectively. The experiments thus provide support for the maghemitization model in which Fe2+ in B sites is preferentially oxidized.

One, two, and three-dimensional metal–organic coordination polymers derived from enantiopure organic phosphorate: homochirality, water stability and proton conduction

CrystEngComm ◽  
2017 ◽  
Vol 19 (42) ◽  
pp. 6325-6332 ◽  
Author(s):  
Xiaoqiang Liang ◽  
Kun Cai ◽  
Feng Zhang ◽  
Jia Liu ◽  
Guangshan Zhu
Keyword(s):  
Activation Energy ◽  
Metal Ions ◽  
Coordination Polymers ◽  
Three Dimensional ◽  
High Water ◽  
Water Stability ◽  
Lower Activation ◽  
Metal Organic ◽  
Lower Activation Energy ◽  
Multifunctional Ligand

A multifunctional ligand reacts with metal ions to generate three new coordination polymers, where 3 has a high water stability, a moderate proton conductivity and a lower activation energy.

scholarly journals Differential Activation Energy and NBO Interaction Approaches to Torquoselectivity and Its Dependence on the Conformational Profile of the Substituent

2021 ◽  
Author(s):  
Veejendra Yadav
Keyword(s):  
Activation Energy ◽  
Ring Opening ◽  
Energy Approach ◽  
Differential Activation ◽  
Distinct Level ◽  
Lower Activation ◽  
Secondary Reactions ◽  
The Subject ◽  
Interaction Approach ◽  
Lower Activation Energy

The torquoselectivity of ring opening of 3-CF<sub>3</sub>-cyclobutene, 3-CHF<sub>2</sub>-cyclobutene, 3-CH<sub>2</sub>F-cyclobutene, 3-CF<sub>3</sub>-oxetene and perfluoro-3-CH<sub>3</sub>-cyclobutene have been studied at the MP2/cc-pVTZ level of theory and the results analysed by using the differential activation energy approach and also differential NBO interactions of the breaking ring bond with the substituent bonds. The outward or inward ring opening that has lower activation energy in the differential activation energy approach or larger interaction in the differential NBO interaction approach constitutes the preferred mode. The predictions from the two approaches are largely found to be contradicting each other, specifically when the substituent is electron-deficient. The CHF<sub>2</sub> and CH<sub>2</sub>F substituents on cyclobutene and oxetene can adopt three distinct conformations with respect to the cleaving ring bond. It has been discovered that each conformer exhibits a distinct level of torquoselectivity and some may even contribute to the overall selectivity substantially. The conformational profile of the substituent, therefore, is recommended to be taken into account in any serious treatment of the subject. The experimental torquoselectivity, if otherwise, is a likely consequence of secondary reactions, specifically equilibration through reaction reversal while honouring the relative thermodynamic stabilities of the ring opened products.

scholarly journals Differential Activation Energy and NBO Interaction Approaches to Torquoselectivity and Its Dependence on the Conformational Profile of the Substituent

2020 ◽  
Author(s):  
Veejendra Yadav
Keyword(s):  
Activation Energy ◽  
Ring Opening ◽  
Energy Approach ◽  
Differential Activation ◽  
Distinct Level ◽  
Lower Activation ◽  
Secondary Reactions ◽  
The Subject ◽  
Interaction Approach ◽  
Lower Activation Energy

The torquoselectivity of ring opening of 3-CF<sub>3</sub>-cyclobutene, 3-CHF<sub>2</sub>-cyclobutene, 3-CH<sub>2</sub>F-cyclobutene, 3-CF<sub>3</sub>-oxetene and perfluoro-3-CH<sub>3</sub>-cyclobutene have been studied at the MP2/cc-pVTZ level of theory and the results analysed by using the differential activation energy approach and also differential NBO interactions of the breaking ring bond with the substituent bonds. The outward or inward ring opening that has lower activation energy in the differential activation energy approach or larger interaction in the differential NBO interaction approach constitutes the preferred mode. The predictions from the two approaches are largely found to be contradicting each other, specifically when the substituent is electron-deficient. The CHF<sub>2</sub> and CH<sub>2</sub>F substituents on cyclobutene and oxetene can adopt three distinct conformations with respect to the cleaving ring bond. It has been discovered that each conformer exhibits a distinct level of torquoselectivity and some may even contribute to the overall selectivity substantially. The conformational profile of the substituent, therefore, is recommended to be taken into account in any serious treatment of the subject. The experimental torquoselectivity, if otherwise, is a likely consequence of secondary reactions, specifically equilibration through reaction reversal while honouring the relative thermodynamic stabilities of the ring opened products.

scholarly journals Electrical Conduction Characteristic of a 2D MXene Device with Cu/Cr2C/TiN Structure Based on Density Functional Theory

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3671
Author(s):  
Lei Wang ◽  
Jing Wen ◽  
Yuan Jiang ◽  
Qiaofeng Ou ◽  
Lei Yu ◽  
...  
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Density Functional Theory ◽  
Electrical Conduction ◽  
Density Functional ◽  
First Principle ◽  
Functional Theory ◽  
Lower Activation ◽  
Lower Activation Energy ◽  
Memristor Device

The electronic structure and the corresponding electrical conductive behavior of the Cu/Cr2C/TiN stack were assessed according to a newly developed first-principle model based on density functional theory. Using an additional Cr2C layer provides the metal-like characteristic of the Cu/Cr2C/TiN stack with much larger electrical conduction coefficients (i.e., mobility, diffusivity, and electrical conductivity) than the conventional Ag/Ti3C2/Pt stack due to the lower activation energy. This device is therefore capable of offering faster switching speeds, lower programming voltage, and better stability and durability than the memristor device with conventional Ti3C2 MXene.

Comparison of the High-Temperature Deformation of Alumina-Zirconia and Alumina-Zirconia-Mullite Composites

2005 ◽  
Vol 20 (1) ◽  
pp. 13-17 ◽  
Author(s):  
Tiandan Chen ◽  
Martha L. Mecartney
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
Strain Rate ◽  
Stress Exponent ◽  
Creep Behavior ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Reactive Processing ◽  
Lower Activation ◽  
Lower Activation Energy

An alumina-based ceramic codispersed with 15 vol% zirconia and 15 vol% mullite (AZM) was synthesized by reactive processing, and the creep behavior was compared to alumina with 30 vol% zirconia (AZ). Constant stress compressive creep behavior for AZM exhibited a stress exponent of 2 and an activation energy of 770 KJ/mol, while a similar stress exponent but lower activation energy of 660 KJ/mol was found for AZ. The strain rate of AZM, however, was more than twice that of the AZ under the same deformation conditions, indicating a better potential for superplastic shape forming.

Electromigration of Cu Interconnect Lines Prepared by a Plasma-based Etch Process

2008 ◽  
Vol 1079 ◽  
Author(s):  
Guojun Liu ◽  
Yue Kuo
Keyword(s):  
Activation Energy ◽  
Bending Stress ◽  
Lifetime Test ◽  
Lower Activation ◽  
Diffusion Paths ◽  
Mechanical Bending ◽  
Cu Interconnect ◽  
Interconnect Lines ◽  
A Current ◽  
Lower Activation Energy

ABSTRACTThe electromigration performance of Cu lines patterned by a Cl2 plasma-based etch process has been studied with the accelerated isothermal lifetime test. An electromigration activation energy of 0.6 eV and a current density acceleration exponent of 2.7 were obtained. Both the copper-silicon nitride cap layer interface and the copper grain boundary were active diffusion paths. The applied mechanical bending stress changed the electromigration void distribution in the film, which leaded to the shorter lifetime and lower activation energy.

scholarly journals Comment on “Enhanced water permeability and tunable ion selectivity in subnanometer carbon nanotube porins”

Science ◽  
2018 ◽  
Vol 359 (6383) ◽  
pp. eaap9173 ◽  
Author(s):  
Andreas Horner ◽  
Peter Pohl
Keyword(s):  
Activation Energy ◽  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Water Transport ◽  
Water Permeability ◽  
Ion Selectivity ◽  
Membrane Interface ◽  
Single File ◽  
Lower Activation ◽  
Lower Activation Energy

Tunuguntla et al. (Reports, 25 August 2017, p. 792) report that permeation of single-file water occurs faster through carbon nanotubes than through aquaporins. We show that this conclusion violates fundamental thermodynamic laws: Because of its much lower activation energy, aquaporin-mediated water transport must be orders of magnitude faster. Leakage at the nanotube-membrane interface may explain the discrepancy.

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