Ethylene Hydrogenation on a Platinum Nanocoating at Various Electric Potentials

The acceleration of Faradaic reactions by oscillating electric potentials has emerged as a viable tool to enhance electrocatalysis, but the non-Faradaic dynamic promotion of thermal catalytic processes remains to be proven. Here, we present experimental evidence showing that oscillating potentials are capable of enhancing the rate of ethylene hydrogenation despite no promotion effect was observed under static potentials. The non-Faradaic dynamic enhancement reaches up to 553% on a Pd/C electrode when cycling between –0.25 VNHE and 0.55 VNHE under optimized conditions with a frequency of around 0.1 Hz and a duty cycle of 99%. Under those conditions, no stoichiometric electron transfer to ethylene can be observed, confirming the non-Faradaic nature of the process. Experiments in different electrolytes reveal a good correlation between the catalytic enhancement and the doublelayer capacitance – a measure for the interfacial electric field strength. Preliminary kinetic data suggests that cycling to a low potential increases the hydrogen adsorption on the catalyst surface while at higher potential, the ethylene adsorption and hydrogenation becomes relatively more favorable<br>

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Non-Faradaic Promotion of Ethylene Hydrogenation Under Oscillating Potentials

10.26434/chemrxiv.13176995.v1 ◽

2020 ◽

Author(s):

Chia Wei Lim ◽

Max J. Huelsey ◽

Ning Yan

Keyword(s):

Kinetic Data ◽

Hydrogen Adsorption ◽

Catalyst Surface ◽

Ethylene Hydrogenation ◽

Promotion Effect ◽

Ethylene Adsorption ◽

Electric Potentials ◽

Dynamic Enhancement ◽

Optimized Conditions ◽

Present Experimental Evidence

The acceleration of Faradaic reactions by oscillating electric potentials has emerged as a viable tool to enhance electrocatalysis, but the non-Faradaic dynamic promotion of thermal catalytic processes remains to be proven. Here, we present experimental evidence showing that oscillating potentials are capable of enhancing the rate of ethylene hydrogenation despite no promotion effect was observed under static potentials. The non-Faradaic dynamic enhancement reaches up to 553% on a Pd/C electrode when cycling between –0.25 VNHE and 0.55 VNHE under optimized conditions with a frequency of around 0.1 Hz and a duty cycle of 99%. Under those conditions, no stoichiometric electron transfer to ethylene can be observed, confirming the non-Faradaic nature of the process. Experiments in different electrolytes reveal a good correlation between the catalytic enhancement and the doublelayer capacitance – a measure for the interfacial electric field strength. Preliminary kinetic data suggests that cycling to a low potential increases the hydrogen adsorption on the catalyst surface while at higher potential, the ethylene adsorption and hydrogenation becomes relatively more favorable<br>

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Electric potentials, forces and torques on bodies moving through rarefied plasmas

10.2514/6.1965-628 ◽

1965 ◽

Author(s):

F. HOHL ◽

G. WOOD

Keyword(s):

Electric Potentials

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Dispersive MHD waves and alfvenons in charge non-neutral plasmas

Nonlinear Processes in Geophysics ◽

10.5194/npg-15-681-2008 ◽

2008 ◽

Vol 15 (4) ◽

pp. 681-693 ◽

Cited By ~ 3

Author(s):

K. Stasiewicz ◽

J. Ekeberg

Keyword(s):

Soliton Solutions ◽

Theoretical Models ◽

Mhd Waves ◽

Space Plasmas ◽

Charge Effects ◽

Novel Technique ◽

Solitary Structures ◽

Spatial Dimensions ◽

Electric Potentials ◽

Linear And Nonlinear

Abstract. Dispersive properties of linear and nonlinear MHD waves, including shear, kinetic, electron inertial Alfvén, and slow and fast magnetosonic waves are analyzed using both analytical expansions and a novel technique of dispersion diagrams. The analysis is extended to explicitly include space charge effects in non-neutral plasmas. Nonlinear soliton solutions, here called alfvenons, are found to represent either convergent or divergent electric field structures with electric potentials and spatial dimensions similar to those observed by satellites in auroral regions. Similar solitary structures are postulated to be created in the solar corona, where fast alfvenons can provide acceleration of electrons to hundreds of keV during flares. Slow alfvenons driven by chromospheric convection produce positive potentials that can account for the acceleration of solar wind ions to 300–800 km/s. New results are discussed in the context of observations and other theoretical models for nonlinear Alfvén waves in space plasmas.

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A gateway for ion transport on gas bubbles pinned onto solids

Communications Chemistry ◽

10.1038/s42004-021-00481-7 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Veton Haziri ◽

Tu Pham Tran Nha ◽

Avni Berisha ◽

Jean-François Boily

Keyword(s):

Ion Transport ◽

Metal Ion ◽

Electrochemical Impedance ◽

Gas Bubbles ◽

Open Circuit ◽

Double Layers ◽

Water Geochemistry ◽

Chemical Potentials ◽

Pore Water Geochemistry ◽

Electric Potentials

AbstractGas bubbles grown on solids are more than simple vehicles for gas transport. They are charged particles with surfaces populated with exchangeable ions. We here unveil a gateway for alkali metal ion transport between oxygen bubbles and semi-conducting (iron oxide) and conducting (gold) surfaces. This gateway was identified by electrochemical impedance spectroscopy using an ultramicroelectrode in direct contact with bubbles pinned onto these solid surfaces. We show that this gateway is naturally present at open circuit potentials, and that negative electric potentials applied through the solid enhance ion transport. In contrast, positive potentials or contact with an insulator (polytetrafluoroethylene) attenuates transport. We propose that this gateway is generated by overlapping electric double layers of bubbles and surfaces of contrasting (electro)chemical potentials. Knowledge of this ion transfer phenomenon is essential for understanding electric shielding and reaction overpotential caused by bubbles on catalysts. This has especially important ramifications for predicting processes including mineral flotation, microfluidics, pore water geochemistry, and fuel cell technology.

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Non-Faradaic Promotion of Ethylene Hydrogenation under Oscillating Potentials

JACS Au ◽

10.1021/jacsau.1c00044 ◽

2021 ◽

Author(s):

Chia Wei Lim ◽

Max J. Hülsey ◽

Ning Yan

Keyword(s):

Ethylene Hydrogenation

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Exact Recovery of Community Detection in k-Partite Graph Models with Applications to Learning Electric Potentials in Electric Networks

Journal of Statistical Physics ◽

10.1007/s10955-020-02690-1 ◽

2021 ◽

Vol 182 (1) ◽

Author(s):

Zhongyang Li

Keyword(s):

Community Detection ◽

Electric Networks ◽

Graph Models ◽

Electric Potentials

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The effect of dipole housing and feeding wires in physical phantoms for EEG

Current Directions in Biomedical Engineering ◽

10.1515/cdbme-2019-0022 ◽

2019 ◽

Vol 5 (1) ◽

pp. 85-88

Author(s):

René Machts ◽

Alexander Hunold ◽

Jens Haueisen

Keyword(s):

Electric Potential ◽

Volume Conductor ◽

Constant Current ◽

Twisted Pair ◽

Eeg Data ◽

Phantom Measurements ◽

Average Change ◽

Electric Potentials ◽

The Difference ◽

Signal Sources

AbstractCurrent dipoles are well established models in the localization of neuronal activity to electroencephalography (EEG) data. In physical phantoms, current dipoles can be used as signal sources. Current dipoles are often powered by constant current sources connected via twisted pair wires mostly consisting of copper. The poles are typically formed by platinum wires. These wires as well as the dipole housing might disturb the electric potential distributions in physical phantom measurements. We aimed to quantify this distortion by comparing simulation setups with and without the wires and the housing. The electric potential distributions were simulated using finite element method (FEM). We chose a homogenous volume conductor surrounding the dipoles, which was 100 times larger than the size of the dipoles. We calculated the difference of the electric potential at the surface of the volume conductor between the simulations with and without the connecting wires and the housing. Comparing simulations neglecting all connecting wires and the housing rod to simulations considering them, the electric potential at the surface of the volume conductor differed on average by 2.85 %. Both platinum and twisted pair copper wires had a smaller effect on the electric potentials with a maximum average change of 6.38 ppm. Consequently, source localization of measurements in physical head phantoms should consider these rods in the forward model.

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