scholarly journals Electrocatalytic Efficiency of the Oxidation of Ethylene glycol, Glycerol, and Glucose under Oscillatory Regime

2021 ◽  
Author(s):  
Gabriel Melle ◽  
Thiago Altair ◽  
Rafael Romano ◽  
Hamilton Varela
Keyword(s):  
Ethylene Glycol ◽  
Formic Acid ◽  
Organic Molecules ◽  
Electrical Energy ◽  
Oscillatory Regime ◽  
Experimental Conditions ◽  
Small Organic Molecules ◽  
Self Organized ◽  
Polycrystalline Platinum ◽  
Surface Poisoning

There is an increasingly interest in the use of small organic molecules in the interconversion between chemical and electrical energies. Among the strategies to improve the processes of yielding electrical energy in fuel cells and the production of clear hydrogen in electrochemical reform is the use of kinetic instabilities to improve the conversion and selectivity. Herein we report on the electrocatalytic efficiency of the oxidation of ethylene glycol, glycerol, and glucose, under regular and oscillatory regimes, on polycrystalline platinum, in sulfuric acid aqueous solution, and at 25 oC. Despite the high overpotentials for the electro-oxidation of these molecules, the electrochemical activity along quasi-stationary potentio/gavanostatic experiments evidenced that, in all cases, relatively lower potential values, and thus higher activity, are reached during oscillations. Noticeably higher power densities for the electrooxidation of ethylene glycol and glycerol under oscillatory regime in a hypothetical direct liquid fuel cell. The use of identical experimental conditions of that of our previous study[J. Phys. Chem. C 120 (2016) 22365] allowed at discussing some universal trends for seven small organic molecules. We compile the results in terms of the peak current, the maximum poisoning rate found along the oscillations, and the oscillation frequency. The three parameters were found to decrease in the order: formaldehyde > formic acid > methanol > ethanol > ethylene glycol > glycerol > glucose. In addition, we discussed the increase of the voltammetric current with the self-organized poisoning rate and reinforce the trend that high electrocatalytic activity implies high susceptibility to surface poisoning for this set of species. Finally, the analysis done for all species (formic acid, formaldehyde, methanol, ethylene glycol, ethanol, glycerol, and glucose) adds to the available thermodynamic data and is a benchmark against which the activities under oscillatory regime at 25 oC may be compared or assessed. This point of reference permits to explore further experimental conditions that are relevant for energy-related devices, including the conversion of chemical into electrical energy and the electrochemical reform to produce clean hydrogen in electrolyzers.

scholarly journals Electrocatalytic Efficiency of the Oxidation of Ethylene glycol, Glycerol, and Glucose under Oscillatory Regime

2021 ◽  
Author(s):  
Gabriel Melle ◽  
Thiago Altair ◽  
Rafael Romano ◽  
Hamilton Varela
Keyword(s):  
Ethylene Glycol ◽  
Formic Acid ◽  
Organic Molecules ◽  
Electrical Energy ◽  
Oscillatory Regime ◽  
Experimental Conditions ◽  
Small Organic Molecules ◽  
Self Organized ◽  
Polycrystalline Platinum ◽  
Surface Poisoning

There is an increasingly interest in the use of small organic molecules in the interconversion between chemical and electrical energies. Among the strategies to improve the processes of yielding electrical energy in fuel cells and the production of clear hydrogen in electrochemical reform is the use of kinetic instabilities to improve the conversion and selectivity. Herein we report on the electrocatalytic efficiency of the oxidation of ethylene glycol, glycerol, and glucose, under regular and oscillatory regimes, on polycrystalline platinum, in sulfuric acid aqueous solution, and at 25 oC. Despite the high overpotentials for the electro-oxidation of these molecules, the electrochemical activity along quasi-stationary potentio/gavanostatic experiments evidenced that, in all cases, relatively lower potential values, and thus higher activity, are reached during oscillations. Noticeably higher power densities for the electrooxidation of ethylene glycol and glycerol under oscillatory regime in a hypothetical direct liquid fuel cell. The use of identical experimental conditions of that of our previous study[J. Phys. Chem. C 120 (2016) 22365] allowed at discussing some universal trends for seven small organic molecules. We compile the results in terms of the peak current, the maximum poisoning rate found along the oscillations, and the oscillation frequency. The three parameters were found to decrease in the order: formaldehyde > formic acid > methanol > ethanol > ethylene glycol > glycerol > glucose. In addition, we discussed the increase of the voltammetric current with the self-organized poisoning rate and reinforce the trend that high electrocatalytic activity implies high susceptibility to surface poisoning for this set of species. Finally, the analysis done for all species (formic acid, formaldehyde, methanol, ethylene glycol, ethanol, glycerol, and glucose) adds to the available thermodynamic data and is a benchmark against which the activities under oscillatory regime at 25 oC may be compared or assessed. This point of reference permits to explore further experimental conditions that are relevant for energy-related devices, including the conversion of chemical into electrical energy and the electrochemical reform to produce clean hydrogen in electrolyzers.

Di(ethylene glycol) methyl ether methacrylate (DEGMEMA)-derived gels align small organic molecules in methanol

2016 ◽  
Vol 55 (3) ◽  
pp. 206-209 ◽  
Author(s):  
Manuela E. García ◽  
Shannon R. Woodruff ◽  
Erich Hellemann ◽  
Nicolay V. Tsarevsky ◽  
Roberto R. Gil
Keyword(s):  
Ethylene Glycol ◽  
Methyl Ether ◽  
Organic Molecules ◽  
Small Organic Molecules ◽  
Glycol Methyl Ether

Electrocatalytic Efficiency of the Oxidation of Small Organic Molecules under Oscillatory Regime

2016 ◽  
Vol 120 (39) ◽  
pp. 22365-22374 ◽  
Author(s):  
M. V. F. Delmonde ◽  
L. F. Sallum ◽  
N. Perini ◽  
E. R. Gonzalez ◽  
R. Schlögl ◽  
...  
Keyword(s):  
Organic Molecules ◽  
Oscillatory Regime ◽  
Small Organic Molecules

scholarly journals On the electro-oxidation of small organic molecules: towards a fuel cell catalyst testing platform

2021 ◽  
Author(s):  
Damin Zhang ◽  
Jia Du ◽  
Jonathan Quinson ◽  
Matthias Arenz
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Formic Acid ◽  
Organic Molecules ◽  
Gas Diffusion ◽  
Gas Diffusion Electrode ◽  
Proton Exchange ◽  
Electrochemical Cells ◽  
Small Organic Molecules ◽  
Electro Oxidation

The electrocatalytic oxidation of small organic compounds such as methanol or formic acid has been the subject of numerous investigations in the last decades. The motivation for these studies is often their use as fuel in so-called direct methanol or direct formic acid fuel cells, promising alternatives to hydrogen-fueled proton exchange membrane fuel cells. The fundamental research spans from screening studies to identify the best performing catalyst materials to detailed mechanistic investigations of the reaction pathway. These investigations are commonly performed in standard three electrode electrochemical cells with a liquid supporting electrolyte to which the methanol or formic acid is added. In fuel cell devices, however, no liquid electrolyte will be present, instead membrane electrolytes are used. The question therefore arises, to which extend results from conventional electrochemical cells can be extrapolated to conditions found in fuel cells. We previously developed a gas diffusion electrode setup to mimic “real-life” reaction conditions and study electrocatalysts for oxygen gas reduction or water splitting. It is here demonstrated that the setup is also suitable to investigate the properties of catalysts for the electro-oxidation of small organic molecules. Using the gas diffusion electrode setup, it is seen that employing a catalyst - membrane electrolyte interface as compared to conventional electrochemical cells can lead to significantly different catalyst performances. Therefore, it is recommended to implement gas diffusion electrode setups for the investigation of the electro-oxidation of small organic molecules.

scholarly journals Solid-state formation of CO and H2CO via the CHOCHO + H reaction

2019 ◽  
Vol 491 (1) ◽  
pp. 289-301 ◽  
Author(s):  
Killian Leroux ◽  
Jean-Claude Guillemin ◽  
Lahouari Krim
Keyword(s):  
Solid State ◽  
Ethylene Glycol ◽  
Organic Molecules ◽  
Solid Phase ◽  
Secondary Product ◽  
Experimental Conditions ◽  
Work Surface ◽  
Reaction Intermediate ◽  
Complex Organic ◽  
Potential Precursor

ABSTRACT Glycolaldehyde (CHOCH2OH) and ethylene glycol (HOCH2CH2OH) are among many complex organic molecules detected in the interstellar medium (ISM). Astrophysical models proposed very often that the formation of these compounds would be directly linked to the hydrogenation of glyoxal (CHOCHO), a potential precursor which is not yet detected in the ISM. We have performed, in this work, surface and bulk hydrogenations of solid CHOCHO under ISM conditions in order to confirm or invalidate the astrophysical modelling of glyoxal transformation. Our results show that the hydrogenation of glyoxal does not lead to the formation of detectable amounts of heavier organic molecules such as glycolaldehyde and ethylene glycol but rather to lighter CO-bearing species such as CO, H2CO, and CO–H2CO, a reaction intermediate resulting from an H-addition–elimination process on CHOCHO and where CO is linked to H2CO. The solid phase formation of such a reaction intermediate has been confirmed through the neon matrix isolation of CO–H2CO species. Additionally, the CHOCHO + H solid-state reaction might also lead to the production of CH3OH formed under our experimental conditions as a secondary product resulting from the hydrogenation of formaldehyde.

CO2-based hydrogen storage: CO2 hydrogenation to formic acid, formaldehyde and methanol

2018 ◽  
Vol 3 (3) ◽  
Author(s):  
Thomas Schaub
Keyword(s):  
Hydrogen Storage ◽  
Formic Acid ◽  
Mobile Applications ◽  
Organic Molecules ◽  
State Of The Art ◽  
Co2 Hydrogenation ◽  
The State ◽  
Reverse Reaction ◽  
Small Organic Molecules ◽  
Hydrogenation Of Co

AbstractThe storage of hydrogen via hydrogenation of CO2to small organic molecules can be attractive for mobile applications. In this article, the state of the art regarding hydrogen storage in Methanol, Formic Acid as well as Formaldehyde and derivates based on CO2hydrogenation is summarized. The reverse reaction, the release of hydrogen from these molecules is also crucial and described in the articles together with possible concepts for the use of hydrogen storage by CO2hydrogenation.

QUBEKit: Automating the Derivation of Force Field Parameters from Quantum Mechanics

2019 ◽  
Author(s):  
Joshua Horton ◽  
Alice Allen ◽  
Leela Dodda ◽  
Daniel Cole
Keyword(s):  
Quantum Mechanics ◽  
Force Field ◽  
Organic Molecules ◽  
Force Fields ◽  
Liquid Density ◽  
Small Organic Molecules ◽  
Automated Generation ◽  
Energy Of Hydration ◽  
Novel Method ◽  
Force Field Parameters

<div><div><div><p>Modern molecular mechanics force fields are widely used for modelling the dynamics and interactions of small organic molecules using libraries of transferable force field parameters. For molecules outside the training set, parameters may be missing or inaccurate, and in these cases, it may be preferable to derive molecule-specific parameters. Here we present an intuitive parameter derivation toolkit, QUBEKit (QUantum mechanical BEspoke Kit), which enables the automated generation of system-specific small molecule force field parameters directly from quantum mechanics. QUBEKit is written in python and combines the latest QM parameter derivation methodologies with a novel method for deriving the positions and charges of off-center virtual sites. As a proof of concept, we have re-derived a complete set of parameters for 109 small organic molecules, and assessed the accuracy by comparing computed liquid properties with experiment. QUBEKit gives highly competitive results when compared to standard transferable force fields, with mean unsigned errors of 0.024 g/cm3, 0.79 kcal/mol and 1.17 kcal/mol for the liquid density, heat of vaporization and free energy of hydration respectively. This indicates that the derived parameters are suitable for molecular modelling applications, including computer-aided drug design.</p></div></div></div>

QUBEKit: Automating the Derivation of Force Field Parameters from Quantum Mechanics

2019 ◽  
Author(s):  
Joshua Horton ◽  
Alice Allen ◽  
Leela Dodda ◽  
Daniel Cole
Keyword(s):  
Quantum Mechanics ◽  
Force Field ◽  
Organic Molecules ◽  
Force Fields ◽  
Liquid Density ◽  
Small Organic Molecules ◽  
Automated Generation ◽  
Energy Of Hydration ◽  
Novel Method ◽  
Force Field Parameters

<div><div><div><p>Modern molecular mechanics force fields are widely used for modelling the dynamics and interactions of small organic molecules using libraries of transferable force field parameters. For molecules outside the training set, parameters may be missing or inaccurate, and in these cases, it may be preferable to derive molecule-specific parameters. Here we present an intuitive parameter derivation toolkit, QUBEKit (QUantum mechanical BEspoke Kit), which enables the automated generation of system-specific small molecule force field parameters directly from quantum mechanics. QUBEKit is written in python and combines the latest QM parameter derivation methodologies with a novel method for deriving the positions and charges of off-center virtual sites. As a proof of concept, we have re-derived a complete set of parameters for 109 small organic molecules, and assessed the accuracy by comparing computed liquid properties with experiment. QUBEKit gives highly competitive results when compared to standard transferable force fields, with mean unsigned errors of 0.024 g/cm3, 0.79 kcal/mol and 1.17 kcal/mol for the liquid density, heat of vaporization and free energy of hydration respectively. This indicates that the derived parameters are suitable for molecular modelling applications, including computer-aided drug design.</p></div></div></div>

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