scholarly journals Investigation of Amorphous Mixed-Metal (Oxy)Fluorides as a New Class of Water Oxidation Electrocatalysts

2019 ◽  
Author(s):  
Kévin Lemoine ◽  
Jérôme Lhoste ◽  
Annie Hémon-Ribaud ◽  
Nina Heidary ◽  
Vincent Maisonneuve ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Spectroscopic Characterization ◽  
Alkaline Electrolyte ◽  
Fluoride Ions ◽  
Mixed Metal ◽  
New Class ◽  
Excellent Activity ◽  
Earth Abundant ◽  
Structure Modulation ◽  
High Electronegativity

<p>The development of electrocatalysts for the oxygen evolution reaction (OER) is one of the principal challenges in the area of renewable energy research. Within this context, mixed-metal oxides have recently emerged as the highest performing OER catalysts. Their structural and compositional modification to further boost their activity is crucial to the wide-spread use of electrolysis technologies. In this work, we investigated a series of mixed-metal F-containing materials as OER catalysts to probe possible benefits of the high electronegativity of fluoride ions. We found that crystalline hydrated fluorides, CoFe<sub>2</sub>F<sub>8</sub>(H<sub>2</sub>O)<sub>2</sub>, NiFe<sub>2</sub>F<sub>8</sub>(H<sub>2</sub>O)<sub>2, </sub>and amorphous oxyfluorides, NiFe<sub>2</sub>F<sub>4.4</sub>O<sub>1.8 </sub>and CoFe<sub>2</sub>F<sub>6.6</sub>O<sub>0.7, </sub>feature excellent activity and stability for the OER in alkaline electrolyte. Subsequent electroanalytical and spectroscopic characterization hinted that the electronic structure modulation conferred by the fluoride ions aided their reactivity. Finally, the best catalyst of the set, NiFe<sub>2</sub>F<sub>4.4</sub>O<sub>1.8</sub>, was applied as anode in an electrolyzer comprised solely of earth-abundant materials.</p>

Investigation of Amorphous Mixed-Metal (Oxy)Fluorides as a New Class of Water Oxidation Electrocatalysts

2019 ◽  
Author(s):  
Kévin Lemoine ◽  
Jérôme Lhoste ◽  
Annie Hémon-Ribaud ◽  
Nina Heidary ◽  
Vincent Maisonneuve ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Spectroscopic Characterization ◽  
Alkaline Electrolyte ◽  
Fluoride Ions ◽  
Mixed Metal ◽  
New Class ◽  
Excellent Activity ◽  
Earth Abundant ◽  
Structure Modulation ◽  
High Electronegativity

<p>The development of electrocatalysts for the oxygen evolution reaction (OER) is one of the principal challenges in the area of renewable energy research. Within this context, mixed-metal oxides have recently emerged as the highest performing OER catalysts. Their structural and compositional modification to further boost their activity is crucial to the wide-spread use of electrolysis technologies. In this work, we investigated a series of mixed-metal F-containing materials as OER catalysts to probe possible benefits of the high electronegativity of fluoride ions. We found that crystalline hydrated fluorides, CoFe<sub>2</sub>F<sub>8</sub>(H<sub>2</sub>O)<sub>2</sub>, NiFe<sub>2</sub>F<sub>8</sub>(H<sub>2</sub>O)<sub>2, </sub>and amorphous oxyfluorides, NiFe<sub>2</sub>F<sub>4.4</sub>O<sub>1.8 </sub>and CoFe<sub>2</sub>F<sub>6.6</sub>O<sub>0.7, </sub>feature excellent activity and stability for the OER in alkaline electrolyte. Subsequent electroanalytical and spectroscopic characterization hinted that the electronic structure modulation conferred by the fluoride ions aided their reactivity. Finally, the best catalyst of the set, NiFe<sub>2</sub>F<sub>4.4</sub>O<sub>1.8</sub>, was applied as anode in an electrolyzer comprised solely of earth-abundant materials.</p>

scholarly journals Highly efficient water oxidation via a bimolecular reaction mechanism on rutile structured mixed-metal oxyfluorides

2021 ◽  
Author(s):  
Zahra Gohari-Bajestani ◽  
Xiao Wang ◽  
Amandine Guiet ◽  
Romain Moury ◽  
Jean-Marc Grenèche ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Water Oxidation ◽  
Active Sites ◽  
Catalyst Surface ◽  
Coupling Reaction ◽  
Bimolecular Reaction ◽  
Fluoride Ions ◽  
Mixed Metal ◽  
Beneficial Effects ◽  
Catalytic Sites

Mixed-metal oxides are generally considered to be the highest-performance catalysts for alkaline water oxidation. Despite significant efforts dedicated to understanding and accelerating their efficiency, most works have been limited investigations of Ni, Co, and Fe oxides, thus overlooking beneficial effects of hetero-anion incorporation. To this end, we report on the development of Co0.5Fe0.5O0.5F1.5 oxyfluoride materials featuring a rutile crystal structure and porous morphology via a scalable and green synthetic route. The catalyst surface, enhanced through electron withdrawing effects imparted by the fluoride ions, give rise to highly effective catalytic sites for electrochemical water oxidation. In particular, their performance across metrics of Tafel slope (27 mV/dec), mass activity (846 A/g at 1.53 V vs. RHE), turnover frequency (21/s at 1.53 V vs. RHE), overpotential (220 mV for 10 mA/cm2), and stability (27 days of continuous operation) largely surpasses most known Co-based catalysts. Mechanistic studies suggest that this performance is driven by a bimolecular, oxygen coupling reaction mechanism through proximal active sites on the catalyst surface, thus enabling a new avenue for achieving accelerated oxygenic electrocatalysis.

Single layer graphene encapsulating non-precious metals as high-performance electrocatalysts for water oxidation

2016 ◽  
Vol 9 (1) ◽  
pp. 123-129 ◽  
Author(s):  
Xiaoju Cui ◽  
Pengju Ren ◽  
Dehui Deng ◽  
Jiao Deng ◽  
Xinhe Bao
Keyword(s):  
Transition Metal ◽  
Water Oxidation ◽  
High Performance ◽  
Precious Metals ◽  
Single Layer ◽  
Single Layer Graphene ◽  
Transition Metal Nanoparticles ◽  
Layer Graphene ◽  
Excellent Activity ◽  
Earth Abundant

Single layer graphene encapsulating earth-abundant 3d transition metal nanoparticles exhibits excellent activity and durability for water oxidation, even exceeding IrO2.

A survey of diverse earth abundant oxygen evolution electrocatalysts showing enhanced activity from Ni–Fe oxides containing a third metal

2014 ◽  
Vol 7 (7) ◽  
pp. 2376-2382 ◽  
Author(s):  
James B. Gerken ◽  
Sarah E. Shaner ◽  
Robert C. Massé ◽  
Nicholas J. Porubsky ◽  
Shannon S. Stahl
Keyword(s):  
Metal Oxides ◽  
Oxygen Evolution ◽  
Water Oxidation ◽  
Mixed Metal Oxides ◽  
Mixed Metal ◽  
Fe Oxides ◽  
Highly Active ◽  
Enhanced Activity ◽  
Earth Abundant

Mixed metal oxides containing Ni, Fe, and a third metal constitute a broad family of highly active water oxidation electrocatalysts.

scholarly journals Investigation of mixed-metal (oxy)fluorides as a new class of water oxidation electrocatalysts

2019 ◽  
Vol 10 (40) ◽  
pp. 9209-9218 ◽  
Author(s):  
Kévin Lemoine ◽  
Jérôme Lhoste ◽  
Annie Hémon-Ribaud ◽  
Nina Heidary ◽  
Vincent Maisonneuve ◽  
...  
Keyword(s):  
Renewable Energy ◽  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Water Oxidation ◽  
Energy Research ◽  
Mixed Metal ◽  
New Class

The development of electrocatalysts for the oxygen evolution reaction (OER) is one of the principal challenges in the area of renewable energy research.

scholarly journals The antimicrobial potential of cannabidiol

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Mark A. T. Blaskovich ◽  
Angela M. Kavanagh ◽  
Alysha G. Elliott ◽  
Bing Zhang ◽  
Soumya Ramu ◽  
...  
Keyword(s):  
Bacterial Infections ◽  
Modern Medicine ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
New Class ◽  
Clostridioides Difficile ◽  
Excellent Activity ◽  
Induce Resistance ◽  
First Time

AbstractAntimicrobial resistance threatens the viability of modern medicine, which is largely dependent on the successful prevention and treatment of bacterial infections. Unfortunately, there are few new therapeutics in the clinical pipeline, particularly for Gram-negative bacteria. We now present a detailed evaluation of the antimicrobial activity of cannabidiol, the main non-psychoactive component of cannabis. We confirm previous reports of Gram-positive activity and expand the breadth of pathogens tested, including highly resistant Staphylococcus aureus, Streptococcus pneumoniae, and Clostridioides difficile. Our results demonstrate that cannabidiol has excellent activity against biofilms, little propensity to induce resistance, and topical in vivo efficacy. Multiple mode-of-action studies point to membrane disruption as cannabidiol’s primary mechanism. More importantly, we now report for the first time that cannabidiol can selectively kill a subset of Gram-negative bacteria that includes the ‘urgent threat’ pathogen Neisseria gonorrhoeae. Structure-activity relationship studies demonstrate the potential to advance cannabidiol analogs as a much-needed new class of antibiotics.

Engineering Sulfur Vacancies into Fe9S10 Nanosheet Arrays for Efficient Alkaline Hydrogen Evolution

Nanoscale ◽  
2021 ◽  
Author(s):  
Wenjun He ◽  
Jianing Cheng ◽  
Yaohui Gao ◽  
Caichi Liu ◽  
Jianling Zhao ◽  
...  
Keyword(s):  
Transition Metal ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Metal Sulfides ◽  
Transition Metal Sulfides ◽  
Nanosheet Arrays ◽  
Excellent Activity ◽  
Earth Abundant ◽  
Iron Based

The development of earth-abundant transition metal sulfides electrocatalysts with excellent activity and stability toward alkaline hydrogen evolution reaction (HER) is critical but challenging. Iron-based sulfides are favored due to their...

scholarly journals Thickness-dependent photoelectrochemical properties of a semitransparent Co3O4 photocathode

2018 ◽  
Vol 9 ◽  
pp. 2432-2442 ◽  
Author(s):  
Malkeshkumar Patel ◽  
Joondong Kim
Keyword(s):  
Water Splitting ◽  
Water Oxidation ◽  
Hydrogen Generation ◽  
Hydrogen Gas ◽  
Generation Rate ◽  
Alkaline Electrolyte ◽  
Stoichiometric Ratio ◽  
Gas Generation ◽  
Pec Cells ◽  
Gas Generation Rate

Co3O4 has been widely studied as a catalyst when coupled with a photoactive material during hydrogen production using water splitting. Here, we demonstrate a photoactive spinel Co3O4 electrode grown by the Kirkendall diffusion thermal oxidation of Co nanoparticles. The thickness-dependent structural, physical, optical, and electrical properties of Co3O4 samples are comprehensively studied. Our analysis shows that two bandgaps of 1.5 eV and 2.1 eV coexist with p-type conductivity in porous and semitransparent Co3O4 samples, which exhibit light-induced photocurrent in photoelectrochemical cells (PEC) containing the alkaline electrolyte. The thickness-dependent properties of Co3O4 related to its use as a working electrode in PEC cells are extensively studied and show potential for the application in water oxidation and reduction processes. To demonstrate the stability, an alkaline cell was composed for the water splitting system by using two Co3O4 photoelectrodes. The oxygen gas generation rate was obtained to be 7.17 mL·h−1 cm−1. Meanwhile, hydrogen gas generation rate was almost twice of 14.35 mL·h−1·cm−1 indicating the stoichiometric ratio of 1:2. We propose that a semitransparent Co3O4 photoactive electrode is a prospective candidate for use in PEC cells via heterojunctions for hydrogen generation.

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