Determining overpotentials for the oxidation of alcohols by molecular electrocatalysts in non-aqueous solvents

Speelman, Amy L.; Gerken, James B.; Heins, Spencer P.; Wiedner, Eric S.; Stahl, Shannon S.; Appel, Aaron M.

doi:10.1039/d2ee01458k

Cited by 11 publications

(23 citation statements)

References 57 publications

(100 reference statements)

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“…Consistent with previous mechanistic studies, this can be attributed to base-promoted formation of the TEMPO + /alkoxide adduct . A linear Tafel plot obtained for this process is shown in Figure S3B ( E ° PrCHO/PrCH 2 OH = −0.762 V vs Ag/AgCl at pH 13).…”

Section: Resultssupporting

confidence: 88%

“…At a higher pH, efficient voltage-assisted catalytic oxidation of ethanol occurs at the TEMPO-modified GCE (Figure A). Figure S3C shows the corresponding Tafel plot ( E ° CH 3 CHO/CH 3 CH 2 OH = −0.767 V vs Ag/AgCl at pH 13). Similar to water oxidation voltammograms (Figure B,C), the apparent current density of ethanol oxidation at a TEMPO CNE (Figure B) is 2–3 orders of magnitude higher than that at a TEMPO GCE (Figure A) due to the higher density of TEMPO molecules attached to the porous carbon layer.…”

Section: Resultsmentioning

confidence: 99%

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Efficient Voltage-Driven Oxidation of Water and Alcohols by an Organic Molecular Catalyst Directly Attached to a Carbon Electrode

et al. 2023

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The integration of heterogeneous electrocatalysis and molecular catalysis is a promising approach to designing new catalysts for the oxygen evolution reaction (OER) and other processes. We recently showed that the electrostatic potential drop across the double layer contributes to the driving force for electron transfer between a dissolved reactant and a molecular catalyst immobilized directly on the electrode surface. Here, we report high current densities and low onset potentials for water oxidation attained using a metal-free voltage-assisted molecular catalyst (TEMPO). Scanning electrochemical microscopy (SECM) was used to analyze the products and determine faradic efficiencies for the generation of H2O2 and O2. The same catalyst was employed for efficient oxidations of butanol, ethanol, glycerol, and H2O2. DFT calculations show that the applied voltage alters the electrostatic potential drop between TEMPO and the reactant as well as chemical bonding between them, thereby increasing the reaction rate. These results suggest a new route for designing next-generation hybrid molecular/electrocatalysts for OER and alcohol oxidations.

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Section: Resultssupporting

confidence: 88%

Section: Resultsmentioning

confidence: 99%

Efficient Voltage-Driven Oxidation of Water and Alcohols by an Organic Molecular Catalyst Directly Attached to a Carbon Electrode

et al. 2023

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“…For example, the latest advance showed that the participation of water could facilitate the protonation of OOH* as the proton source in alkaline electrolyte and further promote the leave of H 2 O 2 , leading to higher 2e-ORR selectivity and H 2 O 2 yield. 46…”

Section: Catalytic Mechanism and Methods For Performance Evaluation O...mentioning

confidence: 99%

Metal–organic frameworks for electrocatalytic hydrogen peroxide production

Zhang,

et al. 2024

Mater. Chem. Front.

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“…Proposed catalytic cycle for oxidation of 2-propanol by Ir(PNP)(H) 2 , where PNP is bis[2-diisopropylphosphino)ethyl]amide, in the presence of the phenoxyl radical mediator. Reproduced from ref with permission from the Royal Society of Chemistry.…”

Section: Recent Examples Of Redox Mediators In Homogeneous Co-electro...mentioning

confidence: 99%

Redox Mediators in Homogeneous Co-electrocatalysis

Reid

Machan

2023

J. Am. Chem. Soc.

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Homogeneous electrocatalysis has been well studied over the past several decades for the conversion of small molecules to useful products for green energy applications or as chemical feedstocks. However, in order for these catalyst systems to be used in industrial applications, their activity and stability must be improved. In naturally occurring enzymes, redox equivalents (electrons, often in a concerted manner with protons) are delivered to enzyme active sites by small molecules known as redox mediators (RMs). Inspired by this, co-electrocatalytic systems with homogeneous catalysts and RMs have been developed for the conversion of alcohols, nitrogen, unsaturated organic substrates, oxygen, and carbon dioxide. In these systems, the RMs have been shown to both increase the activity of the catalyst and shift selectivity to more desired products by altering catalytic cycles and/or avoiding high-energy intermediates. However, the area is currently underdeveloped and requires additional fundamental advancements in order to become a more general strategy. Here, we summarize the recent examples of homogeneous coelectrocatalysis and discuss possible future directions for the field.

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Determining overpotentials for the oxidation of alcohols by molecular electrocatalysts in non-aqueous solvents

Abstract: Molecular electrocatalysts for energy-related transformations offer unique opportunities to elucidate mechanistic principles that contribute to improved rates and energy efficiency. New catalysts for electrochemical alcohol oxidation in non-aqueous conditions have...

Cited by 11 publications

References 57 publications

Efficient Voltage-Driven Oxidation of Water and Alcohols by an Organic Molecular Catalyst Directly Attached to a Carbon Electrode

Efficient Voltage-Driven Oxidation of Water and Alcohols by an Organic Molecular Catalyst Directly Attached to a Carbon Electrode

Metal–organic frameworks for electrocatalytic hydrogen peroxide production

Redox Mediators in Homogeneous Co-electrocatalysis

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