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Spectroelectrochemical studies on the effect of cations in the alkaline glycerol oxidation reaction over carbon nanotube-supported Pd nanoparticles

The effects of the alkali cations Na(+) and K(+) were investigated in the alkaline electrochemical oxidation of glycerol over Pd nanoparticles (NPs) deposited on functionalized carbon nanotubes (CNTs). The electrocatalytic activity was assessed by cyclic voltammetry revealing a lower overpotential o...

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Autores principales: Hiltrop, Dennis, Cychy, Steffen, Elumeeva, Karina, Schuhmann, Wolfgang, Muhler, Martin
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Beilstein-Institut 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6009201/
https://www.ncbi.nlm.nih.gov/pubmed/29977406
http://dx.doi.org/10.3762/bjoc.14.120
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author Hiltrop, Dennis
Cychy, Steffen
Elumeeva, Karina
Schuhmann, Wolfgang
Muhler, Martin
author_facet Hiltrop, Dennis
Cychy, Steffen
Elumeeva, Karina
Schuhmann, Wolfgang
Muhler, Martin
author_sort Hiltrop, Dennis
collection PubMed
description The effects of the alkali cations Na(+) and K(+) were investigated in the alkaline electrochemical oxidation of glycerol over Pd nanoparticles (NPs) deposited on functionalized carbon nanotubes (CNTs). The electrocatalytic activity was assessed by cyclic voltammetry revealing a lower overpotential of glycerol oxidation for nitrogen-functionalized Pd/NCNTs compared with oxygen-functionalized Pd/OCNTs. Whereas significantly lower current densities were observed for Pd/OCNT in NaOH than in KOH in agreement with stronger non-covalent interactions on the Pd surface, Pd/NCNT achieved an approximately three-times higher current density in NaOH than in KOH. In situ electrochemistry/IR spectroscopy was applied to unravel the product distribution as a function of the applied potential in NaOH and KOH. The IR spectra exhibited strongly changing band patterns upon varying the potential between 0.77 and 1.17 V vs RHE: at low potentials oxidized C(3) species such as mesoxalate and tartronate were formed predominantly, and with increasing potentials C(2) and C(1) species originating from C–C bond cleavage were identified. The tendency to produce carbonate was found to be less pronounced in KOH. The less favored formation of highly oxidized C(3) species and of carbonate is deduced to be the origin of the lower current densities in the cyclic voltammograms (CVs) for Pd/NCNT in KOH. The enhanced current densities in NaOH are rationalized by the presence of Na(+) ions bound to the basic nitrogen species in the NCNT support. Adsorbed Na(+) ions can form complexes with the organic molecules, presumably enhanced by the chelate effect. In this way, the organic molecules are assumed to be bound more tightly to the NCNT support in close proximity to the Pd NPs facilitating their oxidation.
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spelling pubmed-60092012018-07-05 Spectroelectrochemical studies on the effect of cations in the alkaline glycerol oxidation reaction over carbon nanotube-supported Pd nanoparticles Hiltrop, Dennis Cychy, Steffen Elumeeva, Karina Schuhmann, Wolfgang Muhler, Martin Beilstein J Org Chem Letter The effects of the alkali cations Na(+) and K(+) were investigated in the alkaline electrochemical oxidation of glycerol over Pd nanoparticles (NPs) deposited on functionalized carbon nanotubes (CNTs). The electrocatalytic activity was assessed by cyclic voltammetry revealing a lower overpotential of glycerol oxidation for nitrogen-functionalized Pd/NCNTs compared with oxygen-functionalized Pd/OCNTs. Whereas significantly lower current densities were observed for Pd/OCNT in NaOH than in KOH in agreement with stronger non-covalent interactions on the Pd surface, Pd/NCNT achieved an approximately three-times higher current density in NaOH than in KOH. In situ electrochemistry/IR spectroscopy was applied to unravel the product distribution as a function of the applied potential in NaOH and KOH. The IR spectra exhibited strongly changing band patterns upon varying the potential between 0.77 and 1.17 V vs RHE: at low potentials oxidized C(3) species such as mesoxalate and tartronate were formed predominantly, and with increasing potentials C(2) and C(1) species originating from C–C bond cleavage were identified. The tendency to produce carbonate was found to be less pronounced in KOH. The less favored formation of highly oxidized C(3) species and of carbonate is deduced to be the origin of the lower current densities in the cyclic voltammograms (CVs) for Pd/NCNT in KOH. The enhanced current densities in NaOH are rationalized by the presence of Na(+) ions bound to the basic nitrogen species in the NCNT support. Adsorbed Na(+) ions can form complexes with the organic molecules, presumably enhanced by the chelate effect. In this way, the organic molecules are assumed to be bound more tightly to the NCNT support in close proximity to the Pd NPs facilitating their oxidation. Beilstein-Institut 2018-06-12 /pmc/articles/PMC6009201/ /pubmed/29977406 http://dx.doi.org/10.3762/bjoc.14.120 Text en Copyright © 2018, Hiltrop et al. https://creativecommons.org/licenses/by/4.0https://www.beilstein-journals.org/bjoc/termsThis is an Open Access article under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The license is subject to the Beilstein Journal of Organic Chemistry terms and conditions: (https://www.beilstein-journals.org/bjoc/terms)
spellingShingle Letter
Hiltrop, Dennis
Cychy, Steffen
Elumeeva, Karina
Schuhmann, Wolfgang
Muhler, Martin
Spectroelectrochemical studies on the effect of cations in the alkaline glycerol oxidation reaction over carbon nanotube-supported Pd nanoparticles
title Spectroelectrochemical studies on the effect of cations in the alkaline glycerol oxidation reaction over carbon nanotube-supported Pd nanoparticles
title_full Spectroelectrochemical studies on the effect of cations in the alkaline glycerol oxidation reaction over carbon nanotube-supported Pd nanoparticles
title_fullStr Spectroelectrochemical studies on the effect of cations in the alkaline glycerol oxidation reaction over carbon nanotube-supported Pd nanoparticles
title_full_unstemmed Spectroelectrochemical studies on the effect of cations in the alkaline glycerol oxidation reaction over carbon nanotube-supported Pd nanoparticles
title_short Spectroelectrochemical studies on the effect of cations in the alkaline glycerol oxidation reaction over carbon nanotube-supported Pd nanoparticles
title_sort spectroelectrochemical studies on the effect of cations in the alkaline glycerol oxidation reaction over carbon nanotube-supported pd nanoparticles
topic Letter
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6009201/
https://www.ncbi.nlm.nih.gov/pubmed/29977406
http://dx.doi.org/10.3762/bjoc.14.120
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