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From NiMoO(4) to γ-NiOOH: Detecting the Active Catalyst Phase by Time Resolved in Situ and Operando Raman Spectroscopy

[Image: see text] Water electrolysis powered by renewable energies is a promising technology to produce sustainable fossil free fuels. The development and evaluation of effective catalysts are here imperative; however, due to the inclusion of elements with different redox properties and reactivity,...

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Autores principales: Dürr, Robin N., Maltoni, Pierfrancesco, Tian, Haining, Jousselme, Bruno, Hammarström, Leif, Edvinsson, Tomas
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2021
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8388116/
https://www.ncbi.nlm.nih.gov/pubmed/34383485
http://dx.doi.org/10.1021/acsnano.1c04126
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author Dürr, Robin N.
Maltoni, Pierfrancesco
Tian, Haining
Jousselme, Bruno
Hammarström, Leif
Edvinsson, Tomas
author_facet Dürr, Robin N.
Maltoni, Pierfrancesco
Tian, Haining
Jousselme, Bruno
Hammarström, Leif
Edvinsson, Tomas
author_sort Dürr, Robin N.
collection PubMed
description [Image: see text] Water electrolysis powered by renewable energies is a promising technology to produce sustainable fossil free fuels. The development and evaluation of effective catalysts are here imperative; however, due to the inclusion of elements with different redox properties and reactivity, these materials undergo dynamical changes and phase transformations during the reaction conditions. NiMoO(4) is currently investigated among other metal oxides as a promising noble metal free catalyst for the oxygen evolution reaction. Here we show that at applied bias, NiMoO(4)·H(2)O transforms into γ-NiOOH. Time resolved operando Raman spectroscopy is utilized to follow the potential dependent phase transformation and is collaborated with elemental analysis of the electrolyte, confirming that molybdenum leaches out from the as-synthesized NiMoO(4)·H(2)O. Molybdenum leaching increases the surface coverage of exposed nickel sites, and this in combination with the formation of γ-NiOOH enlarges the amount of active sites of the catalyst, leading to high current densities. Additionally, we discovered different NiMoO(4) nanostructures, nanoflowers, and nanorods, for which the relative ratio can be influenced by the heating ramp during the synthesis. With selective molybdenum etching we were able to assign the varying X-ray diffraction (XRD) pattern as well as Raman vibrations unambiguously to the two nanostructures, which were revealed to exhibit different stabilities in alkaline media by time-resolved in situ and operando Raman spectroscopy. We advocate that a similar approach can beneficially be applied to many other catalysts, unveiling their structural integrity, characterize the dynamic surface reformulation, and resolve any ambiguities in interpretations of the active catalyst phase.
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spelling pubmed-83881162021-08-31 From NiMoO(4) to γ-NiOOH: Detecting the Active Catalyst Phase by Time Resolved in Situ and Operando Raman Spectroscopy Dürr, Robin N. Maltoni, Pierfrancesco Tian, Haining Jousselme, Bruno Hammarström, Leif Edvinsson, Tomas ACS Nano [Image: see text] Water electrolysis powered by renewable energies is a promising technology to produce sustainable fossil free fuels. The development and evaluation of effective catalysts are here imperative; however, due to the inclusion of elements with different redox properties and reactivity, these materials undergo dynamical changes and phase transformations during the reaction conditions. NiMoO(4) is currently investigated among other metal oxides as a promising noble metal free catalyst for the oxygen evolution reaction. Here we show that at applied bias, NiMoO(4)·H(2)O transforms into γ-NiOOH. Time resolved operando Raman spectroscopy is utilized to follow the potential dependent phase transformation and is collaborated with elemental analysis of the electrolyte, confirming that molybdenum leaches out from the as-synthesized NiMoO(4)·H(2)O. Molybdenum leaching increases the surface coverage of exposed nickel sites, and this in combination with the formation of γ-NiOOH enlarges the amount of active sites of the catalyst, leading to high current densities. Additionally, we discovered different NiMoO(4) nanostructures, nanoflowers, and nanorods, for which the relative ratio can be influenced by the heating ramp during the synthesis. With selective molybdenum etching we were able to assign the varying X-ray diffraction (XRD) pattern as well as Raman vibrations unambiguously to the two nanostructures, which were revealed to exhibit different stabilities in alkaline media by time-resolved in situ and operando Raman spectroscopy. We advocate that a similar approach can beneficially be applied to many other catalysts, unveiling their structural integrity, characterize the dynamic surface reformulation, and resolve any ambiguities in interpretations of the active catalyst phase. American Chemical Society 2021-08-12 2021-08-24 /pmc/articles/PMC8388116/ /pubmed/34383485 http://dx.doi.org/10.1021/acsnano.1c04126 Text en © 2021 The Authors. Published by American Chemical Society https://creativecommons.org/licenses/by/4.0/Permits the broadest form of re-use including for commercial purposes, provided that author attribution and integrity are maintained (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Dürr, Robin N.
Maltoni, Pierfrancesco
Tian, Haining
Jousselme, Bruno
Hammarström, Leif
Edvinsson, Tomas
From NiMoO(4) to γ-NiOOH: Detecting the Active Catalyst Phase by Time Resolved in Situ and Operando Raman Spectroscopy
title From NiMoO(4) to γ-NiOOH: Detecting the Active Catalyst Phase by Time Resolved in Situ and Operando Raman Spectroscopy
title_full From NiMoO(4) to γ-NiOOH: Detecting the Active Catalyst Phase by Time Resolved in Situ and Operando Raman Spectroscopy
title_fullStr From NiMoO(4) to γ-NiOOH: Detecting the Active Catalyst Phase by Time Resolved in Situ and Operando Raman Spectroscopy
title_full_unstemmed From NiMoO(4) to γ-NiOOH: Detecting the Active Catalyst Phase by Time Resolved in Situ and Operando Raman Spectroscopy
title_short From NiMoO(4) to γ-NiOOH: Detecting the Active Catalyst Phase by Time Resolved in Situ and Operando Raman Spectroscopy
title_sort from nimoo(4) to γ-niooh: detecting the active catalyst phase by time resolved in situ and operando raman spectroscopy
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8388116/
https://www.ncbi.nlm.nih.gov/pubmed/34383485
http://dx.doi.org/10.1021/acsnano.1c04126
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