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Electrochemical Activation of Atomic Layer-Deposited Cobalt Phosphate Electrocatalysts for Water Oxidation

[Image: see text] The development of efficient and stable earth-abundant water oxidation catalysts is vital for economically feasible water-splitting systems. Cobalt phosphate (CoPi)-based catalysts belong to the relevant class of nonprecious electrocatalysts studied for the oxygen evolution reactio...

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Autores principales: Zhang, Ruoyu, van Straaten, Gerben, di Palma, Valerio, Zafeiropoulos, Georgios, van de Sanden, Mauritius C.M., Kessels, Wilhelmus M.M., Tsampas, Mihalis N., Creatore, Mariadriana
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2021
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8025676/
https://www.ncbi.nlm.nih.gov/pubmed/33842021
http://dx.doi.org/10.1021/acscatal.0c04933
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author Zhang, Ruoyu
van Straaten, Gerben
di Palma, Valerio
Zafeiropoulos, Georgios
van de Sanden, Mauritius C.M.
Kessels, Wilhelmus M.M.
Tsampas, Mihalis N.
Creatore, Mariadriana
author_facet Zhang, Ruoyu
van Straaten, Gerben
di Palma, Valerio
Zafeiropoulos, Georgios
van de Sanden, Mauritius C.M.
Kessels, Wilhelmus M.M.
Tsampas, Mihalis N.
Creatore, Mariadriana
author_sort Zhang, Ruoyu
collection PubMed
description [Image: see text] The development of efficient and stable earth-abundant water oxidation catalysts is vital for economically feasible water-splitting systems. Cobalt phosphate (CoPi)-based catalysts belong to the relevant class of nonprecious electrocatalysts studied for the oxygen evolution reaction (OER). In this work, an in-depth investigation of the electrochemical activation of CoPi-based electrocatalysts by cyclic voltammetry (CV) is presented. Atomic layer deposition (ALD) is adopted because it enables the synthesis of CoPi films with cobalt-to-phosphorous ratios between 1.4 and 1.9. It is shown that the pristine chemical composition of the CoPi film strongly influences its OER activity in the early stages of the activation process as well as after prolonged exposure to the electrolyte. The best performing CoPi catalyst, displaying a current density of 3.9 mA cm(–2) at 1.8 V versus reversible hydrogen electrode and a Tafel slope of 155 mV/dec at pH 8.0, is selected for an in-depth study of the evolution of its electrochemical properties, chemical composition, and electrochemical active surface area (ECSA) during the activation process. Upon the increase of the number of CV cycles, the OER performance increases, in parallel with the development of a noncatalytic wave in the CV scan, which points out to the reversible oxidation of Co(2+) species to Co(3+) species. X-ray photoelectron spectroscopy and Rutherford backscattering measurements indicate that phosphorous progressively leaches out the CoPi film bulk upon prolonged exposure to the electrolyte. In parallel, the ECSA of the films increases by up to a factor of 40, depending on the initial stoichiometry. The ECSA of the activated CoPi films shows a universal linear correlation with the OER activity for the whole range of CoPi chemical composition. It can be concluded that the adoption of ALD in CoPi-based electrocatalysis enables, next to the well-established control over film growth and properties, to disclose the mechanisms behind the CoPi electrocatalyst activation.
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spelling pubmed-80256762021-04-08 Electrochemical Activation of Atomic Layer-Deposited Cobalt Phosphate Electrocatalysts for Water Oxidation Zhang, Ruoyu van Straaten, Gerben di Palma, Valerio Zafeiropoulos, Georgios van de Sanden, Mauritius C.M. Kessels, Wilhelmus M.M. Tsampas, Mihalis N. Creatore, Mariadriana ACS Catal [Image: see text] The development of efficient and stable earth-abundant water oxidation catalysts is vital for economically feasible water-splitting systems. Cobalt phosphate (CoPi)-based catalysts belong to the relevant class of nonprecious electrocatalysts studied for the oxygen evolution reaction (OER). In this work, an in-depth investigation of the electrochemical activation of CoPi-based electrocatalysts by cyclic voltammetry (CV) is presented. Atomic layer deposition (ALD) is adopted because it enables the synthesis of CoPi films with cobalt-to-phosphorous ratios between 1.4 and 1.9. It is shown that the pristine chemical composition of the CoPi film strongly influences its OER activity in the early stages of the activation process as well as after prolonged exposure to the electrolyte. The best performing CoPi catalyst, displaying a current density of 3.9 mA cm(–2) at 1.8 V versus reversible hydrogen electrode and a Tafel slope of 155 mV/dec at pH 8.0, is selected for an in-depth study of the evolution of its electrochemical properties, chemical composition, and electrochemical active surface area (ECSA) during the activation process. Upon the increase of the number of CV cycles, the OER performance increases, in parallel with the development of a noncatalytic wave in the CV scan, which points out to the reversible oxidation of Co(2+) species to Co(3+) species. X-ray photoelectron spectroscopy and Rutherford backscattering measurements indicate that phosphorous progressively leaches out the CoPi film bulk upon prolonged exposure to the electrolyte. In parallel, the ECSA of the films increases by up to a factor of 40, depending on the initial stoichiometry. The ECSA of the activated CoPi films shows a universal linear correlation with the OER activity for the whole range of CoPi chemical composition. It can be concluded that the adoption of ALD in CoPi-based electrocatalysis enables, next to the well-established control over film growth and properties, to disclose the mechanisms behind the CoPi electrocatalyst activation. American Chemical Society 2021-02-15 2021-03-05 /pmc/articles/PMC8025676/ /pubmed/33842021 http://dx.doi.org/10.1021/acscatal.0c04933 Text en © 2021 The Authors. Published by American Chemical Society Permits non-commercial access and re-use, provided that author attribution and integrity are maintained; but does not permit creation of adaptations or other derivative works (https://creativecommons.org/licenses/by-nc-nd/4.0/).
spellingShingle Zhang, Ruoyu
van Straaten, Gerben
di Palma, Valerio
Zafeiropoulos, Georgios
van de Sanden, Mauritius C.M.
Kessels, Wilhelmus M.M.
Tsampas, Mihalis N.
Creatore, Mariadriana
Electrochemical Activation of Atomic Layer-Deposited Cobalt Phosphate Electrocatalysts for Water Oxidation
title Electrochemical Activation of Atomic Layer-Deposited Cobalt Phosphate Electrocatalysts for Water Oxidation
title_full Electrochemical Activation of Atomic Layer-Deposited Cobalt Phosphate Electrocatalysts for Water Oxidation
title_fullStr Electrochemical Activation of Atomic Layer-Deposited Cobalt Phosphate Electrocatalysts for Water Oxidation
title_full_unstemmed Electrochemical Activation of Atomic Layer-Deposited Cobalt Phosphate Electrocatalysts for Water Oxidation
title_short Electrochemical Activation of Atomic Layer-Deposited Cobalt Phosphate Electrocatalysts for Water Oxidation
title_sort electrochemical activation of atomic layer-deposited cobalt phosphate electrocatalysts for water oxidation
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8025676/
https://www.ncbi.nlm.nih.gov/pubmed/33842021
http://dx.doi.org/10.1021/acscatal.0c04933
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