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Chemical Dissolution of Pt(111) During Potential Cycling Under Negative pH Conditions Studied by Operando X-ray Photoelectron Spectroscopy

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Chemical Dissolution of Pt(111) During Potential Cycling Under Negative pH Conditions Studied by Operando X-ray Photoelectron Spectroscopy. / Ali-Löytty, Harri; Valden, Mika; Hannula, Markku; Eilert, André; Ogasawara, Hirohito; Nilsson, Anders.

In: Journal of Physical Chemistry C, Vol. 123, No. 41, 25.09.2019, p. 25128-25134.

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Ali-Löytty, Harri ; Valden, Mika ; Hannula, Markku ; Eilert, André ; Ogasawara, Hirohito ; Nilsson, Anders. / Chemical Dissolution of Pt(111) During Potential Cycling Under Negative pH Conditions Studied by Operando X-ray Photoelectron Spectroscopy. In: Journal of Physical Chemistry C. 2019 ; Vol. 123, No. 41. pp. 25128-25134.

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@article{ddfd7967d13a470fa6f556f2e090a5d3,
title = "Chemical Dissolution of Pt(111) During Potential Cycling Under Negative pH Conditions Studied by Operando X-ray Photoelectron Spectroscopy",
abstract = "Dissolution of platinum catalyst is a major degradation mechanism of fuel cells but the exact reaction mechanism has remained unclear. Here, electrochemical ambient pressure X-ray photoelectron spectroscopy (EC-APXPS) was utilized to provide direct information on chemical species on a single crystal Pt(111) electrode under extremely low pH conditions. Measurements were conducted using a novel condensed electrolyte film electrochemical cell applying work function measurement as a loss-free probe for electrochemical potential. We show that platinum can dissolve chemically as Pt2+ ion during potential cycling and redeposit as Pt2+ at the onset potential for cathodic reactions. The dissolution of Pt does not require electrochemical oxidation via oxide place-exchange. In contrast, the adsorption of oxygenated species (OH* or O*) at the onset potential for anodic reactions is a sufficient prerequisite to the dissolution. These results provide new insight to the degradation mechanism of Pt under extremely low pH conditions, predicted by the Pourbaix diagram, having practical applications to the durability of Pt-based catalysts in electrochemical energy conversion devices.",
author = "Harri Ali-L{\"o}ytty and Mika Valden and Markku Hannula and Andr{\'e} Eilert and Hirohito Ogasawara and Anders Nilsson",
year = "2019",
month = "9",
day = "25",
doi = "10.1021/acs.jpcc.9b05201",
language = "English",
volume = "123",
pages = "25128--25134",
journal = "Journal of Physical Chemistry C",
issn = "1932-7447",
publisher = "American Chemical Society ACS",
number = "41",

}

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TY - JOUR

T1 - Chemical Dissolution of Pt(111) During Potential Cycling Under Negative pH Conditions Studied by Operando X-ray Photoelectron Spectroscopy

AU - Ali-Löytty, Harri

AU - Valden, Mika

AU - Hannula, Markku

AU - Eilert, André

AU - Ogasawara, Hirohito

AU - Nilsson, Anders

PY - 2019/9/25

Y1 - 2019/9/25

N2 - Dissolution of platinum catalyst is a major degradation mechanism of fuel cells but the exact reaction mechanism has remained unclear. Here, electrochemical ambient pressure X-ray photoelectron spectroscopy (EC-APXPS) was utilized to provide direct information on chemical species on a single crystal Pt(111) electrode under extremely low pH conditions. Measurements were conducted using a novel condensed electrolyte film electrochemical cell applying work function measurement as a loss-free probe for electrochemical potential. We show that platinum can dissolve chemically as Pt2+ ion during potential cycling and redeposit as Pt2+ at the onset potential for cathodic reactions. The dissolution of Pt does not require electrochemical oxidation via oxide place-exchange. In contrast, the adsorption of oxygenated species (OH* or O*) at the onset potential for anodic reactions is a sufficient prerequisite to the dissolution. These results provide new insight to the degradation mechanism of Pt under extremely low pH conditions, predicted by the Pourbaix diagram, having practical applications to the durability of Pt-based catalysts in electrochemical energy conversion devices.

AB - Dissolution of platinum catalyst is a major degradation mechanism of fuel cells but the exact reaction mechanism has remained unclear. Here, electrochemical ambient pressure X-ray photoelectron spectroscopy (EC-APXPS) was utilized to provide direct information on chemical species on a single crystal Pt(111) electrode under extremely low pH conditions. Measurements were conducted using a novel condensed electrolyte film electrochemical cell applying work function measurement as a loss-free probe for electrochemical potential. We show that platinum can dissolve chemically as Pt2+ ion during potential cycling and redeposit as Pt2+ at the onset potential for cathodic reactions. The dissolution of Pt does not require electrochemical oxidation via oxide place-exchange. In contrast, the adsorption of oxygenated species (OH* or O*) at the onset potential for anodic reactions is a sufficient prerequisite to the dissolution. These results provide new insight to the degradation mechanism of Pt under extremely low pH conditions, predicted by the Pourbaix diagram, having practical applications to the durability of Pt-based catalysts in electrochemical energy conversion devices.

U2 - 10.1021/acs.jpcc.9b05201

DO - 10.1021/acs.jpcc.9b05201

M3 - Article

VL - 123

SP - 25128

EP - 25134

JO - Journal of Physical Chemistry C

JF - Journal of Physical Chemistry C

SN - 1932-7447

IS - 41

ER -