Dictating Pt-Based Electrocatalyst Performance in Polymer Electrolyte Fuel Cells, from Formulation to Application

Tim Van Cleve; Sunilkumar Khandavalli; Anamika Chowdhury; Samantha Medina; Svitlana Pylypenko; Min Wang; Karren L. More; Nancy Kariuki; Deborah J. Myers; Adam Z. Weber; Scott A. Mauger; Michael Ulsh; K. C. Neyerlin

doi:10.1021/acsami.9b17614

Dictating Pt-Based Electrocatalyst Performance in Polymer Electrolyte Fuel Cells, from Formulation to Application

Tim Van Cleve, Sunilkumar Khandavalli, Anamika Chowdhury, Samantha Medina, Svitlana Pylypenko, Min Wang, Karren L. More, Nancy Kariuki, Deborah J. Myers, Adam Z. Weber, Scott A. Mauger, Michael Ulsh, K. C. Neyerlin

Center for Nanophase Matls Sciences

Research output: Contribution to journal › Article › peer-review

96 Scopus citations

Abstract

In situ electrochemical diagnostics designed to probe ionomer interactions with platinum and carbon were applied to relate ionomer coverage and conformation, gleaned from anion adsorption data, with O₂ transport resistance for low-loaded (0.05 mg_Pt cm^-2) platinum-supported Vulcan carbon (Pt/Vu)-based electrodes in a polymer electrolyte fuel cell. Coupling the in situ diagnostic data with ex situ characterization of catalyst inks and electrode structures, the effect of ink composition is explained by both ink-level interactions that dictate the electrode microstructure during fabrication and the resulting local ionomer distribution near catalyst sites. Electrochemical techniques (CO displacement and ac impedance) show that catalyst inks with higher water content increase ionomer (sulfonate) interactions with Pt sites without significantly affecting ionomer coverage on the carbon support. Surprisingly, the higher anion adsorption is shown to have a minor impact on specific activity, while exhibiting a complex relationship with oxygen transport. Ex situ characterization of ionomer suspensions and catalyst/ionomer inks indicates that the lower ionomer coverage can be correlated with the formation of large ionomer aggregates and weaker ionomer/catalyst interactions in low-water content inks. These larger ionomer aggregates resulted in increased local oxygen transport resistance, namely, through the ionomer film, and reduced performance at high current density. In the water-rich inks, the ionomer aggregate size decreases, while stronger ionomer/Pt interactions are observed. The reduced ionomer aggregation improves transport resistance through the ionomer film, while the increased adsorption leads to the emergence of resistance at the ionomer/Pt interface. Overall, the high current density performance is shown to be a nonmonotonic function of ink water content, scaling with the local gas (H₂, O₂) transport resistance resulting from pore, thin film, and interfacial phenomena.

Original language	English
Pages (from-to)	46953-46964
Number of pages	12
Journal	ACS Applied Materials and Interfaces
Volume	11
Issue number	50
DOIs	https://doi.org/10.1021/acsami.9b17614
State	Published - Dec 18 2019

Funding

This work was authored in part by Alliance for Sustainable Energy, LLC, the manager and operator of the National Renewable Energy Laboratory for the U.S. Department of Energy (DOE) under contract no. DE-AC36-08GO28308. The submitted manuscript was also created, in part, by U Chicago Argonne, LLC, operator of Argonne National Laboratory, a DOE Office of Science laboratory, under contract DEAC02-06CH11357. Funding was provided by DOE Office of Energy Efficiency and Renewable Energy, Fuel Cell Technology Office, under the Fuel Cell Performance and Durability (FC-PAD) Consortium (contract DE-AC02-05CH11231 for LBNL), technology manager Greg Kleen and through the Fuel Cell Technology Office, technology manager Nancy Garland. Electron microscopy was conducted as a part of a user project at ORNL’s Center for Nanophase Materials Sciences (CNMS), DOE Office of Science User Facility. X-ray scattering was performed at beamline 9-ID-C at the Advanced Photon Source (APS) at Argonne National Laboratory, a U.S. Department of Energy (DOE) Office of Science User Facility, operated for the DOE Office of Science by Argonne National Laboratory under Contract DE-AC02 06CH11357. The Argonne authors thank Jan Ilavsky, Ivan Kuzmenko, and Matthew Firth of 9-ID-C. The authors are grateful for the continued collaborative and engaging discussions with Anu Kongkanand and many others from the GM fuel-cell activity program. The authors appreciate the frequent insightful discussions with Dr. Ahmet Kusoglu. The views expressed in the article do not necessarily represent the views of the DOE or the U.S. Government.

Funders	Funder number
Alliance for Sustainable Energy, LLC
DOE Office of Science	DE-AC02 06CH11357
DOE Office of Science laboratory
FC-PAD	DE-AC02-05CH11231 for LBNL, APS
Fuel Cell Technology Office
Office of Science User Facility
U.S. Department of Energy
Office of Energy Efficiency and Renewable Energy
Argonne National Laboratory
National Renewable Energy Laboratory

Keywords

Pt/C catalyst inks
in situ electrochemical diagnostics
ink formulation and processing
ionomer coverage
oxygen transport resistance

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1021/acsami.9b17614

Cite this

Van Cleve, T., Khandavalli, S., Chowdhury, A., Medina, S., Pylypenko, S., Wang, M., More, K. L., Kariuki, N., Myers, D. J., Weber, A. Z., Mauger, S. A., Ulsh, M., & Neyerlin, K. C. (2019). Dictating Pt-Based Electrocatalyst Performance in Polymer Electrolyte Fuel Cells, from Formulation to Application. ACS Applied Materials and Interfaces, 11(50), 46953-46964. https://doi.org/10.1021/acsami.9b17614

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title = "Dictating Pt-Based Electrocatalyst Performance in Polymer Electrolyte Fuel Cells, from Formulation to Application",

abstract = "In situ electrochemical diagnostics designed to probe ionomer interactions with platinum and carbon were applied to relate ionomer coverage and conformation, gleaned from anion adsorption data, with O2 transport resistance for low-loaded (0.05 mgPt cm-2) platinum-supported Vulcan carbon (Pt/Vu)-based electrodes in a polymer electrolyte fuel cell. Coupling the in situ diagnostic data with ex situ characterization of catalyst inks and electrode structures, the effect of ink composition is explained by both ink-level interactions that dictate the electrode microstructure during fabrication and the resulting local ionomer distribution near catalyst sites. Electrochemical techniques (CO displacement and ac impedance) show that catalyst inks with higher water content increase ionomer (sulfonate) interactions with Pt sites without significantly affecting ionomer coverage on the carbon support. Surprisingly, the higher anion adsorption is shown to have a minor impact on specific activity, while exhibiting a complex relationship with oxygen transport. Ex situ characterization of ionomer suspensions and catalyst/ionomer inks indicates that the lower ionomer coverage can be correlated with the formation of large ionomer aggregates and weaker ionomer/catalyst interactions in low-water content inks. These larger ionomer aggregates resulted in increased local oxygen transport resistance, namely, through the ionomer film, and reduced performance at high current density. In the water-rich inks, the ionomer aggregate size decreases, while stronger ionomer/Pt interactions are observed. The reduced ionomer aggregation improves transport resistance through the ionomer film, while the increased adsorption leads to the emergence of resistance at the ionomer/Pt interface. Overall, the high current density performance is shown to be a nonmonotonic function of ink water content, scaling with the local gas (H2, O2) transport resistance resulting from pore, thin film, and interfacial phenomena.",

keywords = "Pt/C catalyst inks, in situ electrochemical diagnostics, ink formulation and processing, ionomer coverage, oxygen transport resistance",

author = "{Van Cleve}, Tim and Sunilkumar Khandavalli and Anamika Chowdhury and Samantha Medina and Svitlana Pylypenko and Min Wang and More, {Karren L.} and Nancy Kariuki and Myers, {Deborah J.} and Weber, {Adam Z.} and Mauger, {Scott A.} and Michael Ulsh and Neyerlin, {K. C.}",

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Van Cleve, T, Khandavalli, S, Chowdhury, A, Medina, S, Pylypenko, S, Wang, M, More, KL, Kariuki, N, Myers, DJ, Weber, AZ, Mauger, SA, Ulsh, M & Neyerlin, KC 2019, 'Dictating Pt-Based Electrocatalyst Performance in Polymer Electrolyte Fuel Cells, from Formulation to Application', ACS Applied Materials and Interfaces, vol. 11, no. 50, pp. 46953-46964. https://doi.org/10.1021/acsami.9b17614

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T1 - Dictating Pt-Based Electrocatalyst Performance in Polymer Electrolyte Fuel Cells, from Formulation to Application

AU - Van Cleve, Tim

AU - Khandavalli, Sunilkumar

AU - Chowdhury, Anamika

AU - Medina, Samantha

AU - Pylypenko, Svitlana

AU - Wang, Min

AU - More, Karren L.

AU - Kariuki, Nancy

AU - Myers, Deborah J.

AU - Weber, Adam Z.

AU - Mauger, Scott A.

AU - Ulsh, Michael

AU - Neyerlin, K. C.

PY - 2019/12/18

Y1 - 2019/12/18

N2 - In situ electrochemical diagnostics designed to probe ionomer interactions with platinum and carbon were applied to relate ionomer coverage and conformation, gleaned from anion adsorption data, with O2 transport resistance for low-loaded (0.05 mgPt cm-2) platinum-supported Vulcan carbon (Pt/Vu)-based electrodes in a polymer electrolyte fuel cell. Coupling the in situ diagnostic data with ex situ characterization of catalyst inks and electrode structures, the effect of ink composition is explained by both ink-level interactions that dictate the electrode microstructure during fabrication and the resulting local ionomer distribution near catalyst sites. Electrochemical techniques (CO displacement and ac impedance) show that catalyst inks with higher water content increase ionomer (sulfonate) interactions with Pt sites without significantly affecting ionomer coverage on the carbon support. Surprisingly, the higher anion adsorption is shown to have a minor impact on specific activity, while exhibiting a complex relationship with oxygen transport. Ex situ characterization of ionomer suspensions and catalyst/ionomer inks indicates that the lower ionomer coverage can be correlated with the formation of large ionomer aggregates and weaker ionomer/catalyst interactions in low-water content inks. These larger ionomer aggregates resulted in increased local oxygen transport resistance, namely, through the ionomer film, and reduced performance at high current density. In the water-rich inks, the ionomer aggregate size decreases, while stronger ionomer/Pt interactions are observed. The reduced ionomer aggregation improves transport resistance through the ionomer film, while the increased adsorption leads to the emergence of resistance at the ionomer/Pt interface. Overall, the high current density performance is shown to be a nonmonotonic function of ink water content, scaling with the local gas (H2, O2) transport resistance resulting from pore, thin film, and interfacial phenomena.

AB - In situ electrochemical diagnostics designed to probe ionomer interactions with platinum and carbon were applied to relate ionomer coverage and conformation, gleaned from anion adsorption data, with O2 transport resistance for low-loaded (0.05 mgPt cm-2) platinum-supported Vulcan carbon (Pt/Vu)-based electrodes in a polymer electrolyte fuel cell. Coupling the in situ diagnostic data with ex situ characterization of catalyst inks and electrode structures, the effect of ink composition is explained by both ink-level interactions that dictate the electrode microstructure during fabrication and the resulting local ionomer distribution near catalyst sites. Electrochemical techniques (CO displacement and ac impedance) show that catalyst inks with higher water content increase ionomer (sulfonate) interactions with Pt sites without significantly affecting ionomer coverage on the carbon support. Surprisingly, the higher anion adsorption is shown to have a minor impact on specific activity, while exhibiting a complex relationship with oxygen transport. Ex situ characterization of ionomer suspensions and catalyst/ionomer inks indicates that the lower ionomer coverage can be correlated with the formation of large ionomer aggregates and weaker ionomer/catalyst interactions in low-water content inks. These larger ionomer aggregates resulted in increased local oxygen transport resistance, namely, through the ionomer film, and reduced performance at high current density. In the water-rich inks, the ionomer aggregate size decreases, while stronger ionomer/Pt interactions are observed. The reduced ionomer aggregation improves transport resistance through the ionomer film, while the increased adsorption leads to the emergence of resistance at the ionomer/Pt interface. Overall, the high current density performance is shown to be a nonmonotonic function of ink water content, scaling with the local gas (H2, O2) transport resistance resulting from pore, thin film, and interfacial phenomena.

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KW - in situ electrochemical diagnostics

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KW - ionomer coverage

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Dictating Pt-Based Electrocatalyst Performance in Polymer Electrolyte Fuel Cells, from Formulation to Application

Abstract

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Keywords

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