TY - JOUR

T1 - Monitoring the Morphological Changes of Skeleton-PtCo Electrocatalyst during PEMFC Start-Up/Shut-Downprobed by in situ WAXS and SAXS

AU - Janssen, Marek

AU - Drnec, Jakub

AU - Martens, Isaac

AU - Quinson, Jonathan

AU - Pittkowski, Rebecca

AU - Park, Daesung

AU - Weber, Philipp

AU - Arenz, Matthias

AU - Oezaslan, Mehtap

N1 - Publisher Copyright: © 2024 The Authors. ChemSusChem published by Wiley-VCH GmbH.

PY - 2024

Y1 - 2024

N2 - Advanced in situ analyses are indispensable for comprehending the catalyst aging mechanisms of Pt-based PEM fuel cell cathode materials, particularly during accelerated stress tests (ASTs). In this study, a combination of in situ small-angle and wide-angle X-ray scattering (SAXS & WAXS) techniques were employed to establish correlations between structural parameters (crystal phase, quantity, and size) of a highly active skeleton-PtCo (sk-PtCo) catalyst and their degradation cycles within the potential range of the start-up/shut-down (SUSD) conditions. Despite the complex case of the sk-PtCo catalyst comprising two distinct fcc alloy phases, our complementary techniques enabled in situ monitoring of structural changes in each crystal phase in detail. Remarkably, the in situ WAXS measurements uncover two primary catalyst aging processes, namely the cobalt depletion (regime I) followed by the crystallite growth via Ostwald ripening and/or particle coalescence (regime II). Additionally, in situ SAXS data reveal a continuous size growth over the AST. The Pt-enriched shell thickening based on the Co depletion within the first 100 SUSD cycles and particle growth induced by additional potential cycles were also collaborated by ex situ STEM-EELS. Overall, our work shows a comprehensive aging model for the sk-PtCo catalyst probed by complementary in situ WAXS and SAXS techniques.

AB - Advanced in situ analyses are indispensable for comprehending the catalyst aging mechanisms of Pt-based PEM fuel cell cathode materials, particularly during accelerated stress tests (ASTs). In this study, a combination of in situ small-angle and wide-angle X-ray scattering (SAXS & WAXS) techniques were employed to establish correlations between structural parameters (crystal phase, quantity, and size) of a highly active skeleton-PtCo (sk-PtCo) catalyst and their degradation cycles within the potential range of the start-up/shut-down (SUSD) conditions. Despite the complex case of the sk-PtCo catalyst comprising two distinct fcc alloy phases, our complementary techniques enabled in situ monitoring of structural changes in each crystal phase in detail. Remarkably, the in situ WAXS measurements uncover two primary catalyst aging processes, namely the cobalt depletion (regime I) followed by the crystallite growth via Ostwald ripening and/or particle coalescence (regime II). Additionally, in situ SAXS data reveal a continuous size growth over the AST. The Pt-enriched shell thickening based on the Co depletion within the first 100 SUSD cycles and particle growth induced by additional potential cycles were also collaborated by ex situ STEM-EELS. Overall, our work shows a comprehensive aging model for the sk-PtCo catalyst probed by complementary in situ WAXS and SAXS techniques.

KW - accelerated stress test (AST)

KW - oxygen reduction reaction (ORR)

KW - skeleton-PtCo nanoparticles (NPs)

KW - small-angle X-ray scattering (SAXS)

KW - start-up/shut-down (SUSD)

KW - wide-angle X-ray scattering (WAXS)

U2 - 10.1002/cssc.202400303

DO - 10.1002/cssc.202400303

M3 - Journal article

C2 - 38507245

AN - SCOPUS:85190597680

JO - ChemSusChem

JF - ChemSusChem

SN - 1864-5631

M1 - e202400303

ER -