Investigating Degradation Mechanisms in PtCo Alloy Catalysts: The Role of Co Content and a Pt-Rich Shell Using Operando High-Energy Resolution Fluorescence Detection X-ray Absorption Spectroscopy

• DOI: 10.1021/acsami.3c11248
• Publication Date: 2023-11-01T05:13:45Z
• Authors: Yunfei Gao; Neha Thakur; Tomoki Uchiyama; Weijie Cao; Kentaro Yamamoto; Toshiki Watanabe; Mukesh Kumar; Ryota Sato; Toshiharu Teranishi; Hideto Imai; Yoshiharu Sakurai; Yoshiharu Uchimoto
• Keywords: X-ray absorption spectroscopy; Degradation

Low Pt-based alloy catalysts are regarded as an efficient strategy in achieving high activity for the oxygen reduction reaction (ORR) proton-exchange membrane fuel cells (PEMFCs). However, desired durability low catalysts, such Pt1Co3 catalyst, has still been considered a great challenge PEMFCs. In this study, we investigate sub-2.5 nm PtxCoy with varying Co content and Pt1Co3@Pt core-shell (CS) nanostructure obtained through simple displacement reaction. The Pt1Co3@Pt_H showed mass (MA) of 1.46 A/mgPt at 0.9 V 14% MA loss after 10k accelerated degradation test (ADT) cycles, which suggested improved stability compared (52% loss). To clarify mechanism, operando high-energy resolution fluorescence detection X-ray absorption spectroscopy (XAS) was applied addition to conventional advanced measurement techniques, including XAS, analyze electronic state structure changes during operation potentials. We found that introducing improves catalysts' mainly from strain effect, but excessive amount leads increased Pt-oxidation, accelerates catalysts. catalyst shows tolerance benefiting both activity. Our findings demonstrate in-depth understanding mechanism importance designing PtCo CS nanostructures optimal enhanced performance