Tensile-Strain-Promoted <i>In Situ</i> Electrochemical Hydrogen Intercalation Stabilizes Pd Icosahedra toward Oxygen Reduction.
basic_science · Level V
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- Record sourced from PubMed, PMID 41283779.
- Also identified by DOI 10.1021/acs.nanolett.5c04573.
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Abstract
Understanding the strain effect in catalysis is vital for catalyst design but is complicated by the lack of model catalyst systems and strain-induced <i>in situ</i> reconstruction of the catalytically active phase. Here, we employ well-defined Pd-based model catalysts to thoroughly investigate how the surface strain impacts the oxygen reduction reaction (ORR). In contrast to the conventional expectation, Pd icosahedra (Pd-i) with a ∼2% tensile strain exhibit markedly enhanced catalytic stability toward the ORR compared to Pd octahedra (Pd-o). After 10 000 cycles of accelerated durability testing, Pd-i loses only 8.7% of its initial mass activity, while Pd-o suffers a 54.1% decline. Quasi-<i>in situ</i> spectroscopic characterizations and electrochemical analyses demonstrate that tensile strain in Pd-i promotes <i>in situ</i> hydrogen intercalation, leading to the formation of the PdH<sub><i>x</i></sub> active phase. <i>In situ</i> X-ray absorption spectroscopy and theory calculations reveal that H intercalation enhances the oxidation resistance of Pd and suppresses Pd dissolution by a strong Pd-H interaction.