Heterogeneous Corrosion Pathways in Pt-Ni Nanododecahedra Revealed by <i>In Situ</i> Liquid Cell TEM.
basic_science · Level V
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- Record sourced from PubMed, PMID 41575916.
- Also identified by DOI 10.1021/acs.nanolett.5c05291.
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Abstract
Unraveling nanoscale corrosion pathways is essential for understanding materials degradation mechanisms and designing corrosion-resistant metal alloys. Here, we directly visualize the corrosion of Pt-Ni nanododecahedra in 0.1 M HCl using liquid cell TEM. Each nanoparticle features a Ni-rich core and a Pt-rich frame. Our observation reveals that corrosion proceeds in two distinct stages: first the Ni-rich core dissolves without forming porosity, yielding small Pt nanocrystals and transient NiCl<sub>2</sub>·6H<sub>2</sub>O at the retreating interfaces; then the Pt-rich frame fragments into ∼5 nm Pt<sub>3</sub>Ni nanocrystals that subsequently dissolve uniformly, accompanied by fleeting Pt chlorides. A percolation-based theory explains the observed behaviors: The core's ∼8% Pt lies below the Pt connectivity threshold, preventing Pt scaffold formation, whereas the frame's 48% Ni exceeds the Ni percolation threshold and collapses. Ordered Pt<sub>3</sub>Ni suppresses Ni percolation, thereby enforcing uniform dissolution. These findings reveal how composition and structural ordering govern heterogeneous corrosion in Pt-Ni architectured nanoparticles.