Unveiling Corrosion Pathways of Sn Nanocrystals through High-Resolution Liquid Cell Electron Microscopy.

Peng, Xinxing; Shangguan, Junyi; Zhang, Qiubo; Hauwiller, Matthew; Yu, Haobo; Nie, Yifan; Bustillo, Karen C; Alivisatos, A Paul et al. · Nano Lett · 2024

basic_science · Level V

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Abstract

Unveiling materials' corrosion pathways is significant for understanding the corrosion mechanisms and designing corrosion-resistant materials. Here, we investigate the corrosion behavior of Sn@Ni<sub>3</sub>Sn<sub>4</sub> and Sn nanocrystals in an aqueous solution in real time by using high-resolution liquid cell transmission electron microscopy. Our direct observation reveals an unprecedented level of detail on the corrosion of Sn metal with/without a coating of Ni<sub>3</sub>Sn<sub>4</sub> at the nanometric and atomic levels. The Sn@Ni<sub>3</sub>Sn<sub>4</sub> nanocrystals exhibit "pitting corrosion", which is initiated at the defect sites in the Ni<sub>3</sub>Sn<sub>4</sub> protective layer. The early stage isotropic etching transforms into facet-dependent etching, resulting in a cavity terminated with low-index facets. The Sn nanocrystals under fast etching kinetics show uniform corrosion, and smooth surfaces are obtained. Sn nanocrystals show "creeping-like" etching behavior and rough surfaces. This study provides critical insights into the impacts of coating, defects, and ion diffusion on corrosion kinetics and the resulting morphologies.