Nanoscale Kinetics of Asymmetrical Corrosion in Core-Shell Nanoparticles

Hao Shan, Wenpei Gao, Yalin Xiong Fenglei Shi, Yucong Yan, Yanling Ma, Wen Shang , Peng Tao, Chengyi Song, Tao Deng, Hui Zhang, Deren Yang, Xiaoqing Pan & Jianbo Wu, 2018

Image courtesy of Nature Communications

Abstract

Designing new materials and structure to sustain the corrosion during operation requires better understanding on the corrosion dynamics. Observation on how the corrosion proceeds in atomic scale is thus critical. Here, using a liquid cell, we studied the real-time corrosion process of palladium@platinum (Pd@Pt) core-shell nanocubes via transmission electron microscopy (TEM). The results revealed that multiple etching pathways operatively contribute to the morphology evolution during corrosion, including galvanic etching on non-defected sites with slow kinetics and halogen-induced etching at defected sites at faster rates. Corners are the preferential corrosion sites; both etching pathways are mutually restricted during corrosion. Those insights on the interaction of nanostructures with reactive liquid environments can help better engineer the surface structure to improve the stability of electrocatalysts as well as design a new porous structure that may provide more active sites for catalysis.

 

Impact Statement

Core-shell nanoparticle corrosion in the presence of electrolyte was imaged in situ in order to develop mechanistic insights into the degredation of catalytic nanoparticles.  Two competing corrosion pathways were observed:  galvanic corrosion and halogen etching corrosion.  Nanoparticles without defectsin the platinum core were only affected by galvanic corrosion, which preserves the platinum shell of the nanoparticles.  Nanoparticles with defects in the platinum core underwent both galvanic and halogen corrosion and led to a loss of structural integrity and therefore reduced activity.