Stability Limits and Surface Chemistry of Ag Nanoparticles in Non-Adsorbing Electrolytes Probed by Bragg Coherent Diffractive Imaging

TL;DR

This study uses advanced 3D imaging to explore how surface defects and strain influence the stability and dissolution of silver nanoparticles during electrochemical reactions, providing insights relevant to catalysis and nanomaterial stability.

Contribution

It introduces in-situ 3D imaging of nanoparticle dissolution with Bragg Coherent Diffractive Imaging, linking defect dynamics to stability in electrochemical environments.

Findings

Dissolution kinetics measured in real-time with SPRDE and ICP-MS.

3D imaging reveals defect and strain roles in nanoparticle stability.

Insights applicable to electrocatalytic reactions beyond silver.

Abstract

Surface chemistry is important across diverse fields such as corrosion and nanostructure synthesis. Unfortunately, many as-synthesized nanomaterials, including partially dealloyed nanoparticle catalysts for fuel cells, with highly active surfaces are not stable in their reactive environments, preventing widespread application. Thus, understanding instability by focusing on the structure-stability and defect-stability relationship at the nanoscale is crucial and will likely play an important role in meeting grand challenges. To this end, recent advances in imaging nanostructure stability have come via both electron, x-ray, and other techniques such as atomic force microscopy, but tend to be limited to specific sample environments and/or two-dimensional images. Here, we report investigations into the defect-stability relationship of silver nanoparticles to voltage-induced electrochemical dissolution imaged in-situ in three-dimensional (3D) detail by Bragg Coherent Diffractive Imaging (BCDI). We first determine the average dissolution kinetics by Stationary Probe Rotating Disk Electrode (SPRDE) in combination with inductively coupled plasma mass spectrometry (ICP-MS), which allows real-time in-situ measurement of Ag+ ions formation and the corresponding electrochemical current. We then observe the dissolution and redeposition processes in 3D with BCDI in single nanocrystals, providing unique insight about the role of surface strain, defects, and their coupling to the dissolution chemistry. The methods developed and the knowledge gained go well beyond a "simple" silver electrochemistry and are applicable to all electrocatalytic reactions where functional links between activity and stability are controlled by structure and defect dynamics.