Agglomeration compaction promotes corrosion of gold nanoparticles

Area of Science:

• Materials Science
• Nanotechnology
• Physical Chemistry

Background:

• Engineered nanoparticles are widely applied, but their behavior in harsh environments remains unclear.
• Understanding nanoparticle degradation mechanisms is crucial for predicting their fate and impact.

Purpose of the Study:

• To investigate the degradation mechanism of citrate-stabilized gold nanoparticles (GNPs) in acidic hydrogen peroxide solutions.
• To quantify nanoparticle agglomeration and sizing under specific environmental conditions.

Main Methods:

• Utilized optical spectroscopy and nanoparticle tracking analysis.
• Studied 50 nm citrate-stabilized gold nanoparticles (GNPs) in HCl solutions with H2O2.
• Analyzed nanoparticle agglomeration, sizing, and degradation pathways.

Main Results:

• Observed that GNPs disappear from suspension due to aggregate formation, not dissolution.
• High ionic strength neutralizes electrostatic shielding, enabling nanoparticle proximity.
• Casimir and van der Waals forces dominate at subnanometer distances, promoting agglomeration.

Conclusions:

• Nanoparticle degradation in harsh environments is primarily driven by aggregation.
• Near-field forces and reduced double electrical layer thickness facilitate novel chemical reaction pathways.
• The findings provide insights into nanoparticle stability and reactivity in complex solutions.