Nanoscale cooperative adsorption for materials control.

Area of Science:

• Materials Science
• Surface Chemistry
• Nanotechnology

Background:

• Adsorption is crucial for catalysis, sensing, and nanomaterials but quantifying it at the nanoscale is difficult.
• Nanomaterials exhibit heterogeneity, complicating the understanding of adsorbate-surface interactions.
• Ligands are critical for gold nanoparticles' (AuNPs) properties, yet their adsorption behavior is not fully understood.

Purpose of the Study:

• To map molecular adsorption on gold nanoparticles (AuNPs) of various morphologies.
• To differentiate adsorption affinities at different sites on the same nanoparticle.
• To uncover adsorption cooperativity and develop a strategy for facet-controlled nanoparticle synthesis.

Main Methods:

• In situ mapping of nonfluorescent small molecule/ion and polymer ligand adsorption on AuNPs under ambient solution conditions.
• Nanometer-resolution analysis of adsorption affinities and surface densities.
• Investigation of ligand adsorption cooperativity and crossover behaviors between particle facets.

Main Results:

• Quantified adsorption affinities of ligands on different sites of the same AuNP with nanometer resolution.
• Discovered positive and negative adsorption cooperativity, crucial for adsorbate-surface interactions.
• Identified crossover behaviors in ligand adsorption between different particle facets, leading to a synthesis strategy.

Conclusions:

• Developed a method to quantify nanoscale molecular adsorption and cooperativity on heterogeneous nanomaterials.
• Demonstrated a strategy for facet-controlled synthesis of colloidal metal nanoparticles by tuning single ligand concentration.
• Advanced the understanding of adsorbate-surface interactions for improved nanomaterial design and application.