Quantification of Molecule-Defect Site Binding Force Via Single‑Molecule Adhesion

Area of Science:

• Surface Science and Catalysis
• Nanotechnology and Materials Science
• Single-Molecule Biophysics

Background:

• Molecular binding strength dictates catalytic reaction selectivity and efficiency by influencing adsorption energy and activation barriers.
• Traditional methods offer only ensemble-averaged data, hindering the direct quantification of molecule-site binding forces.
• Understanding local binding forces is crucial for designing efficient catalysts.

Purpose of the Study:

• To develop and demonstrate a single-molecule force imaging strategy for quantitative mapping of local binding forces.
• To correlate measured binding forces with catalytic performance at the nanoscale.
• To visualize structure-reactivity relationships at the single-molecule level for various catalysts.

Main Methods:

• Utilized a single-molecule force imaging strategy employing atomic force microscopy (AFM).
• Covalently tethered functional molecules (e.g., dopamine) to an AFM tip to probe molecule-site interactions.
• Performed measurements under realistic liquid conditions to map site-specific interaction forces.

Main Results:

• Achieved quantitative mapping of local binding forces with high spatial resolution.
• Observed significantly stronger adhesion (218 pN) at defective sites on MoS₂ compared to non-defective regions (120 pN).
• Generated nanoscale reactivity maps by correlating force signatures with catalytic performance.

Conclusions:

• The single-molecule force imaging approach enables direct measurement and visualization of molecule-site binding forces.
• Demonstrated a quantitative link between local binding strength and catalytic reactivity.
• The methodology is broadly applicable to various catalysts (e.g., MoS₂, TiO₂) for understanding structure-reactivity relationships.