Boronic Acid Adsorption on Hydrated Rutile TiO₂(110): A DFT + U Study

Area of Science:

• Materials Science
• Physical Chemistry
• Surface Science

Background:

• Boronic acids are key anchoring groups in dye-sensitized solar cells (DSSCs).
• Previous studies focused on boronic acid adsorption on clean TiO₂ surfaces.
• Real-world DSSC performance is affected by hydrated TiO₂ surfaces.

Purpose of the Study:

• Investigate boronic acid adsorption on hydrated rutile TiO₂(110) surfaces.
• Compare adsorption behavior of boric acid and functionalized boronic acids.
• Understand the impact of surface hydration on anchoring group binding.

Main Methods:

• Employed density functional theory (DFT) with DFT + U and D3 dispersion corrections.
• Utilized five distinct models representing low-coverage dissociative water adsorption.
• Analyzed various molecular and dissociative adsorption configurations (monodentate, bidentate).

Main Results:

• Boric acid preferentially adsorbs in a bidentate, doubly dissociative mode on hydrated surfaces.
• Surface hydration weakens boronic acid adsorption compared to clean surfaces.
• Functionalization enhances binding stability; fluorophenylboronic acids show strongest adsorption.
• Hydration reduces Ti surface atom positive charges, decreasing Lewis acidity and adsorption strength.

Conclusions:

• Hydration significantly influences boronic acid adsorption on TiO₂ surfaces.
• Functionalized boronic acids remain effective anchoring groups under hydrated conditions.
• Findings provide a realistic benchmark for designing anchoring groups for TiO₂-based applications.