Hole Scavenging by Organic Adsorbates on the TiO2 Surface: A DFT Model Study

Area of Science:

• Materials Science
• Physical Chemistry
• Surface Science

Background:

• Understanding interfacial charge transfer in photocatalysis is vital for applications in energy, environment, and medicine.
• Photooxidation processes on semiconductor surfaces are fundamental to photocatalysis.

Purpose of the Study:

• To investigate the mechanism of interfacial hole transfer between photoirradiated anatase TiO2 nanoparticles and various organic adsorbates.
• To determine the factors influencing hole transfer and propose a scavenging power scale for organic molecules.

Main Methods:

• Utilized density functional theory (DFT) with the hybrid functional B3LYP.
• Studied hole transfer at the anatase (101) surface with adsorbed organic alcohols and acids.

Main Results:

• Proposed a mechanism involving photoinduced proton dissociation for hole transfer.
• Established a scavenging power scale: glycerol > tert-butanol > iso-propanol > methanol > formic acid.
• Observed that surface dipole reduces the energy cost for hole formation, facilitating transfer upon proton dissociation.

Conclusions:

• Hole transfer to organic adsorbates is dependent on proton dissociation, except for strong scavengers like catechol.
• Surface dipole effects play a role in modulating the hole transfer process.
• The findings provide insights into controlling photooxidation for enhanced photocatalytic efficiency.