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Singlet Oxygen Photocatalytic Generation by Silanized TiO2 Nanoparticles
Francesco Parrino1, Alessandro Gottuso1, Lorenzo Viganò2
1Department of Industrial Engineering, University of Trento, Via Sommarive 9, 38123, Trento, Italy.
Angewandte Chemie (International Ed. in English)
|October 4, 2024
Summary
Surface modification of titanium dioxide (TiO2) with silane enhances photocatalysis. Silanized TiO2 promotes singlet oxygen (1O2) generation via excited Ti3+ defects, improving limonene epoxidation selectivity.
Area of Science:
- Materials Science
- Surface Chemistry
- Photocatalysis
Background:
- Titanium dioxide (TiO2) is a widely used photocatalyst.
- Surface properties significantly influence TiO2 photocatalytic activity.
- Controlling surface chemistry is crucial for enhancing TiO2 performance.
Purpose of the Study:
- To functionalize TiO2 with hexadecyltrimethoxysilane to modify its surface.
- To investigate the impact of silane modification on TiO2 electronic structure and defect formation.
- To evaluate the effect of silanization on photocatalytic activity, specifically singlet oxygen generation.
Main Methods:
- Surface functionalization of TiO2 with hexadecyltrimethoxysilane.
- Characterization using FTIR, solid-state NMR, XPS, UV/Vis, EPR, and N2 physisorption.
- Thermogravimetric analysis for grafting density determination.
- Photocatalytic epoxidation of limonene under UV and NIR irradiation.
Main Results:
- Silane grafting was confirmed, leading to modified Ti ion shielding and crystal field.
- Formation of Ti3+ defects in the sub-surface region of silanized TiO2.
- Silanized TiO2 exhibited inhibited electron transfer to O2 and enhanced singlet oxygen (1O2) formation.
- Improved selectivity in limonene epoxidation photocatalysis with silanized TiO2, especially under simultaneous NIR irradiation.
Conclusions:
- Surface silanization of TiO2 creates Ti3+ defects that stabilize paramagnetic centers.
- These Ti3+ centers are implicated in the generation of singlet oxygen (1O2) via Förster-type energy transfer.
- Silanized TiO2 shows enhanced photocatalytic performance for reactions involving 1O2, suggesting potential for improved catalytic applications.
