Selective Catalytic Reduction of NO Using Phase-Pure Anatase, Rutile, and Brookite TiO2 Nanocrystals
Jinlong Yu1, Anita Lundager Godiksen2, Aref Mamahkel1
1Center for Materials Crystallography, Department of Chemistry and iNANO, Aarhus University, DK-8000 Aarhus, Denmark.
Inorganic Chemistry
|October 8, 2020
Summary
This study presents a simple hydrothermal method to synthesize pure anatase, rutile, and brookite titania (TiO2) nanocrystals. These materials show varying catalytic activities for selective catalytic reduction of NO and photocatalytic degradation of Rhodamine B.
Area of Science:
- Materials Science
- Nanotechnology
- Catalysis
Background:
- Titania (TiO2) nanocrystals exhibit diverse polymorphs (anatase, rutile, brookite) with distinct properties.
- Controlling the synthesis of phase-pure TiO2 polymorphs is crucial for optimizing their performance in various applications.
- Previous synthesis methods often lack selectivity or utilize harsh conditions.
Purpose of the Study:
- To develop a facile and selective hydrothermal synthesis route for phase-pure anatase, rutile, and brookite TiO2 nanocrystals.
- To characterize the morphology and facet termination of the synthesized nanocrystals.
- To evaluate the catalytic and photocatalytic activities of the TiO2 polymorphs.
Main Methods:
- Hydrothermal treatment of titanium oxysulfate (TiOSO4) precursor.
- Use of acetic acid for anatase, glycolic acid for rutile, and a combination for brookite synthesis.
- Characterization using powder X-ray diffraction, transmission electron microscopy, and Raman spectroscopy.
- Evaluation of NH3-selective catalytic reduction (SCR) of NO and Rhodamine B (RhB) photocatalytic decomposition.
Main Results:
- Phase-pure anatase, rutile, and brookite TiO2 nanocrystals were successfully synthesized.
- Morphological analysis revealed specific facet terminations for each polymorph, correcting literature errors for brookite.
- Vanadia-titania catalysts supported on TiO2 showed activity in NH3-SCR with the order: anatase > brookite > rutile.
- Photocatalytic activity for RhB decomposition under UV light followed the order: P25 > anatase ≈ rutile > brookite.
Conclusions:
- The developed hydrothermal method offers a benign and selective approach for synthesizing TiO2 nanocrystal polymorphs.
- Facet engineering of TiO2 nanocrystals significantly influences their catalytic and photocatalytic performance.
- The findings provide insights into the structure-activity relationships of TiO2 polymorphs for environmental applications.
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