Excellent acetone sensing enabled by tunable metal organic framework derived TiO₂ nanodisks

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Metal-Organic Frameworks (MOFs) derived TiO2 (MIL-125) show promise for gas sensing.
• Annealing influences TiO2 polymorphs (anatase, rutile, brookite) and their sensing properties.
• The effect of annealing on MIL-125 properties was previously unstudied.

Purpose of the Study:

• Investigate the impact of annealing temperatures (500-650°C) on MIL-125.
• Characterize the structural and gas sensing property changes.
• Explore the potential for enhanced acetone detection.

Main Methods:

• Controlled annealing of MIL-125 at temperatures from 500-650°C.
• Morphological analysis using electron microscopy (implied).
• X-ray Photoelectron Spectroscopy (XPS) and Electron Paramagnetic Resonance (EPR) for chemical analysis.

Main Results:

• Annealing at 600°C (MT600) resulted in a rough nanodisk surface with high oxygen vacancies.
• Complete transformation to rutile at 650°C (MT650) caused structural collapse.
• MT600 sensor demonstrated high acetone response (SR∼21 at 500ppm, SR∼6.7 at 1ppm) and fast response/recovery (∼13s/12s).

Conclusions:

• Annealing is critical for tuning MOF-derived TiO2 gas sensing performance.
• Optimized annealing conditions (600°C) significantly enhance acetone sensitivity and response kinetics.
• The study provides insights into oxygen vacancy roles and electron migration mechanisms for improved semiconductor gas sensors.