Ordered mesoporous NiFe₂O₄ with ultrathin framework for low-ppb toluene sensing

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Sensing

Background:

• Gas sensor applications face challenges in highly sensitive and selective detection of specific target gases, especially at low part-per-billion (ppb) levels.
• Developing novel materials with enhanced surface area and controlled nanostructure is crucial for improving gas detection performance.

Purpose of the Study:

• To synthesize and characterize ordered mesoporous NiFe2O4 materials for highly sensitive and selective detection of low-ppb toluene.
• To investigate the relationship between the nanostructure (framework thickness, surface area) of NiFe2O4 and its gas sensing properties.

Main Methods:

• Synthesis of ordered mesoporous NiFe2O4 using mesoporous silica KIT-6 as a template.
• Tuning framework thickness and specific surface area by varying KIT-6 pore size.
• Gas sensing measurements of toluene at various concentrations and temperatures.

Main Results:

• Ordered mesoporous NiFe2O4 with an ultrathin framework (5 nm) and high surface area (216 m²/g) demonstrated a highest response of 77.3 towards 1,000 ppb toluene at 230°C.
• The synthesized material showed a response 7.3 and 76.7 times higher than thick-framework and bulk NiFe2O4, respectively.
• A low limit of detection (<2 ppb) and good selectivity for toluene were achieved.

Conclusions:

• Ordered mesoporous NiFe2O4 with optimized nanostructure is a promising material for highly sensitive and selective toluene detection.
• The material's enhanced performance is attributed to its ultrathin framework and large specific surface area.
• This study provides a pathway for designing advanced metal oxide nanomaterials for challenging gas sensing applications.