Sensitivity-Enhanced, Room-Temperature Detection of NH₃ with Alkalized Ti₃C₂T_x MXene

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Layered titanium carbide (Ti3C2Tx) MXene is a promising material for gas sensors.
• Optimizing MXene surface chemistry is crucial for enhancing gas detection capabilities.

Purpose of the Study:

• To investigate the effect of alkalization treatment on the gas-sensing performance of Ti3C2Tx MXene for ammonia (NH3) detection.
• To determine the optimal alkalization conditions for improved NH3 sensing.

Main Methods:

• Ti3C2Tx MXene was prepared by etching MAX-phase Ti3AlC2 with hydrofluoric acid (HF).
• The prepared Ti3C2Tx was subjected to alkalization using sodium hydroxide (NaOH) solutions of varying concentrations and durations.
• Gas sensors were fabricated using both unalkalized and alkalized Ti3C2Tx.
• Sensor performance was evaluated for NH3 detection at room temperature and 40% relative humidity.

Main Results:

• Alkalized Ti3C2Tx MXene sensors exhibited significantly enhanced sensitivity to NH3 compared to unalkalized sensors.
• Optimal performance was achieved with Ti3C2Tx alkalized in 5 M NaOH for 12 hours, showing a response of 100.3% and rapid response/recovery times (73 s/38 s).
• Increased NH3 adsorption capability, attributed to oxygen-rich surface terminations and a higher oxygen-to-fluorine ratio, correlated with improved sensing.

Conclusions:

• Alkalization is an effective strategy for tuning the gas-sensing properties of Ti3C2Tx MXene.
• Optimized alkalization processes can lead to high-performance NH3 gas sensors with fast response and recovery.
• This work provides a viable approach for developing advanced MXene-based gas sensing applications.