High-Performance Ammonia QCM Sensor Based on SnO₂ Quantum Dots/Ti₃C₂T_x MXene Composites at Room Temperature.

Area of Science:

• Materials Science
• Chemical Engineering
• Sensor Technology

Background:

• Ammonia (NH3) is a hazardous industrial gas requiring reliable room-temperature detection.
• Existing sensors often lack the necessary sensitivity, stability, or straightforward design for industrial applications.

Purpose of the Study:

• To develop a highly sensitive and stable room-temperature ammonia gas sensor.
• To investigate the synergistic effects of combining SnO2 colloidal quantum dots (CQDs) with Ti3C2Tx MXene for gas sensing.

Main Methods:

• Fabrication of zero-dimensional (0D) SnO2 CQDs via solvothermal synthesis.
• Preparation of two-dimensional (2D) Ti3C2Tx MXene using in situ etching.
• Construction of Ti3C2Tx/SnO2 heterojunctions with varying mass ratios to optimize sensor performance.

Main Results:

• The Ti3C2Tx MXene/SnO2 composite sensor (12 wt% Ti3C2Tx) exhibited superior sensitivity and response/recovery speeds.
• A significant frequency shift of -1140 Hz was observed for 50 ppm NH3, outperforming individual components.
• The sensor demonstrated a low detection limit (73 ppb), good repeatability, and stable performance over 30 days.

Conclusions:

• The Ti3C2Tx/SnO2 heterojunction effectively enhances ammonia gas sensing capabilities.
• Abundant active sites at the heterojunction facilitate gas adsorption, leading to improved sensor performance.
• This work advances the application of MXenes in gas sensing and offers a pathway for enhanced sensor design.