Ag Nanoparticles for Room-Temperature NH₃ Sensing Using a Two-Dimensional Layered Ti₃C₂T_<i>x</i> MXene/V₂O₅ Nanostructured Composite

The development of room-temperature ammonia (NH3) sensors with ultrahigh sensitivity and unique ammonia selectivity remains a major scientific challenge in the field of gas sensing. In this paper, silver nanoparticle-modified MXene/V2O5 nanocomposites with distinct nanoscale architectures were synthesized using a one-step hydrothermal and chemical reduction method to improve the sensing performance for low-concentration (<10 ppm) NH3 gas at room temperature (25 °C). The MXene/V2O5/Ag nanostructured composites with different nanoscale morphologies and surface characteristics were prepared by modulating the volume of AgNO3 during chemical reduction, and their gas-sensing properties were tested as well as analyzed. The experimental results showed that when the volume of AgNO3 was 4 mL, the response value of the fabricated MXene/V2O5/Ag nanocomposite-based sensor reached up to 19.12 for 10 ppm NH3, which was 1.58 times higher than that of the MXene/V2O5 sensor (12.12) and 16.77 times higher than that of the pure MXene sensor (1.14). In addition, the sensor achieved a response value of 5.19 for 1 ppm NH3, indicating its potential for gas-sensing applications at low concentrations. The excellent room-temperature response to low-concentration NH3 is closely related to the dual catalysis and nanoscale heterojunctions of Ag nanoparticles within the opened-up Ti3C2Tx/V2O5 sheet layers, which provide abundant active sites for gas adsorption and reaction. The high room-temperature sensing performance, arising from these nanoscale design features, makes the MXene/V2O5/Ag-based sensor a promising candidate for real-time low-concentration NH3 detection.