Accordion-like-Ti₃C₂MXene-Based Gas Sensors with Sub-ppm Level Detection of Acetone at Room Temperature

Compared to traditional-metal oxide-based gas sensors (MOS), the progress of high-performance room-temperature (RT) gas-sensing materials has captivated a lot of interest in recent years. MXenes, two-dimensional (2D) transition-metal carbides/nitrides, have recently been discovered and gained tremendous consideration for gas sensing applications due to their superior chemical and physical properties. Herein, we successfully synthesized accordion-like Ti₃C₂T_xMXene multilayers by a selective HF-etching method at 60 °C to be used as a chemiresistive sensor for acetone vapor. The fabricated sensor successfully detected acetone vapor at the parts per billion (ppb) level and showed a p-type sensing behavior. The limit of detection (LOD) of acetone vapor was about 250 ppb with a fast response time of 53 s. The sensor exhibited good repeatability, high selectivity toward acetone among other test gases, and excellent stability even after 4 months. The sensing mechanism was proposed in terms of the interaction between the charge carriers of accordion-like Ti₃C₂T_x, multiple hydrogen bonding between different functional groups on the MXene surface, and acetone vapor species. The prepared sensor also showed high sensitivity toward acetone vapor at RT (23 °C); hence, it lends itself high potential as a breath sensor for diabetic patients.