Accordion-like-Ti₃C₂ MXene-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 Ti3C2Tx MXene multilayers by a selective HF-etching method at 60 ? 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 Ti3C2Tx, 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 ?); hence, it lends itself high potential as a breath sensor for diabetic patients.