High-performance, room temperature-based novel sensing materials are one of the frontier research topics in the gas sensing field, and MXenes, a family of emerging 2D layered materials, has gained widespread attention due to their distinctive properties. In this work, we propose a chemiresistive gas sensor made from V2CTx MXene-derived, urchin-like V2O5 hybrid materials (V2C/V2O5 MXene) for gas sensing applications at room temperature. The as-prepared sensor exhibited high performance when used as the sensing material for acetone detection at room temperature. Furthermore, the V2C/V2O5 MXene-based sensor exhibited a higher response (S% = 11.9%) toward 15 ppm acetone than pristine multilayer V2CTx MXenes (S% = 4.6%). Additionally, the composite sensor demonstrated a low detection level at ppb levels (250 ppb) at room temperature, as well as high selectivity among different interfering gases, fast response-recovery time, good repeatability with minimal amplitude fluctuation, and excellent long-term stability. These improved sensing properties can be attributed to the possible formation of H-bonds in multilayer V2C MXenes, the synergistic effect of the newly formed composite of urchin-like V2C/V2O5 MXene sensor, and high charge carrier transport at the interface of V2O5 and V2C MXene.
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 Ti 3 C 2 T x MXene 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 Ti 3 C 2 T 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.
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