2D V₂C MXene Based Flexible Gas Sensor for Highly Selective and Sensitive Toluene Detection at Room Temperature

While the majority of the reports on toluene gas sensors are on rigid electrodes and based on composite materials, doping with additional noble metals, or a high temperature detection method, this work is the first demonstration of the vanadium carbide (V₂C) MXene based flexible and room-temperature (RT) toluene gas sensor. The V₂C MXene is synthesized by an HF etching route. The field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) images exhibit a typical accordion-like multilayered structure of the V₂C MXene, where the Fourier-transform infrared spectroscopy (FTIR), Raman, and X-ray photoelectron spectroscopy (XPS) data further ensured its successful growth. The V₂C (band gap of 3.9 eV) based flexible gas sensor employing a polyester substrate, displays good reproducibility, quick response/recovery time (14 s/34 s), long-term stability, good cross-selectivity, and a low detection limit of 47.85 ppb over the linear region of 5-200 ppm toluene at RT (27 ± 1 °C). The effect of relative humidity (RH) toward RT toluene gas sensing has also been investigated here. This sensor shows an excellent response of 775% at 200 ppm toluene, with brilliant selectivity toward toluene over six other hazardous gases. The sensor’s plentiful surface functional groups (−F, −OH, −O) and superior electrical characteristics are responsible for its enhanced performance. In light of this, the flexible and RT toluene gas sensor based on the V₂C MXene can be a smart way to fabricate the next-generation toluene gas sensors.