A room-temperature NO2 sensor based on Ti3C2TX MXene modified with sphere-like CuO

In this paper, the Ti3C2Tx/CuO nanocomposites were successfully prepared by an environment-friendly and simple hydrothermal method. The synthetics are evaluated using a series of characterization techniques, such as XRD, SEM, TEM, XPS, FTIR, UV–vis, and BET techniques. The results show that Ti3C2Tx/CuO nanocomposites are mesoporous and have a higher specific surface area than Ti3C2Tx, confirming the presence of more gas adsorption/diffusion regions. Furthermore, the Ti3C2Tx with the introduction of CuO has rich oxygen vacancies and adsorbed oxygen. In particular, the response of Ti3C2Tx/CuO sensor (56.99%) is 5 times higher than that of Ti3C2Tx (11.17%) sensor to 50 ppm NO2 at room temperature (RT). Especially, the Ti3C2Tx/CuO sensor exhibits ultra-fast response/recovery time (16.6/31.3 s to 20 ppm NO2), great reversibility, outstanding selectivity to NO2, and desirable long-term stability (over 40 days). The enhanced gas sensing performance may be attributed to the formation of hybrid heterojunctions between CuO and Ti3C2Tx that provide carrier migration channels to hasten the redox reaction. At the same time, Ti3C2Tx/CuO possesses more oxygen vacancies and adsorbed oxygen than Ti3C2Tx, which will reduce the required energy for gas adsorption to further enhance the gas sensing performance. Hopefully, the above improved gas sensing performance indicators modified with CuO are expected to become the advantage of constructing Ti3C2Tx-based sensor, which will be put into commercial NO2 detection in the future.