Room-Temperature Ammonia Gas Sensor Based on Ti<sub>3</sub>C<sub>2</sub>Tx MXene/Graphene Oxide/CuO/ZnO Nanocomposite
Yotsarayuth Seekaew, Supaporn Kamlue, Chatchawal Wongchoosuk
Abstract
Two-dimensional (2D) Ti 3 C 2 Tx Mxene has currently demonstrated significant potential for gas sensing application with a high signal-to-noise ratio at room temperature. Herein, we present the mixture of popular NH 3 sensing materials such as graphene oxide (GO), copper oxide (CuO), and zinc oxide (ZnO) into Ti 3 C 2 Tx Mxene to be a high-performance NH 3 gas sensor at room temperature. Various nanocomposites such as Mxene/GO, Mxene/ZnO, Mxene/CuO, Mxene/GO/ZnO, Mxene/GO/CuO, Mxene/ZnO/CuO, and Mxene/GO/ZnO/CuO were synthesized via the hydrothermal method and used as NH 3 sensing materials in room-temperature gas sensors. The Ti 3 C 2 Tx MXene/GO/CuO/ZnO nanocomposite gas sensor exhibited the best NH 3 gas sensor. The effects on the weight ratios of Ti 3 C 2 Tx MXene/GO/CuO/ZnO were also investigated, and the optimal Ti 3 C 2 Tx MXene/GO/CuO/ZnO weight ratio was determined to be 9:1:5:5. The optimal Ti 3 C 2 Tx MXene/GO/CuO/ZnO based gas sensor showed a high response of 96% at 200 ppm of NH 3, humidity independence in the range of 30–70%RH, good linear relationship ( R 2 = 0.998), low limit of detection of 4.1 ppm, and high selectivity to NH 3 over several gases/VOCs including formaldehyde, ethanol, methanol, isopropanol, toluene, and acetone. The NH 3 -sensing mechanism was proposed based on the modulation of complex p–n heterojunctions via the electron accumulation layer in the n-type of GO/CuO/ZnO and the electron depletion layer in the p-type Ti 3 C 2 Tx Mxene.