Two-dimensional
(2D) Ti3C2Tx 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 NH3 sensing materials such as graphene
oxide (GO), copper oxide (CuO), and zinc oxide (ZnO) into Ti3C2Tx Mxene to be a high-performance NH3 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 NH3 sensing materials in room-temperature gas sensors.
The Ti3C2Tx MXene/GO/CuO/ZnO nanocomposite gas
sensor exhibited the best NH3 gas sensor. The effects on
the weight ratios of Ti3C2Tx MXene/GO/CuO/ZnO
were also investigated, and the optimal Ti3C2Tx MXene/GO/CuO/ZnO weight ratio was determined to be 9:1:5:5. The
optimal Ti3C2Tx MXene/GO/CuO/ZnO based gas sensor
showed a high response of 96% at 200 ppm of NH3, 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 NH3 over several gases/VOCs
including formaldehyde, ethanol, methanol, isopropanol, toluene, and
acetone. The NH3-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 Ti3C2Tx Mxene.