Interfacial amplification of NH3 sensing at low temperature using Au-decorated MoSe2/Ti3C2Tx MXene heterostructures

초록

Ammonia (NH3) is a highly toxic and flammable gas that is mainly emitted from agricultural activities. In this work, we prepared MoSe2/Ti3C2Tx MXene (hereafter referred to as MXene) nanocomposites with different amounts of both components. Various characterizations demonstrated the successful formation of the nanocomposite and based on gas sensing studies, the sensor with equal amount of both components exhibited the best sensing response towards NH3 gas. However, it suffered from poor selectivity. Hence, Au nanoparticles (NPs, 5, 20, and 30 wt%) were decorated on the sensing material. Optimal sensor with 20 wt% Au, resulted in significant improvement of sensitivity to NH3. In particular, it exhibited a response of 12.65 to 1 ppm NH3 at 75 degrees C, surpassing more than four times of that of Au-free sensor. Furthermore, it showed excellent selectivity, repeatability and long-term stability and maintained an acceptable response in humid environment. Enhanced sensitivity is attributed to heterojunction formation between MoSe2 and MXene, surface functional groups on MXene, and interfacial charge modulation induced by Au decoration. This work highlights the rational design of ternary nanocomposites to achieve high performance NH3 gas sensors at low temperatures.

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