Morphology Tuning of NiMo Layered Double Hydroxide-Modified MXene for Highly Sensitive Detection of NH₃ with Long-Term Stability

The sensitive detection of ammonia at room temperature is crucial for both the chemical industry and human health. In this study, phosphorized NiMo layered double hydroxide (NiMo-P)-modified MXene-based composite materials were prepared using a combination of hydrothermal and calcination processes. A two-dimensional (2D)/2D van der Waals heterojunction formed between the MXene and NiMo-P phases facilitated the interlayer shuttling of charge carriers during gas adsorption. Furthermore, the composite material acquired abundant acidic sites during phosphorization, which fundamentally enhanced its NH 3 sensing performance. In addition, the morphology of the composite was effectively controlled by tuning the poly(methyl methacrylate). The hollow microspherical MXene@NiMo-P (MX-s@NiMo-P) composite material demonstrates highest sensing response to NH 3 . At 25 °C and 45% relative humidity (RH), the response of MX-s@NiMo-P to 100 ppm of NH 3 was as high as 188.9%. After 30 d, the gas-sensing performance of the MX-s@NiMo-P sensor reached 93.4% of the initial value, highlighting its long-term stability over the 30-d period. This study describes an effective approach to improve the response of MXene-based gas sensor with long-term stability.