Chemiresistive gas sensors based on Ti₃C₂T_x-CuGa₂O₄ for ppb-level trimethylamine detection at room temperature

Developing a room temperature, real-time, and efficient sensor for trimethylamine (TMA) detection remains a challenge in food safety and disease screening. Ti₃C₂T_x, a two-dimensional material with abundant surface functional groups, is expected to form sensing materials of low operating temperature when combined with metal oxides. In this work, a series of Ti₃C₂T_x-CuGa₂O₄ composites were prepared using the hydrothermal method. The gas-sensing experiment found that the response values of composites were improved towards TMA at room temperature (RT). Notably, the 9.1 wt% Ti₃C₂T_x-CuGa₂O₄(MCU-10) composite exhibited a response value of 33.5 towards 100 ppm TMA-a 26.8-fold enhancement compared with CuGa₂O₄, with a response time of 4.3 s and a recovery time of 25.7 s. Meanwhile, the MCU-10 sensor showed outstanding gas-sensing selectivity, repeatability, and long-term stability in the sensing process. The reasons of enhanced gas-sensing properties are attributed to the incorporation of abundant surface functional groups and the higher content of oxygen vacancies. Besides, a potential explanation for the abnormal sensing behavior of CuGa₂O₄ towards reducing gases is proposed. This work not only proposes a promising sensing material for TMA gas sensors but also highlights the potence of Ti₃C₂T_x as a sensitizing agent in the field of gas-sensing materials.