Gas-sensing properties and applications of MXenes

The detection of harmful or toxic chemicals has been of great interest as a small amount can cause serious effects to the environment or the human body. This has led to the development of various sensitive and selective chemical sensors in the form of chemiresistors, electrochemical sensors, pH sensors, and so on. Among these, MXenes have been intensively studied for gas sensors due to the unique advantages MXenes have over other nanomaterials. The abundant functional groups on the MXene surface allow the good adsorption of analytes, which leads to a strong sensing signal. Simultaneously, their electrical conductivity provides a low electrical noise, in which such a combination results in a high signal-to-noise ratio. Moreover, MXene-based sensors can be deposited using solution processing techniques onto arbitrary substrates and can function at room temperature, making them ideal candidates in next-generation sensing devices. Here, we introduce the chemical sensing properties of MXene, focusing on their gas sensor applications. The basic sensing properties of pristine MXenes and several strategies to tune their performance, and the sensing applications of MXene-based composites will also be introduced. We wrap up by discussing the challenges and issues that are important for the advancement and practical application of MXene chemical sensors.