Environmentally Stable Organo-MXene Gas Sensors Based on Surface Chemical Functionalization

The demand for low-power chemical sensing has been increasing due to the emergence of flexible, portable, and wearable devices. To achieve this, two-dimensional (2D) nanomaterials have drawn attention due to their high surface area, and high tunability, and room-temperature operation. Among them, MXenes especially show outstanding performance due to their simultaneous existence of high electrical conductivity and high-density surface functional groups. However, issues such as limited environmental stability need to be addressed for further utilization. Here, we introduce ligand-grafting surface chemical functionalization methods to develop organo-MXene gas sensors that have enhanced environmental stability over pristine MXene gas sensors. Based on the good dispersibility of organo-MXenes in organic solvents, a self-assembly method was designed and employed to fabricate nanometer-scale thin film gas sensors. Gas responses were greatly enhanced compared to that of pristine MXene where the modification of surface tail groups allowed tunable selectivity toward various VOC gases. Furthermore, organo-MXene gas sensors showed good stability in ambient environments for extended periods of time.