Progress and Insights on Graphene and MXene-based Emerging 2-Dimensional Conductive Nanomaterials for Fabrication of Flexible Gas Sensors

Owing to the unique properties such as pristine interfaces, ultra-thin and uniform thickness, 2D nanomaterials have attracted the attention from many researchers. Particularly, rGO and MXene 2D nanomaterials have received intense research interest in the application of gas sensors due to their high electrical conductivity. The coating of these 2D nanomaterials onto plastic, paper or textile substrate formed flexible, stretchable and portable gas sensors as an alternative to the conventional rigid gas sensors. To date, numerous research works on flexible gas sensors using either graphene or MXene have been published. However, the reported data is scattered and varied by multiple factors. In this short review, we revisit the advances in the current application of 2D conductive nanomaterials (mainly rGO and MXene) and their nanocomposites with metal oxides on flexible gas sensors. We focus on recent developments regarding the working mechanism, advantages, disadvantages, and performances (including gas response, selectivity, response time, and recovery time) of each type of gas sensor. Finally, this short review sheds light on future directions and prospects in the field of flexible gas sensors using 2D nanomaterials.