Light-emitting MXene quantum dots

MXene (Mn+1Xn) is an emerging class of layered two-dimensional (2D) materials, which are derived from their bulk-state MAX phase (Mn+1AXn, where M: early transition metal, A: group element 13 and 14, and X: carbon and/or nitrogen). MXenes have found wide-ranging applications in energy storage devices, sensors, catalysis, etc. owing to their high electronic conductivity and wide range of optical absorption. However, the absence of semiconducting MXenes has limited their applications related to light emission. Research has shown that quantum dots (QDs) derived from MXene (MQDs) not only retain the properties of the parent MXene but also demonstrate significant improvement on light emission and quantum yield (QY). The optical properties and photoluminescence (PL) emission mechanisms of these light-emitting MQDs have not been comprehensively investigated. Recently, work on light-emitting MQDs has shown good progress, and MQDs exhibiting multi-color PL emission along with high QY have been fabricated. The synthesis methods also play a vital role in determining the light emission properties of these MQDs. This review provides an overview of light-emitting MQDs and their synthesis methods, optical properties, and applications in various optical, sensory, and imaging devices. The future prospects of light-emitting MQDs are also discussed to provide an insight that helps to further advance the progress on MQDs.