Post-processing strategies for improving the electrical and mechanical properties of MXenes

MXenes are a novel two-dimensional material family composed of transition metal carbides and carbonitrides that show promising performances in many applications. The intrinsic properties of MXenes are required to develop in different directions with the broadening applications. However, their properties are determined in the synthesis stage and are affected by various factors, such as precursor MAX phase, etchant, reaction time, and temperature. Since these parameters are difficult to control precisely, the targeted design of MXenes properties remains an open challenge. Herein, the post-processing modification of MXenes comes into play as a route to easily and efficiently tune and optimize their properties. This review critically discusses the research progress of MXenes' post-processing approaches to bridge the gap between theoretical predictions and properties observed experimentally. These strategies include atomic doping, functional group modification, and compounding with other materials, focusing on engineering electrical properties, mechanical properties, chemical stability, and the hydrophilic-hydrophobic nature of MXenes. We thus aim at providing a reference for customizing MXenes with targeted functionalities essential for future applications.