Optimizing MXene: Post-Synthesis treatments strategies & their characterization

MXenes, a group of two-dimensional (2D) nanomaterials, have been gaining traction in the world of material science, contributing to the fields of electrochemical energy storage and conversion devices, sensors, biomedicine, membranes, filtration, catalysis and electromagnetic shielding fields. Being a material with many promising properties, such as intrinsic hydrophilicity, high processability, and good electrical conductivity, the research on MXenes continues, especially regarding strategies for post-synthesis modifications to enhance the desired properties for targeted applications and to improve the thermodynamic stability of MXenes. Although the research on pristine MXene is plentiful, the underlying scientific principles of its surface chemistry and controllable design remain poorly understood and require further investigation. This review briefly discusses general approaches to synthesising MXenes and their properties, followed by an in-depth analysis of ex-situ modifications on MXenes, including film fabrication, drying approaches, intercalation and delamination, annealing treatment, doping, and surface modification. The correlation between MXene composition, morphology and intrinsic properties with the strategies used is summarised. Furthermore, we define the entrenched challenges and scientific gaps that currently impede reliable industrial scaling. By proposing standardised benchmarking protocols, this work aims to decouple material advancements from experimental variables, providing a strategic roadmap for the next generation of MXene research. • Summarises various strategies of MXene post-synthesis treatments • Discusses how each post-synthesis modification manipulates properties and overcome limitations • Addresses the gaps of MXene science • Suggests standardised benchmarking protocols for MXene synthesis and performance evaluation