Recent progress on MXene–polymer composites for soft electronics applications in sensing and biosensing: a review

MXenes are new members of inorganic 2D semiconducting materials that exhibit surface dependent superconductivity and functional group-based reactivity. MXenes with conductive layer properties and tunable surface terminations offer promising applications in the fields of soft electronics, energy storage, photocatalysis, drug/gene delivery, biomedical devices, sensing and biosensing. The surface functionalization with excellent mechanical and physicochemical properties of MXenes can be tuned by compatible polymer substituents to produce superior MXene–polymer composites suitable for further applications. The incorporation of polymer substituents generates a flexible MXene–polymer hybrid structure that can shorten the interlayer spacing; reduce the charge transport distance; and improve electrical conductivity, biocompatibility and flexibility. Although there are already several reviews summarizing the general process of fabrication and applications, in this review, we summarized recent progress and in-depth analysis of polymer incorporation into MXene composites in terms of fabrication strategies, functionalization, and their further utility in soft electronic devices, specifically in sensing and biosensing applications, and future prospects. In addition, possible operating principles and mechanisms are described. Considering the intriguing properties and versatility of MXene polymer materials, these hybrid composites will open up significant new opportunities for advanced optoelectronic sensing and biosensing devices in the future.