M4X3 MXenes: Application in Energy Storage Devices

Abstract MXene has garnered widespread recognition in the scientific community due to its remarkable properties, including excellent thermal stability, high conductivity, good hydrophilicity and dispersibility, easy processability, tunable surface properties, and admirable flexibility. MXenes have been categorized into different families based on the number of M and X layers in M n+1 X n , such as M 2 X, M 3 X 2 , M 4 X 3 , and, recently, M 5 X 4 . Among these families, M 2 X and M 3 X 2 , particularly Ti 3 C 2 , have been greatly explored while limited studies have been given to M 5 X 4 MXene synthesis. Meanwhile, studies on the M 4 X 3 MXene family have developed recently, hence, demanding a compilation of evaluated studies. Herein, this review provides a systematic overview of the latest advancements in M 4 X 3 MXenes, focusing on their properties and applications in energy storage devices. The objective of this review is to provide guidance to researchers on fostering M 4 X 3 MXene-based nanomaterials, not only for energy storage devices but also for broader applications.