MXenes: Versatile 2D materials with tailored surface chemistry and diverse applications

MXenes, the most recent addition to the 2D material family, have attracted significant attention owing to their distinctive characteristics, including high surface area, conductivity, surface characteristics, mechanical strength, etc. This review begins by presenting MXenes, providing insights into their structural characteristics, synthesis methods, and surface functional groups. The review covers a thorough analysis of MXene surface properties, including surface chemistry and termination group impacts. The properties of MXenes are influenced by their synthesis, which can be fluorine-based or fluorinedependent. Fluorine-based synthesis techniques involve etching with fluorine-based reagents, mainly including HF or LiF/HCl, while fluorine-free methods include electrochemical etching, chemical vapor deposition (CVD), alkaline etching, Lewis acid-based etching, etc. These techniques result in the emergence of functional groups such as -F, -O, -OH, -Cl, etc. on the MXenes surface, depending on the synthesis method used. Properties of MXenes, such as electrical conductivity, electronic properties, catalytic activity, magnetic properties, mechanical strength, and chemical and thermal stability, are examined, and the role of functional groups in determining these properties is explored. The review delves into the diverse applications of MXenes, encompassing supercapacitors, battery materials, hydrogen storage, fuel cells, electromagnetic interference (EMI) shielding, pollutant removal, water purification, flexible electronics, sensors, additive manufacturing, catalysis, biomedical and healthcare fields, etc. Finally, this article outlines the challenges and opportunities in the current and future development of MXenes research, addressing various aspects such as synthesis scalability, etching challenges, and multifunctionality, and exploring novel applications. The review concludes with future prospects and conclusions envisioning the impact of MXenes on future technologies and innovation.(c) 2023 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.