Designer surface chemistry of two-dimensional MXenes

Abstract Controlling the surface chemical composition of two-dimensional (2D) transition-metal carbides and nitrides (MXenes) is essential for tailoring their properties. Since 2020, a rapidly growing, community-wide understanding of MXene surface chemistry has transformed the field from handling mixed terminations (–O, –OH, –F, and –Cl) with limited control mechanisms into systematically designing advanced interfaces. However, as we discuss in this issue of MRS Bulletin on MXenes’ surface chemistry, recent breakthroughs in both chemical modification strategies and direct synthesis pathways have unlocked precise substitution, structural editing, and organic–inorganic hybridization of MXenes’ surface as a new metal–organic framework (MOF)-like chemical playground. The articles within this collection aim to serve as a guide to introduce the design concepts behind and novel application directions enabled by MXenes’ surface control and provide a perspective to the field on the areas thatmust be developed to MXenes’ surface chemistry. In addition, this issue aims to spur researchers to address the need for AI-guided predictions in local chemistry and its effects on the relation of composition to properties in surface-controlled MXenes and their eventual best applications. Ultimately, we believe that this emerging “designer era” of MXenes’ surface chemistry will push sophisticated surface engineering as a tool to majorly control MXene’s utility across energy storage, tribology, biointegrated electronics, and other applications far beyond boundaries previously restricted by core-metal chemistry alone.