Dynamic surface chemistry of MXenes: Toward adaptive interfaces

MXenes are a class of two-dimensional materials whose tunable surface chemistry renders them promising for a wide range of applications, including catalysis and energy storage. Their surface chemistry is initially established during synthesis from their parent MAX phases through selective etching and serves as a key tunable parameter that governs MXenes’ functional properties and behavior. However, MXene surfaces are not static. Beyond synthesis, their surface terminations can be deliberately engineered, and, importantly, continue to evolve dynamically under chemical, electrochemical, and thermal operating conditions. Such transformations include termination removal, substitution, reconstruction, and protonation. Consequently, MXenes’ performance is governed by the in operando evolution of surface chemistry, rather than solely by the initial terminations introduced during synthesis or post-synthesis modifications. Embracing this dynamic paradigm reframes MXene surface chemistry from a synthetic descriptor to a design variable, opening opportunities to engineer reaction pathways, stabilize transient active states, and couple structure with function in real time. By conceptualizing MXene surfaces as dynamic interfaces, this article highlights how surface chemistry transforms under working conditions and how this evolution can be rationally harnessed to optimize performance in various applications, including catalysis and energy storage. MXene surface chemistry evolves from synthesis and post-synthesis processing to in operando conditions, where interactions with the working environment can further transform surface terminations andactive sites. Understanding and controlling this dynamic surface evolution provides a pathway to tailor MXene propertiesand optimize performance in applications such as catalysis and energy storage.