Fluorination–defluorination chemistry as a toolbox for 2D materials design

Fluorination is a powerful chemical approach for tailoring the properties of two-dimensional (2D) materials such as graphenes, transition metal carbides/nitrides/carbonitrides (MXenes), hexagonal boron nitride (h-BN), and transition-metal dichalcogenides (TMDs). This review highlights that fluorination should be viewed not only as a final modification step but also as an intermediate state in materials design. Notably, controlled defluorination of fluorine-containing precursors can provide access to materials and structures that are otherwise difficult to produce. Accordingly, here we compare various defluorination strategies, i.e., thermal, chemical, photochemical, electrochemical, and mechanochemical, in terms of their mechanisms, efficiency, structural impact, and functionalization capabilities. This comparison specifically demonstrates that the choice of defluorination route strongly influences the final structure, surface chemistry, and properties of fluorinated 2D materials, including their electrical, catalytic, and energy-storage performance. Moreover, we highlight emerging opportunities, which include atmosphere-controlled defluorination, OH/F exchange chemistry, femtosecond-laser processing, fluorinated nanodiamonds, and fluorine-transfer processes in composite materials. We expect the insights provided in this review to open new avenues for the design of advanced 2D materials with precise physicochemical characteristics.