Laser‐Induced Covalent Defunctionalization of Graphene — Precise Patterning and Site‐Selective Removal of Functional Groups

In this study, for the first time, site-selective defunctionalization concepts for structuring and reusing covalently patterned monolayer graphene are reported. Using a laser-activated precursor deposition approach with dibenzoyl peroxide (DBPO), phenyl moieties are covalently grafted onto graphene with high spatial precision. Temperature-dependent Raman spectroscopy reveals that functionalization is fully reversible, with lattice-scale defunctionalization occurring at 225 °C, independent of the initial functionalization degree. By applying high-power laser irradiation (λ_exc _. = 532 nm) the covalent addends can be selectively removed with high local control, as confirmed by Raman mapping and Kelvin probe force microscopy (KPFM). This photothermal process enables a lateral defunctionalization resolution of ≈0.5 µm. Importantly, it is demonstrated that "erased" regions can be successfully refunctionalized using a second laser "writing" sequence, achieving highly reproducible functionalization levels. The ability to iteratively "write," "erase," and "rewrite" covalent functionalities with a precise control of the grafting pattern establishes graphene as a promising platform for chemically tunable, high-resolution 2D data storage.