Spatially Resolved 2D Laser Writing on Graphene Using Diazonium Salts

We present the first investigation of precise laser-guided patterning, functionalization, defunctionalization, and refunctionalization of single-layer graphene (SLG) with three different aryl diazonium salts. Using scanning Raman microscopy (SRM) we confirmed the spatially resolved nature of the functionalization. We systematically investigated the influence of key laser parameters (power, irradiation time, and wavelength) and the electronic effects of the substituents on both the functionalization efficiency and integrity of graphene. Our solid-phase approach unequivocally demonstrates that laser-triggered covalent attachment can achieve high functionalization levels comparable to solution-based methods. We also unveil a novel laser-induced defunctionalization pathway at high laser powers and prolonged irradiation times, which allows for the precise, patterned functional group "erasure" - a significant advantage over nonselective thermal annealing. Furthermore, we successfully demonstrate the successful readdressing and refunctionalization of these laser "erased" areas, enabling a complete "write-erase-rewrite" cycle. This work establishes a robust and highly adaptable platform for creating complex, mixed-functionalized graphene architectures with micrometer precision.