Electrochemical Modulation of Laser-Induced Covalent Functionalization of Graphene.

The spatially controlled covalent functionalization of graphene allows for local modulation of its electronic and chemical properties. However, existing approaches either offer high lateral precision without independent reaction tuning or provide energetic control at the expense of spatial confinement. Herein, we introduce a photoelectrochemical-driven strategy that combines the spatially resolved laser activation of precursors with electrochemical reaction gating that allows for modulation of the electron-transfer driving force. Within a defined potential window, the degree of covalent addend binding on graphene can be continuously tuned by varying the applied bias under otherwise identical irradiation conditions. The electrochemical potential serves as an independent control parameter, complementing laser power and irradiation time, and thus provides an additional tool for the calibration of the degree of functionalization. Negative potentials enhance the covalent addend binding, whereas positive potentials suppress the reaction. This allows for a reproducible switching between active and inactive states. The electrochemically defined "off" condition enables in situ Raman characterization in the presence of the precursor solution without inducing unintended additional addend binding, enabling uninterrupted, stepwise monitoring of the functionalization process. This combination of laser-pathway guided spatially resolved patterning and voltage-controlled reaction tuning establishes a dual-control platform for future precision graphene chemistry.