Superoxide-Anion-Dominated Labeling of Graphene Defects in an Interfacial Nanoreactor of Electron-Donated Substrate

Harnessing the chemical reactivity of defects delivers a fundamental tool for precise nanoscale characterization of graphene defects. Herein, we develop a confined photochemical strategy based on the photosensitization of dye molecules targeted at the chemically active defects of graphene to label the defects. The graphene/copper interface enriches the electrons of graphene defects to construct a nanoreactor within defect-positioning interfaces, which modulates the preferential adsorption and the photosensitization reaction pathway of photoexcited methylene blue (MB). The nanoscale reactor preferentially channels the reaction through the Type I electron-transfer pathway, significantly triggering the •O₂ ^- generation while concomitantly attenuating the competing Type II energy-transfer pathway. Subsequently, the •O₂ ^- species deduce the selective etching reaction of Cu at defect sites, with the reaction kinetics following the Higuchi model. Moreover, the etching process exhibits pronounced crystallographic specificity, as evidenced by distinct pit morphologies and etching rates on the copper (111), (110), and (100) crystalline planes. DFT calculations confirm preferential adsorption and favorable electron transfer from defects to •O₂ ^- species, unravelling the spatially confined nature of the etching reaction at graphene defects. Collectively, our results demonstrate how localized electronic states can dictate the interfacial reaction landscapes, advancing defect chemistry-guided identification/modification methodology of two-dimensional materials.