Engineering Dirac Cones in Graphene for Efficient Iodide Catalysis: Insights by Nanoscale Electrochemistry.

Advances in atomically thin two-dimensional materials have created new opportunities to regulate interfacial charge transfer and surface reactivity in electrocatalysis. Among anodic reactions relevant to sustainable energy conversion, the iodide oxidation reaction (IOR) has emerged as an attractive alternative to the oxygen evolution reaction because of its lower overpotential, faster kinetics, and simultaneous generation of value-added iodine species. Here, by using scanning electrochemical cell microscopy, we show that the electronic structure of graphene can be engineered to promote IOR through two experimentally distinct routes: electrostatic gating in monolayer graphene and twist-angle control in bilayer graphene. Gate-dependent measurements show that hole doping promotes iodide oxidation, whereas electron doping suppresses it, consistent with Fermi-level modulation of electron extraction from iodide. Magic-angle twisted bilayer graphene (MATBG) exhibits a lower onset potential and stronger IOR response than monolayer and Bernal-stacked bilayer graphene. The enhanced activity of MATBG is associated with a moiré-reconstructed interfacial electronic environment that facilitates IOR. These results establish electronic-structure engineering of graphene as an effective strategy for regulating nanoscale iodide oxidation and highlight Dirac-cone engineering as a tunable platform for sustainable iodine redox electrochemistry.