Capturing Electrochemical Signatures of Real Space Twisted Bilayer Graphene Domains

We solve the steady state Poisson-Nernst-Planck equations inside a 3D nanopipette volume to isolate the electrochemical current response at spatial domains of twisted bilayer graphene. We derive kinetic reaction rates from a modified Marcus-Hush-Chidsey theory combining input from a tight binding model that describes the electronic structure of bilayer graphene. Using the local density of states, reaction rates computed at each spatial coordinate provide a real-space picture of the ionic concentration, flux and current for a given nanopipette radius and position. We observe high rates of redox exchange from AA domains, an effect that reduces with diminished flat bands or averages out with larger cross-section area of the nanopipette. The current maxima may occur on either AA or AB center, whichever confines more number of AA domains inside the nanopipette aperture. Based on the intensity of flat bands and the moire unit cell size, current resolution is highest at the magic angle twist for nanopipettes between 2 nm and 5 nm radii. Using steady state voltammograms, we identify an optimal voltage that maximizes current difference between the domains. Our study lays down the framework to electrochemically capture prominent features of the band structure that arise from spatial domains and deformations in 2D flat-band materials.