  Interfacial electron-transfer (ET) reactions underpin the interconversion of
electrical and chemical energy. Pioneering experiments showed that the ET rate
depends on the Fermi Dirac distribution of the electronic density of states
(DOS) of the electrode, formalized in the Marcus Hush Chidsey (MHC) model.
Here, by controlling interlayer twists in well-defined trilayergraphene moires,
we show that ET rates are strikingly dependent on electronic localization in
each atomic layer, and not the overall DOS. The large degree of tunability
inherent to moire electrodes leads to local ET kinetics that range over three
orders of magnitude across different constructions of only three atomic layers,
even exceeding rates at bulk metals. Our results demonstrate that beyond the
ensemble DOS, electronic localization is critical in facilitating interfacial
ET, with implications for understanding the origin of high interfacial
reactivity typically exhibited by defects at electrode electrolyte interfaces.
