The electronic properties of electrode materials play
a crucial
role in defining their electrochemical behavior in energy conversion
and storage devices. The assembly of van der Waals heterostructures
and fabrication into mesoscopic devices enable the dependence of an
electrochemical response on electronic properties to be systematically
interrogated. Here, we evaluate the effect of charge carrier concentration
on heterogeneous electron transfer at few-layer MoS2electrodes
by combining spatially resolved electrochemical measurements with
field-effect electrostatic manipulation of band alignment. Steady-state
cyclic voltammograms and finite-element simulations reveal a strong
modulation of the measured electrochemical response for outer-sphere
charge transfer at the electrostatic gate voltage. In addition, spatially
resolved voltammetric responses, obtained at a series of locations
at the surface of few-layer MoS2, reveal the governing
role of in-plane charge transport on the electrochemical behavior
of 2D electrodes, especially under conditions of low carrier densities.