Light-addressable electrochemical (LAE) sensing is a
photoelectrochemical
technique that enables high-density, individually addressed electrochemical
measurements using light to activate an electrochemical reaction at
the surface of a semiconducting photoelectrode. However, one major
challenge is that only one electrochemical reaction (oxidation or
reduction) will be activated by light. Here, we used square-wave voltammetry
(SWV) to enable measurement of both types of electrochemical reactions
using n-Si/Au NP LAE sensors. We demonstrated this approach for the
oxidation of ferrocene methanol and the reduction of ruthenium hexamine
and methylene blue. We found that for all molecules, SWV showed dramatic
improvements in current under illumination in comparison with dark
samples. We also demonstrated that this approach works for both fully
illuminated and partially illuminated samples. Altogether, we hope
these results open up new applications for LAE sensors, especially
those based on semiconductor/metal junctions.