Square wave voltammetry enables measurement of light-activated oxidations and reductions on n-type semiconductor/metal junction light-addressable electrochemical sensors

28 March 2023, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

Light-addressable electrochemical sensing (LAES) 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 use square wave voltammetry (SWV) to enable measurements 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 reductions 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 demonstrate 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.

Supplementary materials

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Title
Square wave voltammetry enables measurement of light-activated oxidations and reductions on n-type semiconductor/metal junction light addressable electrochemical sensors
Description
Additional text and figures describing: calibration of local LED power; additional characterization of n-Si/Au NP LAES; impact of SW amplitude and frequency on dark current for Ru(NH3)63+; impact of SW amplitude and frequency on FcMeOH; additional analysis of local illumination SWV measurements.
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