Bottom-Up Designed Porous Coaxial Twin-Electrodes for Efficient Redox Cycling

Redox cycling (RC) is a powerful tool capable of amplifying faradaic currents
in electroanalytical measurements, thus allowing an enhancement of sensitivity
through fast multiple sequential oxidation and reduction reactions of
a redox-active analyte. Present state-of-the-art RC devices are mostly based
on planar electrode geometries either in 2D or 3D configurations, requiring
cleanroom facilities and expensive microfabrication techniques. Here,
the electrochemical elaboration and characterization of a 3D coaxial macroporous
twin-electrode is reported, obtained by following a low-cost
bottom-up approach. A nanoengineered highly organized porous material
is the basis for the design of two threaded cylindrical porous gold microelectrodes
with a gap in the micrometer range that can be fine-tuned. The
potentials of the outer and inner electrodes are biased at values above and
below the redox potential of the analyte so that a given molecule can participate
several times in the electron exchange reaction by shuttling between
both electrodes. The resulting signal amplification, combined with a straightforward
synthesis strategy of the electrode architecture, allows envisioning
numerous (bio)electroanalytical applications.