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Noise Phenomena Caused by Reversible Adsorption in Nanoscale Electrochemical Devices

In cooperation with the group of Serge Lemay  at University of Twente, we have investigated the effect of reversible adsorption in electrochemical devices. Our method can be used to identify molecule-specific adsorption parameters from the current noise spectra.

Enno Kätelhön, Kay J Krause, Klaus Mathwig, Serge G Lemay, Bernhard Wolfrum

Noise Phenomena Caused by Reversible Adsorption in Nanoscale Electrochemical DevicesThe artwork presents a nanofluidic redox-cycling sensor. Redox-active molecules may participate in repeated redox reactions between independently biased electrodes generating a current across the channel. By focusing on the current’s noise characteristics, computational methods allow insights into the adsorption characteristics of the investigated molecular species in various sensor types.

We theoretically investigate reversible adsorption in electrochemical devices on a molecular level. To this end, a computational framework is introduced, which is based on 3D random walks including probabilities for adsorption and desorption events at surfaces. We demonstrate that this approach can be used to investigate adsorption phenomena in electrochemical sensors by analyzing experimental noise spectra of a nanofluidic redox cycling device. The evaluation of simulated and experimental results reveals an upper limit for the average adsorption time of ferrocene dimethanol of approx. 200 μs. We apply our model to predict current noise spectra of further electrochemical experiments based on interdigitated arrays and scanning electrochemical microscopy. Since the spectra strongly depend on the molecular adsorption characteristics of the detected analyte, we can suggest key indicators of adsorption phenomena in noise spectroscopy depending on the geometric aspect of the experimental setup.

ACS Nano, 8 (5), pp 4924-4930 (2014), DOI: 10.1021/nn500941g