Unconventional Electrochemistry in Micro-/Nanofluidic Systems

Reiser

Spolenak

et al. 2021

Preprint

Regulating the state of the solid-liquid interface by means of electric fields is a powerful tool to control electrochemistry. In scanning probe systems, this can be confined closely to a scanning (nano)electrode by means of fast potential pulses, providing a way to probe the interface and control electrochemical reactions locally, as has been demonstrated in nanoscale electrochemical etching. For this purpose, it is important to know the spatial extent of the interaction between pulses applied to the tip, and the substrate. In this paper we use a framework of diffuse layer charging to describe the localization of electrical double layer charging in response to a potential pulse at the probe. Our findings are in good agreement to literature values obtained in electrochemical etching. We show that the pulse can be much more localized by limiting the diffusivity of the ions present in solution, by confined electrodeposition of cobalt in a dimethyl sulfoxide solution, using an electrochemical scanning tunneling microscope. Finally, we demonstrate the deposition of cobalt nanostructures (<100 nm) using this method. The presented framework therefore provides a general route for predicting and controlling the time-dependent region of interaction between an electrochemical scanning probe and the surface.

Section: Introductionmentioning

confidence: 99%

Confined Pulsed Diffuse Layer Charging for Nanoscale Electrodeposition with an STM

Reiser

Spolenak

et al. 2021

Preprint

“…This is due to the fact that when the tip/substrate gap is of the order of nanometers, the reaction dynamics are governed by a complex interplay of electrochemical potential distributions, 19 poor communication with the bulk solution, and mass transport limitations preventing ion access into the small gap. [20][21][22] In general, effects of the structure and dynamics of the electrical double layer (EDL) at the solid-liquid interface on nanoscale electrochemistry are not fully understood. 23,24 In the past years, several groups have focused on using SPM techniques to probe the solid-liquid interface, [25][26][27][28][29][30][31][32] in terms of specific adsorption, 33 charge density, and screening.…”

Section: Introductionmentioning

confidence: 99%

Directed nanoscale metal deposition by the local perturbation of charge screening at the solid–liquid interface

Alarcón-Lladó

2019

Nanoscale

“…The main reason being that when the tip/substrate gap is of the order of nanometers, the reaction dynamics are governed by a complex interplay of electrochemical potential distributions, 19 poor communication with the bulk solution and mass transport limitations of ions into the small gap. 20,21,22 In general, effects of the structure and dynamics of the electrical double layer (EDL) at the solid-liquid interface on nanoscale electrochemistry are not fully understood . 23,24 In the past years, several groups have focused on using scanning probe microscopy techniques to probe the solid-liquid interface 25,26,27,28,29,30,31,32 , in terms of specific adsorption 33 , charge density , and screening 34,35 .…”

Section: Introductionmentioning

confidence: 99%

Dynamic Perturbation of the Electrical Double Layer with an Electrochemical AFM for Confined Metal Electrodeposition

Alarcón-Lladó²

2019

Preprint

<div>We demonstrate the directed electrochemical deposition of copper nanostructures by using an oscillating nanoelectrode operated with an atomic force microscope (AFM). Strikingly, the writing is only possible in highly dilute electrolytes and for a particular combination of AFM and electrochemical parameters. We propose a mechanism based on cyclic charging and discharging of the electrical double layer (EDL). The extended screening length and slower charge dynamics in dilute electrolytes allows the nanoelectrode to operate inside, and disturb, the EDL even for large oscillation amplitudes (~100 nm). Our unique approach can not only be used for controlled additive nano-fabrication but also provides insights into ion behavior and EDL dynamics at the solid-liquid interface.</div>