Visualizing charges accumulated in an electric double layer by three-dimensional open-loop electric potential microscopy

Abstract

Charges accumulated in an electric double layer (EDL) play key roles in various interfacial phenomena and electronic devices. However, direct imaging of their spatial distribution has been a great challenge, which has hindered our nano-level understanding of the mechanisms of such interfacial phenomena and functions. In this study, we present direct imaging of charges accumulated at an electrode-electrolyte interface using three-dimensional open-loop electric potential microscopy (3D-OL-EPM). Conventional OL-EPM allows us to visualize two-dimensional potential distributions in liquid yet the zero of the measured potential is not well defined due to the influence of the long-range (LR) interaction between the cantilever and the sample. Here, we present practical ways to reduce such an influence by improving the equation for the potential calculation and subtracting the LR contribution estimated from a Z potential profile. These improvements enabled the calibration of the measured potential values with respect to the bulk solution potential. With these improvements, we visualized opposite charge accumulation behaviors on a polarizable and non-polarizable electrode with a varying electrode potential. Combining OL-EPM with a 3D tip scanning method, we also performed a 3D-OL-EPM measurement on a Cu fine wire and visualized the nanoscale distribution of the charges accumulated at the interface. Such real-space information on the charge distributions in an EDL should provide valuable insights into the mechanisms of interfacial phenomena and functions that are important in various academic and industrial research on electronic devices, electrochemistry, tribology and life sciences.

Collagen Fiber/Fe3O4/Polypyrrole Nanocomposites for Absorption-Type Electromagnetic Interference Shielding and Radar Stealth

“…First, the core–shell structure generated an increased interface and a heterogeneous system, which can lead to the accumulation of virtual charges at junction interfaces and the induction of a strong polarization effect due to the different dielectric properties of CFs, Fe 3 O 4 NPs, and PPy. This phenomenon is known as interfacial polarization, which can improve the absorptive ability under an alternative electromagnetic field . As shown in Figure S7, CF 0.5 Fe 3 O 40.15 PPy 0.35 exhibited a higher impedance matching property than other prepared suprafibrillar composites, which benefited Fe 3 O 4 NPs and PPy to interact with more incident EMWs.…”

Confined pulsed diffuse layer charging for nanoscale electrodeposition with an STM

“…8 For instance, potential pulsing at scanning nanoelectrodes has been used to locally probe and image ion distributions in the electrical double layer (EDL) that forms in solution at the solid-liquid interface with an electrode substrate. 9,10 Analogously to local probing, potential pulses at scanning nano/micro-electrodes have been used for driving local reactions at a substrate. Conned electrochemical etching, also referred to as micro/nano machining, has demonstrated a feature size of $200 nm, 11 where the duration of the pulse has been shown to inuence the extent of the electrochemical etching through the distance-limited EDL charging.…”

Confined Pulsed Diffuse Layer Charging for Nanoscale Electrodeposition with an STM

“…Combining potential pulsing with nanoscale electrodes has become an exciting approach in recent years to study localized charging phenomena of the solid-liquid interface, which has shown great potential with regards to the understanding and control of charge dynamics at solidliquid interfaces 8 . For instance, potential pulsing at scanning nano-electrodes has been used to locally probe and image ion distributions in the electrical double layer (EDL) that forms in solution at the solid-liquid interface with an electrode substrate 9,10 .…”