Spatial Imaging of Cu²⁺‐Ion Release by Combining Alternating Current and Underpotential Stripping Mode Scanning Electrochemical Microscopy

Abstract

Anodic underpotential stripping voltammetry was integrated into SECM in order to characterize local corrosion of metallic copper deposits on metal surfaces as a model for copper containing alloys. Primarily, the alternating current mode of SECM was applied in an electrolyte of low ionic strength for localizing possible corrosion sites without any perturbation of the corroding surface, e.g., by the presence of any redox mediator. Sequentially, the release of Cu 2þ -ions was confirmed and locally visualized at the previously detected electrochemically active sites by means of spatially resolved anodic underpotential stripping voltammetry performed during SECM scanning. Underpotential stripping voltammetry of Cu 2þ -ions was performed at a specifically developed 15 mm gold-coated Pt microelectrode used as SECM tip with a detection limit of 0.15 nM Cu 2þ (N ¼ 4, RSD ¼ 6%) for an accumulation of 45 s at À 0.4 V. SECM images of model samples such as copper coated microelectrodes and lacquered metallic copper workpieces demonstrated the feasibility and applicability of combining AC-and underpotential stripping mode of SECM for local visualization of Cu 2þ -ion release from corroding surfaces.

Application of AC‐SECM in Corrosion Science: Local Visualisation of Inhibitor Films on Active Metals for Corrosion Protection

“…The applicability of 4D AC-SECM to the investigation of active corrosion processes has been successfully demonstrated in imaging corrosion pits in passivated steels and defects in polymer-coated metals [35,[40][41][42] as well as monitoring selective metal dissolution of alloys. [43,44] From the foregoing, we regard 4D AC-SECM to be a promising tool for analysis of the thin surface layers produced in many inhibitor/metal systems. To demonstrate the feasibility of this approach, copper was chosen as a representative model metal because it is a base metal with a low redox potential in aqueous solutions.…”

Rapid catalytic-adsorptive determination of picomolar concentrations of Cu2+ with the mercury monolayer carbon fiber electrode

“…Because the quantity of copper involved in biochemical processes varies over a wide range, the elaboration of a sensitive and fast method for the copper determination remains a challenge, particularly with respect to the application of scanning electrochemical microscopy (SECM), which is suitable for the examination of processes occurring at nanosized objects [3,4].…”

Alternating‐Current Measurements in Scanning Electrochemical Microscopy, Part 1: Principle and Theory

“…[23][24][25][26][27][28][29][30] Schuhmann et al developed an ac-SECM mode for mapping domains of different conductivity or electrochemical reactivity on surfaces. [31][32][33][34] Their approach is different from that presented here, because they applied a frequency perturbation to the probe, whereas in this work the perturbation is applied to the substrate. Eckhard and Schuhmann reviewed ac techniques in SECM.…”