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Unraveling Nickel Dissolution Kinetics in Sulfuric Acid via Element-Resolved Electrochemical Impedance Spectroscopy

Year: 2025

Type: article

Abstract: High Resolution Image Download MS PowerPoint Slide Dissolution of transition metals in acidic environments is central to corrosion and electrocatalysis, yet decoupling the kinetics of the individual electrochemical steps, remains a longstanding challenge. We introduce a combined atomic emission spectroelectrochemistry–electrochemical impedance spectroscopy (AESEC-EIS) method enabling real-time, element-specific quantification of metal dissolution while simultaneously resolving interfacial impedance. Using nickel in deaerated sulfuric acid as a model system, we construct the first element-resolved Nyquist and Bode plots for an actively dissolving metal. The results reveal a Ni dissolution mechanism involving adsorbed intermediates acting as precursors to soluble Ni(II). A second anodic peak, induced by prior cathodic potential sweep, reflects surface modification. Kinetic modeling and EIS simulations confirm that the surface-mediated pathway dominates under cathodic activation, whereas the passivating route involving NiO formation prevails otherwise. AESEC-EIS offers a robust approach to decompose interfacial electrochemical kinetics and to elucidate metal dissolution mechanisms relevant to corrosion and electrocatalysis.

Source: ACS electrochemistry.

DOI: 10.1021/acselectrochem.5c00428

Authors: Junsoo Han, Bernard Tribollet, Kevin Ogle