Exploring the Kinetic and Thermodynamic Relationship of Charge Transfer Reactions used in Localized Electrodeposition and Patterning in a Scanning Bipolar Cell

Published

May 14, 2019

Author(s)

Trevor M. Braun, D. T. Schwartz

Abstract

Bipolar electrochemistry, defined as simultaneous oxidation and reduction reactions occurring on an electrically floating electrode, involves intricate coupling of the ohmic drop in the electrochemical cell to the thermodynamics and kinetics of the bipolar reaction couple. When paired with a rastering microjet electrode, called a scanning bipolar cell (SBC), local electrodeposition and patterning of metals beneath the microjet can be realized without direct electrical connections to the substrate. Here, we expand on prior research detailing electrolyte design guidelines for electrodeposition and patterning with the SBC, focusing on the relationship between kinetics and thermodynamics of the bipolar couple. The reversibility or irreversibility of the desired deposition reaction influences the thermodynamic range available when selecting an optimal bipolar counter reaction. For irreversible systems (i.e. nickel), a wide thermodynamic window is possible for the bipolar couple. For reversible systems (i.e. copper or silver) that can easily oxidize, tight thermodynamic windows with a small downhill driving force for spontaneous reduction are required to prevent metal patterns from etching. Furthermore, additives used for the bipolar counter reaction can influence deposit morphology and appearance. Cyclic voltammetry measurements elucidate secondary reduction reactions occurring during bipolar nickel deposition and describe the thermodynamic relationship of both irreversible and reversible bipolar couples. Finally, finite element method simulations explore the influence of bipolar electrode area on current efficiency and connect experimental observations of pattern etching to theoretical relationships.

Citation

Frontiers in Chemistry

Volume

7

Pub Type

Journals

Download Paper

DOI Link

Keywords

Electrodeposition, Bipolar electrochemistry, additive manufacturing

Citation

Braun, T. and Schwartz, D. (2019), Exploring the Kinetic and Thermodynamic Relationship of Charge Transfer Reactions used in Localized Electrodeposition and Patterning in a Scanning Bipolar Cell, Frontiers in Chemistry, [online], https://doi.org/10.3389/fchem.2019.00340 (Accessed April 23, 2024)