Microelectrode Testing of LTE Electrocatalysts, Ionomers, and Their Interactions in the Solid State
LaboratoryLawrence Berkeley National Laboratory (LBNL)
Capability ExpertNemanja Danilovic
Node Readiness Category2: Low-Temperature Electrolysis (LTE)
This capability is for evaluating electrochemical properties of alkaline- and acid-based electrocatalysts, membranes, and ionomers using a model system to resolve interfacial reactions between ionomers and electrocatalysts in water vapor and liquid environments (water and electrolyte). This setup is uniquely advantageous for measuring transient, adsorptive, and mass transport effects and diverges from commonly used static microlectrode experimental setups. For conventional microelectrode measurements in well-controlled static environmental chambers, see the complementary NREL node: Electrolysis Catalyst Synthesis, Ex-situ Electrochemical Performance and Durability Characterization, and Standardization.
Microelectrode Cell and Station (Readiness Level 2)
Microelectrodes are model systems for evaluating electrochemical activity, mass transport, and interfacial reactions under conditions approaching the catalyst layer, but without the complexity of a whole membrane electrode assembly (MEA). The microelectrode being used for evaluation is a 10 to 100 μm diameter polycrystalline disk or microcavity for nanoparticles. This electrode can then be characterized in either a 3-electrode liquid cell or a 3-electrode solid state cell (Figure 1). The solid state cell allows for a microelectrode to be interfaced directly with a solid-state electrolyte such as Nafion or Sustanion. The cell’s temperature, gas composition and flowrate, liquid water or electrolyte environment can then be changed in order to evaluate kinetics or diffusion in the systems at various conditions. The cell can be tested with acid or alkaline membranes or ionomers cast to various controlled thickness on top of the microelectrode. It is coupled with mass spectrometry (MS) and inductively coupled plasma mass spectrometry (ICP-MS) for dissolution studies and product analysis.
For microelectrode testing of low-temperature electrolysis (LTE) materials, polycrystalline disk, powders, and nanoparticles can be used to make microelectrodes. Acid and alkaline ionomers can be casted at controlled thickness onto the microelectrode tips for evaluation. The cell can operate at temperatures up to 120°C and be fed with various gases, under liquid or gaseous water, or an electrolyte.
For microelectrode measurements, bulk microelectrodes for most platinum group metal (PGM)-free and PGM materials are available. In addition, the capability to integrate nanoparticles onto microelectrode supports, as well as acid and alkaline membranes or ionomers, is available for testing under solid-state electrolyte conditions.
Facilities are in use for current studies but can accommodate additional projects.
This capability would be central to testing of integrated photoelectrochemical devices and electrolyzers for water splitting.
Microelectrode cell and Pt cyclic voltammogram on Nafion ionomer .
- John G. Petrovick, Douglas I. Kushner, Meron Tesfaye, Nemanja Danilovic, Clayton J. Radke, Adam Z. Weber, "Mass-Transport Resistances of Acid and Alkaline Ionomer Layers: A Microelectrode Study," ECS Transactions Vol. 92 (2019): 77-85.