Scanning Bubble Electrochemical Microscopy: Mapping of Electrocatalytic Activity with Low-Solubility Reactants

Area of Science:

• Electrochemistry
• Surface Science
• Materials Science

Background:

• Electrocatalytic activity determination is challenging for reactions with low-solubility reactants due to mass-transport limitations.
• Key reactions like oxygen reduction, nitrogen reduction, and carbon dioxide reduction are affected by these limitations.
• Existing methods struggle to accurately measure activity under conditions of limited reactant solubility.

Purpose of the Study:

• To introduce a novel technique, scanning bubble electrochemical microscopy (SBEM), for high-resolution mapping of electrocatalytic activity.
• To enable the study of reactions involving reactants with limited solubility by overcoming mass-transport barriers.
• To provide a tool for high mass-transport rate measurements at the microscale.

Main Methods:

• Utilizing a scanning probe approach with a dual-barreled nanopipette.
• Precisely delivering gas-phase reactants to the vicinity of an electrocatalyst surface (micrometers).
• Creating localized high mass-transport conditions directly under the probe tip.

Main Results:

• Demonstrated the capability of SBEM by mapping the oxygen reduction reaction (ORR) on platinum microelectrodes.
• Successfully achieved high mass-transport rates at the electrocatalyst surface under the probe.
• Enabled detection and mapping of electrocatalytic activity for a low-solubility reactant.

Conclusions:

• Scanning bubble electrochemical microscopy is an effective method for measuring electrocatalytic activity with low-solubility reactants.
• The technique overcomes the challenge of reduced mass-transport in such reactions.
• SBEM offers a promising new avenue for advancing research in critical electrochemical processes.