Performance Enhancement of Electrocatalytic Hydrogen Evolution through Coalescence-Induced Bubble Dynamics

Area of Science:

• Electrochemistry
• Materials Science
• Chemical Engineering

Background:

• Electrochemical gas bubble evolution can reduce process efficiency.
• Bubble departure from electrodes is governed by forces like buoyancy and contact.
• Understanding bubble dynamics is crucial for optimizing electrolysis.

Purpose of the Study:

• Investigate the dynamics of hydrogen (H2) bubble pairs during water electrolysis.
• Analyze the impact of electrode spacing and cathodic potential on bubble departure.
• Determine the role of bubble-bubble interactions in enhancing electrolysis efficiency.

Main Methods:

• Utilized a dual platinum microelectrode system for hydrogen evolution reaction in sulfuric acid.
• Employed high-speed imaging to capture bubble dynamics.
• Combined electrochemical analysis with visual observations.

Main Results:

• Bubble coalescence significantly promotes earlier departure compared to buoyancy alone.
• Increased reaction rates were observed due to bubble coalescence at constant potential.
• Beyond a critical current, repeated coalescence can lead to bubble re-attachment, dependent on electrode spacing.
• Larger electrode separations enhanced mean current up to 2.4 times versus a single electrode.

Conclusions:

• Bubble-bubble interactions, specifically coalescence, are key to improving gas bubble departure in electrolysis.
• Electrode spacing critically influences the balance between coalescence-driven departure and re-attachment.
• Optimized dual-electrode configurations can substantially increase overall current efficiency in water electrolysis.