Hydrogen Bubble Size Distribution on Nanostructured Ni Surfaces: Electrochemically Active Surface Area Versus...

Area of Science:

• Materials Science
• Electrochemistry
• Chemical Engineering

Background:

• Nanoscale engineering of electrocatalyst morphology can enhance electrolysis efficiency.
• Electrode-attached bubbles significantly impact electrocatalyst performance.

Purpose of the Study:

• Investigate the influence of electrode surface morphology and wettability on hydrogen bubble behavior.
• Determine the effect of bubble attachment on electrocatalyst performance during electrolysis.

Main Methods:

• Fabrication of nickel-based electrocatalysts with varying hydrophilic and hydrophobic nanostructures via electrodeposition.
• Characterization of surface properties and electrochemical performance.
• High-speed imaging to analyze bubble detachment dynamics.

Main Results:

• Hydrophobic nanostructured electrocatalysts exhibited poorer performance at industrially relevant current densities.
• Increased hydrophobicity led to larger bubble detachment radii, increasing surface area blockage.
• Nanostructuring's surface area gains were outweighed by bubble-induced blockage in hydrophobic samples.
• A 7.5% bubble size reduction was observed with increasing current density in 1 M KOH.

Conclusions:

• Surface wettability plays a critical role in electrocatalyst performance, often overriding benefits from increased surface area.
• Minimizing electrode surface blockage by gas bubbles is essential for efficient electrolysis.
• Further research should focus on optimizing electrocatalyst wettability for improved hydrogen evolution reactions.