Surface Microbubbles Attenuate Gas-Evolution Reaction at Soft Interfaces

Area of Science:

• Materials Science
• Chemical Engineering
• Surface Chemistry

Background:

• Gas-evolution reactions at solid-liquid interfaces are crucial for clean energy technologies.
• Microbubble formation on these interfaces can negatively impact performance by blocking active sites and hindering mass transport.
• The precise mechanism by which microbubbles influence interfacial reactivity is not well understood.

Purpose of the Study:

• To investigate the interplay between interfacial reactions, microbubble formation, and transport phenomena.
• To quantify the effect of microbubbles on local interfacial reactivity.
• To explore the potential for tuning gas-evolution kinetics through controlled bubble dynamics.

Main Methods:

• Utilized a soft composite film containing a liquid organic hydrogen carrier (LOHC).
• Employed dual-wavelength reflective interference contrast microscopy (DW-RICM) to observe nanoscale changes and bubble dynamics.
• Performed spatial mapping to analyze reactivity under and around surface bubbles.

Main Results:

• Observed H2 generation via base-promoted Si-H bond cleavage in LOHC at the film-liquid interface.
• Demonstrated that surface bubbles reduce local reactivity by approximately 2-fold due to restricted access of the alkaline phase.
• Showed that bubble growth induces convective flows, enhancing the transport of reactants and products.

Conclusions:

• Microbubble coverage has a dual effect: it attenuates reactivity locally but can enhance transport through induced convection.
• The kinetics of gas-evolution reactions and bubble growth can be modulated by adjusting LOHC loading.
• The developed platform allows for quantitative investigation of gas-evolution reactions in the presence of bubbles.