The smallest electrochemical bubbles.

Area of Science:

• Electrochemistry
• Materials Science
• Nanotechnology

Background:

• Electrochemical processes often generate gas, leading to bubble formation that blocks electrode surfaces.
• This bubble blockage causes increased overpotentials and Ohmic drop, limiting efficiency in catalysis and energy storage.
• Nanoelectrodes were proposed to mitigate bubble formation, but experiments showed they still form nanobubbles, limiting current.

Purpose of the Study:

• Investigate the potential-current response of nanoelectrodes down to the single-atom level.
• Understand the role of electrode size in gas bubble nucleation and stability.
• Identify optimal nanoelectrode dimensions for enhanced electrochemical gas production.

Main Methods:

• Employed molecular simulations to model electrochemical gas generation at nanoelectrode surfaces.
• Analyzed potential-current responses for disk electrodes with diameters down to atomic scale.
• Calculated the grand potential of surface nanobubbles to determine their thermodynamic stability.

Main Results:

• Nanoelectrodes around 1 nm can deliver twice the current of much larger electrodes.
• Gas phase destabilization on smaller nanoelectrodes boosts extracted current.
• Surface nanobubbles are thermodynamically unstable on supports smaller than 2 nm.

Conclusions:

• Nanoelectrodes smaller than 2 nm prevent stable nanobubble formation, improving electroactive area accessibility.
• Electrode radius significantly impacts current, which becomes sensitive to size below 2 nm.
• An optimal nanoelectrode size exists between single-atom and approximately 3 nm for maximizing gas production.