Probing Electrocatalytic Gas Evolution Reaction at Pt by Force Noise Measurements. Part 1. Hydrogen

Area of Science:

• Electrochemistry
• Surface Science
• Nanotechnology

Background:

• Electrocatalytic processes at heterogeneous interfaces are complex and difficult to understand at the molecular level.
• Atomic force microscopy (AFM) has been primarily used for in situ imaging of electrocatalysts, not for studying dynamic processes like gas evolution.

Purpose of the Study:

• To investigate gas evolution at a platinum ultramicroelectrode (Pt UME) under electrochemical conditions using force noise measurements.
• To demonstrate the viability of in situ AFM for studying gas evolution during electrocatalysis.

Main Methods:

• Utilized atomic force microscopy (AFM) with force noise measurements to study gas evolution.
• Performed in situ electrochemical and optical microscopy analyses.
• Investigated hydrogen (H2) gas bubble nucleation, growth, and detachment events.

Main Results:

• Detected excess force noise corresponding to individual H2 gas bubble events.
• Observed that larger H2 bubbles remain pinned to the Pt UME surface, while smaller bubbles detach.
• Identified an overpotential of -0.8 V vs RHE for bubble release.

Conclusions:

• In situ AFM force noise measurements are a viable method for studying gas evolution in electrocatalysis.
• The study provides mechanistic insights into H2 gas bubble detachment during the hydrogen evolution reaction (HER).
• Understanding bubble dynamics is crucial for optimizing electrocatalytic efficiency.