Probing Electrocatalytic Gas Evolution Reaction at Pt by Force Noise Measurements. Part 2. Oxygen

TL;DR

This study uses AFM imaging combined with a Pt ultramicroelectrode to investigate oxygen bubble nucleation, growth, and detachment during the oxygen evolution reaction, revealing interactions that affect catalytic activity.

Contribution

It introduces a novel approach combining AFM feedback error signals with topography to map nanoscale bubble dynamics at catalytic interfaces.

Findings

Oxygen bubbles nucleate at step edge sites.

Bubble interaction reduces current density during OER.

Nanoscale mapping reveals complex gas evolution phenomena.

Abstract

Understanding O2 bubble nucleation and growth during the oxygen evolution reaction (OER) is crucial to comprehend their influences on catalytically active sites in the process. To achieve this goal, mapping the spatial variation of nanoscale dynamic individual steps at the electrocatalytic interfaces is vital, as it further enables a detailed understanding of the mechanism of the process. Here, we combined tapping mode AFM imaging with a Pt ultramicroelectrode to investigate oxygen bubble nucleation, growth, and detachment. Our AFM feedback error signal and topography data reveal that bubbles of O2 gas nucleate at the step edge sites and interact with the catalytically active sites. This interaction between primary catalytic sites and bubble nucleation sites is the primary reason for a decrease in the current density at a given high overpotential of the OER. Our findings advance the understanding of the complexity of phenomena involved in gas evolution on catalytic surfaces.