Bubble Consumption Dynamics in Electrochemical Oxygen Reduction

Electrochemical oxygen reduction reaction(ORR) is crucial for fuel cells and metal-air batteries, while the oxygen consumption dynamics study during ORR, which affects the ORR efficiency, is not as concerned as catalysts design does. Herein the consumption behavior of an individual oxygen bubble on Pt foils with different wettabilities during ORR was tracked by a real-time approach to reveal whether the surface wettability of electrode can influence the consumption dynamics and determine the reaction reactive zones of oxygen bubble consumption. The oxygen bubble underwent a “constant contact angle” dominant consumption model on aerophobic Pt foil, while an initial “constant radius” and the subsequent “constant contact angle” oxygen consumption models were observed on aero-philic Pt foil. Results here demonstrated that the current was proportional to the bottom contact area, rather than the three-phase contact line of the bubbles according to the fitting curves between individual bubble current and the con-sumption behavior parameters. This study highlights the important role of the gas-solid interface in influencing the efficiency of gas consumption electrochemical reactions, which shall benefit the understanding of reaction kinetics and the rational design of electrocatalysts.