Preliminary investigation of factors influencing the bubbles detachment of iridium oxide in oxygen evolution reaction

Abstract

Oxygen evolution reaction (OER) is a well-known gas-involved reaction in which oxygen bubbles are formed and adhered on anode surface to lead to a sharp decline of performance. Iridium oxide (IrO2) is the catalyst for water oxidation and is often used as a benchmark material. However, the factors affecting the bubbles detachment of IrO2 are still unclear. Herein, we found that: 1. Nafion®, one of the main components of PEM membrane and usually used as electrode binder, can significantly increase the hydrophobicity of the electrode surface and is unfavorable to bubble detachment. 2. IrO2 itself has good hydrophilicity but is not enough for efficient bubble separation, and no obvious linear relationship between bubble detachment performance and the particle size. 3. For improving bubble separation, irregularly rough surfaces should be avoided to prevent cavities trapping effect and multiple unnecessary bubble adhesion sites, both of which play the roles in stabilizing bubbles. In contrast, the uniformity and regularity of electrode surface should be paid more attention, as evidenced by comparing the surface morphology between drop-casting and pyrolysis in IrO2 and RuO2.