Two-step electrodeposition to achieve durable IrOx electrode with a semi-crystalline structure for efficient OER

Abstract

The Development of highly catalytically active and stable anodes for oxygen evolution reaction (OER) in acidic media remains a great challenge. Herein, we proposed a two-step electrodeposition method to optimize an amorphous electrodeposited IrOx electrode (eⅡ-IrOx/Ti). The introduction of a pre-deposition layer, prepared by triangular wave electrodeposition, contributes to the enhancement of surface oxygen vacancies, resulting in a semi-crystalline structure. Compared to directly potentiostatic electrodeposited IrOx electrode (e-IrOx/Ti) and industrially thermally decomposed IrO2 electrode (IrO2–Ta2O5/Ti) at the same iridium loading level, eⅡ-IrOx/Ti exhibited superior OER performance, with a Tafel slope of 52.85 mV/dec and an overpotential as low as 218 mV at 10 mA/cm2. Moreover, eⅡ-IrOx/Ti demonstrates remarkable stability while continuously catalyzing OER at 250 mA/cm2 for 100 h, with little performance decay and a stability number of 3.397 × 106 (comparable to crystal IrO2). The semi-crystalline structure of eII-IrOx/Ti, rich in oxygen vacancies, facilitates the synergistic effect of amorphous and crystalline phases, indicating the potential of electrodeposited IrOx electrodes for sustained and efficient OER in acidic environments.