Galvanostatic Electrodeposition of Durable IrO_x Films on Low-Iridium-Supported Titanium for an Acidic Oxygen Evolution Reaction

Ensuring or even optimizing the activity and stability of iridium oxide-coated titanium anodes while reducing the amount of iridium is still practically significant. In this work, IrOx-Ti electrodes are prepared by galvanostatic deposition at different deposition current densities and times. The iridium loading level, morphology, microstructure, and element composition distribution of these obtained electrodes are characterized, and their cyclic voltammetry and accelerated life tests were carried out in 0.5 M H2SO4 to investigate their electrochemical performance for the acidic oxygen evolution reaction (OER). For a better understanding of the anodic electrodeposition mechanism, a competing mechanistic hypothesis was proposed to describe the reactions and their relationship involved in this process. The results show that the IrOx electrodes electrodeposited at 0.1 mA cm(-2) exhibited a superior performance for the OER in terms of stability. Especially, the electrode electrodeposited for 5 h (0.1 mA cm(-2)) demonstrated a long-term durability for 73.14 h (equivalent to at least 14,642 h, i.e., 610 days, in actual lifetime) with 1.0 mg cm(-2) iridium loading. Simultaneously, a mathematical model was used to fit the relationship between accelerated lifetime and deposition current and iridium loading. This research provides some valuable insights into how to optimally use Ir as an OER electrocatalyst.