Enhancing the cyclic stability of an iridium-based hexagonal perovskite-structured oxygen electrocatalyst in acidic environment

Abstract

As the demand for commercialization of green hydrogen energy increases, the efficiency of the oxygen evolution reaction at the anode becomes a topic of discussion. In the case of green hydrogen produced through water electrolysis, the overall cell efficiency is determined by the efficiency of the oxygen evolution reaction at the anode with high overpotential. Among commercially available water electrolysis cells, the most efficient proton exchange membrane (PEM) cell has a stability issue due to electrode corrosion caused by a locally strong acidic environment on the anode surface. To address this issue, this thesis proposes a design strategy for catalysts that behave stably in an acidic environment. Based on previous research results that highly integrated crystal structures show stable performance, we focused on hexagonal perovskite structure catalysts with strong connection between MO6 through various metal doping based on iridium oxide catalyst. We explain the correlation between the crystal structure of the catalyst for the oxygen evolution reaction in an acidic environment, the thermodynamic properties of the constituent elements, and stability issues based on the results of oxygen evolution reaction tests for various catalyst structures and compositions. In addition, we observe the structural changes of the catalyst due to changes in performance using atomic-scale scanning transmission electron microscopy as the oxidation reaction progresses, and aim to elucidate the catalyst conditions suitable for an acidic environment.