Cation Dissolution-Induced Structural Transformation and Enhanced Stability for Ni–Ir Bimetallic Electrocatalysts during the Oxygen Evolution Reaction in Acid

Abstract

To develop stable electrocatalysts for the oxygen evolution reaction (OER) in acid, it is essential to understand the degradation mechanisms on the catalyst surface. In this work, we compare the OER performance of two Ni–Ir bimetallic oxides (Li2Ir1–xNixO3−δ with x = 0.25 and 0.75) in sulfuric acid. A dynamic structure transformation is observed on LINO-0.25 due to fast delithiation from the layered structure. The resulting catalyst demonstrates ∼10 times enhanced electrochemical activity but 70% less Ir dissolution compared to that of LINO-0.75 oxide. We propose that creating dynamic Li+/H+ exchange channels in structure may be beneficial for achieving a stable OER performance in acid.