Electrochemically Decorated Iridium Electrodes with WS3−x Toward Improved Oxygen Evolution Electrocatalyst Stability in Acidic Electrolytes

Abstract Iridium‐based oxides, currently the state‐of‐the‐art oxygen evolution reaction (OER) electrocatalysts in acidic electrolytes, are cost‐intensive materials which undergo significant corrosion under long‐term OER operation. Thus, numerous researchers have devoted their efforts to mitigate iridium corrosion by decoration with corrosion‐resistant metal oxides and/or supports to maximize OER catalyst durability whilst retaining high activity. Herein a one‐step, facile electrochemical route to obtain improved IrO x thin film OER stability in acid by decorating with amorphous tungsten sulphide (WS 3− x ) upon electrochemical decomposition of a [WS 4 ] 2− aqueous precursor is proposed. The rationale behind applying such WS 3− x decoration stems from the generation of a tungsten oxide phase, a well‐known corrosion‐resistant photoactive OER catalyst. The study demonstrates the viability of the proposed WS 3− x decoration, allowing the tailoring of experimental parameters responsible for WS 3− x nanoparticle size and surface coverage. OER stability tests coupled by ex situ SEM and XPS corroborate the beneficial effect of WS 3− x decoration, yielding improved OER specific activity metrics along with minimized Ir surface roughening, a characteristic of electrodissolution. Iridium decoration with electrodeposited, corrosion‐resistant oxides is consequently shown to be a promising route to maximize OER stabilities.