Electrochemically decorated iridium electrodes with WS_3−x toward improved oxygen evolution electrocatalyst stability in acidic electrolytes

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 [WS₄]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.