Metal–Support Interaction Can Deactivate IrO_<i>x</i>/Sb:SnO₂ OER Catalysts in Polyol Process

Abstract

Only a few materials can remain undissolved under working conditions for the oxygen evolution reaction (OER) in acidic media, which limits the choice of catalysts and supports. One of the practical catalyst/support candidates is IrOx/Sb:SnO2 (Ir/ATO) because both components are thermodynamically stable under low-pH anodic conditions. Moreover, between Ir and ATO, a strong metal–support interaction is present, thereby allowing for long-lasting OER activity unless the support degrades. However, we demonstrate that the strong interaction can paradoxically deactivate Ir/ATO structures when synthesizing them using the polyol process. We reveal that the strong interaction in the presence of polyol at elevated temperatures can cause the reduction of the Sb dopant to zero-valency. Findings show that the varied oxidation state of the dopant decreases the electrical conductivity of the Ir/ATO, impeding the electron transfer through the support, hence deteriorating electrocatalytic activity toward the OER.