Amorphous iridium oxide (IrOx) is a 5d rare metal-based catalyst that has high activity towards the oxygen evolution reaction (OER) over a broad range of pH values. The scarcity of the elemental Ir makes large-scale applications more challenging, so increasing the material utilization efficiency is critical. We developed a sophisticated soft-templating method to synthesize mesoporous nanosheets via solution-based assembly of close-packed polymeric micelles in the presence of metal precursors and reducing agents. Heating the mesoporous nanosheets caused them to form amorphous IrOx perforated with a semi-regular arrangement of ∼13 nm diameter holes. Mesoporous nanosheets have a unique mixture of 2D and 3D topologies that enable superior electrocatalytic activities for the OER, and good stabilities under both acidic and basic conditions.
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