Spatially dispersed redox-active iridium sites are immobilized throughout the porous framework of a zirconium-based metal–organic framework (MOF), UiO-66, to enable charge hopping in the MOF. The resulting iridium sites within UiO-66 not only permit redox hopping-based electron transport within the MOF in aqueous electrolytes, but also exhibit electrocatalytic activity for the oxidation of nitrite. The pH of the electrolyte for this electrocatalysis is optimized, and the electrocatalytic mechanism occurring on the Ir-decorated UiO-66 thin films is investigated. The material is further applied for amperometric nitrite sensing in aqueous solutions. Owing to its high porosity, the Ir-decorated UiO-66 achieves a good sensitivity (168.8 μA/mM-cm2) for detecting nitrite with a low limit of detection (0.41 μM).
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