Ultrahigh Oxygen Evolution Reaction Activity Achieved Using Ir Single Atoms on Amorphous CoOx Nanosheets

Developing efficient electrocatalysts for an oxygen evolution reaction (OER) is important for renewable energy storage. Here, we design high-density Ir single-atom catalysts supported by CoOx amorphous nanosheets (ANSs) for the OER. Experimental results show that Ir single atoms are anchored by abundant surface-absorbed O in CoOx ANSs. Ir single-atom catalysts possess ultrahigh mass activity that is 160-fold of commercial IrO2. The OER of IrCoOx ANSs reached a record low onset overpotential of less than 30 mV. In situ X-ray absorption spectroscopy reveals that Ir–O–Co pairs directly boosted the OER efficiency and enhanced the Ir stability.