Ultrahigh Oxygen Evolution Reaction Activity Achieved Using Ir Single Atoms on Amorphous CoO<i>_x</i> Nanosheets

Abstract

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.