Boosting the OER activity of amorphous IrOx in acidic medium by tuning its electron structure using lanthanum salt nanosheets

Abstract

Promoting the activity of Ir-based nanomaterials for oxygen evolution reaction (OER) in acid media without losing their durability is crucial for reducing overpotentials in energy conversion, such as electrochemical water splitting. Here, a nanocomposite composed of a-IrO_x and lanthanum salt (LaCO₃OH) was constructed to further improve its OER activity by tuning the electronic structure of a-IrO_x, because a-IrO_x is a well-known critical material as the active layer of Ir-based anodic catalysts. The interaction between Ir and La via O atoms as a bridge in the catalyst IrO_x/LaCO₃OH, verified by X-ray absorption near edge structure spectroscopy, tunes the electronic structure of a-IrO_x and thus obviously enhances its activity for the OER in acid media, compared with commercially available IrO₂ as well as most of the reported Ir-based OER electrocatalysts. The overpotential of IrO_x/LaCO₃OH at a current density of 10 mA cm⁻² is 255 mV with a Tafel slope of 55 mV dec⁻¹. This work reveals that the strong electronic interaction between Ir- and La-based materials can efficiently improve activity and reduce energy consumption, as well as enlarging the family of acidic OER electrocatalysts.