Gettering La Effect from La ₃IrO ₇ as a Highly Efficient Electrocatalyst for Oxygen Evolution Reaction in Acid Media

Abstract

Developing highly active, durable, and cost‐effective electrocatalysts for the oxygen evolution reaction (OER) is of prime importance in proton exchange membrane (PEM) water electrolysis techniques. Herein, a surface lanthanum‐deficient (SLD) iridium oxide as a highly efficient OER electrocatalyst is reported (labeled as La ₃IrO ₇‐SLD), which is obtained by electrochemical activation, and shows better activity and durability than that of commerically available IrO ₂ as well as most of the reported Ir‐based OER electrocatalysts. At a current density of 10 mA cm ⁻², the overpotential of La ₃IrO ₇‐SLD is 296 mV, which is lower than that of IrO ₂ (316 mV). Impressively, the increase of potential is less than 50 mV at a voltage–time chronopotentiometry extending for 60 000 s using a glass carbon electrode that is vastly superior to IrO ₂. Moreover, the mass activity of the catalyst is approximately five times higher than that of IrO ₂ at 1.60 V versus reversible hydrogen electrode. Density functional theory calculations suggest that a lattice oxygen participating mechanism with central Ir atoms serving as active sites (LOM‐Ir) rationalizes the high activity and durability for the La ₃IrO ₇‐SLD electrocatalyst. The favorable energy level of surface active Ir 5d orbitals relative to coordinated O 2p orbitals makes the La ₃IrO ₇‐SLD more active.