Synergistically optimizing electrocatalytic performance of IrO2 with double doping and bi-directional strains for acidic oxygen evolution reaction

Abstract

Because of the strong acidic environment and oxidative conditions, realizing the highly active and stable iridium (Ir)-based electrocatalysts toward oxygen evolution reaction (OER) in a proton exchange membrane (PEM) electrolyzer is still a big problem to overcome. to solve this problem, a novel core-shell structured Tm0.1Sb0.2Ir0.7Ox@TB-IrOx nanocatalyst with bi-directional (shear and axial) strains was fabricated. It only needs a low overpotential of 192 mV (10 mA cm-2) for OER in acidic electrolyte with an impressive stability, exceeding most recently reported Ir-based electrocatalysts. Moreover, Tm0.1Sb0.2Ir0.7Ox@TB-IrOx exhibits an exceptionally high mass activity of 3.36 A mgIr-1 (η = 270 mV). The enhanced catalytic activity resulted from the introduction of Tm causing the Ir 5d band center (εd) to be closer to the Fermi level, which demonstrated by theoretical calculations and microscopy characterizations. Additionally, a PEM electrolyzer adopting a Tm0.1Sb0.2Ir0.7Ox@TB-IrOx nanocatalyst indicates efficiency stability for a span of 500 hours and takes a cell voltage of 2.01 V to achieve 2 A cm-2.