Antimony tin oxide supported iridium oxide nanocatalyst with bi-directional strains for oxygen evolution reaction in PEM electrolyzers

Abstract

The use of proton exchange membrane (PEM) electrolyzers in H2 production encounters notable challenges related to the activity and stability of the oxygen evolution reaction (OER). To address these issues, we introduce antimony tin oxide as carriers to support a core–shell structured Sb0.3Ir0.7Ox@TB-IrOx, featuring twin boundaries (TB) with bi-directional (shear and axial) strains. This catalyst exhibits a remarkably low overpotential of 198 mV at 10 mA cm−2 for OER in 0.5 M H2SO4 and impressively maintains stability for 200 h. Moreover, Sb0.3Ir0.7Ox@TB-IrOx/Sb0.2Sn0.8O2 demonstrates an exceptionally high mass activity of 4.06 A mg Ir-1 (η = 270 mV). The improved catalytic activity and stability are attributed to the introduction of antimony, which brings the Ir 5d band center (εd) closer to the Fermi level and results in a smaller catalyst particle size, exposing more active sites. Furthermore, a PEM electrolyzer employing the Sb0.3Ir0.7Ox@TB-IrOx/Sb0.2Sn0.8O2 nanocatalyst maintains a cell voltage of 2 V at 2 A cm−2 and exhibits a stability more than 200 h.