Lanthanum-assisted lattice anchoring of iridium in Co3O4 for efficient oxygen evolution reaction in low-iridium water electrolysis

Abstract

The use of single-atom catalysts is an effective way to reduce the amount of iridium in proton exchange membrane water electrolysis (PEM-WE). However, conventional methods can only obtain surface-loaded single atoms or clusters which cannot meet the needs of high current density and stability. In this study, assisted by lanthanum-doping-induced ion exchange, we realize atomically anchoring iridium within the Co3O4 lattice. The lattice anchored iridium in lanthanum-doped Co3O4 exhibits higher atomic dispersion, a larger average coordination number, and an elevated oxidation state. This improvement stimulates the oxide path mechanism (OPM), resulting in enhanced activity (236 mV at 10 mA cm−2) and stability (1000 h at 10 mA cm−2). Impressively, our catalyst demonstrates notable performance in a PEM electrolyzer with an iridium mass loading of just 0.2 mgIr cm−2, achieving a low cell voltage of 1.61 V at 1.0 A cm−2 and maintaining stable operation for over 1000 h. This work presents an effective strategy for fabricating low-noble-metal-loading catalysts with enhanced efficiency for PEM-WE. Hydrogen production via proton exchange membrane water electrolysis is limited by the high cost and scarcity of iridium catalysts. By doping lanthanum into cobalt oxide, the authors anchor iridium atoms within the oxide lattice, boosting oxygen evolution activity and stability and reducing iridium loading.