Carboxyl-functionalized nano-pockets boost the stability of iridium oxide catalysts for oxygen evolution reaction

Carboxyl-functionalized nano-pockets synergistically stabilize IrO x catalyst. • Dual synergistic stabilization mechanism involving “physical confinement – electron regulating” • Achieves ultra-stable OER for >1000 h at 10 mA cm −2 . • Outstanding PEMWE durability with stable 1 A cm −2 operation for over 120 h at 1.64 V. A novel carboxyl-functionalized nano-pockets catalyst (CNP-IrO x ) was rationally designed to counteract the deactivation of iridium oxide (IrO x ) catalysts in acidic oxygen evolution reaction (OER). The ingenuity of our approach is rooted in the physical confinement afforded by the nano-pockets, which ensure a stable structural environment that fundamentally arrests the severe agglomeration of IrO x nanoparticles typically observed during OER. Yet, the design's ingenuity extends beyond mere structural stabilization. While the nano-pockets exert physical confinement, the strategically anchored carboxyl groups simultaneously function as crucial electronic regulators. They modulate the surface iridium sites to maintain the active +3 oxidation state and suppress over-oxidation to the inactive +4 state, thereby closing a key chemical deactivation pathway. Extensive ex/in situ spectroscopy, synchrotron radiation analysis, and electrochemical evaluations have been utilized to confirm the efficacy of dual synergistic stabilization mechanism involving “physical confinement – electron regulating”. Consequently, CNP-IrO x maintains superior OER activity, sustaining stable operation for over 1000 h at 10 mA cm −2 , while also enabling durable high current density at 1 A cm −2 for more than 120 h with a low cell voltage of 1.64 V. This work, by synergizing confinement effects with electronic regulation, paves a novel avenue for designing highly durable IrO 2 -based catalyst architectures. Download: Download high-res image (128KB) Download: Download full-size image