Controlled Structural Activation of Iridium Single Atom Catalyst for High-Performance Proton Exchange Membrane Water Electrolysis
Wonjae Ko, Jaehyuk Shim, Hyunsoo Ahn, Hee Jung Kwon, Kangjae Lee, Yoon Seok Jung, Wytse Hooch Antink, Chan Woo Lee, Sungeun Heo, Seongbeom Lee, Junghwan Jang, Jiheon Kim, Hyeon Seok Lee, Sung-Pyo Cho, Byoung‐Hoon Lee, Minho Kim, Yung‐Eun Sung, Taeghwan Hyeon
Abstract
Iridium single atom catalysts are promising oxygen evolution reaction (OER) electrocatalysts for proton exchange membrane water electrolysis (PEMWE), as they can reduce the reliance on costly Ir in the OER catalysts. However, their practical application is hindered by their limited stability during PEMWE operation. Herein, we report on the activation of Ir-doped CoMn 2 O 4 in acidic electrolyte that leads to enhanced activity and stability in acidic OER for long-term PEMWE operation. In-depth material characterization combined with electrochemical analysis and theoretical calculations reveal that activating Ir-doped CoMn 2 O 4 induces controlled restructuring of Ir single atoms to IrO x nanoclusters, resulting in an optimized Ir configuration with outstanding mass activity of 3562 A g Ir –1 at 1.53 V (vs RHE) and enhanced OER stability. The PEMWE using activated Ir-doped CoMn 2 O 4 exhibited a stable operation for >1000 h at 250 mA cm –2 with a low degradation rate of 0.013 mV h –1, demonstrating its practical applicability. Furthermore, it remained stable for more than 400 h at a high current density of 1000 mA cm –2, demonstrating long-term durability under practical operation conditions.