Degradation Behavior of Co 3 O 4 Spinel OER Catalyst Under Dynamic Operation and Thermally Driven Healing in Alkaline Water Electrolysis

Abstract Green hydrogen production suffers from the intermittent nature of renewable energy resources, which accelerates the degradation of electrocatalysts in water electrolyzers. Therefore, it is crucial to minimize the catalyst degradation under dynamic operating conditions. This study investigated the degradation behavior of an oxygen evolution reaction catalyst under two types of dynamic operation via controlling the voltage range, elapsed time at high voltage, and power fluctuation frequency. High‐voltage operation and short start/stop periods caused severe catalyst degradation. In addition, chemical and physical characterization identified the formation of amorphous Co(OH) 2 and defects as key factors in Co 3 O 4 degradation. These results indicated that it is possible to respond to dynamic operation by understanding how the degradation phenomenon is intensified by dynamic operating conditions. In addition, a thermal‐healing method is investigated for degraded catalysts, which restores defects by inducing atomic rearrangement toward the original crystal structure, returning the Co 3 O 4 catalyst to its initial performance. The results indicated that a suitable restoration strategy targeting the origin of the catalyst degradation can lead to the realization of a water electrolyzer capable of long‐term operation.