Schematic illustration of the dynamic reconstruction of metal ion vacancies.

A research team led by Professor Zhao Xu from the School of Chemical Engineering and Technology at Xi'an Jiaotong University (XJTU) has made progress in the development of catalysts for anion-exchange membrane (AEM) water electrolysis for hydrogen production.

The study, titled Engineering Co-ion vacancy in dynamically reconstructed Co-based catalysts for practical anion-exchange membrane electrolysis, was published in Nature Communications. It presents the innovative strategy "electrochemical dynamic reconstruction of metal ion vacancies" enabling precise creation of cobalt ion vacancies within catalysts under operational conditions, offering a new pathway for designing high-performance, long-lasting AEM electrolysis catalysts.

AEM water electrolysis combines the low cost of alkaline electrolyzers with the high efficiency and fast response of proton-exchange membrane systems, making it a promising technology for large-scale green hydrogen production.

However, the anode oxygen evolution reaction (OER) under highly corrosive operating conditions often induces structural reconstruction of catalysts, leading to rapid degradation of non-precious metal catalysts and hindering practical deployment. Achieving both high activity and long-term stability under industrial-level current densities remains a major challenge.

To address this, Zhao's team developed a scalable strategy involving electrochemical dynamic reconstruction to generate metal ion vacancies. By pre-weakening the bonds in the precursor catalyst, this method facilitates the formation of hydroxide catalysts rich in metal vacancies during operation. These vacancies enhance metal-oxygen covalency, promoting lattice oxygen activation, while simultaneously increasing hydroxyl affinity to support lattice oxygen regeneration.

This dual effect effectively suppresses metal leaching and structural collapse. As a result, the optimized catalyst achieves a high hydrogen production current density of 3.3 A cm⁻² at 2 V in an AEM electrolyzer and maintains exceptional stability, with a voltage decay rate of only 0.10 mV h⁻¹ over 1000 hours of continuous operation at 80 C and industrial-level current densities.

This work provides a transformative approach to designing robust, high-activity electrocatalysts under real-world operating conditions, marking a critical step toward the industrialization of AEM-based hydrogen production technologies.