Complete Reconstruction of Hydrate Pre-Catalysts for Ultrastable Water Electrolysis in Industrial-Concentration Alkali Media

Fundamental investigations of reconstruction of oxygen evolution reaction (OER) pre-catalysts and performance evaluation under realistic conditions are vital for practical water electrolysis. Here, we capture dynamic reconstruction, including the geometric/phase structure, of hydrate molybdates at oxidized potentials. Etching-reconstruction engineering endows the formed NiOOH with a sub-5-nm particle-interconnected structure, as revealed by multi-angle electron tomography. The key to complete reconstruction is the multicomponent co-leaching-induced loose reconstruction layer, conductive to solution penetration and mass transport. This unique structure avoids particle agglomeration in catalysis and promotes complete exploitation of the catalyst with 1,350 h of durability to meet industrial requirements. Upon addition of iron during reconstruction, mainstream Fe-NiOOH with a retained structure forms. Coupled with MoO2-Ni arrays in a membrane-free and two-electrode cell, it achieves stable electrolysis in industrial-concentration KOH for 260 h. This work highlights the reconstruction chemistry of hydrate oxygen-evolving systems and their performance evaluation under industrial conditions. [Display omitted] Electro-oxidation induces complete reconstruction on hydrate molybdate pre-catalystThe key to complete reconstruction is a loose reconstruction layerMicrostructure of completely reconstructed material provides ultrastable catalystPerformance evaluation of water electrolysis under realistic conditions Fundamental investigations of the reconstruction of pre-catalysts and evaluation of their performance under realistic conditions are vital to promote practical applications. Liu et al. study the dynamic reconstruction, including geometric/phase structure, of hydrate molybdates at oxidized potentials. They highlight that reconstruction engineering toward completely reconstructed catalysts leads to materials that are active and stable under industrial conditions.