Complete Reconstruction of Hydrate Pre-Catalysts for Ultrastable Water Electrolysis in Industrial-Concentration Alkali Media
Xiong Liu, Jiashen Meng, Kun Ni, Ruiting Guo, Fanjie Xia, Jingjing Xie, Li Xu, Bo Wen, Peijie Wu, Ming Li, Jinsong Wu, Xiaojun Wu, Liqiang Mai, Dongyuan Zhao
Abstract
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.