Reconstruction-Induced Bilayered Amorphous-Crystalline Hybrid NiOOH-Based Anode for Ultrastable Seawater Electrolysis.

He, Zeyang; Bu, Hongkai; Zhao, Ke; Lin, Saisai; Yu, Zhoubin; Fu, Yujie; Hou, Wenqing; Gong, Yujie et al. · Adv Mater · 2026

basic_science · Level V

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Abstract

Direct seawater electrolysis represents a critical pathway for large-scale utilization of renewable energy in coastal and island regions without potential impacts on freshwater supply, yet being severely hindered by the corrosion of electrode materials in seawater. Conventional anion-based protection strategies often suffer from lattice degradation during activation or anion desorption in operation. Herein, we report a facile electrodeposition-anodization synthesized amorphous-crystalline hybrid NiFeCoCr anode featuring a vertically bilayered architecture, enabling ultrastable seawater oxidation for over 15 000 h at 500 mA cm<sup>-2</sup>. During anodization, the partial sacrificial leaching of Cr forms an amorphous β-NiOOH phase surface layer, exposing abundant active sites to enhance OER activity. Concurrently, in situ generated CrO<sub>4</sub> <sup>2-</sup> anions stably adsorb and intercalate within the dense crystalline Fe/Co-doped γ-NiOOH underneath layer. The electrolyzer assembled with the NiFeCoCr anode delivers stable operation for over 2500 h in alkaline natural seawater and for 240 h in alkaline saturated NaCl electrolyte at 80°C.