Multiscale Structural Engineering of a Multilayered Nanoarray Electrode Realizing Boosted and Sustained Oxygen Evolution Catalysis in Seawater Electrolysis

Seawater electrolysis is promising for large-scale H-2 production, yet it is bottlenecked by the lack of a high-performing anode with favorable activity, desirable selectivity toward the oxygen evolution reaction (OER), and strong resistance against chloride corrosion. Herein, we propose a multiscale structural engineering strategy to construct a multilayered heterostructured OER electrode with an amorphous FeOOH overlayer coated on the crystalline Mo-doped Co0.85Se nanosheet array aligned on 3D macroporous Ni foam. In such designed NF/(CoMo)(0.85)Se@FeOOH electrode, the integration of aliovalent Mo-doped conductive Co0.85Se with active yet nonconductive FeOOH into a crystalline-amorphous heterostructure, with a unique hierarchical sheet-on-sheet nanoarray configuration, can not only give rise to proliferated catalytic sites with enhanced intrinsic activity via electronic manipulation but also boost mass transfer on account of fascinating surface superhydrophilic and superaerophobic features. Impressively, the multilayered architecture comprising inherently anticorrosive (CoMo)(0.85)Se core and FeOOH shell, together with an in situ formed transition metal (oxy)-hydroxide outmost layer enriched with polyatomic anions (MoOxn- and SeOxn-), can collectively contribute to commendable mechanical stability and chloride-corrosion resistance during harsh seawater oxidation. This work highlights a potent paradigm to construct a high-efficiency, corrosion-resistive, and OER-selective anode toward stable seawater electrolysis via ingenious systematical structural engineering.