Spherical Ni(3)S(2)/Fe‐NiP (x) Magic Cube with Ultrahigh Water/Seawater Oxidation Efficiency

The rational construction of earth‐abundant and advanced electrocatalysts for oxygen evolution reaction (OER) is extremely desired and significant to seawater electrolysis. Herein, by directly etching Ni(3)S(2) nanosheets through potassium ferricyanide, a novel self‐sacrificing template strategy is proposed to realize the in situ growth of NiFe‐based Prussian blue analogs (NiFe PBA) on Ni(3)S(2) in an interfacial redox reaction. The well‐designed Ni(3)S(2)@NiFe PBA composite as precursor displays a unique spherical magic cube architecture composed of nanocubes, which even maintains after a phosphating treatment to obtain the derived Ni(3)S(2)/Fe‐NiP (x) on nickel foam. Specifically, in alkaline seawater, the Ni(3)S(2)/Fe‐NiP (x) as OER precatalyst marvelously realizes the ultralow overpotentials of 336 and 351 mV at large current densities of 500 and 1000 mA cm(–2), respectively, with remarkable durability for over 225 h, outperforming most reported advanced OER electrocatalysts. Experimentally, a series of characterization results confirm the reconstruction behavior in the Ni(3)S(2)/Fe‐NiP (x) surface, leading to the in situ formation of Ni(OH)(2)/Ni(Fe)OOH with abundant oxygen vacancies and grain boundaries, which constructs the Ni(3)S(2)/Fe‐NiP (x) reconstruction system responsible for the remarkable OER catalytic activity. Theoretical calculation results further verify the enhanced OER activity for Ni(3)S(2)/Fe‐NiP (x) reconstruction system, and unveil that the Fe‐Ni(2)P/FeOOH as active origin contributes to the central OER activity.