Spherical Ni S /Fe-NiP 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 S 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 S in an interfacial redox reaction. The well-designed Ni S @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 S /Fe-NiP on nickel foam. Specifically, in alkaline seawater, the Ni S /Fe-NiP as OER precatalyst marvelously realizes the ultralow overpotentials of 336 and 351 mV at large current densities of 500 and 1000 mA cm , 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 S /Fe-NiP surface, leading to the in situ formation of Ni(OH) /Ni(Fe)OOH with abundant oxygen vacancies and grain boundaries, which constructs the Ni S /Fe-NiP reconstruction system responsible for the remarkable OER catalytic activity. Theoretical calculation results further verify the enhanced OER activity for Ni S /Fe-NiP reconstruction system, and unveil that the Fe-Ni P/FeOOH as active origin contributes to the central OER activity.