Spherical Ni3S2/Fe-NiPx 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 Ni3S2 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 Ni3S2 in an interfacial redox reaction. The well-designed Ni3S2@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 Ni3S2/Fe-NiPx on nickel foam. Specifically, in alkaline seawater, the Ni3S2/Fe-NiPx 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 Ni3S2/Fe-NiPx surface, leading to the in situ formation of Ni(OH)(2)/Ni(Fe)OOH with abundant oxygen vacancies and grain boundaries, which constructs the Ni3S2/Fe-NiPx reconstruction system responsible for the remarkable OER catalytic activity. Theoretical calculation results further verify the enhanced OER activity for Ni3S2/Fe-NiPx reconstruction system, and unveil that the Fe-Ni2P/FeOOH as active origin contributes to the central OER activity.

Automated summary

This study proposes a novel self-sacrificing template strategy to realize the in situ growth of NiFe-based Prussian blue analogs (NiFe PBA) on Ni3S2. The resulting Ni3S2/Fe-NiPx composite exhibits excellent OER catalytic activity in alkaline seawater, outperforming most reported catalysts. Experimental and theoretical results confirm the significance of the Ni3S2/Fe-NiPx reconstruction system and the presence of Fe-Ni2P/FeOOH in OER activity.