Distinctive Plasma Engineering Ensuring Deep Reconstruction of Heterostructured Ni2P/Fe2P Into Metal Oxyhydroxides With Activated Lattice Oxygen for Water Oxidation at Industrial Current Density

Abstract

The deep reconstruction of transition metal‐based pre‐catalysts into metal oxyhydroxides as true catalytic species for oxygen evolution reaction (OER) can maximize the exposure of active sites and realize high mass activity. However, it is still challenging to achieve the deep reconstruction of pre‐catalysts. Herein, taking heterostructured Ni2P/Fe2P as an example, a distinctive H2 plasma engineering tactic is introduced to promote the complete reconstruction of Ni2P/Fe2P into NiOOH/FeOOH (NiFeOOH) during activation process. Interestingly, plasma treatment creates abundant phosphorus vacancies (denoted as Pv) in Ni2P while induces amorphization of Fe2P. In/ex situ characterizations and theoretical calculations reveal that the presence of Pv in Ni2P and amorphous structure of Fe2P can notably lower the reconstructed potential, effectively accelerating the conversion of the Ni2P/Fe2P to NiFeOOH. Benefiting from the defect‐rich structure and activated lattice oxygen, the as‐reconstructed NiFeOOH exhibits superior OER activity (240 mV at 500 mA cm−2) and long stability (up to 500 h at 500 mA cm−2) in alkaline solution. Remarkably, the alkaline water electrolyzer (AWE) based on NiFeOOH anode and Ni2P/Fe2P cathode demonstrates exceptional durability of 500 h at 1000 mA cm−2 in KOH at 60 °C. Furthermore, the developed AWE also features excellent performance for real seawater electrolysis.