Multiscale manipulating induced flexible heterogeneous V-NiFe₂O₄@Ni₂P electrocatalyst for efficient and durable oxygen evolution reaction

Water electrolysis is severely impeded by the kinetically sluggish oxygen evolution reaction (OER) due to its inherent multistep four-electron transfer mechanism. However, designing advanced OER electrocatalysts with abundant active sites, robust stability, and low cost remains a huge challenge. Herein, a facile and versatile multiscale manipulating strategy was proposed to construct a novel V-NiFe₂O₄@Ni₂P heterostructure self-supported on Ni foam (V-NiFe₂O₄@Ni₂P/NF). In such unique architecture, the intrinsic OER catalytic activity was greatly boosted by the in-situ generated heterogeneous Ni₂P phase induced by precisely selective phosphorylation of the NiFe-precursor, while the synchronous metal V doping stimulated the activity via modulating the electronic configuration, thus synergistically promoting its OER kinetics. In addition, the binder-free catalyst built from three-dimensional (3D) nanosheet arrays (NSs) can offer a large active surface for efficient charge/mass transfer and a robust scaffold for the integrated structure. The as-prepared flexible electrode exhibited superior OER activity with an ultra-low overpotential of 230 mV at 50 mA·cm⁻² and outstanding long-term stability for 40 h. This discovery is expected to provide an opportunity to explore efficient and stable commercial materials for scalable, efficient, and robust electrochemical hydrogen (H₂) production.