Rational design of chromium-doped NiFe phosphide/phosphate heterostructures for inhibiting chloride ion adsorption and achieving alkaline seawater splitting at industrial-level current density

Electrocatalysts with high activity and corrosion resistance, tailored for industrial-grade current densities, played a crucial role in seawater electrolysis. Here, we synthesized a petal-like Cr-doped NiFe phosphate 'semi-coated' phosphide heterostructure electrocatalyst grown on nickel foam (Cr-NiFeP/PO 3 @NF). This catalyst demonstrated superior catalytic performance in natural seawater, maintaining stability and only a slight increase in cell voltage after operating continuously for 100 h at a current density of 1 A cm −2 . The incorporation of Cr introduced a significant number of unpaired electrons, which enhanced the conductivity of the catalyst, facilitated the creation of electron depletion regions around Ni and Fe, and improved the interaction with adsorption intermediates. Furthermore, the high activity and corrosion resistance during the oxygen evolution reaction (OER) were due to the interaction between the in-situ formed high-valent phosphate and NiFeCrOOH during the anodization process.