Interfacial Electronic Modification of Nickel Phosphide via Iron Doping: An Efficient Bifunctional Catalyst for Water/Seawater Splitting

Abstract Seawater electrolysis is an innovative technique that can potentially transform hydrogen production and contribute to environmental redemption. However, the lack of good bifunctional electrocatalysts may hinder further development of this technology. Herein, nickel hydroxide nanosheets can be employed as a precursor to producing a 3D Prussian blue analogue (PBA) with a distinct dimensional structure. Nickel hydroxide nanosheets are formed within a nickel foam and undergo a reaction with potassium ferricyanide (K 3 [Fe(CN) 6 ]). The nickel hydroxide structure is sheets‐like and well‐preserved, containing a multitude of PBA nanocubes. Following phosphidation at 350 °C, the iron‐doped nickel phosphide (Fe‐doped Ni 2 P (1.0 m M ) nanosheets) demonstrates remarkable potential as a bifunctional electrocatalyst for total water/seawater splitting. This electrocatalyst demonstrates exceptional performance in overall water splitting, achieving current densities of 100 and 500 mA cm −2 in 1.0 M KOH at remarkably low voltages of 1.65 and 2.06 V, respectively. Additionally, its improved ability to resist corrosion and its hydrophilic surface makes it suitable for the seawater splitting process. The material can generate current densities of 100 to 500 mA cm −2 in seawater with 1.0 M KOH, resulting in voltages of 1.74 and 2.32 V. These outstanding results, together with its durability, indicate the material's strong potential for practical seawater electrolysis.