Highly Efficient and Stable Mo-CoP₃@FeOOH Electrocatalysts for Alkaline Seawater Splitting

The introduction of high-valence state elements and highly active species is promisingly desired to design superior electrocatalysts for water electrolysis. Exploring scalable synthetic strategies is necessary for an in-depth understanding of the mechanism of improving electrocatalytic performance. But it remains challenging. Herein, several electrocatalysts through element doping are prepared. The obtained Mo-CoP₃-2@FeOOH samples show the overpotentials (OER) of 232 mV (alkaline seawater) and 262 mV (KOH electrolyte). As HER catalyst, it also presents an excellent electrocatalytic performance. The above electrocatalysts are utilized as anode/cathode to assemble devices for alkaline seawater/water electrolysis, which delivers a cell voltage of 1.58 V and durability of 350 h. Density functional theory calculations reveal that Mo ion doping and FeOOH significantly enhance the density states of the Fermi level and tune the position of the d-band center. It expedites the charge transfer and decreases the adsorption energy of intermediates. It demonstrates that transition-metal phosphides coated with highly active FeOOH offer an effective route to fabricate high-performance and durable catalysts for seawater/water electrolysis.