Construction of phosphide heterostructures for enhanced electrocatalytic seawater oxidation

Hydrogen, a key clean energy carrier, is strategically vital for carbon neutrality and sustainable energy systems. Water electrolysis, a promising hydrogen production method, depends on the HER and OER. Given freshwater scarcity, seawater electrolysis has gained attention due to seawater's abundance. In transition metal phosphides (TMPs), phosphorus's high electronegativity facilitates proton capture and lowers hydrogen desorption barriers. Developing phosphide heterostructures with optimized electronic states is crucial for enhancing seawater splitting efficiency. Here, we synthesized FeP₄/CoP heterostructures from CoFe-PBA and FeCo-LDH precursors via hydrothermal and phosphidation methods. The hollow nanobox-structured catalyst exhibits outstanding OER performance in simulated seawater, requiring only 320 mV overpotential for 10 mA·cm^− 2 with excellent stability. This work presents a simple heterostructure design strategy to boost seawater electrocatalysis, guiding future catalyst development.