Heterostructured Ni ₂ P–Co ₂ P@BMXene/NF as a Bifunctional Electrocatalyst for Energy Efficient Urea-Assisted Seawater Electrolysis

Seawater is abundant but suffers from a high anodic oxidation potential in electrocatalysis. To address this critical challenge, a Ni 2 P–Co 2 P@BMXene/NF heterostructured electrocatalyst was rationally fabricated via a solvent-induced interfacial confinement strategy under low-temperature and atmospheric-pressure conditions followed by a one-step phosphidation process. This heterostructure exhibits excellent bifunctional catalytic activity toward both the hydrogen evolution reaction and urea oxidation reaction. Specifically, the MXene interlayer not only enhances the electrical conductivity of the catalyst but also improves its corrosion resistance in harsh alkaline seawater environments. Meanwhile, the phosphidation treatment induces microstructural reconstruction, thereby optimizing the active site exposure and improving electrolyte accessibility. In urea-assisted alkaline-filtered seawater electrolysis, the symmetric Ni 2 P–Co 2 P@BMXene/NF electrolyzer achieves current densities of 300 and 500 mA cm –2 at 1.59 and 1.66 V, respectively, corresponding to a 290 mV reduction in cell voltage compared with conventional oxygen evolution reaction-driven seawater electrolysis. The system exhibits stable operation for 135 h and enables simultaneous hydrogen production and urea degradation, demonstrating an effective strategy for designing integrated chloride-resistant electrodes for energy-efficient seawater electrolysis.