Coupling Co-Ni phosphides for energy-saving alkaline seawater splitting

The coupling of energy-saving small molecule conversion reactions and hydrogen evolution reaction (HER) in seawater electrolytes can reduce the energy consumption of seawater electrolysis and mitigate chlorine corrosion issues. However, the fabrication of efficient multifunctional catalysts for this promising technology is of great challenge. Herein, a heterostructured catalyst comprising CoP and Ni₂P on nickel foam (CoP/Ni₂P@NF) is reported for hydrazine oxidation (HzOR)-assisted alkaline seawater splitting. The coupling of CoP and Ni₂P optimizes the electronic structure of the active sites and endows excellent electrocatalytic performance for HzOR and HER. Impressively, the two-electrode HzOR-assisted alkaline seawater splitting (OHzS) cell based on the CoP/Ni₂P@NF required only 0.108 V to deliver 100 mA·cm⁻², much lower than 1.695 V for alkaline seawater electrolysis cells. Moreover, the OHzS cell exhibits satisfactory stability over 48 h at a high current density of 500 mA·cm⁻². Furthermore, the CoP/Ni₂P@NF heterostructured catalyst also efficiently catalyzed glucose oxidation, methanol oxidation, and urea oxidation in alkaline seawater electrolytes. This work paves a path for high-performance heterostructured catalyst preparation for energy-saving seawater electrolysis for H₂ production.