Zn-doped cobalt phosphide@N-doped carbon nanoarrays enable self-powered hydrazine-assisted seawater electrolysis

Hydrazine-assisted water electrolysis is a promising avenue for energy-saving hydrogen production and hydrazine wastewater decontamination. Herein, Zn-doped Co₂P nanoarrays encapsulated in N-doped carbon layers (Zn-CoP@NC) are synthesized on Ni foam as a bifunctional electrocatalyst for anodic hydrazine oxidation (HzOR) and cathodic hydrogen evolution (HER). Zn-CoP@NC achieves outstanding performance of low overpotentials of 133 mV for HER and 38 mV for HzOR at 1 A cm^-2, which can be attributed to the adsorption behavior optimization of key intermediates by Zn doping and the expanded active area due to the NC composite. Moreover, the hydrazine-assisted seawater electrolysis system assembled by Zn-CoP@NC can achieve an ultra-low voltage of only 0.46 V at 1 A cm^-2, which delivers a six-fold reduction in cost compared to traditional water electrolysis. Furthermore, an innovative self-powered hydrogen production system is proposed by integrating renewable energy, rechargeable Zn-hydrazine batteries and hydrazine-assisted seawater electrolysis. This design highlights the unique advantages of HzOR and its prospective contribution in advancing the development of sustainable electrochemical energy conversion technologies.