Constructing Ni species-incorporated CoP@N-doped carbon nanosheet arrays for efficient self-powered hydrazine-assisted seawater electrolysis

Abstract

The hydrazine oxidation reaction (HzOR) boasts a low theoretical working potential, rendering it promising for applications in energy-saving hydrogen production and treatment of hydrazine-containing wastewater. Herein, Ni species-incorporated CoP nanosheet arrays encapsulated in N-doped carbon layers grown on Ni foam (Ni-CoP@NC) have been synthesized. Due to the outstanding synergistic effect resulting from metal incorporation and N-doped carbon encapsulation, a high current density of 1 A cm⁻² at low potentials of −143 mV and 51 mV for the hydrogen evolution reaction (HER) and HzOR is achieved by using Ni-CoP@NC, respectively. Furthermore, the Ni-CoP@NC-assembled hydrazine-assisted seawater electrolysis system exhibits a remarkable decrease in voltage input compared to conventional and other hybrid electrolysis devices, achieving an ultra-low voltage of just 0.49 V to attain a current density of 1 A cm⁻². Remarkably, a five-fold cost reduction is offered by this system compared to conventional water electrolysis. Moreover, a novel multi-powered hydrogen production system is proposed, which consists of renewable energy sources, direct hydrazine fuel cells, rechargeable Zn–hydrazine batteries, and hydrazine-assisted seawater electrolysis. This system showcases the unique advantages of the HzOR and its potential contribution to electrochemical energy conversion technologies for sustainable energy supply.