Energy-saving hydrogen production by chlorine-free hybrid seawater splitting coupling hydrazine degradation

Seawater electrolysis offers a pathway to carbon-neutral, grid-scale hydrogen without freshwater reliance but faces high energy costs and detrimental chlorine chemistry. The authors demonstrate chlorine-free hydrogen production by hybrid seawater splitting coupled with hydrazine degradation. Using NiCo/MXene-based electrodes, hydrogen is produced at 9.2 mol h⁻¹ gcat⁻¹ with electricity expense of 2.75 kWh per m³ H₂ at 500 mA cm⁻², representing a 48% lower energy equivalent input than commercial alkaline water electrolysis. Low cell voltages avoid chlorine electrochemistry without anode protection, regardless of Cl⁻ crossover. The electrolyzer also degrades hydrazine rapidly to ~3 ppb residual. Self-powered operation is realized by integrating low-voltage direct hydrazine fuel cells or solar cells, enabling efficient ocean-resource conversion to hydrogen while removing pollutants.

Fu Sun, Jingshan Qin, Zhiyu Wang, Mengzhou Yu, Xianhong Wu, Xiaoming Sun, Jieshan Qiu