Modulation of Electron Structure and Dehydrogenation Kinetics of Nickel Phosphide for Hydrazine‐Assisted Self‐Powered Hydrogen Production in Seawater

Abstract

Abstract The electrocatalytic production of hydrogen from seawater provides a low‐cost way to realize energy conversion, but is restricted by high potential for seawater electrolysis and the chlorine oxidation reaction (ClOR) at the anode. Here, the self‐growth of Mo‐doped Ni 2 P nanosheet arrays with rich P vacancies on molybdenum‐nickel foam (MNF) (Mo‐Ni 2 P v @MNF) is reported as bifunctional catalyst for Cl‐free hydrogen production by coupling hydrogen evolution reaction (HER) with hydrazine oxidation reaction (HzOR) in seawater. Impressively, the Mo‐Ni 2 P v @MNF electrode as bifunctional catalyst has an excellent activity for overall hydrazine splitting (OHzS) with an ultralow voltage of only 571 mV at 1000 mA cm −2 and can maintain stability for an ultra‐long time of 1000 h at 100 mA cm −2 . Moreover, integration of OHzS into self‐assembled hydrazine fuel cells (DHzFC) or solar cells can enable the self‐powered H 2 production. The industrial hydrazine sewage as feed for the above eletrolysis system can be degraded to ≈5 ppb rapidly. Density functional thoery calculations demonstrate that the electronic structure modulation induced by P vacancies and Mo doping can not only achieve thermoneutral ΔG H* for hydrogen evolution reaction but also enhance dehydrogenation kinetics from *N 2 H 4 to *NHNH 2 for HzOR, achieving enhanced dehydrogenation kinetics.