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

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 Ni2P nanosheet arrays with rich P vacancies on molybdenum‐nickel foam (MNF) (Mo‐Ni2Pv@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‐Ni2Pv@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 H2 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 ΔGH* for hydrogen evolution reaction but also enhance dehydrogenation kinetics from *N2H4 to *NHNH2 for HzOR, achieving enhanced dehydrogenation kinetics.