Rechargeable Zinc–Hydrazine/Nitrite Batteries Catalyzed by Al-Doped Ni ₂ P Nanoflowers for Energy Supply and NH ₃ Electrosynthesis

Zinc-nitrite batteries (ZNBs) can simultaneously supply energy and produce ammonia, yet their practical use is limited by the sluggish kinetics of the oxygen evolution reaction (OER) and nitrite reduction reaction (NitRR). Herein, we developed energy-saving zinc-hydrazine/nitrite batteries (ZHNBs) that replace the sluggish OER with the favorable hydrazine oxidation reaction (HzOR) using Al-Ni₂P nanoflowers as catalysts. The optimized ZHNBs employing Al0.1-Ni₂P/NF achieved an ultranarrow charging-discharge voltage gap of 0.59 V, an extended cycle life of 300 h, and a high NH₃ yield of 304 μmol h⁻¹ cm⁻², significantly outperforming conventional ZNBs. Mechanistic studies revealed that dopant-induced lattice expansion in Ni₂P dominantly governs the HzOR by enhancing N₂H₄ adsorption and reducing structural relaxation, while electronic redistribution enhances the NitRR by controlling active H* intermediates, with both effects synergistically improving battery efficiency. This dual-modulation strategy of geometry and electronic structures via doping offers a general approach for designing advanced nanocatalysts in energy devices.