Hydrazine oxidation boosted by RuWO_x nanofibers: Industrial-level H₂ production and Zn-hydrazine battery application

Although replacing the oxygen evolution reaction (OER) with hydrazine oxidation reaction (HzOR) represents a promising strategy for low-voltage hydrogen (H₂) production, bifunctional electrocatalysts capable of operating at industrially relevant currents (≥1000 mA cm^-2) for both HzOR and hydrogen evolution reaction (HER) remain elusive. This work reports RuWO_x nanofibers (NFs) as an all-in-one catalyst that bridges this gap, delivering high activity for both cathodic and anodic half-reactions. With the optimized Ru₁W₁O_x-450 NFs, the working potential of HzOR is just 58 mV vs. RHE to deliver 1000 mA cm^-2, while the HER counterpart requires only 185 mV to reach the same current density, both markedly outperforming Pt/C benchmark. This bifunctional catalyst sustains HzOR operation for 500 h without notable decay under industrial-grade current densities. When integrated into a two-electrode overall hydrazine splitting (OHzS) electrolyzer, the energy input for H₂ production drops to 0.134 kWh m^-3 H₂ at 100 mA cm^-2, an order of magnitude lower than that of conventional water splitting (OWS) (1.85 kWh m^-3 H₂). Density functional theory (DFT) calculations reveal an efficient electron transfer from RuO₂ to WO₃ at their interface in RuWO_x NFs, which regulates the d-band center, modulates the adsorption and desorption for intermediates, and simultaneously reduces the energy barriers for HER and HzOR. This study presents an effective strategy for creating efficient and robust bifunctional electrocatalysts, paving the way toward energy-efficient H₂ production.