Rational Design of Low‐Crystallinity RuMo Alloy Nanofibers Coupled with MoO ₂ Domains Enables Significantly Promoted Hydrazine Oxidation‐Assisted H ₂ Production

Abstract Hydrazine oxidation‐assisted water electrolysis emerges as a promising strategy with low thermodynamic requirements and eco‐friendly byproducts, yet designing highly efficient bifunctional catalysts for alkaline hydrogen evolution reaction (HER) and hydrazine oxidation reaction (HzOR) remains challenging. Herein, a novel heterostructure comprising low‐crystallinity Ruthenium molybdenum (RuMo) alloy nanofibers coupled with molybdenum dioxide (MoO 2 ) domains is presented as a bifunctional electrocatalyst for both HER and HzOR. The optimized catalyst achieves ultralow overpotentials of 31/170 mV for HER at 10/1000 mA cm −2 and working potentials of –0.073/0.028 V for HzOR at 10/500 mA cm −2 , significantly surpassing the benchmark Pt/C catalyst. Theoretical calculations reveal that the coupling of RuMo alloy with MoO 2 regulates the d ‐band center, promotes water dissociation and modulates H* adsorption, thereby realizing superior HER kinetics. The heterostructure also optimizes the reaction pathway to reduce the energy barrier for hydrazine dehydrogenation, achieving an enhanced HzOR performance. Inspiringly, the assembled two‐electrode system for overall hydrazine splitting (OHzS) achieves a low power consumption of 1.52 kWh m −3 H 2 , greatly surpassing Ru NFs‐based cell (3.78 kWh m −3 H 2 ). Furthermore, a rechargeable zinc (Zn)‐hydrazine battery is constructed, showing great potential in practical application.