Dual-Functional Heterogeneous Rh-Sb Alloy Nanomaterials Coupling Electrochemical Hydrazine Oxidation and Hydrogen Evolution

The overall hydrazine splitting (OHzS, N₂H₄ → N₂ + 2H₂) reaction, which is integrated by electrocatalytic hydrazine oxidation reaction (HzOR) and hydrogen evolution reaction (HER), provides an energy-efficient alternative to conventional overall water splitting (OWS) for sustainable hydrogen production. Herein, we present the controlled synthesis of Rh₁Sb₁@Rh-Sb nanoflowers (NFs) that comprise intermetallic Rh₁Sb₁ nanodendrite cores and ultrathin Rh-Sb random alloy nanosheet shells. The alloying of Sb enhances both HzOR and HER performances of Rh nanocatalysts through modulation of growth mechanisms, morphological evolution, and surface electronic configurations. Remarkably, a symmetrical OHzS electrolyzer employing Rh₁Sb₁@Rh-Sb NFs as bifunctional catalysts for both electrodes achieves the current densities of 100 and 500 mA cm^-2 at cell voltages of merely 0.216 and 0.700 V (without iR compensation), respectively, corresponding to 88.1% and 71.9% reductions in electricity consumption compared to alkaline OWS systems. Furthermore, a rechargeable zinc-hydrazine (Zn-Hz) battery using Rh₁Sb₁@Rh-Sb NFs as the positive electrode exhibits high energy efficiency, power density, and durability. The prototype device, integrating a photovoltaic cell, a Zn-Hz battery, and an OHzS cell, demonstrates the potential for efficient and simultaneous solar energy storage, hydrazine pollutant remediation, and hydrogen generation, offering a promising avenue for practical applications.