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.