High quality synthesis of Rh nanocubes and their application in hydrazine hydrate oxidation assisted water splitting

Abstract Hydrazine hydrate oxidation assisted water splitting can effectively reduce the energy consumption of conventional water electrolysis due to the lower thermodynamic anode potential, which stimulates the development of highly efficient bifunctional electrocatalysts. Herein, we report a solvothermal synthesis strategy to prepare Rh nanocubes (NCs) with specific exposed Rh (1 0 0) planes. Benefiting from higher coordination unsaturation and reactivity of the Rh (1 0 0) plane, Rh NCs exhibit higher catalytic performance than commercial Rh black toward hydrazine hydrate oxidation reaction (HHOR) and hydrogen evolution reaction (HER). To achieve the current density of 10 mA cm−2 in HHOR and HER, the anode and cathode potentials required for Rh NCs (240 and –32 mV) are better than those of commercial Rh black (291 and −43 mV). Thus, Rh NCs are used as bifunctional electrocatalysts to drive a HHOR assisted water splitting cell, which can achieve long-term stable electrochemical hydrogen production at a voltage of ∼ 0.223 V, demonstrating a promising energy-saving hydrogen production strategy.