CoFe2O4 nanosheets grown in situ on nickel nanowires for efficient hydrazine oxidation-boosted hydrogen production

The use of the hydrazine oxidation reaction (HzOR) to replace the oxygen evolution reaction (OER), which has a large thermodynamic barrier and a slow kinetic process, is a feasible way to achieve energy saving hydrogen production, but the construction of superior bifunctional catalysts is also challenging. Herein, an array (CoFe 2 O 4 @NNWs) of CoFe 2 O 4 nanosheet grown in situ on nickel nanowires (NNWs) has been prepared and showed the excellent performance for hydrogen evolution reaction (HER) and HzOR under alkaline media, which require a lower potential of −91 mV (vs. RHE) for HzOR and 45 mV (vs. RHE) for HER at the current density (j, 10 mA cm −2 ). The overall hydrazine splitting (OHzS) electrolyzer requires cell voltages of 0.028 V (10 mA cm −2 ) and 1.227 V (1000 mA cm −2 ) by using electricity, wind, solar and thermal energies as power sources and had remarkable long-term stability. In addition, the potential of the OHzS is 1.67 V lower than that of OWS at the j of 10 mA cm −2 . The excellent performance of CoFe 2 O 4 @NNWs is attributed to the fact that the heterojunction fromed by CoFe 2 O 4 and NNWs effectively regulates the electron density of the sample, thereby improving the kinetics of H* adsorption and the N 2 H 4 dehydrogenation, which can be confirmed by DFT. Second, the continuous electron transport channel provided by NNWs improves the electrical conductivity of the sample. In addition, the 2D CoFe 2 O 4 nanosheets grown on NNWs not only expose more catalytic active sites, but also provide a fast channel for the diffusion of the electrolyte.