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

Abstract

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 (CoFe2O4@NNWs) of CoFe2O4 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 CoFe2O4@NNWs is attributed to the fact that the heterojunction fromed by CoFe2O4 and NNWs effectively regulates the electron density of the sample, thereby improving the kinetics of H* adsorption and the N2H4 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 CoFe2O4 nanosheets grown on NNWs not only expose more catalytic active sites, but also provide a fast channel for the diffusion of the electrolyte.