One-step synthesis of Fe-Ni hydroxide nanosheets derived from bimetallic foam for efficient electrocatalytic oxygen evolution and overall water splitting

The research of superior water oxidation electrodes is essential for the green energy in the form of hydrogen by way of electrolytic water splitting, and still remains challenging. Based upon dealloying foam, Fe-Ni hydroxide nanosheets network structure is designed on the surface of Fe-Ni alloy foam. The ratio of Ni/Fe elements was adjusted to realize the optimal catalytic activities for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The obtained electrode of Fe-Ni hydroxide nanosheets/Fe-Ni alloy foam-60% Fe (FN LDH/FNF-60, 60 is the percentage of Fe content) possess low overpotential of 261 mV to reach 10 mA/cm², small Tafel slope (85.5 mV/dec), and superior long-term stability (remaining 10 mA/cm² for over 14 h without attenuation) toward OER in 1.0 mol/L KOH. Moreover, an alkaline water electrolyzer is constructed with the FN LDH/FNF-60 as anode and Ni(OH)2/Fe-Ni alloy foam-25% Fe (Ni(OH)₂/FNF-25) as cathode, which displays superior electrolytic performance (affording 10 mA/cm² at 1.62 V) and lasting durability.