Self-Growing NiFe-Based Hybrid Nanosheet Arrays on Ni Nanowires for Overall Water Splitting

Exploring highly efficient and low-cost electrocatalysts is important for boosting the efficiency of water splitting to obtain clean and renewable energy. In this study, the NiFe layered double hydroxide nanosheets (NiFe-LDH NSs) were developed on Ni nanowires (NWs) via the in situ assembly of oriented 2D nanosheets. Because of its unique composition and hierarchical NS@NW structure with the conductive Ni NW core as electron conduit, this material catalyst performs as a superior electrocatalyst toward the oxygen evolution reaction (OER), exhibiting a low onset overpotential of 230 mV in 1 M KOH. Remarkably, NiFe-LDH NSs can be readily converted to Fe-doped Ni2P nanosheets (Fe-Ni2P NSs) or Fe-doped NiSe2 nanosheets (Fe-NiSe2 NSs) upon phosphorization or selenization treatments, which are both excellent electrocatalysts toward the hydrogen evolution reaction (HER) in alkaline solution. Consequently, two-electrode alkaline water electrolyzers have been constructed using NiFe-LDH NSs as anode and Fe-Ni2P NSs or Fe-NiSe2 NSs as cathode, which can afford a current density of 30 mA cm–2 at cell voltages of 1.69 and 1.76 V, respectively, with excellent long-term durability.