Fe-Doped Ni3S2 Nanowires with Surface-Restricted Oxidation Toward High-Current-Density Overall Water Splitting

It is critical to develop a highly effective and economical electrocatalyst to lower the energy losses for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). In this work, Fe-doped Ni3S2 nanowires with diameters of ca. 17 nm and lengths of 1.4 similar to 2 mu m are synthesized on Ni foam through a one-step solvothermal route for alkaline water splitting, which display notable active and excellent durability for both OER and HER under high current densities. The optimal Fe-13.7%-Ni3S2 nanowires electrode can attain 200 mA cm(-2) at a fairly low overpotential of 223 mV, and 500 mA cm(-2) at 245 mV toward OER. Furthermore, it yields a considerable low overpotential of 109 mV to garner 10 mA cm(-2), and 246 mV for 500 mA cm(-2) toward HER. The incorporation of iron simultaneously modifies the electronic structure and morphology of Ni3S2, which not only enhances the conductivity but also generates abundant active edge sites. The slight surface-restricted oxidation of nanowires in a strongly basic electrolyte in situ generates a large number of interfaces, which enables the reactivity and durability for both OER and HER. Accordingly, an alkaline water electrolyzer with two Fe-13.7%-Ni3S2 electrodes only requires a low cell voltage of 1.53 V to achieve 10 mA cm(-2), and 1.95 V to 500 mA cm(-2) with striking stability. The as-prepared Fe-doped Ni3S2 nanowires can be potentially utilized for actual water electrolysis under high current densities.