Controllable growth of Fe-doped NiS2 on NiFe-carbon nanofibers for boosting oxygen evolution reaction.

The (Ni,Fe)S 2 /NiFe(3:1)-CNFs exhibit a highly efficient property for oxygen evolution reaction at a low potential in an alkaline medium. [Display omitted] • Fe-doped NiS 2 crystals on NiFe-carbon nanofibers are successfully prepared. • The electrocatalyst shows abundant exposed active sites and excellent electron/mass transport properties. • The electrocatalyst presents a low overpotential of 287 mV at 30 mA cm−2 for OER. • The overall water splitting device exhibits a cell voltage of 1.54 V to attain 10 mA cm−2. The construction of high-efficiency and low-cost electrocatalysts toward oxygen evolution reaction (OER) to improve the overall water decomposition performance is a fascinating route to deal with the clean energy application. Herein, Fe-doped NiS 2 crystals grown on the surface of carbon nanofibers (CNFs) encapsulated with NiFe alloy nanoparticles ((Ni,Fe)S 2 /NiFe-CNFs) are fabricated through an electrospinning-calcination-vulcanization process, which has been used as a splendid electrocatalyst for OER. Benefitting from the abundant electrochemical active sites from the incorporation of Fe element in NiS 2 and the synergistic effect between NiFe-CNFs and surface sulfides, the obtained (Ni,Fe)S 2 /NiFe-CNFs catalyst exhibits highly electrochemical activities and satisfactory durability toward OER in an alkaline medium with a low overpotential of only 287 mV at a high current density of 30 mA cm−2, and with a little decline in the current retention after 48 h, suggesting its superior OER performance even compared with some noble metal-based electrocatalysts. Additionally, a two-electrode system conducted by using the (Ni,Fe)S 2 /NiFe-CNFs and commercial Pt/C as electrodes, only needs a cell voltage of 1.54 V to afford 10 mA cm−2 for overall water splitting, which is even much better than the RuO 2 ||Pt/C electrolyzer. This study offers a promising approach to prepare high-efficiency OER catalysts toward overall water splitting. [ABSTRACT FROM AUTHOR]