Activating Three-Dimensional Networks of Fe@Ni Nanofibers via Fast Surface Modification for Efficient Overall Water Splitting

Developing facile approaches to synthesize highly active and stable oxygen and hydrogen evolution electrocatalysts under mild conditions is crucial in water-splitting technology. Herein, Ni-nanofiber-based three-dimensional (3D) network is prepared by a magnetic-field-assisted reduction reaction and then a fast surface modification within only 3 s at room temperature is developed to prepare Fe@Ni-nanofiber-based 3D porous electrode. The unique structure of the nanofiber-based 3D electrode ensures large electrochemical active surface area, short electron diffusion pathway, and fast mass transportation, while the introduction of Fe enhances the activity of each active site with abundant Ni(Fe) (oxy)hydroxide on the surface. Hence, the obtained Fe@Ni nanofiber electrode exhibits excellent activity and stability toward oxygen evolution reaction and hydrogen evolution reaction, with overpotentials as low as 230 and 55 mV to achieve a current density of 10 mA cm–2 in alkaline electrolyte, respectively. Moreover, when assembled into a two-electrode configuration, the cell voltage of only 1.53 V is needed to drive the water-splitting cell at 10 mA cm–2.