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

Abstract

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.

Three‐Dimensional Graphene‐Foam‐Supported Hierarchical Nickel Iron Phosphide Nanosheet Arrays as Efficient and Stable Bifunctional Electrocatalysts for Overall Water Splitting

“…We performed XPS to further analyze the changes in the surface state of the samples after HER and OER testing. It can be seen from Figure S12 that after the OER and HER tests, the binding energy in the Fe spectrum undergoes a shift toward high state, a new peak at 713.5 eV ascribed to Fe‐OH appears, which is in accordance with the previous research for OER . The study consistently indicates that oxides or hydroxides are formed on the surface of NiFe‐P@3DGF during OER and HER.…”

“…It can be seen from Figure S12 that after the OER and HER tests, the binding energy in the Fe spectrum undergoes a shift toward high state, a new peak at 713.5 eV ascribed to Fe-OH appears, which is in accordance with the previous research for OER. [56] The study consistently indicates that oxides or hydroxides are formed on the surface of NiFe-P@3DGF during OER and HER. The peak of Ni 2p 3/2 corresponding to Ni 2 P in the Ni spectrum disappears, while the NiÀ O peak appears at 855.7 eV, revealing the transition from Ni 2 P to nickel (oxy) hydroxides.…”

Single Step Grown NiFe Sponges as Efficient Water Splitting Electrocatalysts in Alkaline Medium

“…The polarization curve in Figure b shows that the NiFe15//NiFe5 catalyst require voltage of only 1.62 V to generate the overall water splitting current density of 10 mA cm −2 , which is on par with other recently reported NiFe electrocatalysts such as NiFe‐NC// NiFeNC (1.67 V), Ni 1‐x Fe x /NC // Ni 1‐x Fe x (1.58 V), and NiFe@OCC // NiFe@OCC (1.70 V) . Moreover, the electrocatalytic overall water‐splitting activity of NiFe sponge is also on par to that of others bifunctional catalysts recently studied (Table ) …”

Highly efficient and self-supported 3D carbon nanotube composite electrode for enhanced oxygen reduction reaction

“…21,22 The G band at 1586 cm À1 was attributed to the in-plane vibration mode E 2g of sp 2 -hybridized carbon atoms. The presence of D band at 1338 cm À1 arose from the structure deformation (e.g., sp 3 -hybridized carbon vibrations) and defects. 23 The I D /I G values of GMPN-800, FMPN-800, FMPN-700 and FMPN-600 samples were 1.14, 1.06, 1.02 and 1.06 (Fig.…”

“…Nevertheless, traditional electrode materials usually contain extra binders and additives apart from catalytic nanomaterials, which may overlay the active sites of catalyst, thus reducing their electrocatalytic performance. 3 For example, the overall activity of the resultant electrode is largely hindered by uncontrollable interfacial evolution due to inevitable aggregation of nanocatalysts, when nanosized materials are processed by the conventional drop-casting methods. 4 Moreover, the utilization of insulated polymer binders (e.g., Naon) somewhat blocks the pathway of electrons and thus lowers electrocatalytic activity.…”