Electrospinning Synthesis of Bimetallic Nickel–Iron Oxide/Carbon Composite Nanofibers for Efficient Water Oxidation Electrocatalysis

Abstract

The development of earth‐abundant water oxidation electrocatalysts with high activity and durability is very important for many renewable energy conversion/storage processes. Herein, we report a facile synthetic method for the preparation of amorphous nickel–iron oxide/carbon composite nanofibers with high electrocatalytic activity and stability for the oxygen evolution reaction (OER). This method involves two main steps: (i) the electrospinning synthesis of Ni‐ and Fe‐embedded polyvinylpyrrolidone (PVP) polymer nanofibers as the precursor and (ii) the thermal conversion of this precursor in air at 250 °C into nickel–iron oxide/carbon composite nanofibers. Moreover, we show that the as‐obtained composite material exhibits a comparable catalytic activity and a superior catalytic stability to IrOx/C and RuOx, which are state‐of‐the‐art noble‐metal‐based water oxidation electrocatalysts. In particular, the obtained amorphous nickel–iron oxide/carbon composite nanofibers with an optimal Ni/Fe molar ratio of 1:2 afford a small overpotential of 310 mV at a current density of 10 mA cm−2, show high catalytic stability for >15 h, and give >90 % Faradaic yield toward the OER. The efficient catalytic activity of the material can be attributed to its overall conducive structural features for the OER, mainly including the amorphous phase structure of nickel–iron oxide, tunable Ni/Fe atomic ratio, and strongly coupled interaction between nickel–iron oxide and nanocarbon.

Porous Microspherical N and P‐co‐doped NiFe2O4/Single‐Walled Carbon Nanotubes for Efficient Electrochemical Oxygen Evolution Reaction

“…In the high‐resolution of Ni 2p spectra (Figure c), the peaks at 855.5 and 872.9 eV as well as 861 and 880 eV are attributed to the Ni 2p 3/2 and Ni 2p 1/2 signals of Ni 2+ species respectively. The other two peaks located at binding energy of 852.29 and 868 eV, which are assigned to the peak of Ni 2p 3/2 and Ni 2p 1/2 of Ni 0 species . The exist of Ni 0 is in good agreement with the XRD result that a new peak appeared at 43.45°.…”

Recent Progress on Multimetal Oxide Catalysts for the Oxygen Evolution Reaction

“…Similarly, Chen et al utilized polyvinylpyrrolidone (PVP) as a precursor of Ni-Fe oxide/carbon composite nanofibers. [182] Ni-and Fe-embedded PVP polymer nanofiber precursors were prepared using electrospinning, followed by heat treatment of the precursor at 250 °C in air, as shown in Figure 10g. The carbon support was strongly coupled to the NiFe oxide, thus effectively enhancing the electrical conductivity of the catalyst.…”

A Facile Synthesis of FeCo Nanoparticles Encapsulated in Hierarchical N‐Doped Carbon Nanotube/Nanofiber Hybrids for Overall Water Splitting

“…Ni foam, due to its 3D porosity, provides more area for the catalyst loading with excellent conductivity, better charge and mass transfer than GCE. [8] Figure 4e shows that a current density of 10 mA cm À 2 was maintained at an overpotential of 260 mV for 53 hours with negligible change of only~20 mV which is comparable with benchmark RuO 2 . The LSV measurements were performed before and after the stability experiments on Ni foam (inset of Figure 4e) showing the negligible shift in the polarization curve, thus, confirming that FeCo@NC-12 can be used as a highly efficient electrocatalyst for OER with much better durability for long-term use.…”

“…To further investigate the stability of the catalyst, another chronopotentiometric experiment was performed on Ni foam by depositing the same amount of sample i. e. 0.14 mg cm −2 . Ni foam, due to its 3D porosity, provides more area for the catalyst loading with excellent conductivity, better charge and mass transfer than GCE . Figure e shows that a current density of 10 mA cm −2 was maintained at an overpotential of 260 mV for 53 hours with negligible change of only ∼20 mV which is comparable with benchmark RuO 2 .…”