Hexagonal Phase Ni₃Fe Nanosheets toward High‐Performance Water Splitting by a Room‐Temperature Methane Plasma Method

Abstract

In addition to tuning the size and shape, exploring highly efficient and costeffective catalysts with active metastable phase represents an alternative strategy to improve electrocatalytic water splitting performance. However, it still remains a big challenge to synthesize unconventional crystal structures under mild conditions. Herein, a facile CH 4 plasma assisted strategy to synthesize hexagonal close-packed (hcp) Ni 3 Fe/C porous nanosheets by in situ topology reduction of Ni 3 Fe-LDH nanosheets is successfully developed. Compared with its face-centered cubic phase counterpart (fcc-Ni 3 Fe/C), the resulting hcp-Ni 3 Fe/C catalyst exhibits much enhanced activity with overpotentials of 70 and 201 mV at a current density of 10 mA cm −2 for the hydrogen evolution reaction and oxygen evolution reaction, respectively. Moreover, a small cell voltage of 1.54 V is realized to drive overall water splitting. Theoretical calculations further reveal that hcp-Ni 3 Fe allows energetically favorable adsorption and dissociation of H 2 O molecules. This work presents a new strategy for designing advanced metastable phase electrocatalysts with high performance for energy and environmentally relevant reactions.

Modulating crystal and electronic structure of NiFe-MOFs by inorganic acid for highly efficient electrochemical water oxidation

“…38,55 Based on the above investigation, we conclude that NiFe-MOF-2/NF has been transformed to Ni/Fe (oxy)hydroxide, which is considered the real active site for OER. This similar phenomenon is also observed in LDH, 56 metal sulfides, 57 selenides, 58 nitrides, 59 phosphides, 60 alloys 51 and other MOF-based electrocatalysts. 15,18,35 Based on the above characterization and OER results, the remarkable OER activity and superior stability of NiFe-MOF-2/NF can be attributed to the following merits.…”

FeNi LDH/Loofah Sponge-Derived Magnetic FeNi Alloy Nanosheet Array/Porous Carbon Hybrids with Efficient Electromagnetic Wave Absorption

“…The presence of oxygen-containing functional groups results from the incompletion of the carbonization treatment, and the oxygen vacancy can increase the charge polarization center, which is beneficial to enhance the EMW attenuation ability. Fe 3/2 0 and Fe 1/2 0 at 705.2 and 718.9 eV, respectively, are shown in the high-resolution Fe 2p spectrum, which are assigned to metallic iron (Figure e). , In addition, two peaks at 854.3 and 872.4 eV in the high-resolution Ni 2p spectrum can be attributed to metallic nickel (Figure f) . The X-ray photoelectron spectroscopy (XPS) investigations are in accordance with XRD analysis and indicate that the FeNi/PC hybrids have been successfully synthesized.…”

“…Fe 3/2 0 and Fe 1/2 0 at 705.2 and 718.9 eV, respectively, are shown in the high-resolution Fe 2p spectrum, which are assigned to metallic iron (Figure 5e). 42,43 In addition, two peaks at 854.3 and 872.4 eV in the highresolution Ni 2p spectrum can be attributed to metallic nickel (Figure 5f). 41 The X-ray photoelectron spectroscopy (XPS) investigations are in accordance with XRD analysis and indicate that the FeNi/PC hybrids have been successfully synthesized.…”

Hierarchically structured nickel/molybdenum nitride heterojunctions as superior bifunctional electrodes for overall water splitting

“…[1][2][3] This process contains two typical half-reactions: the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode. [4][5][6][7][8] The rational utilization of high-efficiency electrocatalysts can significantly improve the reaction kinetics of water splitting and achieve high energy conversion efficiency. Noble metal materials are considered to be excellent active electrocatalysts; however, their scarcity and high cost limit their wide application in water splitting.…”