Efficiently Electrocatalytic Overall Water Splitting over Ni _0.85 Se‐Ni Foam Electrode Modified with Nanoneedle‐Like Ni ₃ Fe Alloy

Electrocatalytic splitting of H₂O into H₂ and O₂ is one of the potential ways to develop clean and storable energy. In this study, the self-supported Ni_0.85Se-Ni foam (Ni_0.85Se-NF) hybrid electrode was modified with Ni₃Fe (Ni₃Fe/Ni_0.85Se-NF) via a facile selenization and electrochemical deposition method. The Ni₃Fe/Ni_0.85Se-NF hybrid electrode exhibited excellent performance of electrocatalytic overall water splitting in an alkaline solution (1 m KOH, pH = 13.9), which is much more active than the individual Ni_0.85Se-NF and Ni₃Fe/NF. In particular, the Ni₃Fe/Ni_0.85Se-NF hybrid electrode generated 10 mA cm^-2 cathodic current at an overpotential of 81 mV, and 10 mA cm^-2 anodic current at an overpotential of 209 mV in KOH solution (1 m, pH = 13.9), respectively. In addition, only 1.68 V potential was required to generate 12 mA cm^-2 current in a two-electrode system for overall water splitting in an alkaline aqueous solution using the Ni₃Fe/Ni_0.85Se-NF working as the anode and cathode, respectively. The TEM images and Raman spectra results indicated that the microstructure reconstruction happened on the surface of the Ni₃Fe/Ni_0.85Se-NF electrode after the HER or OER test. Some Ni and Fe species were found to convert to the Ni_xFe_1-xOOH during water electrocatalysis.