The synthesis of Ni-Co-Fe-Se@NiCo-LDH nanoarrays on Ni foam as efficient overall water splitting electrocatalyst

The development of efficient, stable and low-cost electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is the key to promote the industrialization of electrocatalytic water splitting. In this paper, the CoFe-LDH@NiCo-LDH precursor was first synthesized and then the target catalyst named Ni-Co-Fe-Se@NiCo-LDH was finally synthesized by a selenization reaction based on this precursor. In a three-electrode system with 1.0 M KOH alkaline atmosphere, Ni-Co-Fe-Se@NiCo-LDH requires an overpotential of 286 mV to deliver a current density of 100 mA/cm2 for OER and 113 mV at a current density of 10 mA/cm2 for HER. In addition, the material shows excellent overall water splitting performance and a low cell voltage of 1.55 V at 10 mA/cm2 is expected. By comparing the test results of CoFe-LDH@NiCo-LDH and NiCo-LDH, we found that increasing the number of metal species only slightly reduces the electron transfer impedance and does not help to increase the electrochemical surface area of the material. Density functional theory calculation shows that the presence of the Co-NiSe2 material accelerates the kinetics of hydrogen production and the Fe7Se8 material enhances the conductivity of the material. Their synergistic effect makes the Ni-Co-Fe-Se@NiCo-LDH catalyst exhibit enhanced hydrogen production activity.