A highly active oxygen evolution electrocatalyst: Ni-Fe-layered double hydroxide intercalated with the Molybdate and Vanadate anions

Efficient low-cost electrocatalysts in the oxygen evolution reaction (OER) are important components of renewable energy technologies, e.g. solar fuel synthesis and water splitting for powering fuel cells. A great deal of attention has been attracted toward LDHs due to their electrical power and they are potentially applied in the field of electrocatalysts. The present paper reports synthesis of the Ni-Fe-Molybdate and Ni-Fe-Vanadate layered double hydroxides (LDHs) using a simple co-precipitation method. Powder X-ray diffraction, Fourier transform infrared spectra, Transmission electron microscopy, and X-ray energy dispersive spectroscopy spectrum provide successful intercalation of the Vanadate and Molybdate anions. Compared to the bare glassy carbon electrode, in alkaline media, the as-obtained Ni-Fe-MoO4-LDH represents superior electrocatalytic activity toward water oxidation with the overpotential of 491 mV at10 mA/cm(2 )and a low Tafel slope of 23 mV/ dec. Ni-Fe-MoO4-LDH exhibits good OER activity, which is stated as low onset overpotential, small Tafel slope, and large exchange current density. The current density of the Ni-Fe-MoO4-LDH nanosheets is about 10 mA cm(-2) at the overpotential of 0.491 (V vs SCE). This value is much larger than that of the Ni-Fe-NO3-LDH and Ni-Fe-VO3-LDH nanoparticles. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.