Zn-Fe-layered double hydroxide intercalated with vanadate and molybdate anions for electrocatalytic water oxidation

In this study, vanadate and molybdate anions were intercalated into Zn-Fe layered double hydroxides (LDHs) by co-precipitation methods to obtain VO4-LDH and MoO4-LDH nanohybrids. Powder X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), transmission electron microscopy (TEM), and X-ray energy dispersive spectroscopy (EDS) indicate the successful intercalation of vanadate and molybdate anions. According to the results obtained from TEM and XRD, LDHs have a size in the nanometer scale with a plate-like morphology and high crystalline quality. Moreover, the LDHs were used as an efficient electrocatalyst material for water oxidation in alkali solution. In electrochemical water splitting, Zn-Fe-VO4 shows a superior OER performance compared to the bare glassy carbon electrode. Zn-Fe-VO4-LDH exhibits good OER activity, which is expressed as a low onset overpotential, small Tafel slope, and large exchange current density. At the overpotential of 0.46 (V vs. SCE), the current density of the Zn-Fe-VO4-LDH nanosheets is about 188.43 mA cm(-2), which is much higher than that of the Zn-Fe-MoO4-LDH and Zn-Fe-NO3-LDH nanoparticles.