Synthesis And Characterization Of Zn-Co-Layered Double Hydroxide Intercalated With Vanadate And Molybdate Anions As A More Efficient Electrocatalysts For Oxygen Evolution Reaction

Electrochemical water splitting has great potential in the storage of intermittent energy from the sun, wind, or other renewable sources for sustainable clean energy applications. However, the anodic oxygen evolution reaction (OER) usually determines the efficiency of practical water electrolysis due to its sluggish four-electron process. Layered double hydroxides (LDHs) have attracted increasing attention as one of the ideal and promising electrocatalysts for water oxidationdue to their excellent activity, high stability in basic conditions, as well as their earth-abundant compositions. In the present work, vanadate and molybdate anions were intercalated into Zn–Co layered double hydroxides using the co-precipitation method. The obtained VO4-LDH and MoO4–LDH nanohybrids were characterized by Powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and X-ray energy dispersive spectroscopy (EDS) methods to get information about the structure, composition and morphology. After physicochemical characterization of the prepared samples, the LDHs were used as an efficient electrocatalyst material for water oxidation in alkali solution. In electrochemical water splitting, the obtained results show that the Zn–Co–MoO4-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 0.42 (V vs. SCE), the current density of the Zn–Co–MoO4-LDH nanosheets is about 188.43 mA cm−2, which is significantly higher than that of the Zn–Co–VO4–LDH and Zn–Co–NO3–LDH nanoparticles[1-4].

Keywords:

Zn-Co-NO3-LDH , Intercalation , Vanadate , Molybdate , Water oxidation , Oxygen evolution reaction (OER)