Co–Ni layered double hydroxides for water oxidation in neutral electrolyte

Abstract

The electrochemical properties of Co–Ni layered double hydroxides (LDHs) as efficient electrocatalysts for water oxidation were investigated in potassium phosphate electrolyte under neutral pH condition. The Co–Ni LDHs with a core–shell structure were fabricated using a facile route from a Co–Ni hydroxide precursor with iodine as a topotactic oxidizer. The unique core–shell morphology is likely due to the enrichment of Co(III) hydroxide in the inner core indicated by selected area electron diffraction and energy-dispersive spectroscopy. Through a self-assembling process at the organic/inorganic interface and dip-coating, the Co–Ni LDHs were deposited onto FTO glass substrates to prepare composite electrodes. Low over-potential and high current density was achieved in the oxygen evolution reaction. The excellent electrocatalytic activity of Co–Ni LDHs may be attributed to more accessible Co active sites and rapid movement of interlayer ions within their layered structure.