Preparation of Co–Al and Ni–Al layered double hydroxide thin films by a sol–gel process with hot water treatment

Abstract

Using hot water treatment of sol–gel derived precursor gel films, Co–Al and Ni–Al layered double hydroxide (LDH) thin films were prepared. The precursor gel films of Al2O3–CoO or Al2O3–NiO were prepared from cobalt or nickel nitrates and aluminum tri-sec-butoxide using the sol–gel method. Then, the precursor gel films were immersed in a NaOH aqueous solution of 100 °C. Nanocrystallites of Co–Al and Ni–Al LDH were precipitated with the hot water treatment with NaOH solution. The largest amounts of nanocrystals were obtained with a solution of pH = 10 for Co–Al LDH, and with that of pH = 9 for Ni–Al LDH. X-ray diffraction measurements confirmed that this process formed CO32− intercalated LDHs. Both Co–Al and Ni–Al LDH thin films were confirmed to work as electrodes for electrochemical devices by cyclic voltammogram measurements.