Electrodeposition of α- and β-cobalt hydroxide thin films via dilute nitrate solution reduction

alpha- and beta-cobalt hydroxyde thin fims were synthesized by cathode electrodeposition on transparent conductive oxide (TCO) substrates, at 60 degrees C and 95 degrees C, respectively, using a very low concentration of Co(NO(3))(2) and an alkali nitrate supporting electrolyte. Localized cathodic electrochemical generation of hydroxyl species via the reduction of nitrate precursors led to the formation of well crystallized nanostructured films. Seanning Electron Microscopy and X-ray diffraction confirmed the films were composed of vertically oriented nanoparticle platelets with the c-axis parallel to the substrate surface, and free of turbostractic disorder. UV/V's spectra and thermal gravitmetric analyses (TGA) indicated variation between the cobalt structures. Films deposited at 60 degrees C yielded a hydrotalcite like compound namely and "hydroxyl-deficient" [Co(OH)(2-x)(H(2)O)(x)](x+) with NO(3) intercalated anion along with water molecules in the interlayer region. Those deposited at 95 degrees C yielded the brucite beta-Co(OH)(2)