Lithium Cobalt Oxide (LiCoO₂) Nanocoatings by Sol−Gel Methods

Abstract

Lithium cobalt oxide (LiCoO 2 ) was synthesized using two different sol-gel processes. The first method used stoichiometric molar ratios of cobalt 2-methoxyethoxide and lithium nitrate in alcoholic solutions; the second method used aqueous equimolar ratios of precursors of lithium nitrate and cobalt acetate with poly(ethylene glycol) (PEG) 200 as the chelating agent. Lithium cobalt oxide films were deposited on Si wafers and silica-soda-lime glass using a dipping technique. Based on differential thermal analysis/thermogravimetric analysis results, densification of the films was achieved by thermal treatment at both 500 and 800 °C in the case of silicon wafer substrates and at 500 °C for the silica-soda-lime glass. X-ray diffraction, spectroellipsometry, and atomic force microscopy were used to characterize the films. The correlation between the preparation procedure and the type of support on the structure and morphology of LiCoO 2 compound films is discussed. Uniform ultrathin films were obtained on the glass (heat treated at 500 °C) and Si wafer (heat treated at 800 °C). The alcoholic synthetic procedure was also used to coat particles of LiMn 2 O 4 with films of LiCoO 2 . The sol-gel method resulted in partial coverage of LiMn 2 O 4 by LiCoO 2 as determined by elemental mapping with scanning electron microscopy.

Zn/La Mixed Oxides Prepared by Coprecipitation: Synthesis, Characterization and Photocatalytic Studies

“…The porous structure of the solids was investigated by the adsorption of pure nitrogen at −196 • C. The values of the specific surface obtained by applying the BET model (proper for multilayer physic-sorption) were, respectively, of 56.04 m 2 /g (Zn4La) and 26.34 m 2 /g (Zn4La400) and the corresponding free pore volumes, determined at the highest value of the P/P o value are, respectively, of 0.104 cm 3 /g (Zn4La) and 0.084 cm 3 /g (Zn4La400). These data are in line with the results reported in literature for oxides similarly prepared [27][28][29][30]. The calcination procedure generally determines the decrease of both specific surface area and free pore volume, due to the structure compacting associated with the advanced crystallization process or to the collapse of the "soft" architecture of the solids obtained by precipitation at mild temperatures.…”

Low-Temperature Atomic Layer Deposition of Cobalt Oxide as an Effective Catalyst for Photoelectrochemical Water-Splitting Devices

“…7,9,12,[18][19] The development of methods allowing for precisely controlled deposition of cobalt oxide films is therefore of crucial importance. Typical methods for the fabrication of cobalt oxides include sol-gel processes, [20][21][22] spray pyrolysis, [23][24][25][26] electrodeposition 7 or physical vapor deposition (PVD) [27][28][29][30] . However, in terms of the precise control over the phase and thickness, these methods are outperformed by chemical vapor deposition (CVD) and atomic layer deposition (ALD).…”

Electrochemical properties of the LiCoO2 powder obtained by sol–gel method

“…5 Several sol-gel routes were approached in order to prepare LiCoO 2 . The sol-gel method starting with alkoxides was used by Fey et al, 6 Quinlan et al, 7 Szatvanyi et al 8 The carboxylic route was experienced by Yazami et al, 9 Yoon and Kim, 10 Shlyakhtin et al 11 and Cho et al 12 Some combined inorganic-carboxylic route were also taken into consideration by Zhecheva et al, 13 Kang et al, 14 Kushida and Kuriyama 15 and Uchihida et al 16 Using carboxylic route the bonding of the metallic ions in a chelating complex is assumed to lead to a highly homogeneous precursor gel and should diminish the particle size of the resulting oxides due to their formation in an organic matrix. In the same time during the thermal treatment the organic species evolved by matrix decomposition could be retained on the particle surface, hindering again the particle growth.…”