Preparation of cobalt oxide catalysts on stainless steel wire mesh by combination of magnetron sputtering and electrochemical deposition

Supported catalysts with Co3O4 deposited on stainless steel wire meshes were prepared and examined in the total oxidation of ethanol. Combination of reactive magnetron sputtering of cobalt particles in oxidation Ar + O-2 atmosphere and electrochemical formation of cobalt hydroxide precursors using cathodic reduction of cobalt nitrate in aqueous solution was applied for coating of the supports; the precursors were then transformed to Co3O4 by subsequent heating at 500 degrees C in air. Two plasma enhanced PVD methods, namely the radio-frequency (RF) magnetron sputtering and high-power impulse magnetron sputtering (HiPIMS) were used for obtaining of Co3O4 thin films. The catalysts prepared using RF magnetron sputtering were more active than analogous catalysts prepared using the HiPIMS process. The catalyst obtained by electrochemical deposition on a bare stainless steel mesh had the highest Co3O4 loading and showed the highest efficiency in total ethanol oxidation. Rather poor adhesion of the cobalt oxide layer prepared by electrochemical deposition on stainless steel mesh covered with Co3O4 thin films was significantly improved, when the catalysts were coated with additional Co3O4 thin film by magnetron sputtering. The highest specific catalytic activity and the best adhesion of Co3O4 layer to the stainless steel support was found for the RF-ED-RF catalyst prepared by combination of RF magnetron sputtering and electrochemical deposition. The activity of all supported catalysts, containing about 1 wt. % of Co3O4, in the total oxidation of ethanol to CO2 was better than that of the pelletized commercial Co3O4, though the cobalt oxide content in the bed of supported catalysts was nearly 50 times lower.