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

Abstract Supported catalysts with Co 3 O 4 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 Co 3 O 4 by subsequent heating at 500 °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 Co 3 O 4 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 Co 3 O 4 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 Co 3 O 4 thin films was significantly improved, when the catalysts were coated with additional Co 3 O 4 thin film by magnetron sputtering. The highest specific catalytic activity and the best adhesion of Co 3 O 4 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 Co 3 O 4 , in the total oxidation of ethanol to CO 2 was better than that of the pelletized commercial Co 3 O 4 , though the cobalt oxide content in the bed of supported catalysts was nearly 50 times lower.