| 摘要 |
In the manufacture of porous carbon electrodes for oxygen depolarization in galvanic cells by impregnating a carbon body with heavy metal compounds, dilute solutions of heat-decomposable heavy metal salts capable of effecting partial oxidation of carbon are used for the impregnation and the impregnated bodies are heated to decompose the salts, thereby partially oxidizing the carbon, to form metals or metal compounds in amounts of less than 5 per cent, which metals or metal compounds catalytically accelerate the electrochemical reaction of the depolarizing oxygen. Impregnating solutions should contain salts of at least two, preferably five or more metals, e.g. iron cobalt, nickel, manganese, chromium, copper, silver, gold, platinum, vanadium, thorium, or rare earths. Suitable salts are nitrites, nitrates, chromates, chlorates, oxalates, acetates, or formates, or mixtures thereof. The impregnating solutions may also contain heat-decomposable salts of the alkaline earth metals magnesium, calcium strontium, barium, and beryllium, or of aluminium or mixtures thereof. Impregnation may be effected by suction or pressure. The carbon bodies may be treated, before impregnation, with agents which attack carbon, e.g. concentrated hydrochloric, and/or nitric acids with or without hydrofluoric acid, and dried. The finished electrodes may be given a water-repellent coating, e.g. of paraffin. |
