Electrodeposition of Metals from Organic Solutions

Abstract

General principles, methods, solutes, and solvents used for depositing metals from organic solvents are surveyed. This paper covers general principles and methods for electrodepositing metals from nonaqueous media that are common to four subsequent papers in this series concerned with deposition of A1, Be, Mg, and alloys of A1 with Ti and Zr.Of 70 known metallic elements, only about 30 have been electrodeposited from aqueous solution. Many of the metals which have not been deposited would have useful applications if they could be obtained in the form of coatings or electroformed into objects. Several of these metals are of considerable current interest, namely, Ti, Zr, Mo, Ta, and W. Since a majority of the metals could not be deposited from aqueous solution, electrochemists turned their attention to nonaqueous media. These are of two types: fused salts, and compounds which are liquid at ordinary temperatures.Practically all metals can be deposited from fused electrolytes. However, electrodeposition from fused electrolytes has not solved the problem of obtaining coherent coatings of these metals, because, with the few exceptions noted below, the deposits are obtained in the form of powders, crystals, sponges, or dendrites which are of no value as coatings. Metals in this form may, however, be of value for electrowinning purposes. From fused salt baths operated on a laboratory scale, coatings of Mo about 0.25 mm thick and coatings of Ti and A1 about 0.025 mm thick have been obtained, but thus far no commercially successful process has been developed. Fused electrolytes are not discussed further in this paper.Those metals which can be deposited from aqueous solutions can also be deposited from nonaqueous media, but such plating solutions are at present of no practical importance. In the following discussions, to distinguish between those metals which can and those which cannot be deposited from aqueous solutions, the latter group is referred to as the nonaqueous or "NQ" metals. The following discussions apply only to the NQ metals, unless otherwise noted.Researches reported here deal with the use of organic solvents in plating baths. A nonaqueous plating bath which is liquid at room temperature has obvious advantages over a fused salt bath which must be operated at elevated temperatures. Some inorganic liquids, such as liquid NH3, liquid S02, and hydrazine, have been studied as media for depositing metals, but none of the NQ metals has been deposited from them; therefore, they are not considered further in this paper. Organic compounds which melt at a sufficiently low temperature, e.g., 100~ so that they can be handled with about the same ease as ordinary organic solvents may be considered as intermediate between fused salt baths and organic liquids. In contrast with the universality with which metals have been deposited from fused salt baths, few of the NQ metals have been deposited from organic solvents. Until recent years no satisfactory plating bath had been developed for depositing an NQ metal as a sound coati...

Electrodeposited semiconducting molybdenum selenide films. I. Preparatory technique and structural characterisation

“…The deposition of molybdenum selenide is beset with problems. Attempts to deposit even pure molybdenum were initially unsuccessful, though theoretically it is possible to deposit MO from aqueous solution according to the following reaction (Brenner 1956): H2Mo04(aq) + 6H' + Se-+ MO + 4H20. 0022-3727/84/102115 + 11 $02.25 @ 1984 The Institute of Physics…”

“…Therefore, it has not been possible to deposit pure molybdenum by electrolysis of an aqueous solution. However, many workers have succeeded in codepositing MO together with iron group metals (Safranek and Vaaler 1959, Brenner and Burkhead 1953, Brenner 1956, Higashi and Fukushima 1973, Higashi et a1 1976, 1977, Fukushima et a1 1979, Takai 1979. The electrodeposition of MO in the presence of other metal ions is also referred to as induced codeposition.…”

New Cathode-Anode Couples for Secondary Batteries

“…The most promising couples in molten salts and an experimental program are described in Sections 2. 4 .5.…”

Electrolysis of Organic Solvents with Reference to the Electrodeposition of Metals

“…A dry atmosphere of helium was circulated continuously through the chambers and deoxygenated. For running electrolytic experiments in the laboratory some special cells were designed (12) which excluded the air and yet allowed the cathodes to be removed and examined, and fresh ones put in if necessary.…”