ABSTRACT
Copper Deposition........................................................................................ 467 19.11 Electroless Copper Plating Using Co(II) Complexes as Reducing Agent .................... 469
19.11.1 Oxidation of Co(II)–En Complexes on Copper Electrode Studied by EQCM........................................................................................ 470
19.12 Autocatalytic Reduction of Cu(II) by Co(II) Complexes Studied by EQCM............... 473 19.13 Summary and Outlook ................................................................................................... 475 References ..................................................................................................................................... 475
The chemical reduction of metal ions and its practical applications dates back to the medieval ages, for instance, the ‘‘purple of Cassius’’—colloidal gold prepared via the reduction of Au(III) ions by Sn(II)—was described in the seventeenth century by the Dutch alchemist A. Cassius [1], enabling the preparation of a stable and long-lasting pigment for ruby-red tainting of glass and ceramics. The textbook ‘‘silver mirror’’ reaction (the reduction of an ammonia complex of silver ions by lactose), discovered by Liebig [2], was formerly used to prepare high-quality mercury-free mirrors. Nowadays, the development of electroless metal plating has been stimulated by technological progress that offers the ability to form thin metal films on dielectric materials (plastics, ceramics, glasses) and semiconductors, thus allowing to considerably reduce metal consumption and to uniquely combine materials of very different physical and chemical properties. Furthermore, the chemical reduction of metal ions to fabricate nanometer-sized particles (monometallic, bimetallic, etc.) is an important method, which is used to prepare high-surface-area catalysts, for example, for fuel cell applications [3].
