SUMMARY
The interaction between Pd2+ ions and Cu2-xS coating formed by three cycles and containing ~30 at.% of elementary S has been investigated by the methods of cyclic voltammetry and photoelectron spectroscopy (one cycle of coating formation includes treatment of the surface with Cu(I)+Cu(II) ammoniate solution, hydrolysis of the adsorbed copper compounds and sulphidation of copper oxygen compounds in Na2Sn solution). After exposure of such a coating to Pd2+ ions (1.7 mM PdCl2’ pH-2), an exchange as well as a redox interaction between the coating components and Pd2+ ions has been shown to occur. Due to this the amount of copper in the coating decreases from 2 to 4 times and that of sulphur from 1.5 to 5 times. The coating modified in such a way has been found to contain up to 75 at.% of palladium, ~90% of it being in a metallic state.
It has been determined that at the beginning So is bound into a soluble compound:
2Pd2+ + So + 3H2O → 2Pdo + H2SO3 + 4H+.
The Cu2S present in the coating is considered to interact with Pd2+, with the formation of Pd0 and CuPdS2’, while CuS reacts most likely according to the reaction:
CuS + 3Pd2+ + 3H2O → 3Pdo; + H2SO3 + Cu2+ + 4H+.
The Cu2-xS +So coating formed on a dielectric and modified with Pd2+, contrary to the initial Cu2-xS +So coating, can be plated with copper from any electrolyte for copper deposition.