Some regularities of formation of Cu2-xS coatings

The interaction of Cu2O + Cu(OH)(2) adsorbed wit Na2S4 in he course of form ation of Cu2-xS coatings by a cyclic method has been investigated using the methods of cyclic voltammetry and radiochemistry (S-35). (One cycle of Cu2 -xS coating formation consists of the treatment of the surface to be coated in a solution of Cu (I) + Cu (II) ammoniates, rinsing-hydrolysis and sulph idation in Na2S4 solution). Only 25% of the Cu2-xS coating has been found to be formed due to adsorptio n of Cu(I) + Cu (II) and up to 10% due to S-4(2-) adsorption. The remaining portion (similar to 65%) of the coating is formed due to interaction of Cu (I) with elemental sulphur S-ad(o) +2 Cu+ --> CuSad + Cu2+ and the exchang e occurring in the course of repeating the cycle CuSad+2 (1-x) Cu+-->Cu2-xS ad+ (1-x) Cu2+. Elemental sulphur is supposed to be formed in a sulphidatio n stage through individual and mixed intermediates of Cu(I) and Cu(II) poly sulphides as well as during the hydrolysis of the adsorbed S-4(2-) (less th an or equal to 10% S-o).