The interaction of additives with the cathode in a mixture of saccharin, 2-butyne-1,4-diol and phthalimide during nickel electrodeposition in a Watts-type electrolyte

The interaction of additives with the cathode and the interplay of saccharin, 2-butyne-1,4-diol and phthalimide was investigated by determination of the consumption rates (Vc) of the additives, accumulation rates (Va) of the cathodic reaction products and the incorporation of sulfur and carbon in electrodeposits. The main transformation products of saccharin were benzamide, o-toluene sulphonamide and benzylsultame, while phthalimide gave rise to phthalimidine and o-toluene amide. Cathodic reaction products showed the adsorption modes of the additives on electrodeposits. Saccharin and phthalimide in the mixture increased Vc as well as Va of o-toluene sulfonamide and phthalimidine. 2-Butyne-1,4-diol decreased Va of o-toluene sulfonamide and phthalimidine and increased the Va of benzamide and incorporation of sulfur. The increase of Vc and Va showed a synergistic effect of the additives. The aromatic compounds in the mixture under study increased additive adsorption by the carbonyl group and 2-butyne-1,4-diol increased the adsorption of saccharin by the sulfonyl group.