Co2S3 thin layer: unusual electrochemical behaviour during direct Ni electroplating
Date
2007Author
Naruškevičius, Leonas
Šimkūnaitė-Stanynienė, Birutė
Valiulienė, Genovaitė
Žielienė, Albina
Jasulaitienė, Vitalija
Sudavičius, Aloyzas
Baranauskas, Mykolas
Pakštas, Vidas
Stankevičius, Arvydas
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The electrochemical behaviour of CO2S3 layers deposited on glassy carbon and ABS plastic from colloidal Co(III) compound solution was investigated by cyclic voltammetry and X-ray photoelectron spectroscopy, Auger electron spectroscopy, XRD techniques in Watts Ni electroplating and Ni2+ free background electrolytes. On the basis of experimental data, it was assumed that CO2S3 converts into NiS when it is cathodically polarised at E approximate to -0.2 V (SHE) in the Watts electrolyte. During this process, the sheet resistance of the layer decreases from similar to 3 x 10(9) to similar to 3 x 10(3) Omega square(-1). This change goes on with the direct participation of Ni2+ ions in the electrolyte and this is probably of crucial importance for the following electrodeposition of metallic Ni initiated at more negative potentials. Contrary to Cu2-xS and Bi2S3, the layer of CO2S3 cannot be electroreduced to metallic Co in the Ni2+ free background electrolyte.