Electrodeposition of cadmium selenide

In the present work the process of electrochemical synthesis of cadmium selenide from sulphate solutions has been examined. Electrode reactions taking place at co-deposition of cadmium and selenium were tested with the use of cyclic voltammetry. Two mechanisms of co-deposition of cadmium and selenium were suggested. Within the range of more positive potentials, the following two reactions take place: reduction of selenious acid to selenium, and then underpotential deposition of cadmium on selenium. The second mechanism proceeds within the potentials range below -0.4 V vs. SCE and relies on simultaneous reduction of ions of cadmium and selenious acid in a six-electron process. Next, the influence of selenious acid concentration and potential on the Cd-Se coatings deposition process on copper sheets was examined. The coatings were analysed with X-ray spectrofluorometry, electron scanning microscopy and X-ray diffraction. It was demonstrated that it is possible to obtain coatings stoichiometry corresponding to CdSe compound of hexagonal structure from sulphate electrolyte.