An investigation into the effect of ionic species on the deposition of tellurium and the formation of cadmium telluride

Abstract The reduction of HTeO 2 + in the presence of various inorganic salts and ions has been studied at rotating glassy carbon and dropping mercury electrodes. The effect of added sodium salts (NaSO 4 , NaCl, NaNO 3 ) was attributed to the anion present. SO 4 2− ions caused both a negative shift in the deposition potential and a decrease in the limiting current without changing the deposit morphology. Cl − ions caused a positive shift in the deposition potential, but no change in the limiting current, while NO 3 − had no effect n either current or potential. Neither Cl − nor NO 3 − caused changes in deposit morphology. The effect of SO 4 2− is xplained by complex or ion-pair formation between HTeO 2 + and SO 4 2− . Addition of a wide concentration range of CdSO 4 caused a decrease in the limiting current similar to that produced by SO 4 2− alone, but with no change in deposition potential. A dramatic change in deposit morphology from dendritic to smooth, due to CdTe formation, also accompanied CdSO 4 addition. However, deposit analysis revealed that conversion of Te to CdTe was incomplete at 298 K, even with a very large excess of Cd 2+ over HTeO 2 + .