Photodeposition of CdSe using Se-TiO 2 suspensions as photocatalysts

Abstract

The photodeposition of cadmium selenide (CdSe) using Se-TiO 2 photocatalysts was studied at pH 3.5 and 7 in the presence of formic acid. The Se-TiO 2 photocatalysts were obtained by Se ion photoreduction using selenite (Se(IV)) and selenate (Se(VI)) as precursors. The formation of cadmium selenide was attributed to the reaction between cadmium ions and selenide ions (Se 2−) released from the Se deposited on TiO 2 particles under illumination. The release of the Se 2− ions from the Se–TiO 2 is believed to be the determining step for the formation of the CdSe particles, hence controlling their morphology as either rod-shaped or spherical. Metallic cadmium was also detected on the surface of TiO 2 particles as a product of the photocatalytic reduction at pH 7. Its formation was attributed to the photoreduction of cadmium by the photogenerated electrons in the TiO 2 and/or the Se semiconductors.