Octadecyl amine capped cadmium sulfide quantum dots: morphological studies, electrochemical properties, and its use as photocatalyst for the degradation of methylene blue dyes

We present the structural, optical, electrochemical, and photocatalytic studies of octadecyl amine capped CdS quantum dots (ODA-CdS). TEM micrographs showed CdS quantum dots with particle sizes of 1.9-5.2 nm. The optical bandgaps of the quantum dots are 2.03, 2.06 and 2.01 eV for ODA-CdS1, ODA-CdS2 and ODA-CdS3 respectively, which was less than the bandgap of the bulk CdS (2.42 eV). Photo-electrochemical band gaps of 2.60 V for ODA-CdS1, 2.24 V for ODA-CdS2 and 2.46 V for ODA-CdS3 were obtained from cyclic voltammetry. The photocatalytic degradation efficiency of methylene blue was 62% for ODA-CdS1, 80% for ODA-CdS2, 69% for ODA-CdS3.