CdS quantum dots as photocatalyst for methylene blue and methyl red degradation and its electrochemical properties

Abstract

The study reports the use of oleylamine (OLM), hexadecylamine (HDA) and octadecylamine capped cadmium sulphide (CdS) quantum dots as photocatalyst for the decomposition of methylene blue (MB) and methyl red (MR) illuminated by visible light and their electrochemical properties. The effect of irradiation time and type of nano photocatalysts were investigated on the decomposition efficiency of both cationic (MB) and anionic (MR) dyes. The degradation efficiency and the chemical oxygen demand reduction of methylene blue (MB) and methyl red (MR) are 93% and 83% for OLM-CdS, 75% and 48% for HDA-CdS and 70% and 52% for ODA-CdS respectively. Cyclic Voltagram of the CdS quantum dots were used to study the relationship between the electrochemical band energies and the optical band gaps. Electrochemical band energies were found to be 1.64 V for OLM-CdS 1.92 V for HDA-CdS and 1.90 V for ODA-CdS which are comparable to those obtained from the calculated optical band gaps.