Photophysical and photocatalytic properties of histidine-stabilized CdS quantum dots in the presence of indole

► The photophysical properties of the CdS quantum dots were found to be size dependent. ► Addition of indole resulted in enhancement as well as a blue-shift in the fluorescence band of CdS. ► Indigo and isatin were formed as the products of the photocatalytic reaction of indole on the surface of CdS. ► The presence of adenine resulted in enhancement of the photocatalytic activity of CdS.