Enhanced photocatalytic degradation of methyl orange dye on interaction with synthesized ligand free CdS nanocrystals under visible light illumination.

Methyl orange is widely used dye in textile industry and later, it becomes the major component of industrial waste and pollutes different water body. So, its degradation is required especially in the case of drinking water. Here, chemically synthesized ligand free CdS nanocrystals have been utilized as a photocatalyst to degrade this dye in water. The mean size of the CdS nanocrystal has been found to be 7 nm approximately from TEM analysis, and SAED pattern shows that these are crystalline in nature. Further, the XRD patterns confirms the cubic structure of CdS nanoparticles and mean size calculated from XRD analysis matches well with the obtained size from TEM study. NMR study clearly verifies that CdS nanocrystals are ligand free stable nanoparticles. Due to this absence of ligand on the surface of CdS nanocrystals, a much enhanced MO degradation has been observed, as the e--h+ pair in the CdS and subsequent generation of free radicals such as hydroxyl, can efficiently oxidize the organic material MO and therefore, degrade this pollutant faster under visible light illumination. The degradation efficiency is found to be 95% after 300 min of illumination, which is much better than the other similar reports.