Intrinsic and extrinsic semiconductor nanocrystals seem to be good candidates for modern era optoelectronic and photo-catalytic applications due to their size tunable photo-physical and photo-chemical properties. In the present investigation, polyvinyl pyrrolidone (PVP) capped quencher impurity (Ni) doped ZnS nanocrystals have been synthesized using facile bottom-up synthesis technique; colloidal chemical co-precipitation method. Crystallographic and morphological characterization of synthesized nanomaterials have been carried out using X-ray diffraction (XRD) and transmission electron microscope (TEM), respectively. Photo-catalytic activity of the synthesized nanomaterials has been studied using methylene blue (MB) dye as a test contaminant. Photo-catalytic behavior dependence on dopant concentration, UV radiation curing and annealing of synthesized semiconductor nanomaterials have been studied in detail under sun light exposure.