Influence of Preparative Conditions on the Surface Structure and Photoactivity of ZnS under UV/Sunlight

Abstract

In this study, Zinc Sulfide nanoparticles were synthesized using different reaction conditions and capping agents. ZnS M1 were prepared by using 3-mercaptopropionic acid as capping agent followed by reflux at 100ºC for 6 h. ZnS M2 was prepared at heating temperature of 80ºC using capping agent polyvinyl pyrollidine. Further, ZnS M3 was prepared at room temperature under constant stirring for 4 h without any capping agent. The resultant powdered samples were characterized by XRD, UV- Visible absorption spectroscopy, photoemission spectroscopy, DLS, FTIR and BET. XRD results show the cubic type structure of all the samples with approachable lattice parameter to that of reported value (5.4 Å). Particles size calculated from Scherrer equation was found to be 2.1 nm, 10.26 nm and 2.4 nm for ZnS M1, ZnS M2 and ZnS M3 respectively. Small size of particles can also be predicted from TEM and SEM studies. The blue shift in absorption spectra of all the samples was seen which is attributed to changing surface properties with changing preparation conditions and capping agents. Nitrogen adsorption desorption analysis for all samples resembles with type IV isotherm which is characteristic peak of mesoporus nature. Specific surface area calculated from BET analysis was 252 m2g-1, 205 m2g-1 and 32 m2g-1 for ZnS M1, ZnS M2 and ZnS M3 respectively. Further photoactivity was also studied using crystal violet as model dye under UV and solar illumination. The study shows that changing reaction conditions and capping agent of ZnS shifts its degradation property in sunlight which is more efficient as is free of cost.