New Strategy for Band Gap Tuning of ZnS Nanostructures for Photocatalytic and Solar Cell Application

Abstract

The controlled synthesis of pure ZnS and Zn1-xCdxS nanostructures has been achieved using a new strategy which involves three facile steps. First, Sodium salt of dimethyldithiocarbamate (CH3)2NS2Na was prepared by a reported method from dimethylamine, carbon disulfide and sodium hydroxide. Second, single source precursors Zn1-xCdx-(DMDTC)2 (x= 0, 0.2, 0.3, 0.5, 0.6) were prepared via direct precipitation reaction of stoichiometric amount of zinc nitrate, cadmium nitrate and sodium dimethyldithiocarbamate in methanol at room temperature. Third, hexagonal phase ZnS and Zn1-xCdxS nanostructures (x= 0.2, 0.3, 0.5, 0.6) with different aspect ratio were synthesized by simple reflux method via thermal decomposition of self-prepared precursors in the presence of octylamine at 120 oC. The obtained products were characterized by PXRD, UV-Vis DRS, SEM, TEM and EDS analysis. It was noticed that optical bandgap energy was shifted continuously to the visible region with increase of cadmium incorporation. Their photocatalytic activity was investigated for photodegradation of methylene blue dye and highest degradation rate with rate constant of 4.30 x 10-2 min-1 was observed for Zn0.4Cd0.6S as compared to 7.60 x 10-3 min-1 for pure ZnS. Thus, they are promising material to be used for photocatalytic and solar cell application.