Synthesis and Characterization of Fe3+ and Mn2+ Doped ZnS Quantum Dots for Photocatalytic Applications: Effect of 2-Mercaptoethanol and Chitosan as Capping Agents

Fe3+ and Mn2+ capped ZnS quantum dots were synthesized using the chemical precipitation method at room temperature in aqueous media. The effect of 2-Mercaptoethanol and Chitosan as capping agents and dopants were investigated using Fourier Transform Infra-Red (FTIR), X-ray Diffraction (XRD), UV-Visible and Field Emission Scanning Electron Microscopy (FESEM) analysis of the nanocrystals. FTIR revealed the presence of respective capping agents and FESEM micrograph identifies the particles as poly-dispersed. TEM images showed agglomerated particles with crystal sized similar to 3 nm. Particles were analyzed as cubic structured with peaks indexed at (1 1 1), (2 2 1) and (3 1 1) and an average crystalline size of 2.49 +/- 0.06 nm. Blue shift is obtained by both doping agents, and band gap values of ranging from 3.75-4.95 eV were reported. Characterizations suggests 2-mercaptoethanol as better capping agent compared to chitosan and has a greater potential for photocatalytic applications.