Dopant Effects on the Photocatalytic Activity of Colloidal Zinc Sulfide Semiconductor Nanocrystals for the Oxidation of 2-Chlorophenol

Abstract

In this work, colloidal zinc sulfide nanocrystals, prepared with selected concentrations of manganese(II) ions in the range of 0−2% and stabilized with a polymeric capping agent, were used in the photocatalytic degradation of 2-chlorophenol in aqueous solutions. Particle sizes for the synthesized nanocrystals were determined using UV−vis absorbance spectroscopy and X-ray diffraction (XRD). UV−vis spectra for all of the synthesized nanocrystals display an excitonic peak at around 290 nm, which corresponds to a particle size of approximately 3 nm, in agreement with the XRD analysis. Photoluminescence emission spectra recorded for undoped ZnS nanocrystals exhibit an emission peak at 460 nm in the spectrum, whereas peaks corresponding to the dopant ion are red-shifted to 590 nm. With increasing addition of the dopant ion, the area of the peak at 460 nm first increases and then decreases for higher dopant concentrations, whereas the area of the peak at 590 nm increases. This finding clearly indicates that the ...