Surface Properties and Photocatalytic Activities of the Colloidal ZnS:Mn Nanocrystals Prepared at Various pH ConditionsReportar como inadecuado


Surface Properties and Photocatalytic Activities of the Colloidal ZnS:Mn Nanocrystals Prepared at Various pH Conditions


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Department of Chemistry, Institute of Nanosensor and Biotechnology, Center for Photofunctional Energy Materials GRRC, Dankook University, 152 Yongin-si, Suji-ku, Jukjeon-ro, Gyunggi-do 448-701, South Korea





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Academic Editor: Marek Osinski

Abstract Water-dispersible ZnS:Mn nanocrystals NC were synthesized by capping the surface with mercaptoacetic acid MAA molecules at three different pH conditions. The obtained ZnS:Mn-MAA NC products were physically and optically characterized by corresponding spectroscopic methods. The UV-Visible absorption spectra and PL emission spectra showed broad peaks at 310 and 590 nm, respectively. The average particle sizes measured from the HR-TEM images were 5 nm, which were also supported by the Debye-Scherrer calculations using the X-ray diffraction XRD data. Moreover, the surface charges and the degrees of aggregation of the ZnS:Mn-MAA NCs were determined by electrophoretic and hydrodynamic light scattering methods, indicating formation of agglomerates in water with various sizes 50–440 nm and different surface charge values accordingly the preparation conditions of the NCs −7.59 to −24.98 mV. Finally, the relative photocatalytic activities of the ZnS:Mn-MAA NCs were evaluated by measuring the degradation rate of methylene blue MB molecule in a pseudo first-order reaction condition under the UV-visible light irradiation. As a result, the ZnS:Mn-MAA NC prepared at the pH 7 showed the best photo-degradation efficiency of the MB molecule with the first-order rate constant kobs of 2.0 × 10−3·min−1. View Full-Text

Keywords: ZnS:Mn; water-dispersible; MAA capping; photocatalytic activities; methylene blue degradation; aggregations ZnS:Mn; water-dispersible; MAA capping; photocatalytic activities; methylene blue degradation; aggregations





Autor: Jungho Heo and Cheong-Soo Hwang *

Fuente: http://mdpi.com/



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