Aqueous colloidal dispersions containing Znx Cd1‐x S quantum dots (QDs) of different x compositions were prepared by precipitating zinc and cadmium acetates with sodium sulphide,in the presence of a cetyltrimethylamm...Aqueous colloidal dispersions containing Znx Cd1‐x S quantum dots (QDs) of different x compositions were prepared by precipitating zinc and cadmium acetates with sodium sulphide,in the presence of a cetyltrimethylammonium bromide stabilizer.Ultraviolet‐visible absorption spectroscopy was used to determine the transition energies of the QDs,which in turn were used to calculate their sizes,which depended on their composition.The QD size decreased with increasing Zn content.The photocatalytic activity of the Znx Cd1‐x S QDs was studied by the decomposition of methylene blue under ultraviolet irradiation,at a maximum intensity at 365 nm (3.4 e V).Three different photo‐catalytic activity regions were observed,which depended on the Zn content.The quantum levels of the QDs could be excited by incident irradiation,and influenced the resulting photocatalytic activity.Maximum photocatalytic activity was achieved at x = 0.6,where the QD transition energy was equal to the irradiation photon energy.The photocatalytic efficiency of the QDs depended on their surface area and arrangement of quantum levels,because of the quantum size effect.展开更多
基金supported by the Czech Science Foundation(P107/11/1918)by the Ministry of Education,Youth and Sports of the Czech Republic in the“National Feasibility Program I”,project LO1208“TEWEP”by VSB‐Technical University of Ostrava(SP 2014/55)
文摘Aqueous colloidal dispersions containing Znx Cd1‐x S quantum dots (QDs) of different x compositions were prepared by precipitating zinc and cadmium acetates with sodium sulphide,in the presence of a cetyltrimethylammonium bromide stabilizer.Ultraviolet‐visible absorption spectroscopy was used to determine the transition energies of the QDs,which in turn were used to calculate their sizes,which depended on their composition.The QD size decreased with increasing Zn content.The photocatalytic activity of the Znx Cd1‐x S QDs was studied by the decomposition of methylene blue under ultraviolet irradiation,at a maximum intensity at 365 nm (3.4 e V).Three different photo‐catalytic activity regions were observed,which depended on the Zn content.The quantum levels of the QDs could be excited by incident irradiation,and influenced the resulting photocatalytic activity.Maximum photocatalytic activity was achieved at x = 0.6,where the QD transition energy was equal to the irradiation photon energy.The photocatalytic efficiency of the QDs depended on their surface area and arrangement of quantum levels,because of the quantum size effect.
