Synthesis of Er and Yb-doped cubic and hexagonal phase ZnSe nano-assembled microspheres and their photocatalytic activities

We O2− synthesized ZnSe as well as Er and Yb-doped ZnSe nano-assembled microspheres by a hydrothermal method with and without hydrazine. ZnSe microspheres with a cubic phase were obtained with hydrazine, while ZnSe microspheres showed mixed cubic and hexagonal phases when hydrazine was not used. Introduction of low levels of Yb and Er resulted in morphologies of plates and rods, respectively, and these morphologies were unchanged when higher doping concentrations were used. The synthesized ZnSe was characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction crystallography, thermogravimetric analysis, UV-visible absorption, and photoluminescence spectroscopy. Photodegradation of methyl orange by undoped, Er and Yb-doped ZnSe was tested under visible light. Photoluminescence spectroscopy using terephthalic acid confirmed that OH radicals were efficiently formed over the doped ZnSe nanostructures upon visible light irradiation.