Synthesis and characterization of Er_xZn_1-xSe nanoparticles: A novel visible light responsive photocatalyst

In this study, undoped and Erbium doped ZnSe (Er_xZn_1-xSe) nanoparticles were prepared via a facile hydrothermal method at 150 °C for 24 h. The products were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectroscopy (DRS) and inductively coupled plasma (ICP) techniques. These analyses confirmed the nonometric diameter and significant optical absorption of as-synthesized samples at visible light range. The photocatalytic activity of Er-doped ZnSe nanoparticles was investigated by the decolorization of Orange II solution under visible light irradiation. The color removal efficiency of Er_0.06Zn_0.94Se and pure ZnSe was 95.1 and 28.7% after 120 min of treatment, respectively. The greatly enhanced photocatalytic activity of the Er-doped ZnSe photocatalyst was mainly attributed to the suppression of electron-hole recombination, large content of oxygen vacancies, and strong absorption of OH- ions on the surface of the catalyst due to the Er loading. In this study, 6 mol% was the most suitable content of Er³⁺ in ZnSe, at which the recombination of photoinduced electrons and holes could be effectively inhibited and thereby the highest photocatalytic activity was formed. The photocatalytic degradation of Orange II followed the Langmuir-Hinshelwood kinetic model.