Home Proceedings
Synthesis of CdS Spheres via a Chemical Method and Investigation of Photocatalytic Activities
Oral Presentation XML
Authors
1School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran, Iran
2University of Tehran
Abstract
Cadmium sulfide (CdS) is a yellowish chalcogenide compound that is commonly used in pigment and electronic industries. However, CdS is a promising candidate in photocatalyst applications especially in aqueous medium under visible light, mainly because this inorganic compound is insoluble in water and has a relatively narrow band gap of 2.4 eV which can absorb visible light. The choice of synthesis method has an important effect on the preparation of CdS with different sizes, morphologies, and structures. There are many ways to synthesize CdS for different applications. These methods consist of solvothermal, hydrothermal, sonochemical, and chemical bath deposition. In this study, CdS spheres were prepared using thioacetamide (C2H5NS) and cadmium nitrate (Cd(NO3)2.4H2O), respectively, as sulfide and cadmium precursor materials. The structure of CdS plays an essential role in the photocatalytic performance of CdS. The spherical 3-dimensional structure has more conductivity and photocatalytic activity because of the high surface-to-volume ratio and also low density. The characterization by X-ray diffraction (XRD) verified that the synthesized CdS spheres are single crystalline and pure. Field emission scanning electron microscopy (FESEM) figures showed spherical particles were synthesized by the chemical method. Additionally, FESEM images confirmed that the structure of CdS spheres was uniform and also demonstrated the size of CdS spheres. Energy dispersive spectroscopy (EDS) proved the presence of cadmium and sulfide with stoichiometric compositions and also uniform distribution of the elements. Fourier transform infrared spectroscopy spectra (FTIR) indicated that Cd-S bonding has been obtained by this method. Based on the characterization results, CdS spheres were synthesized. The photocatalytic activity of CdS spheres was investigated by degradation of methylene blue (MB). Finally, it was shown that 80 percent of the absorbed methylene blue on CdS spheres was decomposed under visible light irradiation within 3 hours. Furthermore, it is proved that the adsorption of MB on CdS surfaces obeys the pseudo-second-order kinetic model.
Keywords