All solid-state fabrication strategy of CdS@ZnS nanocomposites and their photocatalytic performance in water purification

Herein a systematic study of two-step solid-phase synthesis of CdS@ZnS nanocomposites and their photocatalytic activity is presented. First, CdS nanoparticles were synthesized in a planetary ball mill through a solid-state ion exchange reaction. In the second step, Cd2+ ions were partially replaced by Zn2+ ions at the surface of the nanoparticles using solvent free long-term activation in a high-energy planetary ball mill. The optimal activation time in a ball mill was determined to be 45 min. Spherical CdS nanoparticles with a diameter of 10 nm and modified CdS@ZnS (45 min) nanocomposites  were characterized by X-ray diffraction analysis, Raman and UV-vis spectroscopy, and scanning electron microscopy. The ability of nanocomposites for photocatalytic water purification was tested on the degradation of the model organic dye Orange II in an aqueous solution under the visible light irradation. The modified CdS@ZnS nanocomposites showed higher photocatalytic activity compared to the original CdS nanoparticles.