Fabrication of tri-layer structured CdS/SiO2/sulfonated PS composite sphere and its photocatalytic behavior

• Tri-layer structured cadmium sulfide/silica/polystyrene (CdS/SiO2/PS) microspheres were synthesized.
• The dispersion of CdS in polluted water containing organic matters was improved by coating with PS.
• Tri-layer structured CdS/SiO2/SPS nanocomposites with porous shell possessed good photocatalytic effect for MB.

Monodispersed tri-layer structured cadmium sulfide/silica/sulfonated polystyrene (CdS/SiO2/SPS) nanospheres were synthesized and used as a photocatalyst to catalyze the degradation of pollutants in polluted water containing organic matters under solar light irradiation. Polystyrene (PS) layer was used to improve the dispersion of CdS/SiO2 in polluted water containing organic matters, and it was sulfonated and etched to form a porous structure in order to avoid the block effect. As PS was difficult to coat on CdS directly, SiO2 was employed in the intermediate shell to work as a jointing layer between CdS and PS, and it also could reduce the release of Cd2+ in photocatalytic degradation procedure. SEM and TEM showed that the tri-layer structured CdS/SiO2/SPS nanocomposites with porous shell were successfully synthesized. Taking a mixture of tetrahydrofuran and water to simulate the polluted water containing organic pollutants, the obtained CdS/SiO2/SPS nanocomposites with porous structure dispersed well in the mixture. The degradation experiments of methylene blue (MB) (simulated organic pollutants) showed that the degradation speed of MB photocatalyzed by porous-structured CdS/SiO2/SPS nanocomposites was much faster than by CdS/SiO2.

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