Highly Crystalline Zinc Oxide/Mesoporous Hollow Silica Composites Synthesized at Low Temperature for the Photocatalytic Degradation of Sodium Dodecylbenzenesulfonate

Abstract

Highly crystalline ZnO/mesoporous hollow silica sphere (MHSS) composites have been successfully synthesized through an impregnation method at 323K without applying calcination. Three composites of different Zn/Si molar ratios of 1:2, 1:1, and 2:1 were prepared. X-Ray diffraction patterns confirmed the presence of highly crystalline ZnO in the materials. A layer of ZnO was formed on the MHSS as evidenced by field emission scanning electron microscopy analysis. Transmission electron microscopy analysis verified the mesoporous structure in ZnO/MHSS composites. N2 adsorption–desorption analysis indicated a type IV isotherm for 1ZnO/2MHSS and 1ZnO/1MHSS samples, confirming the presence of mesopores in the ZnO layer. It has been demonstrated that all the ZnO/MHSS composites exhibit a high photocatalytic activity towards sodium dodecylbenzenesulfonate degradation compared with bare ZnO under UV irradiation. A kinetic study showed that the photodegradation followed a second order model. Among the prepared composites, 1ZnO/1MHSS recorded the highest reaction rate of 6.03×10−3mM−1min−1 which is attributed to a high crystallinity and the monodispersity of a high amount of ZnO on MHSS.