Sequential desilication–isomorphous substitution route to prepare mesostructured silica nanoparticles loaded with ZnO and their photocatalytic activity

•ZnO/MSN catalyst was prepared by a simple electrochemical and impregnation method.•Sequential desilication–isomorphous substitution occurred during impregnation.•The Si–O–Zn bond formed was the active species that enhanced the catalytic activity.•Increasing the ZnO loading increased the electron–hole pair recombination rate.

A simple electrochemical method followed by impregnation was employed to prepare a coral-like zinc oxide catalyst loaded on mesostructured silica nanoparticles (ZnO/MSN). The introduction of zinc species onto a silica framework was found to form an interaction between the host and support material. XRD analysis suggested the presence of zinc on the internal pore walls of MSN. FE-SEM and TEM analyses displayed nanorods, nanoparticles and coral-like shapes of ZnO, MSN and ZnO/MSN, respectively. 29Si NMR and FTIR results showed that desilication occurred in the silica framework of the MSN accompanied by isomorphous substitution of Zn2+ cations to form an active species Zn–O–Si bond. The photocatalytic activity of the ZnO/MSN was tested by decolorizing methyl orange (MO). It was found that increasing the ZnO loading led to a higher recombination rate of photoinduced electron–hole pairs, which resulted in decreased photocatalytic activity. The highest decolorization rate was obtained using 1 g L−1 of 5 wt% ZnO/MSN with an optimum dosage of 3.06 × 10−2 mM MO after 8 h contact time at pH 2 under UV irradiation. A kinetic study demonstrated that the photocatalytic reaction followed the pseudo first-order model. The photocatalyst was still stable after five cycling runs with a small amount of Zn was leached (<3.0%).

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (166 K)Download as PowerPoint slide