APCATA 468-2013-276

Sequential desilication–isomorphous substitution route to preparemesostructured silica nanoparticles loaded with ZnO and theirphotocatalytic activity

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