| dc.description.abstract | Mesoporous silica metal
oxide (ZnO and CdO) thin films have
been used as metal ion precursors to
produce the first examples of mesoporous silica metal sulfide (mesoSiO2@ZnS, meso-SiO2@CdS) or silica
metal selenide (meso-SiO2@ZnSe,
meso-SiO2@CdSe) thin films, in which
the pore walls are made up of silica
and metal sulfide or metal selenide
nanoflakes, respectively. A gentle
chemical etching with a dilute HF solution of the meso-SiO2@CdS (or mesoSiO2@CdSe) produces mesoporous
cadmium sulfide (meso-CdS) (or cadmium selenide, meso-CdSe). Surface
modified meso-CdS displays bright
blue photoluminescence upon excitation with a UV light. The mesoporous
silica metal oxides are formed as metal
oxide nanoislands over the silica walls
through a self-assembly process of a
mixture of metal nitrate salt-two surfactants-silica source followed by calcination step. The reactions, between the
H2S (or H2Se) gas and solid precursors,
have been carried out at room temperature and monitored using spectroscopy and microscopy techniques. It has
been found that these reactions are:
1) taking place through the diffusion of
sulfur or selenium species from the top
metal oxide layer to the silica metal
oxide interface and 2) slow and can be
stopped at any stage to obtain mesoporous silica metal oxide metal sulfide or
silica metal oxide metal selenide intermediate thin films. | en_US |
