TY - JOUR
T1 - TiO 2 coating of high surface area silica gel by chemical vapor deposition of TiCl 4 in a fluidized-bed reactor
AU - Xia, Wei
AU - Mei, Bastian
AU - Sánchez, Miguel D.
AU - Strunk, Jennifer
AU - Muhler, Martin
PY - 2011/9
Y1 - 2011/9
N2 - TiO 2 was deposited on high surface area porous silica gel (400 m 2g -1) in a fluidized bed reactor. Chemical vapor deposition was employed for the coating under vacuum conditions with TiCl 4 as precursor. Nitrogen physisorption, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and UV-vis spectroscopy were applied to characterize the obtained TiO 2-SiO 2 composites with different Ti loadings up to 5 wt%. Only a slight decrease in the specific surface area was detected at low Ti loadings. At a Ti loading of 2 wt%, TiO 2 was found to be highly dispersed on the SiO 2 surface likely in form of a thin film. At higher Ti loadings, two weak reflections corresponding to anatase TiO 2 were observed in the diffraction patterns indicating the presence of crystalline bulk TiO 2. High resolution XPS clearly distinguished two types of Ti species, i.e., Ti-O-Si at the interface and Ti-O-Ti in bulk TiO 2. The presence of polymeric TiOx species at low Ti loadings was confirmed by a blue shift in the UV-vis spectra as compared to bulk TiO 2. All these results point to a strong interaction between the TiO 2 deposit and the porous SiO 2 substrate especially at low Ti loadings.
AB - TiO 2 was deposited on high surface area porous silica gel (400 m 2g -1) in a fluidized bed reactor. Chemical vapor deposition was employed for the coating under vacuum conditions with TiCl 4 as precursor. Nitrogen physisorption, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and UV-vis spectroscopy were applied to characterize the obtained TiO 2-SiO 2 composites with different Ti loadings up to 5 wt%. Only a slight decrease in the specific surface area was detected at low Ti loadings. At a Ti loading of 2 wt%, TiO 2 was found to be highly dispersed on the SiO 2 surface likely in form of a thin film. At higher Ti loadings, two weak reflections corresponding to anatase TiO 2 were observed in the diffraction patterns indicating the presence of crystalline bulk TiO 2. High resolution XPS clearly distinguished two types of Ti species, i.e., Ti-O-Si at the interface and Ti-O-Ti in bulk TiO 2. The presence of polymeric TiOx species at low Ti loadings was confirmed by a blue shift in the UV-vis spectra as compared to bulk TiO 2. All these results point to a strong interaction between the TiO 2 deposit and the porous SiO 2 substrate especially at low Ti loadings.
KW - Chemical vapor deposition
KW - Fluidized-bed reactor
KW - Strong oxide-oxide interactions
KW - TiO
UR - http://www.scopus.com/inward/record.url?scp=84856848463&partnerID=8YFLogxK
U2 - 10.1166/jnn.2011.5107
DO - 10.1166/jnn.2011.5107
M3 - Article
AN - SCOPUS:84856848463
SN - 1533-4880
VL - 11
SP - 8152
EP - 8157
JO - Journal of Nanoscience and Nanotechnology
JF - Journal of Nanoscience and Nanotechnology
IS - 9
ER -