F. Verpoort et al., OLEFIN METATHESIS CATALYST .1. ANGLE-RESOLVED AND DEPTH PROFILING XPSSTUDY OF TUNGSTEN-OXIDE ON SILICA, Journal of molecular catalysis, 90(1-2), 1994, pp. 43-52
Model supports consisting of a thin layer of SiO2 on a silicon single
crystal have been used to study the WO3/SiO2/Si (100) catalyst precurs
or. Compared to the powder analogues, a drastic increase in spectral r
esolution and detailed band structure is observed in the XPS spectra.
Conventional XPS, angle dependent and depth profiling X-ray photoelect
ron spectroscopy show the presence of two types of tungsten oxide on t
he surface: microcrystallites of WO3 and a tungsten oxide monolayer ch
emically bonded to the silica matrix.