Monitoring the surface coverage of W/TiO ₂ catalysts by ion scattering spectroscopy

A series of W/TiO 2 catalysts was prepared by incipient wetness impregnation with W loadings varying from 1.64 to 28.4 wt.% WO 3 . The coverage of the TiO 2 surface by W species was monitored by ion scattering spectroscopy (ISS). The results indicated that the W coverage increased from 21.6% for the 1.64 wt.% WO 3 /TiO 2 catalyst to ∼85% for catalysts with W loadings ≥10.3 wt.% WO 3 . These values agreed with those predicted from monolayer‐like dispersion. The relatively constant coverage for W loadings > 10.3 wt.% WO 3 was taken as an indication of multilayer or WO 3 formation. These results were consistent with Raman and x‐ray photoelectron spectroscopy (XPS) data previously obtained in our laboratory.