XPS quantitative analysis and models of supported oxide catalysts

XPS study of oxidation of rhenium metal on ?-Al2O3 support

“…The authors found by hydrogen consumption in a TPR study that all rhenium oxide remained in the catalyst up to 900 • C as stabilized surface-coordinated ReO 4 groups. We suppose that in our case, slightly different treatment procedures of the samples before chemical analysis and XPS measurements, as well as limitations of quantitative XPS analysis of porous samples with high surface area [66], would partly explain our results. Another explanation for the apparent contradiction between XPS and ICP results could be some encapsulation of the small Re particles in micropores of the support during high-temperature reduction.…”

Influence of the Ethylenediamine Addition on the Activity, Dispersion and Reducibility of Cobalt Oxide Catalysts Supported over ZrO2 for Complete VOC Oxidation

“…These results confirm the high cobalt dispersion on the zirconia support when ethylenediamine is used during the preparation. According to the spherical model proposed by Cimino et al [20,21], D. Pietrogiocomi et al [22] found that up to 2 atoms nm )2 , cobalt species are uniformly spread on the zirconia surface. In our case, for Co(N) samples, the I Co2p/I Zr3d ratio values are well below the expected value corresponding to uniform spreading on spherical ZrO 2 particles.…”

Is Nanostructuring Sufficient To Get Catalytically Active Au?

“…By generating photoelectrons of different kinetics energies, the sample could be probed at various depths. oxide phase can be estimated by quantification of the depth profile using a simplified structural model consisting of a uniform oxide layer of thickness t over a semiinfinite substrate [60,81]. Using known atomic densities and assuming the same IMFP for the metal and oxide, the unknown thickness t can be obtained by fitting the experimental data.…”

“…For calculation we use the equation for semi-infinitive specimen, with uniform over-layer of thickness t A [81]. Suffixes S (support, Au 0 ) and A (active over-layer, cationic Au) are used to specify the nature of the atomic species.…”