SURFACE-CHEMISTRY OF CHROMIA-PILLARED TIN AND ZIRCONIUM-PHOSPHATE MATERIALS - AN X-RAY PHOTOELECTRON SPECTROSCOPIC STUDY

X-Ray photoelectron spectroscopy has been used to examine the surface chemical composition of chromia-pillared Sn and Zr phosphates. All the materials are single-phase with Cr(III) ions octahedrally coordinated in a virtually anhydrous phosphate network, independent of the chromium content and preparation conditions. Quantitative analysis of the surfaces of the materials was achieved within an accuracy of +/-5%. While the atomic ratios M(i):M(j) (M(i),M(j) = Cr, P, Sn, Zr) differ by at most 20% from the chemical composition of the starting materials, the nO:nM(i)(M(j)) atomic ratios show a sizeable depletion (up to 50%) in oxygen content, which we interpret as being due to surface dehydration.