X-ray absorption fine structure combined with X-ray fluorescence spectrometry: Part 18. Tin site structure of Pt–Sn catalyst

Sn Kα1-detecting Sn K-edge XANES spectrum was successfully measured for Pt–Sn/SiO2 catalyst (2.5 wt.% Pt, Sn/Pt atomic ratio 1.0) in the energy resolution 5.0 eV using Rowland-type fluorescence spectrometer equipped with Ge(13,13,13) bent crystal. The steeper, more clearly resolved XANES spectrum thus obtained could be compared quantitatively to theoretical XANES spectra generated by ab initio calculations for thirteen plausible Pt–Sn site models (alloy, adsorbed Sn, and mixture models). This spectral simulation suggested that fluorescence-detecting XANES is a simple method to judge the plausible site structure without detailed spectral analyses. The comparison supported an adsorbed Sn site model structure on highly dispersed Pt[–Sn] nanoparticles on SiO2.