Pair Distribution Function Method for the Structural Diagnostics of Nanomaterials
This review presents data on the use of the modern X-ray method the distribution function of atomic pairs (PDF) for studying the structural characteristics of nanomaterials (catalysts) that play an important role in understanding their properties. The most interest is the structure of catalytically active centres. However, traditional routine X-RAY methods are ineffective for this study. PDF-method is used to study the local structure (interatomic distances and coordination numbers) of nanoparticles. This method is based on the Fourier relationship between intensity of coherent X-ray scattering and the electronic density. To determine features of the local structure of supported nanoparticles, unlike well crystallized analogues, a comparison of the experimental PDF and the model one constructed on the basis of known structural data is used. We report some examples of the PDF analysis application: 1) to determine the structure of highly dispersed active component in supported catalysts; 2) to elucidate structural aspects of interaction between the support and active component. The Au(Pt)/γ-Al2O3, Cu/ZrO2 catalysts were considered.