Electron microscopy and diffraction in heterogeneous catalysis

EM provides local structural information about the samples in both real and reciprocal space, for example local structural information about the surface and the bulk of the sample at the atomic level, together with chemical, electronic and three-dimensional structural information are now routinely available. Some of these methods are described in this chapter. Electron-sample interactions and scattering are fundamental to EM. EM is a diffraction technique in which crystals diffract electrons in accordance with Bragg s law, nX = Idhki sin 9, where X is the 

For the EM of practical (real-life) catalysts as-synthesized powders are used. 

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A researcher in the field of heterogeneous catalysis, alongside the important studies of catalysts chemical properties (i.e., properties at a molecular level), inevitably encounters problems determining the catalyst structure at a supramolecular (textural) level. A powerful combination of physical and chemical methods (numerous variants x-ray diffraction (XRD), IR, nuclear magnetic resonance (NMR), XPS, EXAFS, ESR, Raman of Moessbauer spectroscopy, etc. and achievements of modem analytical chemistry) may be used to study the catalysts chemical and phase molecular structure. At the same time, characterizations of texture as a fairytale Cinderella fulfill the routine and very frequently senseless work, usually limited (obviously in our modem transcription) with electron microscopy, formal estimation of a surface area by a BET method, and eventually with porosimetry without any thorough insight. 

Study the influence of MNP morphology on their surface properties and catalytic performances. In parallel to these methods for the preparation of MNPs, heterogeneous catalysis has developed powerful tools to model and characterize the surface of the nanoparticles. Interestingly, these studies can be achieved during the catalytic process (Transmission Electron Microscopy (TEM), powder X-Ray Diffraction (DRX), X-ray Photoelectron Spectrometry (XPS), Extended X-Ray Absorption Fine Structure (EXAFS), IR in operando) [26-34]. However, simple spectroscopic methods, such as UVA is, IR, or NMR both in solution and in solid state, which are adapted from molecular chemistry and homogeneous catalysis, offer interesting alternatives to precisely characterize the metallic surface of MNPs. 

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