The insights from X-ray absorption spectroscopy into the local atomic structure and chemical bonding of Metal–organic frameworks

Soldatov, Mikhail A.; Martini, Andrea; Bugaev, Aram L.; Панкин, И. А.; Medvedev, P. V.; Guda, Alexander A.; Aboraia, Abdelaziz M.; Podkovyrina, Yulia S.; Budnyk, Andriy P.; Солдатов, А. А.; Lamberti, Carlo

doi:10.1016/j.poly.2018.08.004

Cited by 44 publications

(27 citation statements)

References 453 publications

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“…The backscattering factor F(k) strongly depends on the atomic number, Z. 49 With that, heavy atoms are localized at higher wavenumbers in the EXAFS spectrum compared to the lighter ones. This fundamental issue constitutes the basis for the WT analysis that allows signal discrimination on the basis of a two-dimensional representation of the EXAFS spectrum with a simultaneous signal localization in k and R space.…”

Section: Wt Exafs Analysismentioning

confidence: 99%

Structure of copper sites in zeolites examined by Fourier and wavelet transform analysis of EXAFS

et al. 2020

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Section: Wt Exafs Analysismentioning

confidence: 99%

Structure of copper sites in zeolites examined by Fourier and wavelet transform analysis of EXAFS

et al. 2020

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“…X-ray absorption spectroscopy [24][25][26] was shown to be an efficient approach for investigation of the local structure inside MOFs [12,19,[27][28][29][30][31][32][33][34][35][36][37][38]. Extended X-ray absorption fine structure (EXAFS) spectroscopy provides information on the coordination numbers and bond distances around the absorbing atom.…”

Section: Introductionmentioning

confidence: 99%

Evolution of Pt and Pd species in functionalized UiO-67 metal-organic frameworks

et al. 2019

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Functionalization of metal-organic frameworks (MOFs) with noble metals is a promising way for producing new versatile catalysts that will combine the outstanding porosity and specific surface area of MOFs with high catalytic activity of metals. Here, we present a comparative study of two metal-organic frameworks with UiO-67 topology, functionalized with palladium and platinum moieties. The initial structure of all studied samples contained palladium or platinum atoms grafted into MCl 2 bpydc (M = Pd, Pt) linkers of MOFs. The materials were further activated by heating in inert and H 2 -containing atmospheres. Both Pd-and Pt-functionalized materials exhibited high thermal stability upon heating in these atmospheres. The evolution of Pt and Pd species during the activation procedure was monitored by in situ time-resolved X-ray absorption near-edge structure (XANES) spectroscopy.We applied multivariate curve resolution alternating least squares (MCR-ALS) approach to XANES to unravel the intermediates which can be formed during the activation procedure. For UiO-67-Pd, only simple one-step transformation from PdCl 2 bpydc to Pd nanoparticles (NPs) was observed. For UiO-67-Pt, two additional intermediate states were observed, which behave differently depending on the activation procedure. Theoretical calculation of XANES spectra allowed us to suggest the 3D-atomic structures corresponding to each of the pure spectra determined by MCR-ALS. In addition, reaction enthalpies for different possible reaction routs were calculated within a density functional theory approach. Based on the experimental and theoretical results showed that Pd nanoparticles (NPs) tend to be formed in UiO-67-Pd samples irrespective of the activation procedure, while either Pt NPs or isolated Pt II active sites, grafted in the MOF framework may be formed in UiO-67-Pt samples depending on the activation temperature and atmosphere.

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“…Many mechanistic studies of heterogeneous catalysts are complimented by density functional theory (DFT) calculation of reaction mechanisms, active sites, and adsorbate interactions. Many of these studies have used an indirect comparison between the XAS analysis and DFT calculations (e.g., activation energies at various reaction coordinates) to confirm active sites and favorable reaction paths, such as role of different active sites in HER activity of different CoP-based catalysts [41,42], modified IrO 2 and nanoscale SrRuO 3 catalyst for OER [43,44], zeolite chemistry under reactive SCR conditions [45,46], and many more [47][48][49][50]. Coupling of DFT calculations with XAS simulations [51] and implementation of different spectroscopy modeling modules into common computational tools for materials modeling have made direct theoretical predictions and analysis of XAS spectra more accessible and provided molecular insights into catalytic reaction mechanism and active sites.…”

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confidence: 99%

In Situ X-ray Absorption Spectroscopy Studies of Nanoscale Electrocatalysts

et al. 2019

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HIGHLIGHTS • This is the first review paper on the studies of electrocatalysts using advanced in situ X-ray absorption spectroscopy (XAS). • This paper reviews the literatures to-date on new applications of in situ XAS (e.g., single-atom catalysts, surface reactions, nanoparticle size, and site occupation) that traditional XAS has not touched. • This review focuses mostly on recent publications after 2010.

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The insights from X-ray absorption spectroscopy into the local atomic structure and chemical bonding of Metal–organic frameworks

Cited by 44 publications

References 453 publications

Structure of copper sites in zeolites examined by Fourier and wavelet transform analysis of EXAFS

Structure of copper sites in zeolites examined by Fourier and wavelet transform analysis of EXAFS

Evolution of Pt and Pd species in functionalized UiO-67 metal-organic frameworks

In Situ X-ray Absorption Spectroscopy Studies of Nanoscale Electrocatalysts

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