Pair Distribution Function Analysis of High‐Energy X‐ray Scattering Data

Chapman, Karena W.; Chupas, Peter J.

doi:10.1002/9781118355923.ch5

Cited by 12 publications

(12 citation statements)

References 32 publications

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“…2B). The maximum interatomic distance at which well-defined peaks are evident in the PDFs, which is a measure for nanoparticle dimensions (Chapman and Chupas, 2013), was ~ 2 nm for all FeOx except P9-cop FeOx (~ 1.5 nm).…”

Section: Characterization Of Feoxmentioning

confidence: 99%

Sorption of phosphate and silicate alters dissolution kinetics of poorly crystalline iron (oxyhydr)oxide

et al. 2019

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Iron (oxyhydr)oxides (FeOx) control retention of dissolved nutrients and contaminants in aquatic systems. However, FeOx structure and reactivity is dependent on adsorption and incorporation of such dissolved species, particularly oxyanions such as phosphate and silicate. These interactions affect the fate of nutrients and metal(loids), especially in perturbed aquatic environments such as eutrophic coastal systems and environments impacted by acid mine drainage. Altered FeOx reactivity impacts sedimentary nutrient retention capacity and, eventually, ecosystem trophic state. Here, we explore the influence of phosphate (P) and silicate (Si) on FeOx structure and reactivity. Synthetic, poorly crystalline FeOx with adsorbed and coprecipitated phosphate or silicate at low but environmentally relevant P/Fe or Si/Fe ratios (0.02-0.1 mol mol-1) was prepared by base titration of Fe(III) solutions. Structural characteristics of FeOx were investigated by X-ray diffraction, synchrotron-based X-ray absorption spectroscopy and high-energy X-ray scattering. Reactivity of FeOx was assessed by kinetic dissolution experiments under acidic (dilute HCl, pH 2) and circumneutral reducing (bicarbonate-buffered ascorbic acid, pH 7.8, Eh ~-300 mV) conditions. At these loadings, phosphate and silicate coprecipitation had only slight impact on local and intermediate-ranged FeOx structure, but significantly enhanced the dissolution rate of FeOx. Conversely, phosphate and silicate adsorption at similar loadings resulted in particle surface passivation and decreased FeOx dissolution rates. These findings indicate that varying nutrient loadings and different interaction mechanisms between anions and FeOx (adsorption versus coprecipitation) can influence the broader biogeochemical functioning of aquatic ecosystems by impacting the structure and reactivity of FeOx.

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Section: Characterization Of Feoxmentioning

confidence: 99%

Sorption of phosphate and silicate alters dissolution kinetics of poorly crystalline iron (oxyhydr)oxide

et al. 2019

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“…due to atomic vibrations or static disorder [11]. iv) The maximum distance 𝑟max above which no PDF features exist serves as an estimate for the domain size [22]. v) The slope of the PDF at low 𝑟 gives an estimate of the atomic density [21].…”

Section: Measuring Total Scattering Data and Analysing A Pdfmentioning

confidence: 99%

“…v) The slope of the PDF at low 𝑟 gives an estimate of the atomic density [21]. In addition, when a time series of PDF data is available (such as from in situ studies), the monitoring of the above described PDF features over time allows for the determination of quantitative kinetics, changes in concentration or in the atomic structure without the need for a structural model [22]. A more comprehensive analysis can be obtained through PDF modelling [21].…”

Section: Measuring Total Scattering Data and Analysing A Pdfmentioning

confidence: 99%

“…peak areas are proportional to coordination numbers, iii) peak widths relate to disorder, iv) the maximum r above which there are no more PDF peaks is an estimate of the ordered domain size and v) the initial slope of the PDF is related to the atomic density. Redrawn from [9]. (C) Exemplary PDF fitting, highlighting the ability of PDF to resolve local disorder as the mismatch between the experimentally obtained data (black curve) and an average structure model (blue curve).…”

Section: Measuring Total Scattering Data and Analysing A Pdfmentioning

confidence: 99%

“…Total scattering (see Glossary) includes contributions from both Bragg (coherent) and diffuse (non-coherent) scattering that are associated with periodic order and disorder, respectively [8]. Structural information arising from both contributions is contained in the PDF, making it a powerful method for the study of disordered and nanostructured materials that are frequently used as heterogeneous catalysts [9]. In recent years, advancements in instrumentation and data analysis have enabled PDF to become an increasingly valuable tool for the characterization of heterogeneous catalysts [10,11].…”

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confidence: 99%

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Uncovering the Structure of Heterogeneous Catalysts Using Atomic Pair Distribution Function Analysis

Zimmerli

Müller

Abdala

2022

Preprint

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Heterogeneous catalysts are complex materials, often containing multiple atomic species and phases with various degrees of structural order. The identification of structure – performance relationships that rely on the availability of advanced structural characterization tools, is key for a rational catalyst design. Structural descriptors in catalysts can be defined over different length scales from several Å up to several nanometers (crystalline structure), requiring structural characterization techniques covering these different length scales. Pair distribution function (PDF) analysis is a powerful method to extract structural information spanning from the atomic to the nanoscale under in situ or operando conditions. We discuss recent advances using PDF to provide insight into the atomic-to-nanoscale structure of heterogeneous catalysts.

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