Towards advanced structural analysis of iron oxide clusters on the surface of γ-Al2O3 using EXAFS

Boubnov, Alexey; Roppertz, Andreas; Kundrat, Matthew D.; Mangold, Stefan; Резник, Б.; Jacob, Christoph R.; Kureti, Sven; Grunwaldt, Jan‐Dierk

doi:10.1016/j.apsusc.2016.05.148

Cited by 18 publications

(16 citation statements)

References 68 publications

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“…This may be due to the increase in the iron oxide particle size. For the F 5 film, a slightly higher N value of the first coordination sphere and a lower intensity of the pre-edge peak compared to alumina films with higher Fe 2 O 3 concentrations may be due to the embedding of a part of Fe 3+ into the octahedral vacancies of the γ-Al 2 O 3 matrix on its surface . At the same time, the other part of the iron ions is in the form of a disordered oxide.…”

Section: Resultsmentioning

confidence: 94%

Detection and Adsorption of Cr(VI) ions by Mesoporous Fe–Alumina Films

Mikhaylov

Krivoshapkina

Trigub

et al. 2018

ACS Sustainable Chem. Eng.

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The problem of pollution in general and pollution of wastewater in particular is one of the main problems of our time. It is known that compounds of hexavalent chromium (Cr(VI)) are toxic even at low concentrations because of their ability to penetrate through a cell membrane and react with intracellular material. Adsorption is a promising method for wastewater treatment in terms of efficiency and cost. Thus, there is growing interest in the development of both new highly effective adsorbents for Cr(VI) removal and a new, easy-to-use, and fast method for detecting low concentrations of Cr(VI). This work proposes real-time sensor technologies based on mesoporous alumina-iron oxide films to solve both challenges. For these purposes, the microstructure, optical, and Cr(VI) adsorption properties of alumina–iron oxide composite films, as well as the valence state and local environment of iron atoms in the alumina matrix, are studied. A new method for determining the sorption capacity of film materials based on optical spectroscopy data is proposed. Low roughness, varied spectral characteristics, high Cr(VI) adsorption, easy regeneration, and reusability of films make them excellent materials to be used as adsorbents and optical sensors for Cr(VI) determination.

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Section: Resultsmentioning

confidence: 94%

Detection and Adsorption of Cr(VI) ions by Mesoporous Fe–Alumina Films

Mikhaylov

Krivoshapkina

Trigub

et al. 2018

ACS Sustainable Chem. Eng.

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“…The clearest differences are evident in the x-ray absorption near edge spectroscopy (XANES) region (Fig. 8 a), where the spectrum of the phosphate-directed sample aged for just 1 h is characteristic of akagnéite [ 21 ] whereas the phosphate-directed samples aged for 24 h or longer show peak shapes characteristic of hematite [ 22 ]. These differences are also reflected in the Fe K-edge extended x-ray absorption fine structure (EXAFS) Fourier transforms (Fig.…”

Section: Resultsmentioning

confidence: 99%

The Role of Growth Directors in Controlling the Morphology of Hematite Nanorods

et al. 2020

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The control of the growth of hematite nanoparticles from iron chloride solutions under hydrothermal conditions in the presence of two different structure promoters has been studied using a range of both structural and spectroscopic techniques including the first report of photo induced force microscopy (PiFM) to map the topographic distribution of the structure-directing agents on the developing nanoparticles. We show that the shape of the nanoparticles can be controlled using the concentration of phosphate ions up to a limit determined to be~6 × 10 −3 mol. Akaganéite (β-FeOOH) is a major component of the nanoparticles formed in the absence of structure directors but only present in the very early stages (< 8 h) of particle growth when phosphate is present. The PiFM data suggest a correlation between the areas in which phosphate ions are adsorbed and areas where akaganéite persists on the surface. In contrast, goethite (α-FeOOH) is a directly observed precursor of the hematite nanorods when 1,2-diamino propane is present. The PiFM data shows goethite in the center of the developing particles consistent with a mechanism in which the iron hydroxide redissolves and precipitates at the nanorod ends as hematite.

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“…The obtained information on the structure of the active catalyst provides insight into the reaction mechanism at the atomic scale and is a key to improve and validate theoretical modeling efforts of reactions on surfaces (see below). In combination with theory, suggested structures from DFT calculations can be directly evaluated with respect to structures derived from EXAFS spectra and theoretical calculation of spectra enhance the interpretation of XANES and XES spectra . Another promising approach is modulation excitation spectroscopy (MES).…”

Section: In Situ/operando Characterization Techniquesmentioning

confidence: 99%

Moving Frontiers in Transition Metal Catalysis: Synthesis, Characterization and Modeling

et al. 2019

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Nanosized transition metal particles are important materials in catalysis witha key role not only in academic research but also in many processes with industrial and societal relevance. Although small improvements in catalytic properties can lead to significant economic and environmental impacts, it is only now that knowledge-based design of such materials is emerging, partly because the understanding of catalytic mechanisms on nanoparticle surfaces is increasingly improving. A knowledge-based design requires bottom-up synthesis of well-defined model catalysts, an understanding of the catalytic nanomaterials "at work" (operando), and both a detailed understanding and a prediction by theoretical methods. This article reports on progress in colloidal synthesis of transition metal nanoparticles for preparation of model catalysts to close the materials gap between the discoveries of fundamental surface science and industrial application. The transition metal particles, however, often undergo extensive transformations when applied to the catalytic process and much progress has recently been achieved operando characterization techniques under relevant reaction conditions. They allow better understanding of size/structure-activity correlations in these systems. Moreover, the growth of computing power and the improvement of theoretical methods uncover mechanisms on nanoparticles and have recently predicted highly active particles for CO/CO 2 hydrogenation or direct H 2 O 2 synthesis.

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Towards advanced structural analysis of iron oxide clusters on the surface of γ-Al2O3 using EXAFS

Cited by 18 publications

References 68 publications

Detection and Adsorption of Cr(VI) ions by Mesoporous Fe–Alumina Films

Detection and Adsorption of Cr(VI) ions by Mesoporous Fe–Alumina Films

The Role of Growth Directors in Controlling the Morphology of Hematite Nanorods

Moving Frontiers in Transition Metal Catalysis: Synthesis, Characterization and Modeling

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