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XANES

About: XANES is a research topic. Over the lifetime, 7737 publications have been published within this topic receiving 188032 citations.


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Journal ArticleDOI
TL;DR: XANES of vanadium and niobium oxide on silica or alumina have been analyzed quantitatively by a deconvolution technique as discussed by the authors, based on the results for reference compounds.
Abstract: XANES of vanadium and niobium oxide on silica or alumina have been analyzed quantitatively by a deconvolution technique. Based on the results for reference compounds, local structures of supported vanadium and niobium species were identified. The composition was estimated from difference spectra for the samples which consisted of two kinds of species.

97 citations

Journal ArticleDOI
D. Trong On1, Laurent Bonneviot1, A. Bittar1, A. Sayari1, Serge Kaliaguine1 
TL;DR: In this article, three titanium silicalite samples with MEL structure and different Ti loadings have been examined by Near-Edge and Extended X-ray Absorption Fine Structure techniques.

97 citations

Journal ArticleDOI
TL;DR: In this paper , the as-fabricated Ni cationic vacancies (VNi)−enriched Ni2−xP−VNi electrocatalyst exhibits remarkable 2e ORR performance with H2O2 molar fraction of >95% and Faradaic efficiencies of >90% in all pH conditions under a wide range of applied potentials.
Abstract: Electrocatalytic hydrogen peroxide (H2O2) synthesis via the two‐electron oxygen reduction reaction (2e ORR) pathway is becoming increasingly important due to the green production process. Here, cationic vacancies on nickel phosphide, as a proof‐of‐concept to regulate the catalyst's physicochemical properties, are introduced for efficient H2O2 electrosynthesis. The as‐fabricated Ni cationic vacancies (VNi)‐enriched Ni2−xP‐VNi electrocatalyst exhibits remarkable 2e ORR performance with H2O2 molar fraction of >95% and Faradaic efficiencies of >90% in all pH conditions under a wide range of applied potentials. Impressively, the as‐created VNi possesses superb long‐term durability for over 50 h, suppassing all the recently reported catalysts for H2O2 electrosynthesis. Operando X‐ray absorption near‐edge spectroscopy (XANES) and synchrotron Fourier transform infrared (SR‐FTIR) combining theoretical calculations reveal that the excellent catalytic performance originates from the VNi‐induced geometric and electronic structural optimization, thus promoting oxygen adsorption to the 2e ORR favored “end‐on” configuration. It is believed that the demonstrated cation vacancy engineering is an effective strategy toward creating active heterogeneous catalysts with atomic precision.

96 citations

Journal ArticleDOI
TL;DR: In this paper, the authors explored the oxidation/dissolution of Pt and Pt monolayer (ML) electrocatalysts over a wide range of applied potentials using cells that facilitate in situ measurements by combining X-ray absorption spectroscopy (XAS) and Xray diffraction (XRD) measurements.
Abstract: A detailed understanding of oxidation/dissolution mechanisms of Pt is critical in designing durable catalysts for the oxygen reduction reaction (ORR), but exact mechanisms remain unclear. The present work explores the oxidation/dissolution of Pt and Pt monolayer (ML) electrocatalysts over a wide range of applied potentials using cells that facilitate in situ measurements by combining X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) measurements. The X-ray absorption near edge structure (XANES) measurement demonstrated that Pt nanoparticle surfaces were oxidized from metallic Pt to α-PtO2-type oxide during the potential sweep from 0.41 to 1.5 V, and the transition state of O or OH adsorption on Pt and the onset of the place exchange process were revealed by the delta mu (Δμ) method. Only the top layers of Pt nanoparticles were oxidized, while the inner Pt atoms remained intact. At a higher potential over 1.9 V, α-PtO2-type surface oxides dissolve due to local acidification caused by the oxyg...

96 citations

Journal ArticleDOI
TL;DR: In this article, the authors investigated the electrochemical mechanism leading to the pseudocapacitance of MnFe 2 O 4 in aqueous electrolyte solutions and concluded that charge transfer at both the Mn- and Fe-ion sites, balanced by insertion/extraction of proton into/from the lattice.
Abstract: The electrochemical mechanism leading to the pseudocapacitance of MnFe 2 O 4 in aqueous electrolyte solutions has been investigated by, in addition to electrochemical characterization, synchrotron X-ray absorption near-edge spectroscopy (XANES) and X-ray diffraction (XRD) analyses using KCl solution as the model electrolyte. The ferrite crystallites, prepared by a solution method, contain Mn and Fe ions randomly distributed over the tetrahedral and octahedral sites of the spinel structure and exhibit an average capacitance exceeding 100 F/g-ferrite. Based on the data from the in situ XANES and XRD measurements and open-circuit-potential dependence on solution pH, it is concluded that the pseudocapacitance of MnFe 2 O 4 involves charge transfer at both the Mn- and Fe-ion sites, balanced by insertion/extraction of proton into/from the lattice. In addition, compared with MnO 2 -nH 2 O electrode, the ferrite exhibits a far reduced, by ∼90%, lattice expansion upon cycling.

96 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023186
2022403
2021212
2020232
2019242
2018256