Topic
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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TL;DR: In this paper, the cobalt phosphate oxygen evolving catalyst (OEC) was photochemically grown on the surface of TiO2 photoanodes short-circuited to a Pt wire under bandgap illumination in the presence of Co(NO3)2 and NaPi buffer.
Abstract: The cobalt phosphate “CoPi” oxygen evolving catalyst (OEC) was photochemically grown on the surface of TiO2 photoanodes short-circuited to a Pt wire under bandgap illumination in the presence of Co(NO3)2 and sodium phosphate (NaPi) buffer. Extended photodeposition (15 h) using a hand-held UV lamp readily permitted quantitative structural and electrochemical characterization of the photochemically deposited CoPi OEC on titania. The formed catalytic material was characterized by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy experiments, illustrating the production of easily visualized micrometer scale clusters throughout the titania surface containing both cobalt and phosphate. X-ray absorption fine structure (XAFS) and X-ray absorption near edge structure (XANES) studies indicated that the newly formed material was structurally consistent with the production of molecular cobaltate clusters composed of a cobalt oxide core that is most likely terminated by phosphate ions. ...
55 citations
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TL;DR: In this paper, the sensitivity of near-edge X-ray absorption fine structure (NEXAFS) spectroscopy to Bronsted donation and the protonation state of nitrogen in the solid state is investigated through a series of multicomponent bipyridine-acid systems alongside XPS data.
Abstract: The sensitivity of near-edge X-ray absorption fine structure (NEXAFS) spectroscopy to Bronsted donation and the protonation state of nitrogen in the solid state is investigated through a series of multicomponent bipyridine–acid systems alongside X-ray photoelectron spectroscopy (XPS) data. A large shift to high energy occurs for the 1s → 1π* resonance in the nitrogen K-edge NEXAFS with proton transfer from the acid to the bipyridine base molecule and allows assignment as a salt (C═NH+), with the peak ratio providing the stoichiometry of the types of nitrogen species present. A corresponding binding energy shift for C═NH+ is observed in the nitrogen XPS, clearly identifying protonation and formation of a salt. The similar magnitude shifts observed with both techniques relative to the unprotonated nitrogen of co-crystals (C═N) suggest that the chemical state (initial-state) effects dominate. Results from both techniques reveal the sensitivity to identify proton transfer, hydrogen bond disorder, and even the...
55 citations
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TL;DR: Electrical measurements showed that the Co dopants not only enhanced the sensor response at low ozone levels but also led to a decrease in the operating temperature and improved selectivity.
Abstract: A detailed study of the structural, surface, and gas-sensing properties of nanostructured CoxZn1-xO films is presented. X-ray diffraction (XRD) analysis revealed a decrease in the crystallization degree with increasing Co content. The X-ray absorption near-edge structure (XANES) and X-ray photoelectron spectroscopies (XPS) revealed that the Co2+ ions preferentially occupied the Zn2+ sites and that the oxygen vacancy concentration increased as the amount of cobalt increased. Electrical measurements showed that the Co dopants not only enhanced the sensor response at low ozone levels (ca. 42 ppb) but also led to a decrease in the operating temperature and improved selectivity. The enhancement in the gas-sensing properties was attributed to the presence of oxygen vacancies, which facilitated ozone adsorption.
55 citations
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TL;DR: In this article, Nanocrystalline Ni Zn ferrites were synthesized by a novel and facile chemical method via a polymer precursor and their structural and magnetic properties were evaluated and discussed in correlation with the cationic distribution.
55 citations
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TL;DR: The early stage of barium titanate (BaTiO3) nanoparticle formation was investigated by in situ X-ray diffraction (XRD) and Xray absorption near-edge structure (XANES) using synchrotron radiation as discussed by the authors.
Abstract: The early stage of barium titanate (BaTiO3) nanoparticle formation is investigated by in situ X-ray diffraction (XRD) and X-ray absorption near-edge structure (XANES) using synchrotron radiation. BaTiO3 nanoparticles are synthesized via dissolution of barium hydroxide octahydrate and hydrolysis of titanium (IV) isopropoxide in isopropanol. In the course of raising the temperature of the alkoxide–hydroxide mixture solution to 80°C, in situ synchrotron XRD reveals that BaTiO3 nanocrystals smaller than 6 nm begin to nucleate at 50°C without intermediate TiO2 anatase formation, and Ti K edge absorption spectra also confirm the formation of corner-sharing TiO6 octahedra at 60°C. The average size of BaTiO3 precipitates increases to about 7.5 nm at 80°C. The synthesized nanopowders show an anomalously high tetragonality according to the Rietveld refinement of synchrotron XRD data.
55 citations