scholarly journals Интеркалирование графена, сформированного на карбиде кремния, атомами железа

2018 ◽  
Vol 60 (7) ◽  
pp. 1423
Author(s):  
М.В. Гомоюнова ◽  
Г.С. Гребенюк ◽  
В.Ю. Давыдов ◽  
И.А. Ермаков ◽  
И.А. Елисеев ◽  
...  
Keyword(s):  
Buffer Layer ◽  
Photoelectron Spectroscopy ◽  
Chemical Interaction ◽  
High Energy ◽  
High Energy Resolution ◽  
Iron Film ◽  
Graphene Monolayer ◽  
X Ray Absorption ◽  
Layer Coating

AbstractThe intercalation of iron under a graphene monolayer grown on 4 H -SiC(0001) is studied. The experiments have been carried out in situ under conditions of ultrahigh vacuum by low-energy electron diffraction, high-energy-resolution photoelectron spectroscopy using synchrotron radiation, and near carbon K -edge X-ray absorption spectroscopy. The deposited iron film thicknesses have been varied within 0.1–2 nm and the sample temperatures from room temperature to 700°C. It is shown that the intercalation process begins at temperatures higher than ~350°C. In this case, it is found that intercalated iron atoms are localized not only between graphene and a buffer layer coating SiC, but also under the buffer layer itself. The optimal conditions of the intercalation are realized in the range 400–500°C, because, at higher temperatures, the system becomes unstable due to the chemical interaction of the intercalated iron with silicon carbide. The inertness of the intercalated films to action of oxygen is demonstrated.

scholarly journals High-energy resolution X-ray absorption and emission spectroscopy reveals insight into unique selectivity of La-based nanoparticles for CO2

2015 ◽  
Vol 112 (52) ◽  
pp. 15803-15808 ◽  
Author(s):  
Ofer Hirsch ◽  
Kristina O. Kvashnina ◽  
Li Luo ◽  
Martin J. Süess ◽  
Pieter Glatzel ◽  
...  
Keyword(s):  
Energy Resolution ◽  
Emission Spectroscopy ◽  
High Energy ◽  
Unit Cell ◽  
High Energy Resolution ◽  
Electron Configuration ◽  
Edge Structure ◽  
X Ray ◽  
X Ray Absorption

The lanthanum-based materials, due to their layered structure and f-electron configuration, are relevant for electrochemical application. Particularly, La2O2CO3 shows a prominent chemoresistive response to CO2. However, surprisingly less is known about its atomic and electronic structure and electrochemically significant sites and therefore, its structure–functions relationships have yet to be established. Here we determine the position of the different constituents within the unit cell of monoclinic La2O2CO3 and use this information to interpret in situ high-energy resolution fluorescence-detected (HERFD) X-ray absorption near-edge structure (XANES) and valence-to-core X-ray emission spectroscopy (vtc XES). Compared with La(OH)3 or previously known hexagonal La2O2CO3 structures, La in the monoclinic unit cell has a much lower number of neighboring oxygen atoms, which is manifested in the whiteline broadening in XANES spectra. Such a superior sensitivity to subtle changes is given by HERFD method, which is essential for in situ studying of the interaction with CO2. Here, we study La2O2CO3-based sensors in real operando conditions at 250 °C in the presence of oxygen and water vapors. We identify that the distribution of unoccupied La d-states and occupied O p- and La d-states changes during CO2 chemoresistive sensing of La2O2CO3. The correlation between these spectroscopic findings with electrical resistance measurements leads to a more comprehensive understanding of the selective adsorption at La site and may enable the design of new materials for CO2 electrochemical applications.

scholarly journals Wetting Induced Oxidation of Pt-based Nano Catalysts Revealed by In Situ High Energy Resolution X-ray Absorption Spectroscopy

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Yi-Tao Cui ◽  
Yoshihisa Harada ◽  
Hideharu Niwa ◽  
Tatsuya Hatanaka ◽  
Naoki Nakamura ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Energy Resolution ◽  
High Energy ◽  
High Energy Resolution ◽  
X Ray ◽  
Nano Catalysts ◽  
X Ray Absorption

scholarly journals Electrochemical Adsorption on Pt Nanoparticles in Alkaline Solution Observed Using In Situ High Energy Resolution X-ray Absorption Spectroscopy

Nanomaterials ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 642 ◽  
Author(s):  
Shogo Kusano ◽  
Daiju Matsumura ◽  
Kenji Ishii ◽  
Hirohisa Tanaka ◽  
Jun’ichiro Mizuki
Keyword(s):  
Absorption Spectroscopy ◽  
Energy Resolution ◽  
Alkaline Solution ◽  
Superoxide Anion ◽  
Atomic Oxygen ◽  
High Energy ◽  
High Energy Resolution ◽  
X Ray ◽  
X Ray Absorption

The oxygen reduction reaction (ORR) on Pt/C in alkaline solution was studied by in situ high energy resolution X-ray absorption spectroscopy. To discuss the X-ray absorption near-edge structure (XANES), this paper introduced the rate of change of the Δμ (RCD), which is an analysis method that is sensitive to surface adsorption. The surface adsorptions as hydrogen (below 0.34 V), superoxide anion (from 0.34 V to 0.74 V), hydroxyl species (from 0.44 V to 0.74 V), atomic oxygen (above 0.74 V), and α-PtO2 (above 0.94 V) were distinguished. It is clarified that the catalytic activity in an alkaline solution is enhanced by the stability of atomic oxygen and the low stability of superoxide anion/peroxide adsorption on the platinum surface.

scholarly journals Интеркаляционный синтез силицидов кобальта под графеном, выращенным на карбиде кремния

2020 ◽  
Vol 62 (3) ◽  
pp. 462
Author(s):  
Г.С. Гребенюк ◽  
И.А. Елисеев ◽  
С.П. Лебедев ◽  
Е.Ю. Лобанова ◽  
Д.А. Смирнов ◽  
...  
Keyword(s):  
Buffer Layer ◽  
Photoelectron Spectroscopy ◽  
Single Layer ◽  
High Energy ◽  
Single Layer Graphene ◽  
High Energy Resolution ◽  
Kelvin Probe ◽  
Layer Graphene ◽  
Atomic Force ◽  
Cobalt Silicides

Abstract The process of formation of cobalt silicides near the graphene-silicon carbide interface by intercalation of single-layer graphene grown on the 4 H - and 6 H -SiC(0001) polytypes with cobalt and silicon is studied. The experiments were carried out in situ in ultrahigh vacuum. The analysis of the samples is performed by high-energy-resolution photoelectron spectroscopy using synchrotron radiation, low-energy electron diffraction, and also Raman spectroscopy, atomic-force and kelvin-probe microscopies. The thicknesses of the deposited cobalt and silicon layers is varied to 2 nm, and the sample temperature, from room temperature to 1000°C. Co and Si atoms deposited on heated samples is found to penetrate under graphene and are localized between the buffer layer and the substrate, which leads to a transformation of the buffer layer into additional graphene layer. It is shown that the result of intercalation of the system with cobalt and silicon is the formation under two-layer graphene of a Co–Si solid solution and silicide CoSi coated by the surface Co_3Si phase. It is shown that the thickness and the composition of the formed silicide films can be changed by varying the amount of the intercalated material and the order of their depositions.

In-situ high-energy-resolution X-ray absorption spectroscopy for UO2 oxidation at SSRF

2016 ◽  
Vol 28 (1) ◽  
Author(s):  
Pei-Quan Duan ◽  
Hong-Liang Bao ◽  
Jiong Li ◽  
Han-Jie Cao ◽  
Yu-Ying Huang
Keyword(s):  
Absorption Spectroscopy ◽  
Energy Resolution ◽  
High Energy ◽  
High Energy Resolution ◽  
X Ray ◽  
Uo2 Oxidation ◽  
X Ray Absorption

scholarly journals Интеркалирование графена на карбиде кремния кобальтом

2019 ◽  
Vol 61 (7) ◽  
pp. 1374
Author(s):  
Г.С. Гребенюк ◽  
Е.Ю. Лобанова ◽  
Д.А. Смирнов ◽  
И.А. Елисеев ◽  
А.В. Зубов ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Chemical Interaction ◽  
Single Layer ◽  
High Energy ◽  
Single Layer Graphene ◽  
High Energy Resolution ◽  
Cobalt Films ◽  
Cobalt Silicides

AbstractIn this paper, we studied cobalt intercalation of single-layer graphene grown on the 4 H -SiC(0001) polytype. The experiments were carried out in situ under ultrahigh vacuum conditions by high energy resolution photoelectron spectroscopy using synchrotron radiation and low energy electron diffraction. The nominal thicknesses of the deposited cobalt layers varied in the range of 0.2–5 nm, while the sample temperature was varied from room temperature to 800°C. Unlike Fe films, the annealing of Co films deposited on graphene at room temperature is shown to not intercalate graphene by cobalt. The formation of the graphene–cobalt–SiC intercalation system was detected upon deposition of Co atoms on samples heated to temperatures of above ~400°C. Cobalt films with a thickness up to 2 nm under graphene are formed using this method, and they are shown to be magnetized along the surface at thicknesses of greater than 1.3 nm. Graphene intercalation by cobalt was found to be accompanied by the chemical interaction of Co atoms with silicon carbide leading to the synthesis of cobalt silicides. At temperatures of above 500°C, the growth of cobalt films under graphene is limited by the diffusion of Co atoms into the bulk of silicon carbide.

Sign in / Sign up

Export Citation Format

Share Document