Determination of Hafnium Zirconium Oxide Interfacial Band Alignments Using Internal Photoemission Spectroscopy and X-ray Photoelectron Spectroscopy

We show that the degree of oxidation of graphene oxide (GO) can be obtained by using a combination of state-of-the-art ab initio computational modeling and X-ray photoemission spectroscopy (XPS). We show that the shift of the XPS C1s peak relative to pristine graphene, ΔEC1s, can be described with high accuracy by ΔEC1s=A(cO−cl)2+E0, where c0 is the oxygen concentration, A=52.3 eV, cl=0.122, and E0=1.22 eV. Our results demonstrate a precise determination of the oxygen content of GO samples.

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An Insight into Chemistry and Structure of Colloidal 2D-WS2 Nanoflakes: Combined XPS and XRD Study

Nanomaterials ◽

10.3390/nano11081969 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1969

Author(s):

Riccardo Scarfiello ◽

Elisabetta Mazzotta ◽

Davide Altamura ◽

Concetta Nobile ◽

Rosanna Mastria ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Xrd Analysis ◽

Crystal Habit ◽

Phase Identification ◽

X Ray Diffraction ◽

X Ray ◽

Morphological Evaluation ◽

Rational Understanding ◽

Structural Inspection

The surface and structural characterization techniques of three atom-thick bi-dimensional 2D-WS2 colloidal nanocrystals cross the limit of bulk investigation, offering the possibility of simultaneous phase identification, structural-to-morphological evaluation, and surface chemical description. In the present study, we report a rational understanding based on X-ray photoelectron spectroscopy (XPS) and structural inspection of two kinds of dimensionally controllable 2D-WS2 colloidal nanoflakes (NFLs) generated with a surfactant assisted non-hydrolytic route. The qualitative and quantitative determination of 1T’ and 2H phases based on W 4f XPS signal components, together with the presence of two kinds of sulfur ions, S22− and S2−, based on S 2p signal and related to the formation of WS2 and WOxSy in a mixed oxygen-sulfur environment, are carefully reported and discussed for both nanocrystals breeds. The XPS results are used as an input for detailed X-ray Diffraction (XRD) analysis allowing for a clear discrimination of NFLs crystal habit, and an estimation of the exact number of atomic monolayers composing the 2D-WS2 nanocrystalline samples.

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Determination of the valence band edge of Fe oxide nanoparticles dispersed in aqueous solution through resonant photoelectron spectroscopy from a liquid microjet

Nanoscale Advances ◽

10.1039/d1na00275a ◽

2021 ◽

Author(s):

Giorgia Olivieri ◽

Gregor Kladnik ◽

Dean Cvetko ◽

Matthew A. Brown

Keyword(s):

Aqueous Solution ◽

Electronic Structure ◽

Valence Band ◽

Photoelectron Spectroscopy ◽

Band Edge ◽

Photoemission Spectroscopy ◽

Oxide Nanoparticles ◽

Valence Band Edge ◽

Resonant Photoemission

The electronic structure of hydrated nanoparticles can be unveiled by coupling a liquid microjet with a resonant photoemission spectroscopy.

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A Two-step Electrodeposition of Pd-Cu/Cu2O Nanocomposite on FTO Substrate for Non-enzymatic Hydrogen Peroxide Sensor

Current Analytical Chemistry ◽

10.2174/1573411017666210520153409 ◽

2021 ◽

Vol 17 ◽

Author(s):

Ke Huan ◽

Li Tang ◽

Dongmei Deng ◽

Huan Wang ◽

Xiaojing Si ◽

...

Keyword(s):

Hydrogen Peroxide ◽

Cyclic Voltammetry ◽

Photoelectron Spectroscopy ◽

Chemical Structure ◽

Pd Nanoparticles ◽

Optimal Conditions ◽

Potential Oscillation ◽

X Ray Diffraction ◽

X Ray

Background: Hydrogen peroxide (H2O2) is a common reagent in the production and living, but excessive H2O2 may enhance the danger to the human body. Consequently, it is very important to develop economical, fast and accurate techniques for detecting H2O2. Methods: A simple two-step electrodeposition process was applied to synthesize Pd-Cu/Cu2O nanocomposite for non-enzymatic H2O2 sensor. Cu/Cu2O nanomaterial was firstly electrodeposited on FTO by potential oscillation technique, and then Pd nanoparticles were electrodeposited on Cu/Cu2O nanomaterial by cyclic voltammetry. The chemical structure, component, and morphology of the synthesized Pd-Cu/Cu2O nanocomposite were characterized by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. The electrochemical properties of Pd-Cu/Cu2O nanocomposite were studied by cyclic voltammetry and amperometry. Results: Under optimal conditions, the as-fabricated sensor displayed a broad linear range (5-4000 µM) and low detection limit (1.8 µM) for the determination of H2O2. The proposed sensor showed good selectivity and reproducibility. Meanwhile, the proposed sensor has been successfully applied to detect H2O2 in milk. Conclusion: The Pd-Cu/Cu2O/FTO biosensor exhibits excellent electrochemical activity for H2O2 reduction, which has great potential application in the field of food safety.

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Graphitic Nitrogen in Carbon Catalysts Important for the Reduction of Nitrite Revealed by 15N NMR Spectroscopy at Natural Abundance

10.26434/chemrxiv.12906227.v1 ◽

2020 ◽

Author(s):

Zheng Chen ◽

Aleksander Jaworski ◽

Jianhong Chen ◽

Tetyana Budnyak ◽

Ireneusz Szewczyk ◽

...

Keyword(s):

Electron Microscopy ◽

Photoelectron Spectroscopy ◽

Reduction Reaction ◽

Nitrite Reduction ◽

15N Nmr ◽

Carbon Catalyst ◽

X Ray ◽

Wide Range ◽

Alkaline Conditions

Metal-free nitrogen-doped carbon is considered as a green functional material, but the structural determination of the atomic positions of nitrogen remains challenging. We recently demonstrated that directly-excited solid state 15N NMR (ssNMR) spectroscopy is a powerful tool for the determination of such positions in an N-doped carbon at natural 15N isotope abundance. Here we present a green chemistry approach to the synthesis of N-doped carbon using cellulose as precursor, and a study of the catalytic properties and atomic structures of the related catalyst. The N-doped carbon (NH3) was obtained by oxidation of cellulose with HNO3 followed by ammonolysis at 800°C. It had a N content of 6.5 wt.% and a surface area of 557 m2 g–1, and 15N ssNMR spectroscopy provided evidence for graphitic nitrogen besides of regular pyrrolic and pyridinic nitrogen. This structure determination enabled probing the role of graphitic nitrogen for electrocatalytic reactions, such as the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and nitrite reduction reaction. The N-doped carbon catalyst (NH3) had higher electrocatalytic activities in OER and HER under alkaline conditions and a higher activity for nitrite reduction, as compared with a catalyst prepared by carbonization of the HNO3-treated cellulose in N2. The electrocatalytic selectivity for nitrite reduction of the N-doped carbon catalyst (NH3) was directly related to the graphitic nitrogen functions. Complementary structural analysis by means of 13C and 1H ssNMR, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and low-temperature N2 adsorption were preformed and provided support to the findings. The results show that directly-excited 15N ssNMR at natural 15N abundance is generally capable to provide information on N-doped carbon materials, and it is expected that the approach can be applied to a wide range of solids with an intermediate amount of N atoms.

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