scholarly journals Domino Reaction for the Sustainable Functionalization of Few-Layer Graphene

Nanomaterials ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 44 ◽  
Author(s):  
Vincenzina Barbera ◽  
Luigi Brambilla ◽  
Alberto Milani ◽  
Alberto Palazzolo ◽  
Chiara Castiglioni ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Cycloaddition Reaction ◽  
Domino Reaction ◽  
Thermal Treatments ◽  
X Rays ◽  
Xps Spectra ◽  
Graphene Layers ◽  
Ft Ir ◽  
Bulk Structure

The mechanism for the functionalization of graphene layers with pyrrole compounds was investigated. Liquid 1,2,5-trimethylpyrrole (TMP) was heated in air in the presence of a high surface area nanosized graphite (HSAG), at temperatures between 80 °C and 180 °C. After the thermal treatments solid and liquid samples, separated by centrifugation, were analysed by means of Raman, Fourier Transform Infrared (FT-IR) spectroscopy, X-Rays Photoelectron Spectroscopy (XPS) and 1H-Nuclear Magnetic Resonance (1H NMR) spectroscopy and High Resolution Transmission Electron Microscopy (HRTEM). FT-IR spectra were interpreted with the support of Density Functional Theory (DFT) quantum chemical modelling. Raman findings suggested that the bulk structure of HSAG remained substantially unaltered, without intercalation products. FT-IR and XPS spectra showed the presence of oxidized TMP derivatives on the solid adducts, in a much larger amount than in the liquid. For thermal treatments at T ≥ 150 °C, IR spectral features revealed not only the presence of oxidized products but also the reaction of intra-annular double bond of TMP with HSAG. XPS spectroscopy showed the increase of the ratio between C(sp2)N bonds involved in the aromatic system and C(sp3)N bonds, resulting from reaction of the pyrrole moiety, observed while increasing the temperature from 130 °C to 180 °C. All these findings, supported by modeling, led to hypothesize a cascade reaction involving a carbocatalyzed oxidation of the pyrrole compound followed by Diels-Alder cycloaddition. Graphene layers play a twofold role: at the early stages of the reaction, they behave as a catalyst for the oxidation of TMP and then they become the substrate for the cycloaddition reaction. Such sustainable functionalization, which does not produce by-products, allows us to use the pyrrole compounds for decorating sp2 carbon allotropes without altering their bulk structure and smooths the path for their wider application.

scholarly journals An estimation on the mechanical stabilities of SAMs by low energy Ar+ cluster ion collision

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Y. Tong ◽  
G. R. Berdiyorov ◽  
A. Sinopoli ◽  
M. E. Madjet ◽  
V. A. Esaulov ◽  
...  
Keyword(s):  
Electron Irradiation ◽  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Crystal Surface ◽  
Depth Profiling ◽  
Low Energy ◽  
Cross Linking ◽  
Xps Spectra ◽  
Self Assembled ◽  
The Stability

AbstractThe stability of the molecular self-assembled monolayers (SAMs) is of vital importance to the performance of the molecular electronics and their integration to the future electronics devices. Here we study the effect of electron irradiation-induced cross-linking on the stability of self-assembled monolayer of aromatic 5,5′-bis(mercaptomethyl)-2,2′-bipyridine [BPD; HS-CH2-(C5H3N)2-CH2-SH] on Au (111) single crystal surface. As a refence, we also study the properties of SAMs of electron saturated 1-dodecanethiol [C12; CH3-(CH2)11-SH] molecules. The stability of the considered SAMs before and after electron-irradiation is studied using low energy Ar+ cluster depth profiling monitored by recording the X-ray photoelectron spectroscopy (XPS) core level spectra and the UV-photoelectron spectroscopy (UPS) in the valance band range. The results indicate a stronger mechanical stability of BPD SAMs than the C12 SAMs. The stability of BPD SAMs enhances further after electron irradiation due to intermolecular cross-linking, whereas the electron irradiation results in deterioration of C12 molecules due to the saturated nature of the molecules. The depth profiling time of the cross-linked BPD SAM is more than 4 and 8 times longer than the profiling time obtained for pristine and BPD and C12 SAMs, respectively. The UPS results are supported by density functional theory calculations, which show qualitative agreement with the experiment and enable us to interpret the features in the XPS spectra during the etching process for structural characterization. The obtained results offer helpful options to estimate the structural stability of SAMs which is a key factor for the fabrication of molecular devices.

Preparation and Characterization of Ni2+-Montmorillonite/Polyvinyl Alcohol Water-Soluble Nanocomposite Film

2005 ◽  
Vol 13 (8) ◽  
pp. 839-846 ◽  
Author(s):  
Li-Ping Wang ◽  
Yun-Pu Wang ◽  
Fa-Ai Zhang
Keyword(s):  
Polyvinyl Alcohol ◽  
Photoelectron Spectroscopy ◽  
Thermal Characteristics ◽  
Water Soluble ◽  
Scanning Calorimetry ◽  
Xps Spectra ◽  
X Ray ◽  
Alcohol Water ◽  
Ft Ir ◽  
Silicate Layers

A new type of nano-composite film was prepared from polyvinyl alcohol, Ni2+-montmorillonite (Ni2+-MMT), defoamer, a levelling agent and a plasticizer. Its thermal characteristics were studied by Differential Scanning Calorimetry (DSC). The intermolecular interactions were measured by Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS), and the tensile strength (TS) and elongation at break (%E) were measured. The microstructures were studied by X-ray diffraction (XRD) and atomic force microscopy (AFM). FT-IR and XPS spectra indicated that cross-linking has taken place between PVA and Ni2+-MMT. XRD and AFM indicate that the PVA molecules had inserted themselves into the silicate layers of MMT, exfoliating them and dispersing them randomly into the PVA matrix. Compared to pure PVA film, the TS of the films was increased and %E decreased when the Ni2+-Montmorillonite was added and the dissolution temperature of the film was also reduced.

scholarly journals Magnetic Properties and the Electronic Structure of the Gd0.4Tb0.6Co2 Compound

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5481
Author(s):  
Marcin Sikora ◽  
Anna Bajorek ◽  
Artur Chrobak ◽  
Józef Deniszczyk ◽  
Grzegorz Ziółkowski ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Magnetic Measurements ◽  
Plane Waves ◽  
Full Potential ◽  
Theory Approach ◽  
Xps Spectra

We report on the comprehensive experimental and theoretical studies of magnetic and electronic structural properties of the Gd0.4Tb0.6Co2 compound crystallization in the cubic Laves phase (C15). We present new results and compare them to those reported earlier. The magnetic study was completed with electronic structure investigations. Based on magnetic isotherms, magnetic entropy change (ΔSM) was determined for many values of the magnetic field change (Δμ0H), which varied from 0.1 to 7 T. In each case, the ΔSM had a maximum around room temperature. The analysis of Arrott plots supplemented by a study of temperature dependency of Landau coefficients revealed that the compound undergoes a magnetic phase transition of the second type. From the M(T) dependency, the exchange integrals between rare-earth R-R (JRR), R-Co (JRCo), and Co-Co (JCoCo) atoms were evaluated within the mean-field theory approach. The electronic structure was determined using the X-ray photoelectron spectroscopy (XPS) method as well as by calculations using the density functional theory (DFT) based Full Potential Linearized Augmented Plane Waves (FP-LAPW) method. The comparison of results of ab initio calculations with the experimental data indicates that near TC the XPS spectrum collects excitations of electrons from Co3d states with different values of exchange splitting. The values of the magnetic moment on Co atoms determined from magnetic measurements, estimated from the XPS spectra, and results from ab initio calculations are quantitatively consistent.

Theoretical core spectroscopy of molecules interacting with ice surfaces 

2021 ◽  
Author(s):  
Richard Asamoah Opoku
Keyword(s):  
Electronic Properties ◽  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Trace Gases ◽  
Binding Energies ◽  
Photoelectron Spectra ◽  
Development Fund ◽  
Xps Spectra ◽  
The Core ◽  
Ice Surfaces

<p><strong>Céline TOUBIN</strong><strong><sup>2</sup></strong><strong> and </strong><strong>André Severo Pereira GOMES</strong><strong><sup> 3</sup></strong></p><p><sup>2,3</sup> Laboratoire de Physique des Lasers, des atomes et des Molécules, Université de Lille, Cité Scientifique, 59655 Villeneuve d’Ascq Cedex, France</p><p>E-mail : [email protected]<sup>2</sup> ; [email protected]<sup>3</sup></p><p>Ice plays an essential role as a catalyst for reactions between atmospheric trace gases. The uptake of trace gases to ice has been proposed to have a major impact on geochemical cycles, human health, and ozone depletion in the stratosphere [1]. X-ray photoelectron spectroscopy (XPS) [2], serves as a powerful technique to characterize the elemental composition of such interacting species due to its surface sensitivity. Given the existence of complex physico-chemical processes such as adsorption, desorption, and migration within ice matrix, it is important to establish a theoretical framework to determine the electronic properties of these species under different conditions such as temperature and concentration. The focus of this work is to construct an embedding methodology employing Density Functional (DFT) and Wave Function Theory (WFT) to model and interpret photoelectron spectra of adsorbed halogenated species on ice surfaces at the core level with the highest accuracy possible. </p><p>We make use of an embedding approach utilizing full quantum mechanics to divide the system into subunits that will be treated at different levels of theory [3].</p><p>The goal is to determine core electron binding energies and the associated chemical shifts for the adsorbed halogenated species such as molecular HCl and the dissociated form Cl- at the surface and within the uppermost bulk layer of the ice respectively [4]. The core energy shifts are compared to the data derived from the XPS spectra [4].</p><p>We show that the use of a fully quantum mechanical embedding method, to treat solute-solvent systems is computationally efficient, yet accurate enough to determine the electronic properties of the solute system (halide ion) as well as the long-range effects of the solvent environment (ice).</p><p>We acknowledge support by the French government through the Program “Investissement d'avenir” through the Labex CaPPA (contract ANR-11-LABX-0005-01) and I-SITE ULNE project OVERSEE (contract ANR-16-IDEX-0004), CPER CLIMIBIO (European Regional Development Fund, Hauts de France council, French Ministry of Higher Education and Research) and French national supercomputing facilities (grants DARI x2016081859 and A0050801859).</p><p> </p>

scholarly journals Aggregation-Induced Emission Luminogen: The New Perspective in Photo-Degradation of Organic Pollution

2019 ◽  
Author(s):  
Xing Feng ◽  
Ying Li ◽  
Zhen Hu ◽  
Qingsong Wang ◽  
mengsi chem ◽  
...  
Keyword(s):  
Organic Pollutants ◽  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Degradation Products ◽  
Rapid Development ◽  
Organic Pollution ◽  
High Definition ◽  
Photo Degradation ◽  
Xps Spectra ◽  
Aggregation Induced Emission

<p>Both the variety and uniqueness of organic semiconductors has contributed to the rapid development of environmental engineering applications and renewable fuel production, typified by photo-degradation of organic pollutants or water splitting. This paper presents a rare example of an aggregation-induced emission luminogen (AIEgen) as a highly efficient photo-catalyst for pollutant decomposition in an environmentally relevant application. Under irradiation, the tetraphenylethene-based AIEgen (TPE-Ca) exhibited high photo-degradation efficiency of up to 98.7% of Rhodaminein (RhB) in aqueous solution. The possible photocatalytic mechanism was studied by electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS) spectra, electrochemistry, thermal imaging technology, ultra-performance liquid chromatography and high-definition mass spectrometry (UPLC/HDMS), as well as by density functional theory (DFT) calculations. Cytotoxicity experiments indicated that the final photo-catalytic degradation products show biocompatibility. Among the many diverse AIEgens, this is the first AIEgen to be developed as a photo-catalyster of organic pollutants. This research will open up new avenues for AIEgens research, particularly for applications of environmental relevance.</p>

Epitaxial Graphene Elaborated on 3C-SiC(111)/Si Epilayers

2010 ◽  
Vol 645-648 ◽  
pp. 585-588 ◽  
Author(s):  
Abdelkarim Ouerghi ◽  
Marc Portail ◽  
A. Kahouli ◽  
L. Travers ◽  
Thierry Chassagne ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Low Cost ◽  
Near Field ◽  
Silicon Substrates ◽  
Xps Spectra ◽  
X Ray ◽  
Graphene Layers ◽  
Surface Reconstructions ◽  
High Level ◽  
Modification Of The Surface

This article explores the formation of graphene layers on 3C-SiC(111) epilayers grown on silicon substrates using thermal annealing under Ultra High Vaccum (UHV) environment. The formation of graphene is demonstrated by use of near field microscopy (STM and AFM) and X-ray Photoelectron Spectroscopy (XPS). The evolution of the surface stoichiometry of the 3C-SiC(111) pseudo substrates during the graphitization process is similar to that of the commonly used Si terminated -SiC bulk substrates, starting from a Si rich to the C rich surface characterized by a diffraction pattern. Graphitization process leads to a strong modification of the surface at a microscopic scale which is compared to that reported in case of 6H-SiC substrates. XPS spectra reveal the presence of typical C-C bonds related to a graphitic arrangement. Its high level of ordering is attested by the observation both of (66)SiC and (11)graphene surface reconstructions by STM. These results demonstrate the formation of graphene on 3C-SiC(111)/Si pseudo substrates. They open perspectives for developing novel C/SiC/Si heterostructures and put light on the ability of 3C-SiC/Si templates to become a low cost alternative of onerous -SiC substrates.

Mechano-Chemical Modification of Nanodiamond with GW

2008 ◽  
Vol 375-376 ◽  
pp. 87-91
Author(s):  
Yong Wei Zhu ◽  
Xiang Yang Xu ◽  
Bai Chun Wang ◽  
Jian Liang Shen
Keyword(s):  
Fourier Transform ◽  
Chemical Modification ◽  
Photoelectron Spectroscopy ◽  
Silane Coupling Agent ◽  
Xps Spectra ◽  
X Ray ◽  
Silane Coupling ◽  
Before And After ◽  
New Type ◽  
Ft Ir

Mechano-chemical modification (MCM) of nanodiamond was conducted with a stirring mill. A new type of silane coupling agent, GW was chosen as its modifier. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) were employed to study the surface properties of nanodiamond before and after treatments. Results showed that the peaks related to GW and the ball (for example, Fe, Si and Cl) appeared obviously after its MCM on their XPS spectra and mostly disappeared after its further purification with acid X or Y. A new peak located at 1382.48cm-1 was very strong after further purification. It was proven by their FT-IR spectra.

scholarly journals Aggregation-Induced Emission Luminogen: The New Perspective in Photo-Degradation of Organic Pollution

2019 ◽  
Author(s):  
Xing Feng ◽  
Ying Li ◽  
Zhen Hu ◽  
Qingsong Wang ◽  
mengsi chem ◽  
...  
Keyword(s):  
Organic Pollutants ◽  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Degradation Products ◽  
Rapid Development ◽  
Organic Pollution ◽  
High Definition ◽  
Photo Degradation ◽  
Xps Spectra ◽  
Aggregation Induced Emission

<p>Both the variety and uniqueness of organic semiconductors has contributed to the rapid development of environmental engineering applications and renewable fuel production, typified by photo-degradation of organic pollutants or water splitting. This paper presents a rare example of an aggregation-induced emission luminogen (AIEgen) as a highly efficient photo-catalyst for pollutant decomposition in an environmentally relevant application. Under irradiation, the tetraphenylethene-based AIEgen (TPE-Ca) exhibited high photo-degradation efficiency of up to 98.7% of Rhodaminein (RhB) in aqueous solution. The possible photocatalytic mechanism was studied by electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS) spectra, electrochemistry, thermal imaging technology, ultra-performance liquid chromatography and high-definition mass spectrometry (UPLC/HDMS), as well as by density functional theory (DFT) calculations. Cytotoxicity experiments indicated that the final photo-catalytic degradation products show biocompatibility. Among the many diverse AIEgens, this is the first AIEgen to be developed as a photo-catalyster of organic pollutants. This research will open up new avenues for AIEgens research, particularly for applications of environmental relevance.</p>

scholarly journals Combined DFT and XPS Investigation of Cysteine Adsorption on the Pyrite (1 0 0) Surface

Minerals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 366 ◽  
Author(s):  
Xingfu Zheng ◽  
Xuan Pan ◽  
Zhenyuan Nie ◽  
Yi Yang ◽  
Lizhu Liu ◽  
...  
Keyword(s):  
First Principles ◽  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Interaction Mechanism ◽  
Energy Calculation ◽  
Ionic Bond ◽  
Frontier Orbitals ◽  
Functional Theory ◽  
Xps Spectra ◽  
X Ray

The adsorption of cysteine on the pyrite (1 0 0) surface was evaluated by using first-principles-based density functional theory (DFT) and X-ray photoelectron spectroscopy (XPS) measurements. The frontier orbitals analyses indicate that the interaction of cysteine and pyrite mainly occurs between HOMO of cysteine and LUMO of pyrite. The adsorption energy calculation shows that the configuration of the -OH of -COOH adsorbed on the Fe site is the thermodynamically preferred adsorption configuration, and it is the strongest ionic bond according to the Mulliken bond populations. As for Fe site mode, the electrons are found transferred from cysteine to Fe of pyrite (1 0 0) surface, while there is little or no electron transfer for S site mode. Projected density of states (PDOS) is analyzed further in order to clarify the interaction mechanism between cysteine and the pyrite (1 0 0) surface. After that, the presence of cysteine adsorption on the pyrite (1 0 0) surface is indicated by the qualitative results of the XPS spectra. This study provides an alternative way to enhance the knowledge of microbe–mineral interactions and find a route to improve the rate of bioleaching.

scholarly journals Edge Functionalized Graphene Layers for (Ultra) High Exfoliation in Carbon Papers and Aerogels in the Presence of Chitosan

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 39
Author(s):  
Silvia Guerra ◽  
Vincenzina Barbera ◽  
Alessandra Vitale ◽  
Roberta Bongiovanni ◽  
Andrea Serafini ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Graphene Layers ◽  
Biobased Polymers ◽  
Transmission Electron ◽  
Wide Range ◽  
Ft Ir ◽  
Hydroxy Groups ◽  
Thermal Stability Of

Ultra-high exfoliation in water of a nanosized graphite (HSAG) was obtained thanks to the synergy between a graphene layer edge functionalized with hydroxy groups and a polymer such as chitosan (CS). The edge functionalization of graphene layers was performed with a serinol derivative containing a pyrrole ring, serinol pyrrole (SP). The adduct between CS and HSAG functionalized with SP was formed simply with a mortar and pestle, then preparing water dispersions stable for months in the presence of acetic acid. Simple casting of such dispersions on a glass support led to carbon papers. Aerogels were prepared through the freeze-dry procedure. Exfoliation was observed in both these families of composites and ultra-high exfoliation was documented in aerogels swollen in water. Carbon papers and aerogels were stable for months in solvents in a wide range of solubility parameter and in a pretty wide range of pH. By considering that a moderately functionalized nanographite was straightforwardly exfoliated in water in the presence of one of the most abundant biobased polymers, the obtained results pave the way for the simple and sustainable preparation of graphene-based nanocomposites. HSAG–SP/CS adducts were characterized by wide angle X-ray diffraction (WAXD), scanning and transmission electron microscopy (SEM, TEM and HRTEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Thermal stability of the composites was studied by thermogravimetric analysis (TGA) and their direct electrical conductivity with the four-point probe method.

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