Peculiarities of electronic structure and composition in ultrasound milled silicon nanowires

The combined X-ray absorption and emission spectroscopy approach was applied for the detailed electronic structure and composition studies of silicon nanoparticles produced by the ultrasound milling of heavily and lowly doped Si nanowires formed by metal-assisted wet chemical etching. The ultrasoft X-ray emission spectroscopy and synchrotron based X-ray absorption near edges structure spectroscopy techniques were utilize to study the valence and conduction bands electronic structure together with developed surface phase composition qualitative analysis. Our achieved results based on the implemented surface sensitive techniques strongly suggest that nanoparticles under studies show a significant presence of the silicon suboxides depending on the pre-nature of initial Si wafers. The controlled variation of the Si nanoparticles surface composition and electronic structure, including band gap engineering, can open a new prospective for a wide range Si-based nanostructures application including the integration of such structures with organic or biological systems. © 202

From graphene oxide towards aminated graphene facile synthesis, its structure and electronic properties

In this paper we present a facile method for the synthesis of aminated graphene derivative through simultaneous reduction and amination of graphene oxide via two-step liquid phase treatment with hydrobromic acid and ammonia solution in mild conditions. The amination degree of the obtained aminated reduced graphene oxide is of about 4 at.%, whereas C/O ratio is up to 8.8 as determined by means of X-ray photoelectron spectroscopy. The chemical reactivity of the introduced amine groups is further verified by successful test covalent bonding of the obtained aminated graphene with 3-Chlorobenzoyl chloride. The morphological features and electronic properties, namely conductivity, valence band structure and work function are studied as well, illustrating the influence of amine groups on graphene structure and physical properties. Particularly, the increase of the electrical conductivity, reduction of the work function value and tendency to form wrinkled and corrugated graphene layers are observed in the aminated graphene derivative compared to the pristine reduced graphene oxide. As obtained aminated graphene could be used for photovoltaic, biosensing and catalysis application as well as a starting material for further chemical modifications

Investigating the fine structure of near edge X ray absorption in the molecular spectra of C60F18 adsorbed on a single nickel crystal

Angular dependences of the fine structure of near edge X ray absorption NEXAFS of carbon C1s spectra are obtained for a monolayer film of C60F18 polar molecules on a Ni 100 substrate. The fine structure and angular dependences of these spectra are interpreted using calculation data obtained by the density functional method upon fitting NEXAFS spectra by the set of trial functions. It is shown that during deposition, the dipole moment of molecules is oriented perpendicular to the surface and fluorine atoms are the ones closest to the surfac

Experimental observation of C60F18 molecules orientation onto nickel single crystal 100 surface

The angular dependence of near edge X ray absorption fine structure NEXAFS spectra has been obtained in the vicinity of carbon and fluorine 1s absorption edges in a monolayer film of polar fullerene fluoride C60F18 molecules on a Ni 100 substrate. The fine structure of the spectra has been identified according to experimental data via calculations based on the density functional theory, and the angular dependence of the spectra has been explained. The orientations of structural molecular fragments are determined from the angular dependence of the NEXAFS spectra. It is demonstrated that the electric dipole moment of a C60F18 molecule is oriented along the normal to the substrate surface with an accuracy of

Crystallochemical design of metal–organic polymer CuBTC and activated carbon composite

Metal–organic polymer CuBTC and composite with CuBTC and activated carbon (CuBTC/C) were prepared by hydrothermal method (BTC3− is a linker 1,3,5-benzenetricarboxylate ion, hydrolysis temperature 130 °C, ethanol + H2O in equal proportion as a solvent) and detailed characterized by a set of methods (X-ray diffraction—XRD, X-ray absorption spectroscopy—XAS, differential scanning calorimetry—DSC, scanning electron microscopy—SEM, low-temperature sorption capacity of samples to nitrogen—BET, X-ray photoelectron spectroscopy—XPS, FTIR-spectroscopy). According to XRD and XAS data, it was found that the composition of main phase CuBTC is [Cu3BTC2(H2O)3] × (nH2O + mC2H5OH) in both samples. The catalytic properties of CuBTC and CuBTC/C samples in the reaction of ethanol dehydrogenation were studied for the first time and the selectivity to acetaldehyde (AcH) was 100% in both cases. It was shown that on the CuBTC/C catalysis, the AcH yield is two times higher than on the CuBTC sample in the reaction of ethanol (Lewis base) dehydrogenation to acetaldehyde. This fact can be explained by the higher content of main phase CuBTC in composite CuBTC/C (~ 97.5 wt%) and the Cu2+ ions (Lewis acid sites) in bulk, the higher water and Cu2+ ions content on the particle surface in CuBTC/C (DSC, FTIR, XPS), the larger pore radii in CuBTC framework of the composite CuBTC/C (according to crystallochemical calculations) and the larger hydrogenation degree of CuBTC/C (XRD, DSC, FTIR) and the smaller specific surface area of CuBTC/C (SBET = 44.4 m2/g for CuBTC/C sample and SBET = 551.3 m2/g for CuBTC). It was found that in the reaction of propane conversion to ethylene C2H4 and methane CH4, the conversion degree on the samples CuBTC and CuBTC/C was the same from 100 °C up to 340 °C, which is caused by the absence of the Bronsted acid sites on the samples with CuBTC. Graphical abstract: [Figure not available: see fulltext.]. © 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature

New composites based on zeolites (H-Beta, H-ZSM-5) and nanosized titanium(iv) oxide (anatase and η-phase) doped by Ni, Ag, V with photocatalytic, adsorption and bactericidal properties

New NT:M/zeolite composites with functional nanoparticles of titanium(iv) oxides NT (η-phase and anatase) have been prepared by introducing nitrates with dopant metals (M = Ag, Ni, and V) and zeolites (H-Beta and H-ZSM-5) within the process of NT synthesis during the hydrolysis of TiOSO4·nH2O. The prepared composites have been characterized by X-ray diffraction, XAS-method, XPS-spectroscopy, UV-Vis diffuse reflectance spectroscopy, and Brunauer-Emmett-Teller and chemoluminescence methods. The greatest photodegradation rate constants (visible light radiation) were achieved in the reaction of thiamethoxam pesticide and difenoconazole fungicide oxidation in the presence of NE:Ni/H-Beta (NE - η-phase with composition TiO2−x·nH2O),i.e. k= 0.0270 min−1andk= 0.0147 min−1respectively, that is 2.5 times higher than thekvalue obtained for the commercial anatase Hombifine N (UV-irradiation). A relationship between the photocatalytic activity (PCA) and the NT:zeolite ratio, the type and concentration of M, the type of NT and zeolite, the content of OH groups and the reactive oxygen species (radical anions ˙OH, ˙O2−and H2O2) on the surface, and the composition and structure of the decomposed pollutant has been found. The decisive role of the composition of the volume and surface of nanocomposites in the realization of PCA has been noted. The adsorption (removal of P(v), As(v), Se(vi) ions from aqueous solutions) and antimicrobial activities (against bacteriaStaphylococcus epidermidis,Bacillus antracoides,Escherichia coli) of the NT:M/zeolite composites, in the absence of light emission, have been studied for the first time and their high performance has been demonstrated: the removal degrees of P(v), As(v), and Se(vi) ions from aqueous solutions in the presence of all composites were more than 99% and the inhibition growth zone of composites NA:Ag/zeolite was >13 mm. New composites could be recommended for preparing wound dressings, antiseptic ointments for external use and water filters. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2021

Peculiarities of electronic structure and composition in ultrasound milled silicon nanowires

The combined X-ray absorption and emission spectroscopy approach was applied for the detailed electronic structure and composition studies of silicon nanoparticles produced by the ultrasound milling of heavily and lowly doped Si nanowires formed by metal-assisted wet chemical etching. The ultrasoft X-ray emission spectroscopy and synchrotron based X-ray absorption near edges structure spectroscopy techniques were utilize to study the valence and conduction bands electronic structure together with developed surface phase composition qualitative analysis. Our achieved results based on the implemented surface sensitive techniques strongly suggest that nanoparticles under studies show a significant presence of the silicon suboxides depending on the pre-nature of initial Si wafers. The controlled variation of the Si nanoparticles surface composition and electronic structure, including band gap engineering, can open a new prospective for a wide range Si-based nanostructures application including the integration of such structures with organic or biological systems. © 202

Speciation of organosulfur compounds in carbonaceous chondrites.

Despite broad application of different analytical techniques for studies on organic matter of chondrite meteorites, information about composition and structure of individual compounds is still very limited due to extreme molecular diversity of extraterrestrial organic matter. Here we present the first application of isotopic exchange assisted Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) for analysis of alkali extractable fraction of insoluble organic matter (IOM) of the Murchison and Allende meteorites. This allowed us to determine the individual S-containing ions with different types of sulfur atoms in IOM. Thiols, thiophenes, sulfoxides, sulfonyls and sulfonates were identified in both samples but with different proportions, which contribution corroborated with the hydrothermal and thermal history of the meteorites. The results were supported by XPS and thermogravimetric analysis coupled to FTICR MS. The latter was applied for the first time for analysis of chondritic IOM. To emphasize the peculiar extraterrestrial origin of IOM we have compared it with coal kerogen, which is characterized by the comparable complexity of molecular composition but its aromatic nature and low oxygen content can be ascribed almost exclusively to degradation of biomacromolecules

On the possibility of PhotoEmission Electron Microscopy for E. coli advanced studies

The novel approach was proposed for detailed high-resolution studies of morphology and physico-chemical properties concomitantly at one measurement spot of E. coli bacterial cells culture immobilized onto silicon wafer surface in UHV conditions applying PhotoEmission Electron Microscopy under Hg lamp irradiation. For the E. coli characterization scanning electron microscopy (electron beam) and X-ray photoelectron spectroscopy (X-ray tube radiation) were applied prior to PhotoEmission Electron Microscopy measurements. In spite of irradiation doses collected for the cell arrays we were successful in detection of high-resolution images even of single E. coli bacterium by PhotoEmission Electron Microscopy technique followed by detailed high-resolution morphology studies by scanning electron microscopy. These results revealed widespread stability of the E. coli membranes shape after the significant number of applied characterization techniques. © 2019 The Author