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Contamination of water sources is a major environmental problem with far-reaching consequences for humanity. Organic substances are among the most widespread and persistent pollutants. Advanced oxidation processes, especially photocatalysis, have been considered as one of the most promising technologies for organic pollution control. In this study, hybrid photocatalysts based on N-doped TiO 2 , which exhibits activity in the visible region of the spectrum, and different content of octahedral Mo 6 bromide and iodide cluster complexes were synthesized to achieve the highest efficiency of the formed S-scheme photocatalytic system under white light irradiation. According to the data obtained, the resulting materials are nanoparticles with a diameter of ∼10 nm exhibiting absorption up to ∼550 nm. Photocatalytic studies were performed using model organic molecules - the more colored rhodamine B (RhB) and the less colored antibiotic tetracycline (TET). The most active samples showed high efficiencies against both pollutants with k eff ∼0.3-0.4 and 0.4-0.5 min -1 , respectively, while the activity of iodide complexes was ∼1.3 times higher than that of bromide complexes. The stability of the catalysts is preserved for up to 5 cycles of TET photodegradation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

This research presents the first examples of heterometallic octahedral cluster complexes incorporating both 5d and 3d metals, specifically, tungsten and iron. The key compound, (TBA) 2 [FeW 5 Br 14 ] (TBA = tetrabutylammonium), exhibits selective ligand substitution reactions at the iron site when exposed to various solvents. Several {FeW 5 }-type anions, namely, [FeW 5 Br 14 ] 2- , [FeW 5 Br 13 (L)] - (L = H 2 O, DMSO, CH 3 CN), and [(FeW 5 Br 13 ) 2 O] 4- , were revealed and characterized by single-crystal X-ray diffraction analysis. The redox properties of [FeW 5 Br 14 ] 2- were studied and compared with those of [W 6 Br 14 ] 2- . Density functional theory calculations demonstrated that the bonding between Fe and W atoms is fundamentally different from the bonding between 4d (Mo-Mo) or 5d (W-W) metals in isotypic {M 6 } clusters.

Diamond is an important material for electrical and electronic devices. Because the diamond is in contact with the metal in these applications, it becomes necessary to study the metal-diamond interaction and the structure of the interface, in particular, at elevated temperatures. In this work, we study the interaction of the (100) and (111) surfaces of a synthetic diamond single crystal with spattered titanium and molybdenum films. Atomic force microscopy reveals a uniform coating of titanium and the formation of flattened molybdenum nanoparticles. A thin titanium film is completely oxidized upon contact with air and passes from the oxidized state to the carbide state upon annealing in an ultrahigh vacuum at 800 °C. Molybdenum interacts with the (111) diamond surface already at 500 °C, which leads to the carbidization of its nanoparticles and catalytic graphitization of the diamond surface. This process is much slower on the (100) diamond surface; sp 2 -hybridized carbon is formed on the diamond and the top of molybdenum carbide nanoparticles, only when the annealing temperature is raised to 800 °C. The conductivity of the resulting sample is improved when compared to the Ti-coated diamond substrates and the Mo-coated (111) substrate annealed at 800 °C. The presented results could be useful for the development of graphene-on-diamond electronics.

The family of chalcogenide molybdenum clusters is well presented in the literature by a series of compounds of nuclearity ranging from binuclear to multinuclear articulating octahedral fragments. Clusters actively studied in the last decades were shown to be promising as components of superconducting, magnetic, and catalytic systems. Here, we report the synthesis and detailed characterization of new and unusual representatives of chalcogenide clusters: square pyramidal complexes [{Mo 5 (μ 3 -Se) i 4 (μ 4 -Se) i (μ-pz) i 4 }(pzH) t 5 ] 1+/2+ (pzH = pyrazole, i = inner, t = terminal). Individually obtained oxidized (2+) and reduced (1+) forms have very close geometry (proven by single-crystal X-ray diffraction analysis) and are able to reversibly transform into each other, which was confirmed by cyclic voltammetry. Comprehensive characterization of the complexes, both in solid and in solution, confirms the different charge state of molybdenum in clusters (XPS), magnetic properties (EPR), and so on. DFT calculations complement the diverse study of new complexes, expanding the chemistry of molybdenum chalcogenide clusters.

Two-dimensional black phosphorus (BP) has attracted great attention as a perspective material for various applications. The chemical functionalization of BP is an important pathway for the preparation of materials with improved stability and enhanced intrinsic electronic properties. Currently, most of the methods for BP functionalization with organic substrates require either the use of low-stable precursors of highly reactive intermediates or the use of difficult-to-manufacture and flammable BP intercalates. Herein we report a facile route for simultaneous electrochemical exfoliation and methylation of BP. Conducting the cathodic exfoliation of BP in the presence of iodomethane makes it possible to generate highly active methyl radicals, which readily react with the electrode's surface yielding the functionalized material. The covalent functionalization of BP nanosheets with the P-C bond formation has been proven by various microscopic and spectroscopic methods. The functionalization degree estimated by solid-state 31 P NMR spectroscopy analysis reached 9.7%.

Ni supported on N-doped carbon is rarely studied in traditional catalytic reactions. To fill this gap, we compared the structure of 1 and 6 wt% Ni species on porous N-free and N-doped carbon and their efficiency in hydrogen generation from gaseous formic acid. On the N-free carbon support, Ni formed nanoparticles with a mean size of 3.2 nm. N-doped carbon support contained Ni single-atoms stabilized by four pyridinic N atoms (N 4 -site) and sub-nanosized Ni clusters. Density functional theory calculations confirmed the clustering of Ni when the N 4 -sites were fully occupied. Kinetic studies revealed the same specific Ni mass-based reaction rate for single-atoms and clusters. The N-doped catalyst with 6 wt% of Ni showed higher selectivity in hydrogen production and did not lose activity as compared to the N-free 6 wt% Ni catalyst. The presented results can be used to develop stable Ni catalysts supported on N-doped carbon for various reactions.

Poly(vinyl trimethylsilane) (PVTMS) films were subjected to direct surface fluorination in liquid medium (perfluorodecalin). The samples were investigated using several techniques: SEM-XEDS, XPS, ATR-IR, and contact angle measurement. The methods used allowed us to estimate chemical changes occurring because of the treatment. ATR-IR showed that most of the changes occurred in the Si(CH 3 ) 3 group. Monofluorinated Si(CH 3 ) 3 groups formed in the near-surface layer (Ge crystal, 0.66 µm penetration) after 30 min of fluorination, and then di- and trifluorinated groups appeared. Oxidation of the film with oxygen was also shown with the use of ZnSe crystal (2 µm penetration). The XPS method allowed an assessment of the ratio of the main elements at the surface of the fluorinated film. Two different exponential models were proposed to fit the experimental data of SEM-XEDS. Based on the model with the intercept, the depth of fluorination was estimated to be ≤1.1 µm, which is consistent with the result from the literature for the gas-phase fluorination. Contact angle measurements showed that oxidation of the PVTMS surface prevailed for the first 45 min of fluorination (surface hydrophilization) with a subsequent fluorine content increase and hydrophobization of the surface upon 60 min of fluorination.

Single-walled carbon nanotubes (SWCNTs) with their high surface area, electrical conductivity, mechanical strength and elasticity are an ideal component for the development of composite electrode materials for batteries. Red phosphorus has a very high theoretical capacity with respect to lithium, but has poor conductivity and expends considerably as a result of the reaction with lithium ions. In this work, we compare the electrochemical performance of commercial SWCNTs with red phosphorus deposited on the outer surface of nanotubes and/or encapsulated in internal channels of nanotubes in lithium-ion batteries. External phosphorus, condensed from vapors, is easily oxidized upon contact with the environment and only the un-oxidized phosphorus cores participate in electrochemical reactions. The support of the SWCNT network ensures a stable long-term cycling for these phosphorus particles. The tubular space inside the SWCNTs stimulate the formation of chain phosphorus structures. The chains reversibly interact with lithium ions and provide a specific capacity of 1545 mAh·g -1 (calculated on the mass of phosphorus in the sample) at a current density of 0.1 A·g -1 . As compared to the sample containing external phosphorus, SWCNTs with encapsulated phosphorus demonstrate higher reaction rates and a slight loss of initial capacity (~7%) on the 1000th cycle at 5 A·g -1 .

Emissions of various organic pollutants in the environment becomes a more and more acute problem in the modern world as they can lead to an ecological disaster in foreseeable future. The current situation forces scientists to develop numerous methods for the treatment of polluted water. Among these methods, advanced photocatalytic oxidation is a promising approach for removing organic pollutants from wastewater. In this work, one of the most common photocatalysts-titanium dioxide-was obtained by direct aqueous hydrolysis of titanium (IV) isopropoxide and impregnated with aqueous solutions of octahedral cluster complexes [{M 6 I 8 }(DMSO) 6 ](NO 3 ) 4 (M = Mo, W) to overcome visible light absorption issues and increase overall photocatalytic activity. XRPD analysis showed that the titania is formed as anatase-brookite mixed-phase nanoparticles and cluster impregnation does not affect the morphology of the particles. Complex deposition resulted in the expansion of the absorption up to ~500 nm and in the appearance of an additional cluster-related band gap value of 1.8 eV. Both types of materials showed high activity in the photocatalytic decomposition of RhB under UV- and sunlight irradiation with effective rate constants 4-5 times higher than those of pure TiO 2 . The stability of the catalysts is preserved for up to 5 cycles of photodegradation. Scavengers' experiments revealed high impact of all of the active species in photocatalytic process indicating the formation of an S-scheme heterojunction photocatalyst.

A direct fluorination technique was applied for the surface treatment of PIM-1 films in a liquid phase (perfluorodecalin). The fluorinated samples were analyzed by various instrumental techniques. ATR-IR spectroscopy showed that the fluorination predominantly takes place in methylene- and methyl-groups. Cyano-groups, aromatic hydrogens and the aromatic structure of the PIM-1 repeat unit were shown to be relatively stable at the fluorination conditions. XPS confirmed that the concentration of fluorine, as well as oxygen, in the near surface layer (~1 nm) increases with fluorination time. C1s and O1s surface spectra of the fluorinated PIM-1 samples indicated an appearance of newly-formed C-F and C-O functional groups. Scanning electron microscopy and X-ray energy-dispersive spectroscopy of the fluorinated PIM-1 samples showed an increase of the fluorine concentration at the surface (~0.1-1 μm) with the treatment duration. Analysis of the slices of the PIM-1 films demonstrated a decline of the fluorine content within several microns of the film depth. The decline increased with the fluorination time. A model of fluorine concentration dependence on the film depth and treatment duration was suggested. A change in the specific free surface energy as a result of PIM-1 fluorination was revealed. The fluorination time was shown to affect the surface energy (γ SV ), providing its shift from a low value (25 mJ∙m -2 ), corresponding to tetrafluoroethylene, up to a relatively high value, corresponding to a hydrophilic surface.

Herein, we report the characterization of two types of luminescent carbon dots (CDs) synthesized by the hydrothermal treatment of citric acid and trans -aconitic acid by using ammonia solution as a nitrogen dopant. The lateral size range of nanoparticles for CDs lies in the range of 3-15 nm. The intense blue photoluminescence (PL) was emitted by the CDs at around 409-435 nm under the excitation of 320 nm. The PL quantum yield of the synthesized CDs ranged from 26.4 to 51%. Our results of the structural and optical properties of CDs imply that molecular fluorophores are an important part of the structure; in particular, the main contribution to the PL is carried by the fluorophores based on citrazinic acid derivatives, which formed during the synthesis of CDs., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

Fluorinated graphitic layers with good mechanical and chemical stability, polar C-F bonds, and tunable bandgap are attractive for a variety of applications. In this work, we investigated the photolysis of fluorinated graphites with interlayer embedded acetonitrile, which is the simplest representative of the acetonitrile-containing photosensitizing family. The samples were continuously illuminated in situ with high-brightness non-monochromatized synchrotron radiation. Changes in the compositions of the samples were monitored using X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The NEXAFS N K-edge spectra showed that acetonitrile dissociates to form HCN and N 2 molecules after exposure to the white beam for 2 s, and the latter molecules completely disappear after exposure for 200 s. The original composition of fluorinated matrices CF 0.3 and CF 0.5 is changed to CF 0.10 and GF 0.17 , respectively. The highly fluorinated layers lose fluorine atoms together with carbon neighbors, creating atomic vacancies. The edges of vacancies are terminated with the nitrogen atoms and form pyridinic and pyrrolic units. Our in situ studies show that the photolysis products of acetonitrile depend on the photon irradiation duration and composition of the initial CF x matrix. The obtained results evaluate the radiation damage of the acetonitrile-intercalated fluorinated graphites and the opportunities to synthesize nitrogen-doped graphene materials.

The interlayer space of 2D materials can be a slit reactor where transformations not typical for the gas phase occur. We report redox reactions involving acetonitrile and nitrogen oxide guests in galleries of fluorinated graphite. Fluorinated graphite intercalation compounds with acetonitrile are treated with dinitrogen tetraoxide and the synthesis products are studied by a set of experimental methods. Data analysis reveals that N2O4 dissociates in fluorinated graphite matrices to form nitrogen-containing species NO3, NO2, NO, and N2. The interaction of NO3 with acetonitrile yields HNO3, which predominates as a guest in the synthesis products independently of the fluorination degree of the matrix. This reaction is accompanied by the removal of fluorine atoms weakly bonded to the graphite layers, leading to partial defluorination of the matrices. Our work demonstrates the possibility of using fluorinated graphite as a test nanoreactor whose dimension can be controlled by fluorination of the layers.

Robust electrode materials without the addition of binders allow increasing efficiency of electrical storage devices. We demonstrate the fabrication of binder-free electrodes from modified single-walled carbon nanotubes (SWCNTs) for electrochemical double-layer capacitors (EDLCs). Modification of SWCNTs included a sonication in 1,2-dichlorobenzene and/or fluorination with gaseous BrF 3 at room temperature. The sonication caused the shortening of SWCNTs and the splitting of their bundles. As a result, the film prepared from such SWCNTs had a higher density and attached a larger amount of fluorine as compared to the film from non-sonicated SWCNTs. In EDLCs with 1M H 2 SO 4 electrolyte, the fluorinated films were gradually defluorinated, which lead to an increase of the specific capacitance by 2.5-4 times in comparison with the initial values. Although the highest gravimetric capacitance (29 F g -1 at 100 mV s -1 ) was observed for the binder-free film from non-modified SWCNT, the fluorinated film from the sonicated SWCNTs had an enhanced volumetric capacitance (44 F cm -3 at 100 mV s -1 ). Initial SWCNT films and defluorinated films showed stable work in EDLCs during several thousand cycles.

Carbon nanohorns (CNHs) are attractive for various applications, where a high specific surface area and long dispersion stability in water are important. In the present work, we study these parameters of CNHs prepared by arc evaporation of graphite depending on the conditions of the synthesis and subsequent oxidation in air. It is shown that the addition of toluene in the reactor during the arcing allows obtaining CNHs functionalized with -CH x groups. Heating of CNHs in air at 400 °C leads to substitution of -CH x groups for oxygen-containing groups. Moreover, the CNH endcaps are opened at 500 °C, and as a result, the specific surface area of CNHs increases 4 times. Aqueous suspensions with a concentration of oxidized CNHs of 100 µg/mL are stable for 8 months.

Thermal decomposition of (NH4)3[IrCl6]·H2O, (NH4)2[IrCl6] and (NH4)2[IrBr6] in reductive and inert atmospheres has been investigated in situ using quick-EXAFS and temperature-resolved powder X-ray diffraction. For the first time, (NH4)2[Ir(NH3)Cl5] and (NH4)2[Ir(NH3)Br5] have been proven as intermediates of thermal decomposition of (NH4)3[IrCl6]·H2O, (NH4)2[IrCl6] and (NH4)2[IrBr6]. Thermal degradation of (NH4)2[IrCl6] and (NH4)2[IrBr6] is a more complex process as suggested previously and includes simultaneous formation of (NH4)2[Ir(NH3)Cl5] and (NH4)2[Ir(NH3)Br5] intermediates mixed with metallic iridium. In the inert atmosphere, complexes (NH4)[Ir(NH3)2Cl4] and (NH4)[Ir(NH3)2Br4] as well as [Ir(NH3)3Br3] were proposed as possible intermediates before formation of metallic iridium particles.

The electrical conductivity of graphene materials is strongly sensitive to the surface adsorbates, which makes them an excellent platform for the development of gas sensor devices. Functionalization of the surface of graphene opens up the possibility of adjusting the sensor to a target molecule. Here, we investigated the sensor properties of fluorinated graphene films towards exposure to low concentrations of nitrogen dioxide NO 2 . The films were produced by liquid-phase exfoliation of fluorinated graphite samples with a composition of CF 0.08 , CF 0.23 , and CF 0.33. Fluorination of graphite using a BrF 3 /Br 2 mixture at room temperature resulted in the covalent attachment of fluorine to basal carbon atoms, which was confirmed by X-ray photoelectron and Raman spectroscopies. Depending on the fluorination degree, the graphite powders had a different dispersion ability in toluene, which affected an average lateral size and thickness of the flakes. The films obtained from fluorinated graphite CF 0.33 showed the highest relative response ca. 43% towards 100 ppm NO 2 and the best recovery ca. 37% at room temperature.

Nowadays, the development of new effective photocatalytic materials for the purification of real wastewaters and model systems containing organic molecules constitutes an important challenge. Here we present a preparation strategy for composite materials based on hexamolybdenum cluster complexes and exfoliated hexagonal boron nitride (h-BN) nanosheets. Cluster deposition on the nanosheet surface was achieved by impregnation of the matrix by a (Bu 4 N) 2 [{Mo 6 I 8 }(NO 3 ) 6 ]/acetone solution. Successful cluster immobilization and chemical composition of the samples were verified by inductively coupled plasma atomic emission spectroscopy, transmission electron microscopy with elemental mapping (TEM/EDS), X-ray photoelectron spectroscopy (XPS), and optical diffuse-reflectance spectroscopy. A small amount of water in acetone initiates the hydrolysis of a molybdenum cluster precursor with labile NO 3 - ligands, which are absent in the final composite, according to the XPS data. Intermediate hydrolyzed cluster forms anchor to the surface of h-BN nanosheets and promote growth of the insoluble compound [{Mo 6 I 8 }(H 2 O) 2 (OH) 4 ]· y H 2 O as the final hydrolysis product. TEM/EDS proves that the cluster exists at the nanosheet surface in the form of an X-ray diffraction amorphous thin film. The samples obtained show high photocatalytic activity in the degradation of a model pollutant rhodamine B under UV- and visible-light irradiation. The materials retain their initial photocatalytic efficacy during at least six cycles without the need for recovery.

Diamond films are advanced engineering materials for various industrial applications requiring a coating material with extremely high thermal conductivity and low electrical conductivity. An approach for the synthesis of diamond films via high-speed jet deposition of thermally activated gas has been applied. In this method, spatially separated high-speed flows of methane and hydrogen were thermally activated, and methyl and hydrogen radicals were deposited on heated molybdenum substrates. The morphology and structure of three diamond films were studied, which were synthesized at a heating power of 900, 1700, or 1800 W, methane flow rate of 10 or 30 sccm, hydrogen flow rate of 1500 or 3500 sccm, and duration of the synthesis from 1.5 to 3 h.The morphology and electronic state of the carbon on the surface and in the bulk of the obtained films were analyzed by scanning electron microscopy, Raman scattering, X-ray photoelectron, and near-edge X-ray absorption fine structure spectroscopies. The diamond micro-crystals with a thick oxidized amorphous sp 2 -carbon coating were grown at a heating power of 900 W and a hydrogen flow rate of 1500 sccm. The quality of the crystals was improved, and the growth rate of the diamond film was increased seven times when the heating power was 1700-1800 W and the methane and hydrogen flow rates were 30 and 3500 sccm, respectively. Defective octahedral diamond crystals of 30 μm in size with a thin sp 2 -carbon surface layer were synthesized on a Mo substrate heated at 1273 K for 1.5 h. When the synthesis duration was doubled, and the substrate temperature was decreased to 1073 K, the denser film with rhombic-dodecahedron diamond crystals was grown. In this case, the thinnest hydrogenated sp 2 -carbon coating was detected on the surface of the diamond crystals.

Biocompatible Pt x Ir (1-x) layers combining high mechanical strength of the iridium component and outstanding corrosion resistance of the platinum component providing reversible charge transfer reactions in the living tissue are one of the important materials required for implantable medical electrodes. The modern trend to complicate the shape and reduce the electrode dimensions includes the challenge to develop precise methods to obtain such bimetallic coatings with enhanced surface area and advanced electrochemical characteristics. Herein, Pt x Ir (1-x) coatings were firstly obtained on cathode and anode pole tips of endocardial electrodes for pacemakers using chemical vapor deposition technique. To deposit Pt x Ir (1-x) coatings with a wide range of metal ratios (x = 0.5-0.9) the combination of acetylacetonate-based volatile precursors with compatible thermal characteristics was used for the first time. The expected metal ratio in the coatings was regulated by a partial pressure of the precursor vapors in the reaction zone and was in the good agreement with its real value measured by various methods, including energy-dispersive and wavelength dispersive spectroscopy, X-ray photoelectron spectroscopy. According to the X-ray powder diffraction analysis, Pt x Ir (1-x) coatings consisted of fcc-Pt x Ir (1-x) solid solution phases. The microscopy data confirmed the formation of Pt x Ir 1-x coatings with the enhanced surface areas. The effect of electrochemical activation on the surface composition and morphology of the samples was studied. The electrochemical characteristics of samples were estimated from cyclic voltammetry and electrochemical impedance spectroscopy data. The charge storage capacity (CSC) values of activated samples were in the range of 19-108 mCcm -2 (phosphate buffer saline solution, 100 mV/s).

Tungsten trioxide has been found to be a convenient precursor for the synthesis of metal cluster compounds with new types of cluster cores. The reaction between WO3 and KCN led to the formation of the cluster complex [{W6(μ4-O)2(μ3-CCN)4}(CN)16]10-. Unexpectedly, it includes the fully deprotonated form of acetonitrile, the CCN3- anion, as a μ3-bridging ligand coordinated to the trigonal faces of the bitetrahedral W6 metallocluster. A similar complex [{W6(μ4-O)2(μ3-As)4}(CN)16]10- containing μ3-As3- ligands instead of μ3-CCN3- ones has been synthesized by the reaction between WO3, As and KCN.

The synthesis, characterization, experimental X-ray photoelectron spectra (XPS) and density-functional theory (DFT) investigations on solid solutions of Mo1-xRexS2 (x = 0.05, 0.10, 0.15 and 0.20) are reported herein. It is shown that even at a low concentration of dopant Re atoms, clustering occurs. At an Re concentration of 5% the formation of dimer-like impregnations is observed. An increase in the dopant concentration leads to an increase in the amount of clustered rhenium atoms and to the formation of rhombic clusters. The absence of magnetism within the studied Mo1-xRexS2 solid solutions allowed us to suggest a mechanism for the distribution of rhenium inside molybdenum disulphide through the initial formation of rhenium disulphide and its subsequent spreading.

Holes with an average size of 2-5 nm have been created in graphene layers by heating of graphite oxide (GO) in concentrated sulfuric acid followed by annealing in an argon flow. The hot mineral acid acts simultaneously as a defunctionalizing and etching agent, removing a part of oxygen-containing groups and lattice carbon atoms from the layers. Annealing of the holey reduced GO at 800 °C-1000 °C causes a decrease of the content of residual oxygen and the interlayer spacing thus producing thin compact stacks from holey graphene layers. Electrochemical tests of the obtained materials in half-cells showed that the removal of oxygen and creation of basal holes lowers the capacity loss in the first cycle and facilitates intercalation-deintercalation of lithium ions. This was attributed to minimization of electrolyte decomposition reactions, easier desolvation of lithium ions near the hole boundaries and appearance of multiple entrances for the naked ions into graphene stacks.

Electronic configuration of chemically bound atoms at the surface, including adsorbed species, or in the bulk of a solid contains a set of natural traps for energy absorption provided by valence band transitions or plasmon oscillations. The core level excitation of any origin is generally coupled with those traps, forming a multichannel route for nonradiative energy dissipation. Using an example of Pt and graphite-based materials, the study shows experimental tracing over these channels by means of elastic electron scattering and X-ray photoelectron spectroscopy. As a complement to the experimental data, calculations of the density of states provide information on chemical behavior and local geometry of the atoms in a sample.

Structural changes of (NH 4 ) 2 [OsCl 6 ] occurring during thermal decomposition in a reduction atmosphere have been studied in situ using combined energy-dispersive X-ray absorption spectroscopy (ED-XAFS) and powder X-ray diffraction (PXRD). According to PXRD, (NH 4 ) 2 [OsCl 6 ] transforms directly to metallic Os without the formation of any crystalline intermediates but through a plateau where no reactions occur. XANES and EXAFS data by means of Multivariate Curve Resolution (MCR) analysis show that thermal decomposition occurs with the formation of an amorphous intermediate {OsCl 4 } x with a possible polymeric structure. Being revealed for the first time the intermediate was subjected to determine the local atomic structure around osmium. The thermal decomposition of hexachloroosmate is much more complex and occurs within a minimum two-step process, which has never been observed before.

Nitrogen-containing multi-wall carbon nanotubes (N-MWCNTs) were synthesized using aerosol assisted chemical vapor deposition (CVD) techniques in conjunction with benzylamine:ferrocene or acetonitrile:ferrocene mixtures. Different amounts of toluene were added to these mixtures in order to change the N/C ratio of the feedstock. X-ray photoelectron and near-edge X-ray absorption fine structure spectroscopy detected pyridinic, pyrrolic, graphitic, and molecular nitrogen forms in the N-MWCNT samples. Analysis of the spectral data indicated that whilst the nature of the nitrogen-containing precursor has little effect on the concentrations of the different forms of nitrogen in N-MWCNTs, the N/C ratio in the feedstock appeared to be the determining factor. When the N/C ratio was lower than ca. 0.01, all four forms existed in equal concentrations, for N/C ratios above 0.01, graphitic and molecular nitrogen were dominant. Furthermore, higher concentrations of pyridinic nitrogen in the outer shells and N2 molecules in the core of the as-produced N-MWCNTs suggest that the precursors were decomposed into individual atoms, which interacted with the catalyst surface to form CN and NH species or in fact diffused through the bulk of the catalyst particles. These findings are important for a better understanding of possible growth mechanisms for heteroatom-containing carbon nanotubes (CNTs) and therefore paving the way for controlling the spatial distribution of foreign elements in the CNTs using CVD processes.

Development of graphene spintronic devices relies on transforming it into a material with a spin order. Attempts to make graphene magnetic by introducing zigzag edge states have failed due to energetically unstable structure of torn zigzag edges. Here, we report on the formation of nanoridges, i.e., stable crystallographically oriented fluorine monoatomic chains, and provide experimental evidence for strongly coupled magnetic states at the graphene-fluorographene interfaces. From the first principle calculations, the spins at the localized edge states are ferromagnetically ordered within each of the zigzag interface whereas the spin interaction across a nanoridge is antiferromagnetic. Magnetic susceptibility data agree with this physical picture and exhibit behaviour typical of quantum spin-ladder system with ferromagnetic legs and antiferromagnetic rungs. The exchange coupling constant along the rungs is measured to be 450 K. The coupling is strong enough to consider graphene with fluorine nanoridges as a candidate for a room temperature spintronics material.

Detonation nanodiamonds (NDs) were deposited on the surface of aligned carbon nanotubes (CNTs) by immersing a CNT array in an aqueous suspension of NDs in dimethylsulfoxide (DMSO). The structure and electronic state of the obtained CNT-ND hybrid material were studied using optical and electron microscopy and Infrared, Raman, X-ray photoelectron and near-edge X-ray absorption fine structure spectroscopy. A non-covalent interaction between NDs and CNT and preservation of vertical orientation of CNTs in the hybrid were revealed. We showed that current-voltage characteristics of the CNT-ND cathode are changed depending on the applied field; below ~3 V/µm they are similar to those of the initial CNT array and at the higher field they are close to the ND behavior. Involvement of the NDs in field emission process resulted in blue luminescence of the hybrid surface at an electric field higher than 3.5 V/µm. Photoluminescence measurements showed that the NDs emit blue-green light, while blue luminescence prevails in the CNT-ND hybrid. The quenching of green luminescence was attributed to a partial removal of oxygen-containing groups from the ND surface as the result of the hybrid synthesis.

Graphene is a remarkable material with the best surface to volume ratio as a result of its 2D nature, which implies that every atom can be considered as a surface one. These features make graphene attractive for use as a sensing material; however, the limiting factor is the chemical inertness of pristine graphene. Here we propose a method to create reactive centers by removal of fluorine atoms from the outer surface of fluorinated graphene while preserving the backside fluorination. Such partially recovered graphene layers were produced by the action of hydrazine-hydrate vapor on initially non-conducting fluorinated graphite. The reduction degree of the material and its electrical response revealed upon ammonia exposure were controlled by measuring the surface conductivity. We showed experimentally that the sensing properties depend on the reduction degree and found the correlation of the adsorption energy of ammonia with the number of residual fluorine atoms by the use of quantum-chemical calculations.

Highly oriented pyrolytic graphite characterized by a low misorientation of crystallites is fluorinated using a gaseous mixture of BrF(3) with Br(2) at room temperature. The golden-colored product, easily delaminating into micrometer-size transparent flakes, is an intercalation compound where Br(2) molecules are hosted between fluorinated graphene layers of approximate C(2)F composition. To unravel the chemical bonding in semifluorinated graphite, we apply angle-resolved near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and quantum-chemical modeling. The strong angular dependence of the CK and FK edge NEXAFS spectra on the incident radiation indicates that room-temperature-produced graphite fluoride is a highly anisotropic material, where half of the carbon atoms are covalently bonded with fluorine, while the rest of the carbon atoms preserve π electrons. Comparison of the experimental CK edge spectrum with theoretical spectra plotted for C(2)F models reveals that fluorine atoms are more likely to form chains. This conclusion agrees with the atomic force microscopy observation of a chain-like pattern on the surface of graphite fluoride layers.

A simple method for formation of CdS nanoparticles on the surface of carbon nanotubes (CNTs) aligned perpendicularly to the silicon substrate has been developed. The size and shape of the CdS nanoparticles were found to depend on the temperature of a solution containing CdCl(2), (NH(2))(2)CS, and NH(3) and the deposition time. Electron microscopy study revealed a direct contact between CdS nanoparticles and CNT surface. X-Ray photoelectron spectroscopy examination of the CdS/CNT hybrid material detected surface oxidation of the grown nanoparticles.