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Bimetallic PtXNi5/SBA-15 catalysts with 5 wt% Ni and X = 0.1–2.0 wt% Pt were synthesized and characterized. The XPS characterization of bimetallic catalysts showed the presence of oxide Ni2+, Pt2+ and reduced Pt0 species in the calcined catalysts. After the reduction, metallic Ni0 appeared in addition to the above-mentioned species. The proportions of the reduced Ni and Pt increased with increasing Pt content in the catalysts. The presence of metal species of different oxidation states at the Ni–Pt interface was crucial for their catalytic performance in the hydrodeoxygenation of anisole. The Pt0.5Ni5/SBA-15 catalyst was the most active and selective. [ABSTRACT FROM AUTHOR]

In the study at hand, a systemic investigation regarding the tribochemical effects of crankcase soot is presented. Sooted oils were generated via an engine dynamometer test. Both conventional as well as advanced oil condition monitoring methods indicated a mild degradation of additives. The wear volume was greatly increased with the sooted oils in model tribometer tests, despite the high residual zinc dialkyl dithiophosphate (ZDDP) antiwear (AW) levels. Once the soot was removed via ultracentrifugation, the wear volume returned to levels comparable to the fresh oil. Surface investigations revealed that ZDDP tribofilms could not form in the sooted oils, as only a thin sulfide layer was present on the metal surfaces. Meanwhile, typical tribofilms were observable with centrifuged oils. The results indicated that a tribocorrosive mechanism is most likely responsible for the elevated wear in the sooted oils, where only the iron sulfide base layer of ZDDP films is formed, which is then rapidly removed by the soot particles in an abrasive manner. [ABSTRACT FROM AUTHOR]

Tin‐based halide perovskite solar cells can be efficient and environmentally friendly substitutions to lead‐based halide perovskite solar cells, but they have a drawback due to oxidation from Sn2+ to Sn4+. Using vacuum deposition, epitaxially aligned CsSnBr3 ultrathin films are prepared on Au(111) and Au(100) and characterized with scanning tunneling microscopy (STM), low‐energy electron diffraction (LEED), and X‐ray photoelectron spectroscopy (XPS). By co‐evaporation of the precursor molecules CsBr and SnBr2, few monolayers of perovskite are obtained. On Au(111), CsSnBr3 grows in three differently oriented domains due to the hexagonal symmetry of the substrate. On Au(100), which has square symmetry, identical to CsSnBr3, but with about half the lattice constant of the perovskite, a (2×2) superstructure is observed. The perovskite is terminated with the (001) facet showing a square surface structure in agreement with density functional theory (DFT) calculations. Chemical analysis is performed in ultra‐high vacuum (UHV) conditions and no indication of a tin oxidation state higher than Sn2+ is found in the films. However, after exposure to air, rapid and severe changes in the films are observed, highlighting the importance of preparing tin perovskites in a controlled environment to maintain their stability and avoid oxidation‐related issues. [ABSTRACT FROM AUTHOR]

Understanding surface stability becomes critical as 2D materials like SnSe are developed for piezoelectric and optical applications. SnSe thin films deposited by molecular beam epitaxy showed no structural changes after a two-year exposure to atmosphere, as confirmed by X-ray diffraction and Raman spectroscopy. X-ray photoelectron spectroscopy and reflectivity show a stable 3.5 nm surface oxide layer, indicating a self-arresting oxidative process. Resistivity measurements show an electrical response dominated by SnSe post-exposure. This work shows that SnSe films can be used in ambient conditions with minimal risk of long-term degradation, which is critical for the development of piezoelectric or photovoltaic devices. [ABSTRACT FROM AUTHOR]

Chlorate (ClO3-) is a toxic oxyanion pollutant from industrial wastes, agricultural applications, drinking water disinfection, and wastewater treatment. Catalytic reduction of ClO3- using palladium (Pd) nanoparticle catalysts exhibited sluggish kinetics. This work demonstrates an 18-fold activity enhancement by integrating earth-abundant vanadium (V) into the common Pd/C catalyst. X-ray photoelectron spectroscopy and electrochemical studies indicated that VV and VIV precursors are reduced to VIII in the aqueous phase (rather than immobilized on the carbon support) by Pd-activated H2. The VIII/IV redox cycle is the predominant mechanism for the ClO3- reduction. Further reduction of chlorine intermediates to Cl- could proceed via VIII/IV and VIV/V redox cycles or direct reduction by Pd/C. To capture the potentially toxic V metal from the treated solution, we adjusted the pH from 3 to 8 after the reaction, which completely immobilized VIII onto Pd/C for catalyst recycling. The enhanced performance of reductive catalysis using a Group 5 metal adds to the diversity of transition metals (e.g., Cr, Mo, Re, Fe, and Ru in Groups 6-8) for water pollutant treatment via various unique mechanisms.

This study takes a detailed look at the corrosion inhibition capabilities of two benzodiazepine‐derived organic compounds, 3,3‐dimethyl‐11‐(4‐nitrophenyl)‐2,3,4,5,10,11‐hexahydro‐1H‐dibenzo[b,e][1,4]diazepin‐1‐one (PNO) and 3,3‐dimethyl‐11‐(2‐nitrophenyl)‐2,3,4,5,10,11‐hexahydro‐1H‐dibenzo[b,e][1,4]diazepin‐1‐one (ONO), in a 1.0‐M hydrochloric acid environment using a variety of analytical methods, including electrochemical approaches — electrochemical impedance spectroscopy (EIS) and potentio‐dynamic polarization (PDP). The results show that the concentration‐dependent inhibitory efficacy of PNO and ONO increases with increasing concentration. Both inhibitors exhibit mixed‐type behaviour, which is confirmed by the polarization results. At the optimum concentration, the inhibition efficiencies of PNO and ONO are 92.9% (PNO) and 87.6% (ONO), respectively. The effective adsorption of these inhibitors on the metal surface was also confirmed by X‐ray photoelectron spectroscopy (XPS) analysis. The existence of a barrier layer surrounding the mild steel was demonstrated using scanning electron microscopy (SEM) and energy‐dispersive X‐ray analysis (EDX), all of which were used to study the surface characterization. The most important interactions with the iron surface are achieved by inhibitors with electron‐accepting properties, according to density functional theory results and molecular dynamic simulation (MDS). With encouraging prospects for industry and metal preservation, these results pave the way for promising applications for effective corrosion protection in a 1.0‐M HCl environment. [ABSTRACT FROM AUTHOR]

In this perspective we discuss the progress made in the mechanistic studies of the surface chemistry associated with the atomic layer deposition (ALD) of metal films and the usefulness of that knowledge for the optimization of existing film growth processes and for the design of new ones. Our focus is on the deposition of late transition metals. We start by introducing some of the main surface-sensitive techniques and approaches used in this research. We comment on the general nature of the metallorganic complexes used as precursors for these depositions, and the uniqueness that solid surfaces and the absence of liquid solvents bring to the ALD chemistry and differentiate it from what is known from metalorganic chemistry in solution. We then delve into the adsorption and thermal chemistry of those precursors, highlighting the complex and stepwise nature of the decomposition of the organic ligands that usually ensued upon their thermal activation. We discuss the criteria relevant for the selection of co-reactants to be used on the second half of the ALD cycle, with emphasis on the redox chemistry often associated with the growth of metallic films starting from complexes with metal cations. Additional considerations include the nature of the substrate and the final structural and chemical properties of the growing films, which we indicate rarely retain the homogeneous 2D structure often aimed for. We end with some general conclusions and personal thoughts about the future of this field. [ABSTRACT FROM AUTHOR]

BeCu material has the characteristics of high thermal conductivity and low thermal emissivity, which can reduce temperature rise. Furthermore, BeCu material is able to reduce the outgassing with the special heat treatment. These characteristics make it easier to get a high vacuum. The surface structure of BeCu material was confirmed by X-ray photoelectron spectroscopy (XPS) analysis, the absorbed gas in the material was measured by thermal desorption spectroscopy (TDS), and the outgassing from the material were measured by a build-up test. These test results confirmed that BeCu material has excellent vacuum properties. [ABSTRACT FROM AUTHOR]

The KSF-clay is a material that presents a high density of acidic active sites, ideal for being a heterogeneous acid catalyst with outstanding activity. For this study, KSF-clay was characterized by X-ray photoelectron spectroscopy and temperature-programmed desorption of ammonia. Additionally, studies of the adsorption of ethanol, propan-2-ol, and acetic acid molecules over KSF-clay surface to establish their thermal stability species were studied by diffuse reflectance infrared Fourier transform spectroscopy. The relationship between the properties of KSF-clay and the adsorption-interaction process with organic molecules is related to its performance as an acid catalyst. [ABSTRACT FROM AUTHOR]

Silicon has dimensional limitations in following Moore's law; thus, new 2D materials complementing Silicon are being researched. Molybdenum disulfide (MoS2) is a prospective material anticipated to bridge the gap to complement Silicon and enhance the performances of semiconductor devices and embedded systems in the package. For a synthesis process to be of any relevance to the industry. it needs to be at the wafer scale to match existing Silicon wafer-processing standards. Atomic Layer Deposition (ALD) is one of the most promising techniques for synthesizing wafer-scale monolayer MoS2 due to its self-limiting, conformal, and low-temperature characteristics. This paper discusses the wafer-scale ALD synthesis of Molybdenum trioxide (MoO3) using Mo (CO)6 as a precursor with Ozone as a reactant. An ALD-synthesized wafer-scale MoO3 thin film was later sulfurized through Chemical Vapor Deposition (CVD) to transform into stoichiometric MoS2, which was evaluated using X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM). The roles of activation energy and first-order reaction kinetics in determining the ALD recipe parameters of the pulse time, reactor temperature, and purge time are explicitly discussed in detail. Discretized pulsing for developing one-cycle ALD for monolayer growth is suggested. Remedial measures to overcome shortcomings observed during this research are suggested. [ABSTRACT FROM AUTHOR]

The present study employs X-ray photoelectron spectroscopy (XPS) to analyze plastic samples subjected to degradation processes with the aim to gain insight on the relevant chemical processes and disclose fragmentation mechanisms. Two model plastics, namely polystyrene (PS) and polyethylene (PE), are selected and analyzed before and after artificial UV radiation-triggered weathering, under simulated environmental hydrodynamic conditions, in fresh and marine water for different time intervals. The object of the study is to identify and quantify chemical groups possibly evidencing the occurrence of hydrolysis and oxidation reactions, which are the basis of degradation processes in the environment, determining macroplastic fragmentation. Artificially weathered plastic samples are analyzed also by Raman and FT-IR spectroscopy. Changes in surface chemistry with weathering are revealed by XPS, involving the increase in chemical moieties (hydroxyl, carbonyl, and carboxyl functionalities) which can be correlated with the degradation processes responsible for macroplastic fragmentation. On the other hand, the absence of significant modifications upon plastics weathering evidenced by Raman and FT-IR spectroscopy confirms the importance of investigating plastics surface, which represents the very first part of the materials exposed to degradation agents, thus revealing the power of XPS studies for this purpose. The XPS data on experimentally weathered particles are compared with ones obtained on microplastics collected from real marine environment for investigating the occurring degradation processes. [ABSTRACT FROM AUTHOR]

In order to predict the shelf life of non-ferrous metals, laboratory studies into the kinetics of corrosion processes of metals under various temperature and humidity conditions were performed. The results of 12-month corrosion tests of the following non-ferrous metals are presented: aluminum, cobalt, copper, nickel, tin, lead, and zinc at various relative humidity and air temperature conditions. All the metals studied were found to be corrosion-resistant under atmospheric conditions at a relative humidity of no more than 80% and an air temperature of no more than 30 °C. An increase in air humidity from 70 to 95% and air temperature from 20 to 50 °C leads to an increase in corrosion-induced losses of metals, primarily for zinc, cobalt, and lead. During the tests, changes in the appearance of the sample surface were recorded. The chemical and phase composition of oxide films on the metal surface, as well as their morphology, were studied after different test periods. The results will be used in future works in developing methods for predicting the shelf life of non-ferrous metals. [ABSTRACT FROM AUTHOR]

This study tackles the critical demand for sustainable synthesis methods of reduced graphene oxide (rGO), highlighting the environmental drawbacks of conventional chemical processes. We introduce a novel, green synthesis technique involving the irradiation of a 500 eV argon ion beam, which not only facilitates the creation of micro-patterned rGO on a graphene oxide (GO) film but also enables simultaneous material characterization and patterning. By adjusting the irradiation exposure time between 0 and 80 s, we achieve meticulous control over the attributes and the reduction process of the material. The use of X-ray photoelectron spectroscopy (XPS) allows for real-time monitoring of the reduction from GO to rGO, evidenced by a notable reduction in the intensities of C-O, C=O, and O-C=O bonds, and an increase in C-C bond intensities, indicating a significant reduction level. Our research demonstrates the efficient production of eco-friendly rGO using precise, controlled argon ion beam irradiation, proving its advantages over traditional methods. These results contribute to the development of sustainable material science technologies, with potential applications in electronics, energy storage, and more. [ABSTRACT FROM AUTHOR]

A complex study of the adhesion of multi-walled carbon nanotubes to a titanium surface, depending on the modes of irradiation with He+ ions of the "MWCNT/Ti" system, was conducted using atomic force microscopy and X-ray photoelectron spectroscopy. A quantitative assessment of the adhesion force at the interface, performed using atomic force microscopy, demonstrated its significant increase as a result of treatment of the "MWCNT/Ti" system with a beam of helium ions. The nature of the chemical bonding between multi-walled carbon nanotubes and the surface of the titanium substrate, which causes this increase in the adhesion of nanotubes to titanium as a result of ion irradiation, was investigated by X-ray photoelectron spectroscopy. It was established that this bonding is the result of the formation of chemical C–O–Ti bonds between titanium and carbon atoms with the participation of oxygen atoms of oxygen-containing functional groups, which are localized on defects in the nanotube walls formed during ion irradiation. It is significant that there are no signs of direct bonding between titanium and carbon atoms. [ABSTRACT FROM AUTHOR]

Due to their unique properties, organosols of silver nanoparticles are widely used in optical and semiconductor devices, to produce electrically and thermally conductive films, as catalysts, antibacterial materials, etc. This work proposes a simple and highly productive method for the preparation of silver organosols, which have a metal concentration as high as 1800 g/L and contain spherical nanoparticles with low polydispersity and a median size of 9.1 nm. The method consists in the initial preparation of silver nanoparticle hydrosols with a concentration of higher than 30 g/L followed by the transfer of the NPs into an organic phase of o-xylene. A set of physical research methods has been employed to study the regularities of the extraction of silver nanoparticles with o-xylene in the presence of cetyltrimethylammonium bromide (CTAB) and ethanol and to determine the optimal process conditions, under which the extraction degree is as high as 62.5%. It has been found that bromine anions contained in CTAB molecules cause the aggregation of some amount of silver nanoparticles with the formation of silver metal sediment in the aqueous phase. According to X-ray photoelectron spectroscopy data, the sediment contains bromide ions (up to 4 at %) on the particle surface. Organosols synthesized under optimal conditions are stable for more than 7 months and withstand repeated cycles of drying and redispersing. Silver organosols have been used to obtain metal films with an electrical conductivity of about 68 500 S/cm, which increases to 412 000 and 509 500 S/cm (87.8% of the electrical conductivity of bulk silver) after thermal treatment at 150 and 250°C, respectively. [ABSTRACT FROM AUTHOR]

Adsorption and desorption of ethylene on BaO-terminated (001) barium titanate are investigated by X-ray photoelectron spectroscopy. Carbon is found in an oxidized state, at a binding energy similar to that resulting from CO adsorption on BaTiO3(001). The amount of carbon adsorbed on the surface is also similar to the case of CO/BaTiO3(001). Upon heating the substrate up to the loss of its ferroelectric polarization, the C 1s signal from the oxidized spectral region vanishes. At the same time, there was no noticeable oxygen depletion of the surface after repeated C2H4 adsorption and desorption. The substrate remains stable after repeated oxidative adsorption and desorption of ethylene. Desorption occurs at different temperatures, depending on the adsorption temperature, which suggests different adsorption geometries: non-dissociated adsorption at high temperature with ethylene bond on two surface oxygen atoms, and locally dissociated adsorption at lower temperatures, in “formaldehyde-like” local configurations.

The products of intertidal and super tidal (splash zone) corrosion on steel piles have been characterised at 3 UK sites with contrasting environmental conditions in order to determine corrosion reaction mechanism and if a common mechanism for accelerated low water corrosion occurs across sites. Intertidal corrosion samples at Shoreham and Newhaven ports show an internal composition of iron mono- and bi-sulphide, with intermediate sulphur oxidation state compounds, and an outer surface dominated by iron oxides and oxyhydroxides with a component of iron sulphates. The FTIR spectra are characteristic of sulphate green rust. In contrast, samples from Southend have all sulphur species below detection levels and are dominated by iron oxides and oxyhydroxides. Carbon binding energy spectra are consistent with the development of biofilms at all sites except for a splash zone sample at Southend. The results demonstrate a common mechanism for ALWC at Newhaven and Shoreham, involving the action of sulphate-reducing bacteria generating iron sulphides on the steel surface. These are subsequently oxidised to produce sulphate green rust, which may in turn oxidise to produce lepidocrocite. At Southend differences in environment are inferred to restrict the activity of sulphate reducing bacteria, resulting in direct oxidation of steel to generate iron oxyhydroxide gels, which subsequently recrystallise, dehydrate and oxidise to goethite, magnetite and ultimately hematite in both splash zone and intertidal samples. The multi-technique approach used here characterises the full range of corrosion products.

Herein, we demonstrate the fabrication of sub-20 nm MoS2 horizontal nanowire arrays on silicon substrates using a self-assembled block copolymer assisted in situ inclusion approach. Microphase separated long-range ordered polystyrene-b-polyethylene oxide (PS-b-PEO) block copolymer (BCP) line-space nanopatterns were achieved through thermo-solvent annealing. The patterns produced had long-range order and domain sizes > 1 µm. The BCP structures were lightly etched and modified by anhydrous ethanol to facilitate insertion of molybdenum precursor within the film maintaining the parent BCP arrangements. Horizontal ordered molybdenum oxide nanowire arrays were then fabricated by ultraviolet (UV)/ozone treatment at room temperature. The oxides were converted to sulphides by thermal evaporation at different temperatures in Ar/H2 environment. X-ray photoelectron spectroscopy revealed the composition and phases of the molybdenum oxide and sulphide nanowires. Elemental mapping was performed to investigate the interfaces between the oxide and sulphide nanowires with the substrate surface. The formation and stability of the sulphide nanowires were studied at different temperatures. The photoluminescence and Raman properties were studied at different formation temperatures to investigate defects and estimate the number of layers. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Southeast University / Dongnan Daxue Xuebao is the property of Journal of Southeast University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this work, we used X-ray photoelectron spectroscopy (XPS) to perform a comparative study of the interaction of NO2 with two samples of highly oriented pyrolytic graphite (HOPG), on the surfaces of which rhodium was preliminarily deposited by evaporation in a vacuum, at room temperature and a pressure of 10–5 mbar. Before metal deposition, one of the HOPG samples was annealed in a vacuum at 600°C, and the other was bombarded with argon ions followed by exposure to air at room temperature for 1 h in order to introduce strongly bound oxygen atoms into the surface composition. After the deposition of rhodium onto the two HOPG samples, two model catalysts designated as Rh/C and Rh/C(A)–O were prepared. It was found that the interaction of NO2 with Rh/C led to the oxidation of graphite with the destruction of the surface layer. The Rh particles remained in a metallic state, but they were introduced into the near-surface layer of the carbon support. On the contrary, when the Rh/C(A)–O sample was treated with NO2, the deposited rhodium was partially converted into Rh2O3, while the graphite was oxidized to an insignificant degree and retained its original structure. The role of surface oxygen in the stabilization of graphite with respect to oxidation in NO2 was discussed. [ABSTRACT FROM AUTHOR]

In the presented study, X-ray photoelectron spectroscopy and total reflection X-ray photoelectron spectroscopy methods were applied to analyze the Ti (75 nm) and Pd (100 nm) nanolayers deposited on the Si substrate using magnetron sputtering. The aim of the research was to determine the elemental composition and surface homogeneity of the analyzed nanolayers before their irradiation with highly charged xenon ions and to estimate the detection limit of the X-ray photoelectron spectroscopy technique for various glancing angles. The measurements were conducted using the SPECS mono-XPS system in the Institute of Physics at the Jan Kochanowski University (Kielce, Poland). The experimental setup and measurement conditions for the studied Ti and Pd layers are described. The X-ray photoelectron spectroscopy spectra were registered both for the non-total (35° and 10° angles) and total reflection (2:2° for the Pd nanolayer and 1:5° for the Ti nanolayer) regimes. The position of the C 1s photoelectron peak was applied (C-C component, binding energy 284.8 eV) to calibrate energy. First, the homogeneity of the nanolayers was investigated. The analysis of spectra concentrated on investigating the photoelectron peaks and, consequently, on determining the following: the binding energy of electrons, the intensity and full width at half maximum of photoelectron peaks, the background level, and the elemental composition of the nanolayer surface. In this study, the detection limit of the X-ray photoelectron spectroscopy measurements for different photoelectron peaks was calculated in relation to the excitation angle. An improvement of the X-ray photoelectron spectroscopy detection limit by a factor of 3-6, depending on the type of photoelectron peak, was observed for the angles below the critical angle of the X-ray total reflection phenomenon. [ABSTRACT FROM AUTHOR]

In this work, we used X-ray photoelectron spectroscopy (XPS) to perform a comparative study of the interaction of NO2 with two samples of highly oriented pyrolytic graphite (HOPG), on the surfaces of which rhodium was preliminarily deposited by evaporation in a vacuum, at room temperature and a pressure of 10–5 mbar. Before metal deposition, one of the HOPG samples was annealed in a vacuum at 600°C, and the other was bombarded with argon ions followed by exposure to air at room temperature for 1 h in order to introduce strongly bound oxygen atoms into the surface composition. After the deposition of rhodium onto the two HOPG samples, two model catalysts designated as Rh/C and Rh/C(A)–O were prepared. It was found that the interaction of NO2 with Rh/C led to the oxidation of graphite with the destruction of the surface layer. The Rh particles remained in a metallic state, but they were introduced into the near-surface layer of the carbon support. On the contrary, when the Rh/C(A)–O sample was treated with NO2, the deposited rhodium was partially converted into Rh2O3, while the graphite was oxidized to an insignificant degree and retained its original structure. The role of surface oxygen in the stabilization of graphite with respect to oxidation in NO2 was discussed. [ABSTRACT FROM AUTHOR]

The changes in thallium bromide (TlBr) surfaces induced by plasma etching were characterized by X-ray photoelectron spectroscopy (XPS). A TlBr crystal was grown by the traveling molten zone method with zone-purified material. TlBr wafers were obtained from the crystal. Ar plasma etching was performed on the TlBr wafers. XPS revealed that Tl metal (Tl0) was created in TlBr by the plasma etching. The Tl0 concentration increased with the irradiation time of the plasma. The net Tl0 concentrations of TlBr wafers etched by the plasma for 45 and 180 s were 0.7 and 2.6 wt%, respectively. [ABSTRACT FROM AUTHOR]

Amphiphilic copolymers were synthesized by grafting poly(lactic-co-glycolic) acid with two lignin types: alkaline lignin and lignosulfonate. An interphase formation technique was used to produce films based on the copolymers. Films presented one side as being more hydrophobic (O-side) and smoother, and the second side more polar and with an uneven surface (W-side). Contact angle of water on the W-side was lower than the O-side corresponding to a higher lignin content and influenced by the lignin type (alkaline < lignosulfonate) and lignin: PLGA ratio. X-ray photoelectric spectroscopy analysis showed higher percentages of sulfur on the W-side, which supports a preferential partitioning of the lignin. Tensile testing demonstrated the significant impact of lignin type on the mechanical properties of the films. Alkaline films showed a higher maximum strength, a higher stiffness, and a higher tensile strength at the elastic limit compared to lignosulfonate films. However, for lignosulfonate films, ductility at break point was 4-fold higher than that of alkaline films.

Fiber sizing is one of the most important components in manufacturing composites by affecting mechanical properties, including strength and stiffness. The sizing of manmade fibers offers many advantages, such as improving fiber/matrix adhesion and bonding properties, protecting fiber surfaces from damage during the processing and weaving stages, and enhancing the surface wettability of polymer matrices. In this work, the influence of fiber sizing levels on carbon fibers' (CFs) mechanical properties is reported at room temperature using single fiber tensile testing (Favimat+), single fiber pullout testing (SFPO), and interfacial elemental analysis by X-ray photoelectron spectroscopy (XPS). Standard modulus CFs (7 ± 0.2 μm in diameter) were sized using two commercially available Michelman sizing formulations. The average solid content for each sizing formulation was 26.3 ± 0.2% and 34.1 ± 0.2%, respectively. HEXION RIMR 135 with curing agent RIMH 137 was used as a model thermoset epoxy matrix during SFPO measurements. A predictive engineering fiber sizing methodology was also developed. Sizing amounts of 0.5, 1, and 2 wt.% on the fiber surface were achieved for both sizing formulations. For each fiber size level, 50 single-fiber tensile testing experiments and 20 single-fiber pull-out tests were conducted. The ultimate tensile strength (σult) of the carbon fibers and the interfacial shear strength (τapp) of the single fiber composite were analyzed. The sizing levels' effect on interfacial shear stress and the O/C (Oxygen/Carbon) surface composition ratio was investigated. Based on our experimental findings, an increase of 6% in fiber performance was recorded for ultimate tensile and interfacial shear strengths. As a result, generalized fiber sizing and characterization methods were established. These developed methods can be used to characterize the strength and interfacial shear strength of manmade fibers with different sizing formulations and solid contents irrespective of the matrix, i.e., thermoset or thermoplastic. [ABSTRACT FROM AUTHOR]

Samples of model single-site catalysts based on iridium and rhodium were synthesized by immobilizing the complexes [Ir(COD)(IMes)Cl] and [Rh(COD)(IMes)Cl] (where COD is 1,5-cyclooctadiene and IMes is 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene) on silica, the surface of which was modified with a linker containing a diphenylphosphine group (Ph2P). The supports were silicon plates with a flat surface coated with a layer of natural oxide 1–3 nm thick (Si–SiO2(nat)) or with a specially grown SiO2 film (∼300 nm) (Si–SiO2(ox)). The states of chemical elements in the modified silicon plates and samples of model catalysts were determined by XPS. Based on the results obtained, the nature of the coordination of the immobilized complexes was assumed. Samples of the catalysts were tested in the reaction of gas-phase hydrogenation of propene with parahydrogen. [ABSTRACT FROM AUTHOR]

All inorganic perovskites have recently received substantial attention as prospective substances for energy storage in electrochemical systems. Here, we report on the utility of CsPb2Br5 as supercapacitor electrode material. As fabricated electrode based on CsPb2Br5 shows a specific capacitance of 886 F g−1 at a scan rate of 2 mV s−1. It retained 76% of its initial specific capacitance and demonstrated a Columbic efficiency of ~ 99% after 5000 operational cycles. On the basis of real C′(ω) and imaginary C″(ω) capacitances as a function of frequency, the observed capacitive behaviour is explained in detail, and the charge transfer mechanism is explored using Mott–Schottky analysis. [ABSTRACT FROM AUTHOR]

Hexagonal boron nitride (h‐BN) is an extensively investigated 2D material with exceptional quantum effects, which renders it promising for use in next‐generation nanoelectronic devices. However, the synthesis of single‐ or few‐layer h‐BN nanosheets with large‐area single‐crystal structures is extremely challenging. In this article, a new method is presented for synthesizing h‐BN on a Cu substrate via magnetron sputtering and heat annealing. Three samples with different radio‐frequency (RF) power levels are prepared to evaluate the effect of RF power on h‐BN nanosheet synthesis. Under a higher RF power, the B‐to‐N bonding ratio is closer to 1:1 and further reduces the full width at half maximum of X‐Ray photoelectron spectroscopy B1s and N1s narrow spectra. Heating at 1000 °C reveals white domains with 60° facets, which may correspond to the hexagonal honeycomb lattice structure of h‐BN. Cross‐sectional observations show that a layered structure comprising 10–20 layers forms along the Cu interface. The elemental composition ratio and bonding states reveal the presence of equal amounts of N and B as well as a single peak derived from the B–N bond. Meanwhile, the E2g mode of h‐BN's six‐membered ring structure is indicated at 1364.6 cm−1, thus demonstrating the successful synthesis of an h‐BN film. [ABSTRACT FROM AUTHOR]

In this work, nanostructured TiAlCrN coatings were deposited on a WC-Co substrate using a co-sputtering process varying the silicon composition on the coatings. The influence of silicon content on the mechanical, chemical, and tribological performance of the coatings was studied. The hardness increases from 11 to 16 GPa with the Si content; also, Young's modulus increases from 260 to 295 GPa. The H/E ratio, which is a measure of materials' ability to take the strain before deformation, is also increased with the increase in Si content, suggesting increased toughness. XPS analysis reveals that the coatings present titanium, aluminum, chromium, and silicon nitrides. The tribological behavior of the coatings was conducted through ball-on-disc tests, in which the results show that the coefficients of friction range from 0.15 to 0.55, with the lowest for the samples with the highest Si content. This behavior is benefited by the formation of oxynitride species, identified by XPS, which acts as lubricating layers and diffusion barriers. TiAlCrSixN coating presents a potential application for severe wear owing to its tribological performance. [ABSTRACT FROM AUTHOR]

Copyright of Science of Sintering is the property of National Library of Serbia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

X-ray photoelectron emission spectra of thermally reduced graphene oxide samples and carbon nanotubes (CNTs) with various oxidation degrees are presented in this paper. A method for the reconstruction of differential electron inelastic scattering cross sections from the energy loss spectra of photoelectrons is described and discussed. The analysis of the part of the characteristic photoelectron energy loss spectrum adjacent to the C1 peak indicated a considerable influence of the thermal reduction of graphene oxide on the electron properties of the samples obtained. On the contrary, the oxidation of CNTs by refluxing in a concentrated HNO3 solution does not change the free electron excitation spectrum.

Complex ion substitution is gaining more attention as an appealing method of modifying the structure and performance of microwave ceramics. In this work, Li2Zn[Ti1−x(Ni1/3Nb2/3)x]3O8 (LZTNNx, 0 ≤ x ≤ 0.3) ceramics were designed based on the complex ion substitution strategy, following the substitution rule of radius and valence to investigate the relationship among phase compositions (containing oxygen vacancies and Ti3+ ions), microstructures, and microwave dielectric characteristics of the LZTNNx ceramics. The samples maintained a single Li2ZnTi3O8 solid solution phase as x ≤ 0.2, whereas the sample of x = 0.3 produced a second phase with the LiNbO3 structure. The appropriate amount of (Ni1/3Nb2/3)4+ substitution could slightly improve the densification of the LZTNNx ceramics due to the formation of the Li2ZnTi3O8 solid solution accompanied by a decrease in the average grain size. The presence of a new A1g Raman active band at about 848 cm−1 indicated that local symmetry changed, affecting atomic interactions of the LZTNNx ceramics. The variation of the relative dielectric constant (εr) was closely related to the molar volume ionic polarizability (αDT), and the temperature coefficient of the resonant frequency (τf) was related to the bond valence (Vi) of Ti. The increase in density, the absence of the Ti3+ ions and oxygen vacancies, and the reduction in damping behavior were responsible for the decreased dielectric loss. The LZTNN0.2 ceramics sintered at 1120 ℃ exhibited favorable microwave dielectric properties: εr = 22.13, quality factor (Q×f) = 97,350 GHz, and τf = −18.60 ppm/℃, which might be a promising candidate for wireless communication applications in highly selective electronics.

A complex study of the adhesion of multi-walled carbon nanotubes to a titanium surface, depending on the modes of irradiation with He+ ions of the “MWCNT/Ti” system, was conducted using atomic force microscopy and X-ray photoelectron spectroscopy. A quantitative assessment of the adhesion force at the interface, performed using atomic force microscopy, demonstrated its significant increase as a result of treatment of the “MWCNT/Ti” system with a beam of helium ions. The nature of the chemical bonding between multi-walled carbon nanotubes and the surface of the titanium substrate, which causes this increase in the adhesion of nanotubes to titanium as a result of ion irradiation, was investigated by X-ray photoelectron spectroscopy. It was established that this bonding is the result of the formation of chemical C–O–Ti bonds between titanium and carbon atoms with the participation of oxygen atoms of oxygen-containing functional groups, which are localized on defects in the nanotube walls formed during ion irradiation. It is significant that there are no signs of direct bonding between titanium and carbon atoms.

Objectives: This study aimed to investigate whether the atmospheric pressure plasma jet (APPJ) could modify the surface of lithium disilicate glass ceramics (LDC) instead of hydrofluoric acid (HF) in LDC resin cementation.Methods: Two hundred and thirty-two LDC blocks were randomly divided into seven groups: Group 1 (16 specimens) was the blank control group (without HF or APPJ treatment); Group 2 (36 specimens) was etched by HF; Groups 3–7 (36 specimens each) were treated with APPJ, and the relative air humidity (RAH) of the discharge was 22.8%, 43.6%, 59.4%, 75.2%, and 94.0%, respectively. Three LDC blocks in each group were characterized via X-ray photoemission spectroscopy (XPS) analyses, 3 blocks via contact angle measurements, and other 10 blocks via surface roughness measurements. The residual LDC blocks in groups 2–7 were cemented to composite cylinders. Testing the cemented specimens’ shear bond strength (SBS) before and after thermocycling (6,500 cycles of 5°C and 55°C) revealed fracture patterns. Data were analyzed by ANOVA (post hoc: Bonferroni) (α = 0.05).Results: After APPJ treatment, the water contact angle values of APPJ treated blocks dropped from 31.37° to 5.66°, while that of HF etched ones dropped to 18.33°. The O/C ratio increased after HF etching or APPJ treatment according to the calculated results, except for the APPJ-treated samples at a RAH of 22.8%. The surface roughness of LDC blocks showed no statistic difference before and after APPJ treatment, but experienced significant difference after HF etching. The O/Si and O/C ratios varied after HF etching or APPJ treatment. No significant difference in SBS values could be found among groups 2–7 before or after artificial aging (p > 0.05). All specimens showed mixed failure patterns.Conclusion: The APPJ treatment method reported in this study is a promising novel strategy for surface modification of the LDC. With acceptable bonding strength, it might be an alternative to HF in LDC-resin cementation.

Ammonia has been proposed as a promising solution for hydrogen carriers as well as clean fuels. However, the reaction kinetics is still not robust in many engineering applications, where the deviation is mainly caused by the surface reactions of ammonia on the wall. To examine the ammonia surface reaction on engineering materials, in the present study, the thermal decomposition of ammonia is systematically investigated in uniformly heated quartz/SUS304 tubular flow reactors with the prescribed heating length. A decrease in the inner diameter of the quartz tubular reactor leads to an increase in the ammonia thermal decomposition rate, showing that the thermal decomposition reaction occurs even on quartz surfaces, which is usually believed to be inert. The thermal decomposition on the SUS304 reactor surface starts from as low as 700 K, indicating it is much more reactive than the quartz surface. One-step surface reaction models of ammonia for quartz/SUS304 surfaces are proposed, with which the reaction rates are estimated based on the experimental data. The inner surface of the SUS304 tubular reactor after the thermal decomposition experiments is examined by X-ray photoelectron spectroscopy. The formation of iron nitride on SUS304, which in turn facilitates ammonia thermal decomposition, reveals the positive feedback between ammonia decomposition and nitriding. Moreover, the present one-step surface reaction on stainless steel has been validated by measuring ammonia distributions in the preheat zone of NH 3 /O 2 /N 2 premixed flame impinging on a stainless steel plate through a two-photon absorption laser-induced fluorescence (TALIF) technique. • Thermal decomposition of NH3 in isothermal quartz/SUS304 tubular flow reactors. • NH3 surface decomposition on quartz is not negligible. • Highly reactive NH3 surface decomposition on stainless steel starts from around 673 K. • One-step surface reaction kinetics for quartz and stainless steel are proposed. • Self-enhancement in ammonia decomposition due to the formation of iron nitride. [ABSTRACT FROM AUTHOR]

The microstructure and chemical composition of iron phosphate conversion coatings were investigated by surface/cross–sectional observation using FE–SEM/STEM and chemical state analysis using XPS. As a result, it was suggested that the conversion reaction progressed while the surface oxide on the base material remained, and the fine particles of coatings components were deposited and agglomerated to cover the material surface. The upper layer of coatings was mainly composed of iron phosphate, while the interface between the coatings and base material was deposited iron oxide. The proportion of iron phosphate and iron oxide was almost equal at the initial stage, and the amount of iron phosphate increased as the coating thickness. [ABSTRACT FROM AUTHOR]

The processes at the interface between ionic liquids (ILs) and metals are a key factor for understanding especially in electrochemical deposition, nanoscale tribology applications and batteries. In the present work, the interfaces of 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([Py1,4]TFSI) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIm]TFSI) and platinum and aluminum were investigated by depositing thin IL films and studying them with X-ray photoelectron spectroscopy (XPS) in ultrahigh vacuum. It is found that there is no evidence of a decomposition reaction of either IL on platinum; however, the imidazolium cation of [EMIm]TFSI shows a strong interaction with the surface in the monolayer regime. In contrast, [Py1,4]TFSI and [EMIm]TFSI show massive decomposition on the aluminum surface without applying any electrochemical potential. The spectra for the [TFSI]− anion components show cleavage of C-F or N-S bonds in both cases. Both cleavage of a single fluorine atom and complete cleavage were observed, leading to further decomposition reactions of the anion. Consequently, new components such as AlOOH, Al(OH)3, Al2S3, Al2(SO4)3 and AlF3 appear at the interface. In addition, there is also evidence of decomposition of the cation by the splitting off hydrogen atoms or parts of the alkyl chain in both ILs. [ABSTRACT FROM AUTHOR]

Bamboo pretreatment is a key technology for the preparation of bamboo fibers (BFs) for composites. This study examined the properties of BFs prepared by steam explosion (SE) BFs following pretreatment by enzyme, alkali, and salt. The microstructure, functional groups, crystallinity, and surface chemical elements of BFs were characterized by environmental scanning electron microscope (ESEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The results indicated that bamboo could be separated into fiber bundles through SE after pretreatment. The separation of BFs pretreated by enzyme and alkali were better, but colloid remained and was able to stick the fibers together. Through performing different pretreatments before SE, the lignin and hemicellulose of BFs were partially removed, and alkali pretreatment had the best effect on lignin removal. The crystal structure of the BFs did not change significantly, and the crystallinity of BFs was highest at 2 MPa and 6 min when pretreated by alkali. The XPS results showed that the effect of alkali pretreatment at 2 MPa for 6 min was the best.

In this work, X-ray photoelectron spectroscopy (XPS) was used to study the effect of preliminary oxidative treatment of a carbon support surface on the results of NO2 interaction with model systems prepared by palladium deposition onto highly oriented pyrolytic graphite (HOPG). It was found that, in Pd/HOPG samples with the atomic ratios [O]/[C] ≤ 0.0035, the carbon support was oxidized with the destruction of its structure to a depth of 10–15 graphene layers. In this case, the palladium particles remained in a metallic state, and they penetrated into the near-surface layer of the support due to the deep oxidation of adjacent carbon atoms. At the atomic ratio [O]/[C] ≈ 0.01–0.02, the result of the interaction changed dramatically. In this case, the support remained stable, and the palladium particles were oxidized to form an oxide. This finding explained the high stability of supported palladium catalysts prepared on Sibunit carbon supports in oxidative catalysis reactions. [ABSTRACT FROM AUTHOR]

In this article, using a radio frequency magnetron sputtering system at room temperature, Cu–Al doped ZnO films were deposited on quartz substrates. XPS studies have shown that the broad bands at around 932.5, 943, and 952 eV correspond to the Cu 2 P3/2 peak of Cu+1, Cu 2p3/2 of Cu+2, and Cu 2p1/2, respectively. In the case of Al2p3/2, the peak with binding energy 74.2 eV may be attributed to the presence of Al3+ oxide. The optical density, Dopt, of films annealed at 600 °C has a maximum value about of 0.25. Films annealed at 600 °C have a minimum value of the fractal dimensions, Df, about 2.65. It is observed that films annealed at 500 °C, have a maximum value of the single layer. The minimum value of dissipation factor occurred in films annealed at 500 °C. It can be seen that with doping Cu and Al atoms into ZnO films, the oxygen vacancies were nearly removed and the quality of films was increased; hence the porosity which is introduced in ZnO films can be removed by Cu–Al doping of ZnO films. Due to high evaporation in films annealed at 600 °C, they were rougher and they have a maximum value of RMS roughness at about 4.68 nm. Films annealed at 400 °C have a minimum value of dissipation factor. [ABSTRACT FROM AUTHOR]

X-ray photoelectron emission spectra of thermally reduced graphene oxide samples and carbon nanotubes (CNTs) with various oxidation degrees are presented in this paper. A method for the reconstruction of differential electron inelastic scattering cross sections from the energy loss spectra of photoelectrons is described and discussed. The analysis of the part of the characteristic photoelectron energy loss spectrum adjacent to the C1 peak indicated a considerable influence of the thermal reduction of graphene oxide on the electron properties of the samples obtained. On the contrary, the oxidation of CNTs by refluxing in a concentrated HNO3 solution does not change the free electron excitation spectrum. [ABSTRACT FROM AUTHOR]

The electronic and atomic structure and transport properties of black phosphorus single crystals prepared by high-pressure and gas-transport methods were studied by X-ray photoelectron spectroscopy and scanning probe microscopy (STM, AFM). The atomic resolution of the single crystal surface was obtained by scanning tunneling microscopy. After exposure of the clean surface under ambient conditions, the features in X-ray photoelectron spectroscopy spectra corresponding to the oxidized form of phosphorus were observed and detected using atomic force microscopy. Using low-temperature transport measurements, impurity activation energies were determined and negative magnetoresistance was detected. [ABSTRACT FROM AUTHOR]

We present an ARXPS study on the surface composition and interfacial behavior of commercial [Rh(COD)2][TfO] in [C2C1Im][TfO], [C4C1Im][TfO], [C8C1Im][TfO], and [C2C1Im][EtOSO3]. The complex was found to be non-intact in a solution of these ILs through the loss of COD ligands, accompanied by the depletion of the metal center from the IL/vacuum interface. Increasing the chain length of the aliphatic substituent on the imidazolium cation of the [TfO]−-based ILs led to a more pronounced depletion from the interface, due to the higher surface affinity of the solvent cations with the longer alkyl chains. The loss of COD ligands offered facile in situ ligand substitution with surface-active TPPTS to afford a moderate increase in the surface concentration of Rh. We propose the formation of a Schrock−Osborn-type catalyst [Rh(COD)(TPPTS)2][TfO]. Information on the surface composition and targeted design of the gas/IL interface is highly relevant for applications in IL-based catalytic systems, such as in supported ionic liquid phase (SILP) catalysis. [ABSTRACT FROM AUTHOR]

Over the past few years, cellulose nanocrystals (CNCs), also known as nanocrystalline cellulose (NCCs), have received significant attention owing to their diverse spectrum of applications. CNCs are commonly considered in nanomedicine, the food industry, tissue engineering, energy and storage applications, paper and textile industry, polymeric composites, and bio-catalysis. Due to the versatility of CNCs and CNC-derived materials, there is increasing importance in characterizing their properties using spectroscopic techniques. These spectroscopic techniques include solid-state nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron (XPS) spectroscopy, and Raman spectroscopy. This review focuses on the characterization of CNCs and CNCs-derived materials using the aforementioned spectroscopic techniques. This review also discusses the background, experimental procedures, sample preparation, and spectral analysis methods used in these techniques. [ABSTRACT FROM AUTHOR]