Chemical State Analysis Research Articles

A comparative study of the pyrolysis and hydrolysis conversion of tire

In the present study, we pyrolyzed a waste tire at various temperatures under an N2 atmosphere and a water environment in an autoclave reactor to investigate the effect of water on tire degradation. The analysis involved a comparison of product distribution, char properties, oil composition, and the behavior of heteroatom elements (especially oxygen, nitrogen, and sulfur) under different atmospheres. Elemental analysis, functional-group identification, and chemical state analysis of sulfur were performed for chars. In addition, the chemical composition, elemental composition, and molecular weight of the produced oils were evaluated. The heavy fraction of oils, not detectable by gas chromatography-mass spectrometry (GC-MS), was analyzed through Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The findings revealed that high temperatures promoted oil cracking, resulting in the formation of light oils in both pyrolysis and hydrolysis processes. Compared to pyrolysis, hydrolysis generated a higher yield of low molecular–weight oil. Elevated hydrolysis temperatures promoted aromatization, yielding an oil with a low H/C ratio and a high double bond equivalent number. Consequently, the concentration of aromatics in the light fraction of oils generated from the hydrolysis process exceeded that in oils from the pyrolysis process. Temperature exhibited a limited impact on oil composition during the pyrolysis process. Hydrolysis promoted the release of heteroatom-containing compounds at low temperatures. During pyrolysis, nitrogen was gradually released from the solid phase, whereas nitrogen-containing compounds were released early during hydrolysis, with gas-phase nitrogen accounting for more than 50 wt% at 320 °C. A maximum D-limonene yield of 45.58% was obtained at 360 °C within 0 min of hydrolysis, with the potential conversion of D-limonene into aromatics at higher hydrolysis temperatures. These results contribute to the understanding of tire valorization via hydrolysis.

Effect of hydrogen on the chemical state, stoichiometry and density of amorphous Al2O3 films grown by thermal atomic layer deposition

Amorphous oxide thin films grown by thermal atomic layer deposition (ALD) typically contain high impurity concentrations of hydrogen, which affects both chemistry and structure and thereby the functional properties, such as the barrier properties in, for example, microelectronic and photovoltaic devices. This study discloses the effect of H incorporation in amorphous Al2O3 ALD oxide films on the local chemical binding states of Al, O and H, as well as the oxide density and stoichiometry, by a combined analytical approach using elastic recoil detection analysis, Rutherford backscattering spectroscopy and full chemical state analysis by dual‐source X‐ray photoelectron spectroscopy (XPS)/hard X‐ray photoelectron spectroscopy (HAXPES). The experimental findings are compared with crystalline anhydrous α‐Al2O3 and hydroxide α‐Al (OH)3 reference phases and further supported by molecular dynamic simulations. It is shown that H preferably forms covalent –OH hydroxyl bonds with O in the nearest‐neighbour coordination spheres of interstitial Al cations, which affects both the ligand electronic polarizability and the bond length of the randomly interconnected [AlOn] polyhedral building blocks in the amorphous ALD oxide films.

A two dimensional Co(OH)2 catalytic gravity-driven membrane for water purification: a green and facile fabrication strategy and excellent water decontamination performance.

Cobalt-based materials are reported to be the most efficient catalysts in sulfate radical advanced oxidation processes (SR-AOPs). A green and facile method was developed in this work to prepare uniform Co(OH)2 hexagonal nanosheets, which was void of any organic solvents via mere ambient temperature stirring. The obtained nanosheets were assembled into a catalytic gravity-driven membrane, through which the removal efficiency of a typical pharmaceutical contaminant, ranitidine (RNTD), could reach ∼100% within 20 min. Meanwhile, the catalytic membrane also demonstrated effective removal performance towards various pollutants. In order to augment the long-term stability of catalytic membranes, Co(OH)2/rGO composites were fabricated using the same strategy, and a Co(OH)2/rGO catalytic membrane was prepared correspondingly. The Co(OH)2/rGO membrane could maintain a ∼100% removal of RNTD over a constant reaction period lasting for up to 165 hours, which was approximately 11 times that of the sole Co(OH)2 membrane (15 h). Analysis of element chemical states, metal ion concentration in filtrates, and quenching experiments suggested that the combination with rGO could promote the electron transfer to accelerate the Co(II) regeneration, restrain the cobalt dissolution to alleviate the active site loss, and contribute to the production of 1O2via synergistic effects of oxygen-containing groups in rGO. Toxicity assessment was performed on RNTD and its degradation intermediates to confirm the reduction in ecotoxicity of the treated feed. Overall, this work not only offered guidance for the application of nanosheets in AOP membranes, but also had implications for the environmentally-friendly preparation protocol to obtain functional metal hydroxides.

Synergistic effect of metal cation and 1-dimethylamino-2-propanol on copper corrosion protection in alkaline solution

BackgroundCopper (Cu) has versatile applications in microelectronic industry and its corrosion protection in the manufacturing process is an important reliability issue. MethodsIn this study, mixed type corrosion inhibitor is formulated by complexation of metal cation (Ni2+) and tertiary amine (1-dimethylamino-2-propanol), and its synergistic effect on the corrosion protection of Cu in alkaline solution is systematically investigated. Electrochemical, microstructural, and chemical state analyses of the Cu surfaces with and without the inhibitor protection are performed to realize the protection efficacy of the mixed type inhibitor against corrosion. Significant findingsThe results show that the polarization resistance of the Cu surface is increased with the introduction of mixed type inhibitor (Ni2+-1-dimethylamino-2-propanol), achieving a higher inhibition efficiency of 48 % compared to the cation-free inhibitor (1-dimethylamino-2-propanol) of 25 %. The higher inhibition efficiency is attributed to the stronger adsorption capability of mixed type inhibitor on the Cu surface as confirmed by the X-ray photoelectron spectroscopy analysis and quantum chemical calculations.

Electron Irradiation-Induced Degradation of TiN Thin Films on Quartz and Sapphire Substrates.

In this contribution, we investigated the properties of magnetron-sputtered TiN thin films on sapphire and quartz substrates before and after 5 MeV electron irradiation with a fluence of 7 × 1013 e/cm2. Structural, morphological, optical, and electrical properties were analyzed to observe the impact of electron irradiation on the TiN thin films. The results showed improved electrical properties of the TiN thin films due to high-energy electron irradiation, resulting in increased specific conductivity compared to the as-deposited thin films on both sapphire and quartz substrates. The structural features of the TiN thin films on the sapphire substrate transformed from polycrystalline to amorphous, while the TiN thin films deposited on the quartz substrate remained unchanged. Chemical state analysis indicated changes in the metallic bonding between Ti and N in the deposited TiN on the sapphire substrate, while TiN deposited on the quartz substrate retained its Ti-N bonding. This study provides insights into the effects of electron irradiation on TiN thin films, emphasizing the importance of investigating radiation resistance for the reliable operation of optoelectronic devices and photovoltaic systems in extreme ionizing radiation environments.

Sol-gel synthesis and photoluminescent properties of metal oxide-metal oxide coupled nanocomposites

Tin oxide (SnO2) and zinc oxide (ZnO) coupled metal-oxide nanocomposites or SnO2–ZnO were prepared using a sol-gel method. The stretching mode frequencies and crystal structures were examined by using Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD), respectively. The microscopic analyses by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed a flower-like morphology of the nanocomposites. The analysis of surface chemical and electronic states was conducted by X-ray photoelectron spectroscopy (XPS). The band gap energies as confirmed from the ultraviolet–visible spectroscopy (UV–Vis) data were found to be larger than those of the bulk band gaps due to the increase between energy levels associated with smaller particle sizes. The UV (380 nm) and orange (595) photoluminescence (PL) emissions observed from the SnO2:ZnO nanocomposites were attributed to a combinatorial contribution from radiative transitions in SnO2 and ZnO components. The proposed mechanisms of these emissions are discussed.

Biological Oxidation of Manganese Mediated by the Fungus Neoroussoella solani MnF107

Manganese oxides are highly reactive minerals and influence the geochemical cycling of carbon, nutrients, and numerous metals in natural environments. Natural Mn oxides are believed to be dominantly formed by biotic processes. A marine Mn-oxidizing fungus Neoroussoella solani MnF107 was isolated and characterized in this study. SEM observations show that the Mn oxides are formed on the fungal hyphal surfaces and parts of the hypha are enveloped by Mn oxides. TEM observations show that the Mn oxides have a filamentous morphology and are formed in a matrix of EPS enveloping the fungal cell wall. Mineral phase analysis of the fungal Mn oxides by XRD indicates that it is poorly crystalline. Chemical oxidation state analysis of the fungal Mn oxides confirms that it is predominantly composed of Mn(IV), indicating that Mn(II) has been oxidized to Mn (IV) by the fungus.

Sub-Nanometer Depth Profiling of Native Metal Oxide Layers Within Single Fixed-Angle X-Ray Photoelectron Spectra.

Many metals form nanometer-thin self-passivating oxide layers upon exposure to the atmosphere, which affects a wide range of interfacial properties and shapes the way how metals interact with their environment. Such native oxide layers are commonly analyzed by X-ray photoelectron spectroscopy (XPS), which provides a depth-resolved chemical state and compositional analysis either by ion etching or modeling of the electron escape depths. The latter is commonly used to calculate the average thickness of a native oxide layer. However, the measurement of concentration profiles at the oxide-metal interface remains challenging. Here, a simple and accessible approach for the depth profiling of ultrathin oxide layers within single fixed-angle XPS spectra is proposed. Instead of using only one peak in the spectrum, as is usually the case, all peaks within the energy range of a standard lab device are utilized, thus resembling energy-resolved XPS without the need for a synchrotron. New models that allow the calculation of depth-resolved concentration profiles at the oxide-metal interface are derived and tested, which are also valid for angular- and energy-resolved XPS. The proposed method not only improves the accuracy of earlier approaches but also paves the way for a more holistic understanding of the XPS spectrum.

Scanning photoelectron microscopy discloses the role of Cr and Mo in the selective corrosion of hardmetal grades with Co-Ni binders

Advanced applications of hardmetal (HM) in chemically aggressive ambients call for the improvement of their corrosion resistance, combined with optimal abrasion and toughness properties. This goal is chiefly achieved with binder alloying. In particular, Cr and Mo additions to Co-Ni matrices have proved effective in many cases, but the physico-chemical mechanisms underlying this functional improvement are poorly understood. This situation, on the one hand does not enable the fine-tuning of the composition, and, on the other hand, does not allow to reliably extrapolate the performance of these grades to new ambients. The aim of this work is to propose a molecular-level approach to the understanding of the electrochemical corrosion of HM, based on space-resolved compositional and chemical-state analysis of the surface of HM subjected to controlled electrochemical corrosion. This type of analysis is enabled by synchrotron-based scanning photoelectron microscopy (SPEM) and photoelectron microspectroscopy (μ-XPS). Specifically, we studied a WC-based grade with 15 w% binder with 4.67 Co/Ni ratio, alloyed with 0.78 w% Cr and 0.94 w% Mo, corroded potentiostatically in neutral sulphate aqueous solution in the pseudopassive and transpassive ranges. SPEM and μ-XPS allowed to locate and distinguish the chemical state of the binder and carbide elements in the respective phases and to distinguish the surface stoichiometry brought about by corrosion in different conditions. In particular, we found that pseudopassive conditions lead to the formation of surface films, enriched in W(VI) and Cr(III). Transpassive conditions cause notable surface enrichment in Cr(III) as well as to the formation of mixed Cr-W oxides in the WC regions. Mo is leached from the binder at all potentials investigated, while Mo(0) is present in the WC region under pseudopassive conditions, while transpassivity leads to its oxidative removal. Chloride in the electrolyte favours dissolution of oxidized metals, in particular causing the leaching of Cr(III), while Mo(III) is found at the surface of WC grains.

Observation of interfacial magnetic interaction in Eu-doped BiFeO3 and YMnO3 nanocomposites

The results of structural and magnetic properties of (1-x)Bi0.96Eu0.04FeO3-(x)YMnO3 (x = 0.0,0.25,0.50,0.75,1) nanocomposites, synthesized using physical mixing method are presented in this work. The Eu doped bismuth ferrite and yttrium manganite nanoparticles are synthesized separately and then physically mixed using hydrothermal method. The physical mixing of the parent materials helps to retain the properties of both the materials in the nanocomposites. XRD patterns show the presence of both phases (R3c and P63cm) in the nanocomposites, without any structural distortion or presence of other intermediate phases. Morphological analysis of the samples is done using FESEM and HRTEM techniques. The FESEM results show that the particles in the parent as well as nanocomposites are irregularly distributed with agglomeration of particles in Eu doped BiFeO3 and the nanocomposite (BY-50). The interplanar distances corresponding to crystal planes of both phases are calculated for BY-50 nanocomposite from the HRTEM results. Chemical state analysis of BY-50, using XPS confirms the formation of nanocomposite. Multiple valence states for Fe (Fe2+ and Fe3+) and Mn (Mn2+, Mn3+ and Mn4+) are formed as a result of charge compensation phenomenon. The dominant Fe3+ and Mn3+ plays an important role in the magnetic properties of nanocomposites. Magnetic studies on the parent as well as the nanocomposites are done using room-temperature VSM. The M−H loops show wasp-waisted nature with the presence of weak ferromagnetism along with anti-ferromagnetic or paramagnetic ordering. The constricted nature of loops has been confirmed using ΔH (loop-width) versus M (magnetization) loops. The addition of YMnO3 in the nanocomposites slightly increases the maximum magnetization from 0.149 emu/g for Eu doped BiFeO3 nanoparticles to 0.364 emu/g for BY-75 nanocomposites. The maximum magnetization in the nanocomposites increases because of the constructive alignment of the spins at the interface. The presence of interfacial magnetic interaction in the samples has been corroborated through room-temperature X-band ESR analysis.

5D Analysis of Capacity Degradation in Battery Electrodes Enabled by Operando CT-XANES.

For devices encountering long-term stability challenges, a precise evaluation of degradation is of paramount importance. However, methods for comprehensively elucidating the degradation mechanisms in devices, particularly those undergoing dynamic chemical and mechanical changes during operation, such as batteries, are limited. Here, a method is presented using operando computed tomography combined with X-ray absorption near-edge structure spectroscopy (CT-XANES) that can directly track the evolution of the 3D distribution of the local capacity loss in battery electrodes during (dis)charge cycles, thereby enabling a five-dimensional (the 3D spatial coordinates, time, and chemical state) analysis of the degradation. This paper demonstrates that the method can quantify the spatiotemporal dynamics of the local capacity degradation within an electrode during cycling, which has been truncated by existing bulk techniques, and correlate it with the overall electrode performance degradation. Furthermore, the method demonstrates its capability to uncover the correlation among observed local capacity degradation within electrodes, reaction history during past (dis)charge cycles, and electrode microstructure. The method thus provides critical insights into the identification of degradation factors that are not available through existing methods, and therefore, will contribute to the development of batteries with long-term stability.

Analysis of microstructure, chemical state and electrical features of Ti/WO3/p-InP heterojunction with a tungsten oxide insulating layer

Analysis of microstructure, chemical state and electrical features of Ti/WO3/p-InP heterojunction with a tungsten oxide insulating layer

Synchrotron science for sustainability: life cycle of metals in the environment.

The movement of metals through the environment links together a wide range of scientific fields: from earth sciences and geology as weathering releases minerals; to environmental sciences as metals are mobilized and transformed, cycling through soil and water; to biology as living things take up metals from their surroundings. Studies of these fundamental processes all require quantitative analysis of metal concentrations, locations, and chemical states. Synchrotron X-ray tools can address these requirements with high sensitivity, high spatial resolution, and minimal sample preparation. This perspective describes the state of fundamental scientific questions in the lifecycle of metals, from rocks to ecosystems, from soils to plants, and from environment to animals. Key X-ray capabilities and facility infrastructure for future synchrotron-based analytical resources serving these areas are summarized, and potential opportunities for future experiments are explored.

News Article

Book, “X-Ray Spectroscopy for Chemical State Analysis” (Jun Kawai, Springer, 2023) Professor Jun Kawai (Kyoto University, Japan) has published an interesting and useful book on materials characterization methods using X-ray emission, absorption, and photoelectron spectroscopies. Readers will be able to learn about basic X-ray physics topics such as “Particle and Wave Duality of X-rays” (Chapter 1), “Profile Change of X-Ray Spectra” (Chapter 2), and “Chemical Effects of Multiply Ionized Satellites” (Chapter 3). They can also gain some practical knowledge on instrumentation, including “Pyroelectric X-Ray Emission” (Chapter 4), “Small-Size and Low-Power X-Ray Instruments” (Chapter 5), “Synchrotron Radiation Experiments” (Chapter 6), and “Quantitative Analysis Using XRF and SEM” (Chapter 7). The book includes some interesting historical episodes, such as Professor Yoneda's discovery of enhanced diffuse scattering at the total reflection critical angle (now often called the Yoneda peak or Yoneda wing in grazing-incidence small angle X-ray scattering) and TXRF. The author also describes his own experience - how he has achieved novel experiments. The book consists of 243 pages. Overall, this book seems to provide a good overview of X-ray spectroscopy methods and their applications. The inclusion of historical context and the author's experiences helps to give readers insight into how these techniques were developed and applied in practice. For further information of the book, see the following page, https://doi.org/10.1007/978-981-19-7361-1

Investigation of paint removal by atmospheric pressure plasma jet

Acrylic polyurethane paint on the surface of 2A12 Al alloy was cleaned utilizing an atmospheric pressure plasma jet in this work. The dynamic evolution of the paint removal process during plasma treatment with time was explored through analysis of morphology and chemical states. The results showed that although the thickness of paint could be reduced effectively with an increase in cleaning time, the removal rate of paint gradually decreased with time. During the initial cleaning process range, its original smooth morphology of paint turned rugged quickly and was almost unchanged with further plasma treatment. Element and chemical state analysis showed that the content of C in the paint layer decreased obviously after plasma treatment. In contrast, the O content increased remarkably. The cleaning mechanism could be mainly attributed to the reaction between active O-containing species in air plasma and organic components in the paint. After removal of superficial organic matter, residue inorganic metal oxide substances aggregated on the base. The exposed metal oxides on the one hand elevated the superficial O content, but on the other hand hindered further plasma penetration, resulting in a gradual decrease in cleaning rate with cleaning time. Therefore, physical wiping was proposed to be incorporated with the plasma method and effective removal of paint was realized.

Electrochemical Performance of Chemically Integrated N-Doped Carbon Dots/Bi2MoO6 Nanocomposites for Symmetric Supercapacitors

Mixed transition-metal oxides (MTMOs) are attracting tremendous attention as a battery-type electrode due to their high electrical conductivity and structural stability. However, utilizing these electrodes in practical applications is hindered by capacity degradation, especially during the long-term cycle. These limitations could be overcome by constructing electrodes by introducing the carbonaceous material into the MTMO matrix. Accordingly, in this work, a facile hydrothermal method is employed to develop nitrogen-doped carbon dots (NCDs)-integrated bismuth molybdenum oxide (Bi2MoO6; BMO) (NCD/BMO) composites, where the concentration of NCDs is varied, such as 2, 5, 10, and 15 wt %. The structural and chemical state analyses of the samples confirm the formation of the orthorhombic BMO system and the chemically integrated NCD/BMO composites. The morphology analysis revealed a brick-like structure for bare-BMO with an average size of ∼100 nm and a rod-like morphology for the NCD/BMO composites, which is attributed to the interaction of NCDs with growing BMO particles leading to the rod-like formation of the resultant composites. The electrochemical performance of the developed materials is studied in a three-electrode and symmetric assembly system. Among the composites, the 10 wt % NCD/BMO (BMO–C10) composite exhibited an enhanced specific capacity of 561 C g–1 (155.8 mA h g–1) at a current density of 1 A g–1 in 6 M KOH electrolyte. Besides, the assembled symmetric device achieved an energy density and a power density of 44.2 W h kg–1 and 720 W kg–1, respectively, at a current density of 1 A g–1. In addition, the assembled symmetric device maintained excellent cyclic stability of ∼87.3% up to 10,000 cycles at 20 A g–1 current density. The obtained results demonstrate that the NCD/BMO composite could be an efficient battery-type electrode material for promising supercapacitor applications.

Simultaneous immobilization of ammonia and phosphorous by thermally treated sediment co-modified with hydrophilic organic matter and zeolite

The use of calcined sediments (CS) for thin-layer capping is an environment-friendly technology for controlling nitrogen (N) or phosphorus (P) release. However, the effects of CS derived materials and efficiency in controlling the sedimentary N/P ratio have not been thoroughly investigated. While zeolite-based materials have been proven efficient to remove ammonia, it is limited by the low adsorption capacity of PO43−. Herein, CS co-modified with zeolite and hydrophilic organic matter (HIM) was synthesized to simultaneously immobilize ammonium-N (NH4+-N) and remove P, due to the superior ecological security of natural HIM. Studies on the influences of calcination temperature and composition ratio indicated that 600 °C and 40% zeolite were the optimal parameters leading to the highest adsorption capacity and lowest equilibrium concentration. Compared with doping with polyaluminum chloride, doping with HIM not only enhanced P removal but also achieved higher NH4+-N immobilization efficacy. The efficiency of zeolite/CS/HIM capping and amendment in prohibiting the discharge of N/P from sediments was assessed via simulation experiments, and the relevant control mechanism was studied at the molecular level. The results indicated that zeolite/CS/HIM can reduce 49.98% and 72.27% of the N flux and 32.10% and 76.47% of the P flux in slightly and highly polluted sediments, respectively. Capping and incubation with zeolite/CS/HIM simultaneously resulted in substantial reductions in NH4+-N and dissolved total P in overlying water and pore water. Chemical state analysis indicated that HIM enhanced the NH4+-N adsorption ability of CS owing to its abundant carbonyl groups and indirectly increased P adsorption by protonating mineral surface groups. This research provides a novel strategy to control sedimentary nutrient release by adopting an efficient and ecologically secure remediation method to rehabilitate eutrophic lake systems.

Surface chemical states analysis and operational parameters dependent photocatalytic activity of mixed-phase TiO2:Ag photocatalysts

Surface chemical states analysis and operational parameters dependent photocatalytic activity of mixed-phase TiO2:Ag photocatalysts

Hydrophilic Surface Modification of Amorphous Hydrogenated Carbon Nanocomposite Films via Atmospheric Oxygen Plasma Treatment

Herein we investigated hydrophilic surface modification of SiOx containing amorphous hydrogenated carbon nanocomposite films (DLC:SiOx) via the use of atmospheric oxygen plasma treatment. The modified films exhibited effective hydrophilic properties with complete surface wetting. More detailed water droplet contact angle (CA) measurements revealed that oxygen plasma treated DLC:SiOx films maintained good wetting properties with CA of up to 28 ± 1° after 20 days of aging in ambient air at room temperature. This treatment process also increased surface root mean square roughness from 0.27 nm to 1.26 nm. Analysis of the surface chemical states suggested that the hydrophilic behavior of DLC:SiOx treated with oxygen plasma is attributed to surface enrichment with C-O-C, SiO2, and Si-Si chemical bonds as well as significant removal of hydrophobic Si-CHx functional groups. The latter functional groups are prone to restoration and are mainly responsible for the increase in CA with aging. Possible applications of the modified DLC:SiOx nanocomposite films could include biocompatible coatings for biomedical applications, antifogging coatings for optical components, and protective coatings to prevent against corrosion and wear.

Resolving Oxidation States and X–site Composition of Sn Perovskites through Auger Parameter Analysis in XPS (Adv. Mater. Interfaces 7/2023)

Resolving Chemical States in Sn-Based Perovskites In article 2201828, Alexander Wieczorek, Sebastian Siol, and colleagues demonstrate how Auger parameter analysis enables more reliable chemical state analysis of Sn-based perovskites. Through systematic compositional variation a high sensitivity of this parameter on the X-site composition and oxidation state of Sn-based perovskites is demonstrated. The latter aspect can be used to detect and understand aging of these compounds under ambient conditions. This approach can be easily adopted using standard XPS equipment and enables better reproducibility of results across laboratories. [Artwork by Alexander Wieczorek]