Microcrystal Structure Research Articles

Annealing Process-Induced Microstructural Variation in NiV/B4C Multilayers

The annealing process is one of the most common methods used to study the thermal stability of multilayers. To study the effect of the annealing process on the microstructural variation in NiV/B4C multilayers, different annealing experiments were performed on NiV/B4C multilayers with a d-spacing of 8 nm. This work provides a foundation for the fabrication of non-periodic NiV/B4C multilayers. The NiV/B4C multilayers were investigated by grazing-incidence X-ray reflectometry (GIXR), X-ray diffuse scattering (XRS), atomic force microscopy (AFM), X-ray diffraction (XRD), grazing-incidence small-angle X-ray scattering (GISAXS) and transmission electron microscopy (TEM). The temperature-dependent experiments showed that annealing at 70–290 °C slightly increased the period thickness and interface width. Annealing at higher temperatures resulted in significant structural changes and thickness ratio (Г = dNiV/d) changes from 0.4 to 1/3 at 340 °C. The time-dependent results showed that the microstructural variations primarily occurred after 60 min. The XRD, XRS, GISAXS and TEM were further used to study microstructural changes. It was found that the NiV/B4C multilayers exhibited a microcrystal structure after annealing, and that enhanced crystallinity and an increase in interface roughness were the main reasons for the microstructural changes.

КОЛИЧЕСТВЕННО-КАЧЕСТВЕННАЯ ХАРАКТЕРИСТИКА КРИСТАЛЛИЧЕСКОГО СТРОЕНИЯ РОТОВОЙ ЖИДКОСТИ ЧЕЛОВЕКА С ИСПОЛЬЗОВАНИЕМ ТЕОРИИ ФРАКТАЛОВ. ЧАСТЬ II

The subject of the study is human oral fluid. The goal is quantitative and qualitative assessment of the crystalline structure of the oral fluid of personal computer users using the theory of fractals. The task is to characterize qualitatively the crystals of the oral fluid of volunteers; apply a computer program to calculate the fractal dimension and area of oral fluid crystals. Methodology. Research work consists of two stages. In the first stage, a quantitative and qualitative assessment of the crystalline structure of users’ oral fluid was carried out over time without exposure to electromagnetic radiation from a computer. In the second stage, a quantitative and qualitative assessment of the crystalline structure of the users’ oral fluid in dynamics under the influence of electromagnetic radiation from a computer was performed. A laboratory analysis of oral fluid was performed according to physicochemical parameters: pH, buffer capacity, surface tension, total protein, inorganic phosphorus, ammonium, potassium, sodium, magnesium, calcium and α-amylase. The type of structure of saliva microcrystals was determined using the method of P.A. Leus. Additionally, the structure of representative crystals was assessed. A fractal analysis of crystals was carried out (calculation of the fractal dimension and area of the crystals). Results. Qualitative and quantitative assessment of the state of users' oral fluid over time without exposure to electromagnetic radiation from a computer did not reveal statistically significant changes in physicochemical parameters and crystal structure. Based on the results of the second stage of research, the negative effect of the computer’s electromagnetic field on the oral fluid of users was established. Assessment of the crystalline structure of oral fluid according to the method of P.A. Leus did not reveal any negative changes against the background of computer radiation. However, a visual assessment of the representative crystals showed that there are disturbances in the structure of the crystal structures as a result of their destruction and loss of the first and second order axes, which was confirmed by fractal analysis. Conclusion. The negative impact of laptop electromagnetic radiation on the oral fluid of users has been revealed. Qualitative and quantitative crystallographic methods are complementary. Integration of these methods in the form of a quantitative and qualitative assessment of the crystalline structure of human oral fluid will allow the doctor to expand diagnostic capabilities in the field of saliva diagnostics.

Tailored Regulation of Graphite Microcrystals via Tandem Catalytic Carbonization for Enhanced Electrochemical Performance of Hard Carbon in the Low‐Voltage Plateau

AbstractThe sodium storage behavior in the plateau region is crucial for determining the capacity and rate capability of hard carbon (HC) anodes in sodium‐ion batteries (SIBs). Key structural features for achieving excellent plateau performance include extended graphite domains and increased interlayer spacing. However, synchronously optimizing these two structures is challenging due to their inherent trade‐off. Herein, a tandem catalytic carbonization strategy is developed to construct HC with long graphite domains (La = 5.31 nm) and large interlayer spacing (d002 = 0.389 nm) simultaneously. Comprehensive in situ and ex situ tests unravel the catalytic selective bond breaking and aromatization effects of ZnCl2, the catalytic graphitic layers enlargement and occupied effects of formed ZnO and Zn in different temperature stages, leading to the formation of the unique structure. The optimal HCZ‐0.1 exhibits a high reversible capacity of 346.9 mAh g−1 with a plateau capacity of 249.4 mAh g−1, and high‐rate performance (114.0 mAh g−1 at 5 A g−1). In addition, the sodium storage mechanism and origin of enhanced Na+ kinetics of HCZ‐0.1 are also revealed. This work offers a precise method to engineer the graphite microcrystal structure in HC for superior sodium storage in the plateau region.

Electrochemical Growth of Copper Crystals on SPCE for Electrocatalysis Nitrate Reduction.

Copper is efficient, has a high conductivity (5.8 × 107 S/m), and is cost-effective. The use of copper-based catalysts is promising for the electrocatalytic reduction of nitrates. This work aims to grow and characterize copper micro-crystals on Screen-Printed Electrodes (SPEs) for NO3- reduction in water. Copper micro-crystals were grown by cyclic voltammetry. Different cycles (2, 5, 7, 10, 12, 15) of copper electrodeposition were investigated (potential ranges from -1.0 V to 0.0 V, scan rate of 0.1 V s-1). Electrodeposition generated different morphologies of copper crystals on the electrodes, as a function of the number of cycles, with various performances. The presence of numerous edges and defects in the copper micro-crystal structures creates highly reactive active sites, thus favoring nitrate reduction. The manufactured material can be successfully employed for environmental applications.

Evolution of microstructure and mechanical properties of electroplated nanocrystalline Ni–Co coating during heating

Ni–Co alloy coating is applied to crystallizer surface to enhance its wear resistance for continuous steel casting. This study investigated the effects of heating temperature on the hardness, strength, and elongation of Ni–21wt.% Co coatings obtained by electroplating. The evolution of microstructure was analyzed by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The results indicated that the as-deposited coating had a mixed structure of nanocrystals and microcrystals, containing numerous nanotwins and stacking faults. Its hardness, tensile strength, yield strength, and elongation were 371 HV0.1, 1170MPa, 1117MPa, and 13.8%, respectively. After low-temperature heating, the number of nanocrystals decreased, whereas the fraction of microcrystals increased. At heating temperatures of 100–200 °C, a reverse Hall–Petch phenomenon occurred owing to the formation of annealing twins and the transformation of dislocation-emission mechanisms, resulting in a stable hardness and tensile strength. As the heating temperature was further increased, the grains continuously grew, thereby decreasing the hardness and tensile strength. After annealed at 400 °C, the elongation reached 32.5%, whereas the hardness, tensile strength, and yield strength decreased to 200 HV0.1, 662MPa, and 577MPa, respectively.

Mechanism of one-step hydrothermal nitric acid treatment for producing high adsorption capacity porous materials from coal gasification fine slag

The increasing amount of coal gasification fine slag (CGFS) necessitates its resource utilization. CGFS, mainly composed of porous carbonaceous particles and partially fused spherical or agglomerated ash particles, is an inexpensive and high-quality raw material for preparing adsorbent materials. However, the challenge remains in developing a simple, low-cost, and environmentally friendly method to produce high-performance porous materials from CGFS. In this study, a one-step treatment method using 2 mol/L nitric acid under hydrothermal conditions was proposed for CGFS. The adsorbent material (CGFS-2 M) prepared under a solid–liquid ratio of 2:5 and an initial concentration of 200 mg/L methylene blue (MB) exhibited an equilibrium adsorption capacity as high as 210.20 mg/g. The excellent adsorption performance of CGFS-2 M can be attributed to several factors: acid leaching for mineral removal and pore formation, resulting in a specific surface area and total pore volume 2.2 and 1.6 times that of untreated CGFS, respectively, and an optimized mesoporous pore size distribution favorable for MB adsorption; optimal mineral removal and a well-defined carbon microcrystal structure providing more space for MB adsorption; nitric acid treatment increasing the surface oxygen content and hydrophilicity, enhancing its ability to remove MB. The synergistic effect of pore structure improvement and surface modification indicates a feasible research direction for enhancing the performance of CGFS-based adsorbent materials. These results provide theoretical support for the development of efficient CGFS-based adsorbents.

Microcrystal electron diffraction structure of Toll-like receptor 2 TIR-domain-nucleated MyD88 TIR-domain higher-order assembly.

Eukaryotic TIR (Toll/interleukin-1 receptor protein) domains signal via TIR-TIR interactions, either by self-association or by interaction with other TIR domains. In mammals, TIR domains are found in Toll-like receptors (TLRs) and cytoplasmic adaptor proteins involved in pro-inflammatory signaling. Previous work revealed that the MAL TIR domain (MALTIR) nucleates the assembly of MyD88TIR into crystalline arrays in vitro. A microcrystal electron diffraction (MicroED) structure of the MyD88TIR assembly has previously been solved, revealing a two-stranded higher-order assembly of TIR domains. In this work, it is demonstrated that the TIR domain of TLR2, which is reported to signal as a heterodimer with either TLR1 or TLR6, induces the formation of crystalline higher-order assemblies of MyD88TIR in vitro, whereas TLR1TIR and TLR6TIR do not. Using an improved data-collection protocol, the MicroED structure of TLR2TIR-induced MyD88TIR microcrystals was determined at a higher resolution (2.85 Å) and with higher completeness (89%) compared with the previous structure of the MALTIR-induced MyD88TIR assembly. Both assemblies exhibit conformational differences in several areas that are important for signaling (for example the BB loop and CD loop) compared with their monomeric structures. These data suggest that TLR2TIR and MALTIR interact with MyD88 in an analogous manner during signaling, nucleating MyD88TIR assemblies unidirectionally.

Experimental Study on the Dielectric Properties of Coal In Situ with Variable Temperatures.

The aim of this study was to explore the mapping relationship between the temperature and the dielectric parameters of coal and rock under variable temperatures as well as to determine the characteristics of a dielectric anomaly response. Experiments were performed using lignite, nonstick coal, gas coal, coking coal, and anthracite. The evolution of pyrolysis characteristics, microcrystal structure, and dielectric properties with changing temperature was investigated, and the changes in the dielectric parameters of coal and rock were comprehensively analyzed. As such, the cause of the dielectric anomaly with changing temperatures of coal and rock was revealed. The results show that the dielectric properties of coal at different pyrolysis temperatures are closely related to the degree of intermolecular thermal motion, the evolution of microcrystal structure, and the mechanism of polarization response. In the low-temperature stage, the thermal motion of coal molecules is weak and exhibits electronic polarization, and the dielectric parameters change slightly with temperature while being dependent on the moisture content. In the high-temperature pyrolysis stage, the intense molecular thermal motion leads to the breaking of chemical bonds and the release of volatiles; moreover, the distance between aromatic layers of coal decreases, the order of aromatic structure increases, the dipole turning polarization is the main polarization type, and the dielectric response is obvious. When the pyrolysis reaction is basically complete, the dielectric constants of the five coal samples reach the maximum. As the temperature increases continuously, the coal structure is destroyed by the weakening of the thermal motion of the coal molecules and the accumulation of thermal stress; meanwhile, the dielectric constant decreases gradually, while the dielectric loss and tangent of dielectric loss increase rapidly. At the same temperature, the dielectric constant decreases with an increase in test frequency. These results lay a foundation for the inversion of dielectric data in fire areas of coal mines.

N, S co-doped coal-based hard carbon prepared by two-step carbonization and a molten salt template method for sodium storage

Hard carbon, known for its abundant resources, stable structure and high safety, has emerged as the most popular anode material for sodium-ion batteries (SIBs). Among various sources, coal-derived hard carbon has attracted extensive attention. In this work, N and S co-doped coal-based carbon material (NSPC1200) was synthesized through a combination of two-step carbonization process and heteroatom doping using long-flame coal as a carbon source, thiourea as a nitrogen and sulfur source, and NaCl as a template. The two-step carbonization process played a crucial role in adjusting the structure of carbon microcrystals and expanding the interlayer spacing. The N and S co-doping regulated the electronic structure of carbon materials, endowing more active sites. Additionally, the introduction of NaCl as a template contributed to the construction of pore structure, which facilitates better contact between electrodes and electrolytes, enabling more efficient transport of Na+ and electrons. Under the synergistic effect, NSPC1200 exhibited exceptional sodium storage capacity, reaching 314.2 mAh g-1 at 20 mA g-1. Furthermore, NSPC1200 demonstrated commendable cycling stability, maintaining a capacity of 224.4 mAh g-1 even after 200 cycles. This work successfully achieves the strategic tuning of the microstructure of coal-based carbon materials, ultimately obtaining hard carbon anode with excellent electrochemical performance.

Optical thermosensor using Cr3+ doped NaGdF4: Yb, Er microcrystals

ABSTRACT In this work, NaGdF4: 20%Yb, 2%Er microcrystals with varying contents of Cr3+ doping were obtained by conventional hydrothermal process. The microcrystal phase structure, morphology, upconversion luminescence mechanism, as well as temperature sensing behaviour under different treatment methods were researched. Based on the thermally coupled 2H11/2 and 4S3/2 levels of Er3+ and the dependence of fluorescence intensity ratio (FIR) on temperature, the optical temperature sensing behaviour of micrometer crystals were experimentally demonstrated. The NaGdF4: 20%Yb, 2%Er, 7%Cr microcrystals treated with high-temperature annealing show the best temperature sensing behaviour within the temperature span of 298–498 K. NaGdF4: 20%Yb, 2%Er, 7%Cr microcrystals with high temperature annealing presented the feasibility and promising properties for optical temperature sensing. The endeavour of emerging materials could lay the groundwork for future sustainable photonics engineering industrial growth.

Gd Effect on Micro-Crystal Structure and Thermomagnetic Behavior of NiMnSn Magnetic Shape Memory Alloy

In this study, the rare earth Gadolinium (Gd) element was added to the NiMnSn alloy, which is an alternative to the NiMnGa alloy group, with the increasing popularity of magnetic shape memory alloys. Since rare earth elements have strategic importance for our country in recent years, Gd element has been preferred in this study. X-rays and SEM-EDX analysis were performed to determine the morphological properties of the crystal structure and microstructure of the alloys. Magnetic measurements of the alloys were made with the physical property measuring device and it was determined that the magnetization values decreased with the addition of Gd.

Constructing micro/nano-photonics barcodes based on micro-region upconversion emission spectrum of single core-shell microcrystal

The construction of core-shell structures with different structural properties based on the epitaxial growth technique has become an effective technique for regulating the luminescence properties of micro/nanocrystals. In order to obtain richer spectral information, NaYF<sub>4</sub>:50%Yb<sup>3+</sup>/2%Tm<sup>3+</sup>@NaYF<sub>4</sub>@NaYF<sub>4</sub>:20%Yb<sup>3+</sup>/2%Er<sup>3+</sup>@NaYF<sub>4</sub>@NaYbF<sub>4</sub>:2%Er<sup>3+</sup> multilayered core-shell microcrystals are prepared by using multiple epitaxial growth through introducing surface modifiers and controlling their reaction conditions. The XRD and SEM results clearly show that the core-shell microcrystals possess a pure hexagonal crystal structure in the form of a disk. The microdesk has a thickness of about 2.32 μm and a diameter of about 28.31 μm. The upconversion luminescence characteristics of different single microcrystal structures are investigated by a confocal microspectroscopy system. In order to realize the selective excitation and emission of a single microcrystal, the spatial distribution of luminescent ions can be controlled through introducing an intermediate isolation layer. Under 980 nm laser excitation, different excitation sites of the single microdisk exhibit different upconversion emission characteristics. The significant blue (450 and 475 nm), red (648 nm) and green (524 and 540 nm) emissions are observed, which mainly originat from Tm<sup>3+</sup> and Er<sup>3+</sup> radiative transitions. Meanwhile, the red and blue upconversion emission intensities of the microcrystals are improved by using various shell layers. In addition, the luminescence and energy-transfer features of single microcrystals are explored by changing the excitation position. The experimental results demonstrate that the incorporation of NaYF<sub>4</sub> inert shells between luminescent layers can regulate luminescence and prevent ions from interacting. By utilizing the spectral fingerprint data of dopant ions in various shell layers, we create customizable micro-nano photonic barcodes and employ them for optical anti-counterfeiting detection. This study explores the use of constructed core-shell structures with luminescent tunable micron core-shell structures to acquire diverse spectral information and maintain stability through their structural properties. Thus, this core-shell structure provides a novel method for using upconversion luminescent microcrystals into micro- and nanophotonics to achieve anti-counterfeiting and display purposes.

Heat Treatment Effect on Thermal, Micro-Crystal Structure and Magnetic Behavior of Ni45Mn40Sn10Cu5 Heusler Shape Memory Alloy

Ni-Mn-Sn-based Heusler alloys are important materials that have potential applications as environmentally friendly smart materials with beneficial properties as well as being magnetic. Both the magnetic field-induced reverse martensitic transformation and the high operating temperature are crucial for the applications of Ni-Mn-Sn-based magnetic shape memory alloys. In this study, martensite transformation temperatures were determined by applying different heat treatments (700 °C, 900 °C, 1100 °C) to Ni45Mn40Sn10Cu5 sample produced by Arc Melter melting method. While reverse conversion was observed in T2 (no heat treatment) and 700°C heat treatment, no reverse conversion was observed at 900°C and 1100°C. When the X-ray diffractogram was examined, martensite phase and γ phase were determined. When the magnetic hysteresis of the samples was examined, it was observed that the magnetic saturation went towards zero with the increase in heat treatment and accordingly, there was a decrease in the magnetization effect.

Petal-like Patterning of Polylactide/Poly (Butylene Succinate) Thin Films Induced by Phase Separation.

Biodegradable plastics are attracting attention as a solution to the problems caused by plastic waste. Among biodegradable plastics, polylactide (PLA) and poly (butylene succinate) (PBS) are particularly noteworthy because of their excellent biodegradability. However, the drawbacks of their mechanical properties prompts the need to compound them to achieve the desired strength. The characteristics of the interface of the composite material determine the realization of its final performance. The study of the interface and microstructure of composites is essential for the development of products from degradable polymers. The morphology evolution and microcrystal structure of spin-casted fully biodegradable (PLA/PBS) blend films were investigated using atomic force microscopy (AFM)-based nanomechanical mapping. Results show that intact blend films present an obvious phase separation, where the PBS phase is uniformly dispersed in the PLA phase in the form of pores. Furthermore, the size and number of the PBS phase have a power exponential relationship and linear relationship with PBS loading, respectively. Intriguingly, after annealing at 80 °C for 30 min, the PLA phase formed an orderly petal-like microcrystalline structure centered on the PBS phase. Moreover, the microcrystalline morphology changed from a "daisy type" to a "sunflower type" with the increased size of the PBS phase. Since the size of the PBS phase is controllable, a new method for preparing microscopic patterns using fully biodegradable polymers is proposed.

Catalytic steam gasification of bituminous coal for syngas production with catalyst derived from calcium-rich construction demolition waste

A disposable Ca-containing catalyst was generated from a sort of calcium-rich construction demolition waste and utilized in the steam gasification of a bituminous coal in a fixed bed reactor. The effects of catalyst loading amount, gasifying temperature and catalyst loading method on steam gasification with respect to the production of syngas with high H2/CO mole ratio and CH4 content were investigated. The H2 and CO molar yields as well as carbon conversion increased noticeably with the increase of catalyst loading amount despite there was a saturation quantity. After loading 6.0 wt% catalyst into coal by kneading method, the carbon conversion and total gas molar yield increased from 52.56% and 136.06 mmol/g-C to 62.77% and 160.23 mmol/g-C, respectively. At low temperature, kneading method displayed superiority over mechanical mixing method in steam gasification performance of bituminous coal while they had approximately the same catalytic effect on coal steam gasification at high temperature. Characterization of SEM images and Raman spectroscopy of coal chars derived from catalytic pyrolysis confirmed that addition of catalyst changed the micro-crystal structure and formed more defects and amorphous structures. Overall, the catalyst showed satisfactory catalytic effect in steam gasification of bituminous coal and could be used as a suitable alternative of CaO for syngas production.

Insights into the carbonization mechanism of bituminous coal-derived carbon materials for lithium-ion and sodium-ion batteries

Despite recent interest in the low-temperature carbonization of coal to prepare disordered carbon materials for the anodes of lithium-ion (LIBs) and sodium-ion batteries (SIBs), the carbonization mechanism is still poorly understood. We selected bituminous coal as the raw material and investigated the chemical, microcrystal, and pore structure changes during the carbonization process from coal to the resulting disordered carbon. These structural changes with temperature below 1 000 °C show an increase in both interlayer spacing (3.69–3.82 Å) and defect concentration (1.26–1.90), accompanied by the generation of a large amount of nano-microporous materials. These changes are attributed to the migration of the local carbon layer and the release of small molecules. Furthermore, a decrease in interlayer spacing and defect concentration occurs between1 000 °C and 1 600 °C. In LIBs, samples carbonized at 1 000 °C showed the best electrochemical performance, with a reversible capacity of 384 mAh g−1 at 0.1 C and excellent rate performance, maintaining 170 mAh g−1 at 5 C. In SIBs, samples carbonized at 1 200 °C had a reversible capacity of 270.1 mAh g−1 at 0.1 C and a high initial Coulombic efficiency of 86.8%. This study offers theoretical support for refining the preparation of carbon materials derived from coal.

Nitrogen doping regulates microcrystal structure of interconnected Mn oxide particles/rods for oxygen reduction electrocatalysis

Manganese (Mn) oxide possessing considerable catalytic activity toward oxygen reduction reaction (ORR) exhibits promising potential in driving energy conversion technologies. However, small specific surface area, poor electron conductivity, and more importantly uncontrollable microgeometry of crystal greatly restraint their activity. Herein, a crystal regulation strategy induced by nitrogen doping is developed to construct interconnected Mn oxide nano-particles/rods (N-MnOx-Y) with different contents of [MnO6] octahedron for ORR. In N-MnOx-Y, "Y" refers to the mass ratio of melamine to α-MnO2 nanorods during calcination. Nitrogen doping induced increased content of crystalline [MnO6] octahedron is the primary factor boosting the intrinsic activity of N-MnOx-Y. The overall activity of N-MnOx-Y is also determined by electrochemically active area (ECSA) which is closely related to nitrogen doping. The crystal optimal N-MnOx-30 with high content of crystalline [MnO6] octahedron and large ECSA exhibits the highest half-wave potential for ORR and the largest kinetic current density (jk) among the N-MnOx-Y catalysts. When used as a cathodic catalyst, a homemade zinc-air battery driven by N-MnOx-30 delivers a peak power density higher than the one driven by Pt/C, along with better rate performance and a larger discharging specific capacity. This impressive electrocatalytic performance of N-MnOx-30 superior to Pt/C originates from the synergistic effect between crystalline [MnO6] octahedron, active area exposure, oxygen vacancy, Mn-N sites, and the three-dimensional hierarchical structure, which benefiting electronic/mass transmission and structural stability. This work offers a feasible strategy for constructing hierarchical and crystal tunable metal oxides electrocatalysts for efficient energy conversion.

Structure determination of a DNA crystal by MicroED

Microcrystal electron diffraction (MicroED) is a powerful tool for determining high-resolution structures of microcrystals from a diverse array of biomolecular, chemical, and material samples. In this study, we apply MicroED to DNA crystals, which have not been previously analyzed using this technique. We utilized the d(CGCGCG)2 DNA duplex as a model sample and employed cryo-FIB milling to create thin lamella for diffraction data collection. The MicroED data collection and subsequent processing resulted in a 1.10Å resolution structure of the d(CGCGCG)2 DNA, demonstrating the successful application of cryo-FIB milling and MicroED to the investigation of nucleic acid crystals.

COS and H2S simultaneous removal from blast furnace gas over a tailored Cu/Zr co-doped K@TiO2 bifunctional catalyst under low temperature

The lengthy processes and cumbersome operations for the separate removal of COS and H2S have severely limited the development of blast furnace gas recycling process. CuO exhibits excellent H2S oxidation performance, but weak COS hydrolysis performance; in contrast, ZrO2 shows the opposite trend. However, the functional combination of CuO and ZrO2 has never been used for simultaneous removal of COS and H2S. In this study, a Cu/Zr co-doped K@TiO2 bifunctional catalyst was tailored to simultaneously remove COS and H2S. The combined COS and H2S capacity of this catalyst reaches 340.5 mg/g at a low temperature of 60 °C, which is much higher than those of other reported bifunctional catalysts. The microcrystal structure formed by Cu/Zr co-doping increases the specific surface area of the catalyst and promotes the adsorption of COS/H2S. Specifically, Zr doping increases the content of moderate basic sites and significantly improves the hydrolysis efficiency of COS. Moreover, Cu doping induces lattice distortion of TiO2, while CuO captures 4 s valence electrons of K to form Cu2O. These two processes lead to the release of lattice oxygen from TiO2 and CuO, generating oxygen vacancies and ·O2−, which promotes H2S oxidation. By proposing a simple route for the bifunctionalization of a desulfurization catalyst, this study drives innovation in both the theory and application of simultaneous removal of COS and H2S.

Characteristics of coal oxidation and spontaneous combustion in Baishihu Mine, Xinjiang, China

The characteristics of oxidized spontaneous combustion of coal can reflect the performance of coal, and an appropriate structural model can reflect it more intuitively. In this study, samples from Baishihu Coal Mine were used to study the macromolecular structure, microcrystal structure, and oxidation process of coal by X-ray photoelectron spectroscopy (XPS), carbon nuclear magnetic resonance (13C-NMR), and Fourier infrared spectroscopy (FTIR). The molecular formula C198H164O40N2 and the molecular structure model were obtained. ChemDraw and Materials Studio were used for the experimental data, and high-resolution transmission electron microscopy (HRTEM) was used to verify the aromatic ring structure built to make the constructed structural model more accurate. In the water evaporation stage, the high ring aromatic layer is converted into the low ring number. Furthermore, in the high-temperature stage, the low ring aromatic layer is transformed due to the coking and condensation reaction of the coal sample. The C element in the coal sample mainly participates in the reaction in C–C and C–H forms. The spacing and effective number of aromatic layers are relatively stable. The aggregation state of coal is a macromolecular group formed between molecules with different aromatic structures and fat structures, which is formed by the interaction of internal defects and pores of molecular groups. With the increase in the treatment temperature, water loss is heavier, oxygen absorption and weight gain are perplexing, and the value of the burnout temperature is higher. The apparent activation energy of the coal–oxygen reaction increases, and the reaction is more intricate to achieve. This study furthers the understanding of coal spontaneous combustion in this mining area, provides a reference for the prevention and control of coal spontaneous combustion.