High Dispersion Research Articles

High-order multilayer-coated blazed grating for a high-transmission and high-resolution tender X-ray monochromator/spectrometer

Grating optics lie in the heart of X-ray spectroscopy instruments. The low efficiency and angular dispersion of conventional single-layer-coated gratings significantly limit the transmission and energy resolution of monochromators and spectrometers, particularly in the tender X-ray region (E=1−5 keV). Multilayer-coated blazed gratings (MLBGs) operating at high diffraction orders offer the advantage of achieving both high efficiency and high dispersion simultaneously. Tender X-ray monochromators and spectrometers using different high-order MLBGs have been designed, all demonstrating one to two orders of magnitude higher transmission compared to conventional systems. By employing a 2400 l/mm MLBG at the −4th or −8th diffraction order, the theoretical energy resolution of the instrument is improved by two to three times at 2.5 keV. Two MLBGs operating at the −2nd and −4th orders have been fabricated, showcasing remarkable efficiencies of 34%–12% at 2.5 keV, surpassing that of single-layer-coated gratings by an order of magnitude. Further optimization of manufacturing accuracy can yield even higher efficiencies. The measured angular dispersion agrees well with theoretical predictions, supporting the potential for high resolution. High-order MLBG optics pave the way for a new generation of tender X-ray monochromators/spectrometers that offer both high transmission and high resolution.

Carbon dots as smart biosensing and imaging materials delving with antimicrobial, antifungal, and antiviral potentials against infectious pathogens

AbstractIn the emerging era of infectious diseases, antimicrobials are widely applied against pathogenic microbes (i.e., bacteria, fungus, or virus) to avoid global mortality. Nonetheless, quite a few of the microbiome adopted genetic mutations over extended period and fostered sustainable resistance towards the existing and newer antibiotics. Carbon dots (CDs) are the carbon‐based nanomaterials, unveiled their potential as antifungal, antibacterial, and antiviral agents resembled with ease of synthesis, reduced toxicity, smart functionalization, high aqueous dispersibility, and auspicious biocompatibility. This review has emphasized over the discussion corroborated with the types of CDs and their synthesis, and numerous properties of CDs tailored to their biofunctionalization. Further the article was featured with the antibacterial, antiviral, antifungal, bioimaging, biosensing, and anticancer responsiveness of CDs (in vivo and in vitro mode) followed by their biocompatibility, toxicity assessments, challenges, and future prospectives.

Research on Controllable Synthesis and Growth Mechanism of Sodium Vanadium Fluorophosphate Nanosheets.

Sodium vanadium fluorophosphate is a sodium ion superconductor material with high sodium ion mobility and excellent cyclic stability, making it a promising cathode material for sodium-ion batteries. However, most of the literature and patents report preparation through traditional methods, which involve complex processes, large particle sizes, and low electronic conductivity, thereby limiting development progress. Aiming at the limitation of high cost and poor performance of vanadium sodium fluorophosphate cathode material, the low temperature and high-efficiency nano preparation technology was developed. This study uses a homogenizer with high dispersion and shear force to directionally control the collision of sodium vanadium fluorophosphate nanoparticles with higher specific surface energy during the initial nucleation stage, forming nanosheet structures. The growth mechanism of these nanosheets was analyzed using SEM, XRD, AFM, and DFT simulation. Results indicate that the crystal surfaces with higher surface energy undergo directional collisions in the early nucleation stage, gradually reducing the surface energy and stabilizing the system, resulting in sodium vanadium fluorophosphate nanosheets. Due to the larger specific surface area and pore structure, these nanosheets exhibit excellent rate performance and cycle stability, making them suitable for application and promotion in the field of fast-charging energy storage.

Fast synthesis of Cu@zeolitic imidazolate framework-8 (ZIF-8) derived Cu/ZnO catalysts via a facile mechanical grinding method for CO2 hydrogenation to methanol.

Direct conversion of CO2 with renewable H2 to produce methanol provides a promising way for CO2 utilization and H2 storage. Cu/ZnO catalysts are active, but their activities depend on the preparation methods. Here, we reported a facile mechanical grinding method for the fast synthesis of Cu@zeolitic imidazolate framework-8 (ZIF-8) derived Cu/ZnO catalysts applied in CO2 hydrogenation to methanol. The confinement in ZIF-8 cages led to the formation of metal oxide particles with controlled crystallite sizes after pyrolysis in air. ZnO derived from ZIF-8 with ultrahigh specific surface area offered high CuO dispersion, obtaining higher Cu0 surface area and smaller Cu crystallite size after reduction. The effects of the Cu/(Cu + Zn) molar ratio and alcohol types during catalyst preparation on the textural properties of final catalysts were systemically studied. The resultant catalyst exhibited high activity with STY of methanol up to 128.7 g kgcat -1 h-1 at 200 °C, much higher than that of catalysts prepared by the conventional impregnation and coprecipitation methods and commercial Cu/ZnO. The present work offers an efficient method for optimizing Cu/ZnO catalysts for CO2 hydrogenation to methanol.

Rapid on-site colorimetric detection of Arsenic(V) by NH2-MIL-88(Fe) nanozymes-based Ultraviolet-visible spectroscopic and smartphone-assisted sensing platforms

BackgroundBecause arsenate (As(V)) is a highly toxic pollutant, timely on-site monitoring of its concentration is crucial for mitigating potential environmental and health hazards. Traditional on-site detection methods for As(V) often face limitations of long response time and low sensitivity. Nanozymes are nanomaterials that exhibit enzyme-like catalytic activity. Nanozyme-based colorimetric detection can amplify signals and improve detection sensitivity by catalytically converting a minimal substrate quantity into a substantial amount. However, current nanozymes-based As(V) detection methods still suffer from prolonged response time and the lack of convenient detection tools. ResultsWe develop a rapid and sensitive strategy for on-site colorimetric As(V) detection using a metal-organic framework (MOF) nanozyme, NH2-MIL-88(Fe). NH2-MIL-88(Fe) featured abundant Fe unsaturated metal centers (UMCs) and ordered porous structure, exhibiting excellent peroxidase-like activity, rapid As(V) adsorption, and high water dispersity. Fe UMCs efficiently catalyzed the oxidization of colorless tetramethylbenzidine (TMB) to blue oxTMB in the presence of H2O2. As(V) selectively inhibited this activity, reducing Ultraviolet-visible (UV-vis) absorption at 650 nm and fading the solution color. Mechanistically, As(V) interacted with Fe UMCs through As-O-Fe bonds, impeding Fe3+ reduction and Fe2+ catalytic ability, reducing •OH production. Under optimized conditions, As(V) was detected within 15 minutes, with detection limits of 2.78 μg•L-1 via UV-vis and 13.56 μg•L-1 via smartphone-assisted platform, covering a linear range of 5.00 - 600.00 μg•L-1. Additionally, NH2-MIL-88(Fe) was incorporated into an agarose hydrogel to create a portable composite for smartphone-based colorimetric analysis As(V). Significance and noveltyThis study addresses the existing issues of nanozyme-based As(V) sensors, elucidates the molecular mechanism by which As(V) affects NH2-MIL-88(Fe) nanozymes activity, and confirms the precision and accuracy of the established method in spiked river samples. Our rapid, sensitive, and facile approach offers a practical and efficient solution for on-site As(V) detection, facilitating swift intelligent risk identification and effective pollution prevention and remediation.

Optimization Strategies for Electrocatalytic CO2 Reduction Based on Atomically Dispersed Copper: A Review

AbstractThe electroreduction reaction of CO2 (eCO2RR) is considered an effective pathway for clean fuel production, greenhouse gas reduction, and resource recycling. Atomically dispersed catalysts exhibit excellent catalytic activity due to the high dispersion of atoms, especially for atomically dispersed copper (AD Cu). Although copper‐based materials are considered major single component materials capable of producing multi‐carbon products, the reaction mechanism is usually not very clear. For AD Cu catalysts, the dynamic transformation of Cu species in the form of single atoms, (nano)clusters, and ions during the reaction process significantly has an effect on the performance of eCO2RR. The core issue that needs to be addressed is how to control and tune the aggregation of Cu atoms to make it most favorable for the desired product or reaction pathways. This review summarizes the optimization strategies for AD Cu in recent years from three main perspectives: interface engineering, electrode engineering, and external field coupling.

Preparation and performance of nanoscale antimony tin oxide aqueous slurry with high water dispersion stability

Preparation and performance of nanoscale antimony tin oxide aqueous slurry with high water dispersion stability

Identifying therapeutic target for prostate cancer: exploring Diosmetin as a CYP inhibitor

Prostate cancer is a prevalent and highly heterogeneous malignancy that affects men globally. Despite the availability of various treatment targets, Cytochrome P450 (CYP) enzymes have gained significant attention due to their crucial role in metabolizing both endogenous and exogenous compounds. This study explores Diosmetin as a potential CYP antagonist for treating prostate cancer. To evaluate Diosmetin's potential as a CYP antagonist, we employed a comprehensive in silico approach. Molecular docking was conducted using the Glide software to assess the binding affinity of Diosmetin with CYP enzymes, specifically CYP17A1 and CYP19A1, which are associated with prostate cancer. The druglike properties of Diosmetin were evaluated, focusing on its pharmacokinetic attributes. Additionally, Diosmetin’s ADMET (Absorption, Distribution, Metabolism, Excretion, and Toxicity) characteristics were analyzed to determine its suitability as a therapeutic agent. Molecular dynamics (MD) simulations were performed using Desmond to assess the stability and persistence of Diosmetin binding with the CYP enzymes over a 200 ns simulation period. Molecular docking studies revealed robust binding affinities between Diosmetin and CYP17A1 (− 11.261 kcal/mol) and CYP19A1 (− 11.145 kcal/mol). Diosmetin demonstrated favorable pharmacokinetic properties and advantageous ADMET characteristics, including high bioavailability, good dispersion, and favorable metabolism. MD simulations indicated persistent binding interactions between Diosmetin and the CYP enzymes throughout the 200 ns simulation, reinforcing the reliability of these interactions. Pharmacoinformatics investigations provide valuable insights into the potential of Diosmetin as a promising lead compound for the development of novel drug candidates against prostate cancer. The strong binding affinity and favorable pharmacokinetic and ADMET profiles suggest that Diosmetin could be an effective CYP antagonist and warrants further investigation as a potential therapeutic agent for prostate cancer.

Fractionation methods of eucalyptus kraft lignin for application in biorefinery

Abstract Kraft lignin has high dispersity and low reactivity. This study aimed to obtain more homogeneous and modified chemical fractions from the application of fractionation methods using organic solvents and acid precipitation. Organic solvents used were ethyl acetate, ethanol, methanol and acetone. The pHs tested were 9, 7, 5, 3 and 1, by adding hydrochloric acid. The fractions were characterized of acid-soluble and insoluble lignin, carbohydrates, ashes, elemental analysis and by Py-GC/MS. All fractions obtained in both fractionation methods showed higher carbon contents, higher purity and lower S/G ratio than the corresponding initial materials, characteristics that are very favorable for the application in biorefinery. Acetone-soluble (sequential) and pH 1 (one-step) precipitated fractions are the most promising for carbon fiber production. Fractions soluble in ethyl acetate (one-step) and insoluble at pH 3 and 1 (sequential) appear to be the most appropriate for applications that require good oxidative properties. The fractions soluble in ethanol (one-step), methanol (one-step), acetone (one-step) and precipitated at pH 9 (one-step) and pH 5 (sequential) are the ones that allow better chemical substitution in obtaining bioproducts. Fractions soluble in ethanol (sequential) and precipitated at pHs 5 and 1 (sequential) are not of commercial interest due to their low yield.

Enhancement of Mechanical and Chloride Binding Properties in Seawater Cement Using a Novel Carbon Nanomaterial

Chloride binding technology can effectively reduce the content of free chloride ions in seawater (used for cementitious materials), thereby extending the service life of seawater concrete structures. Currently, affordable and highly dispersed nanomaterials that can enhance the chloride binding capability of seawater cement are finite. This paper presents the first experimental study on N-doped graphene quantum dots (NGQDs), an innovative carbon nanomaterial with low price and high dispersibility, to strengthen the mechanical and chloride binding capabilities of seawater cement. Concretely, NGQDs are prepared through the hydrothermal process. The morphology and structure of NGQDs are measured by TEM, AFM, FTIR, and XPS. And the strengths and chloride binding performance of different specimens are analyzed by compressive/flexural strength tests and chloride adsorption equilibrium tests. The phase compositions of various specimens are analyzed by XRD, TGA/DTG, and SEM. The consequences indicate that the unique structure of the prepared NGQDs endows them with excellent water solubility and dispersibility. Notably, the introduction of NGQDs enhances the mechanical performance of seawater cement and 0.05 wt.% NGQDs have the greatest improvement effect. The compressive and flexural strengths of seawater cement containing 0.05 wt.% NGQDs increase by 8.21% and 25.77% after 28 d curing, respectively. Additionally, the seawater cement containing 0.2 wt.% NGQDs have the best chloride binding capability and are 41.08% higher than the blank group. More importantly, the chloride binding mechanism is that NGQDs accelerate seawater cement hydration, resulting in an increased formation of hydrated calcium silicate (C–S–H) and Friedel’s salt (Fs), thereby strengthening the physisorption and chemical combination of chloride. This study highlights an inexpensive and highly dispersible nanomaterial to heighten the stability of seawater concrete structures, opening up a new path for the better utilization of seawater resources.

Cobalt-Based ZIF Composite Membranes: In Situ Defect Engineering for Enhanced Water Stability and Gas Separation.

Porous coordination polymers with excellent molecular sieving ability, high dispersibility, and good compatibility with engineered polymer matrices hold promise for various industrial applications, such as gas separation and battery separators. Here, an in situ defect engineering approach is proposed for highly processable cobalt (Co)-based zeolitic imidazolate frameworks (ZIFs) with enhanced molecular sieving ability and water stability. By varying alkylamine (AA)modulators, the pore structures and textural properties of ZIFs can be fine-tuned. The resulting high-loading composite membrane exhibits excellent C3H6/C3H8 separation performance and mechanical properties. This in situ defect engineering approach enables efficient interfacial engineering for high-performance composite membranes.

The High Time Resolution Universe Pulsar Survey – XIX. A coherent GPU-accelerated reprocessing and the discovery of 71 pulsars in the Southern Galactic plane

ABSTRACT We conducted a GPU-accelerated reprocessing of $\sim 87~{{\ \rm per\ cent}}$ of the archival data from the High Time Resolution Universe South Low Latitude (HTRU-S LowLat) pulsar survey by implementing a pulsar search pipeline that was previously used to reprocess the Parkes Multibeam Pulsar Survey (PMPS). We coherently searched the full 72-min observations of the survey with an acceleration search range up to $|50|\, \rm m\, s^{-2}$, which is most sensitive to binary pulsars experiencing nearly constant acceleration during 72 min of their orbital period. Here we report the discovery of 71 pulsars, including six millisecond pulsars, of which five are in binary systems, and seven pulsars with very high dispersion measures (DM $\gt 800 \, \rm pc \, cm^{-3}$). These pulsar discoveries largely arose by folding candidates to a much lower spectral signal-to-noise ratio than in previous surveys and by exploiting the coherence of folding over the incoherent summing of the Fourier components to discover new pulsars as well as candidate classification techniques. We show that these pulsars could be fainter and on average more distant as compared with both the previously reported 100 HTRU-S LowLat pulsars and the background pulsar population in the survey region. We have assessed the effectiveness of our search method and the overall pulsar yield of the survey. We show that through this reprocessing we have achieved the expected survey goals, including the predicted number of pulsars in the survey region, and discuss the major causes why these pulsars were missed in previous processing of the survey.

Engineering Green- to Blue-Emitting CsPbBr3 Quantum Dots in Nanozeolite with High Stability for Backlight Display Application.

The performance of blue devices utilizing perovskite quantum dots (PQDs) has lagged remarkably behind that of green light-emitting diodes because of low luminescence quantum yields and poor spectral stability. Here, benefiting from the rapid and short diffusion paths within the nanosized silicalite-1 (N-Si-1) zeolite (∼40 nm) channels, CsPbBr3 PQDs encapsulated within N-Si-1 show a high dispersion with an ultrasmall particle size of ∼2.38 nm and a blue emission of 474 nm with a high photoluminescence quantum yield (PLQY) of 44.4%. Subsequently, the surface hydrophobization of CsPbBr3-N-Si-1 using octadecyltrimethoxysilane (ODTMS) enables ultrastable blue luminescence. A white-light-emitting diode (WLED) device with CIE color coordinates (0.31, 0.28) was constructed by combining CsPbBr3-M (blue), CsPbBr3-N-Si-1 (green), and KSF:Mn4+ phosphor (red) on a 365 nm chip. This work introduces a feasible strategy to modulate the emission of CsPbBr3 PQDs through a strong confinement effect within a hydrophobic nanozeolite matrix, offering promising applications in backlight displays.

Filtering-free complex-valued DSB-16QAM generation for a 100 G direct detection optical interconnection.

In this Letter, a complex-valued double-sideband 16QAM (CV-DSB-16QAM) signaling scheme is proposed and experimentally demonstrated in a 100-Gb/s intensity modulation/direct detection (IM/DD) interconnection system. Unlike the conventional real-valued double-sideband (DSB) quadrature amplitude modulation (QAM) of relatively lower spectral efficiency (SE) and single-sideband (SSB) QAM relying on sharp-edged optical filtering, the CV-DSB-16QAM signal is generated by combining two independent sideband modulated QPSK signals using a single intensity modulator with an optical filtering-free profile, which also saves one photodiode and one analog-to-digital-converter compared with the twin-SSB scheme. Compared to typical pulse amplitude modulation or SSB schemes, the proposed approach offers a compelling alternative for complex-valued DD systems' evolution, particularly in scenarios with high SE demands and controllable chromatic dispersion. The experimental demonstration evaluates a 25-GBaud CV-DSB-16QAM signal over a 2-km standard single-mode fiber (SSMF), achieving a net bit rate of 100 Gb/s and occupying only a 25.1-GHz electrical bandwidth with a 4% guard band.

Trophic Structure and Isotopic Niche of Invaded Benthic Communities on Tropical Rocky Shores.

When a species is introduced in a new location, it is common for it to establish itself when it finds favorable conditions in the receptor community with regard to interspecific interactions with native species. The azooxanthellate corals Tubastraea coccinea and Tubastraea tagusensis are invasive species introduced in the Caribbean Sea, the Gulf of Mexico, and the Brazilian Southwest Atlantic. They are successful competitors for space, have multiple reproductive modes, and have high larval dispersion and recruitment, but studies on food and trophic relationships of the genus Tubastraea are still scarce. In the present study, we used isotopic values of δ13C and δ15N to investigate trophic relationships in rocky shore communities invaded by T. tagusensis and T. coccinea corals under different oceanographic and anthropogenic contexts. Using metrics derived from the isotopic values, we show that invaded communities have a lower degree of trophic diversity, with species characterized by similar trophic ecologies while abiotic factors seem to contribute to the biotic resistance of communities exposed to invasion events. Tubastraea spp. occupy a niche space similar to that occupied by the native community of suspension feeders, sharing resources already consumed by the receptor community, which makes invading corals successful competitors for food.

The Formation of γ-Valerolactone from Renewable Levulinic Acid over Ni-Cu Fly Ash Zeolite Catalysts.

Zeolites with different structures (P1, sodalite, and X) were synthesized from coal fly ash by applying ultrasonically assisted hydrothermal and fusion-hydrothermal synthesis. Bimetallic catalysts, containing 5 wt.% Ni and 2.5 wt.% Cu, supported on the zeolites, were prepared by a post-synthesis incipient wetness impregnation method. The catalysts were characterized by X-ray powder diffraction (XRPD), N2 physisorption, transmission electron microscopy (TEM), Mössbauer and X-ray photoelectron spectroscopies (XPS), and H2-temperature-programmed reduction (H2-TPR) analyses. The XRPD results showed that crystalline Cu0 and NixCuy intermetallic nanoparticles were formed in the reduced catalysts. The presence of the intermetallic phase affected the reducibility of the nickel by shifting it to a lower temperature, as confirmed by the H2-TPR curves. Based on the Mössbauer spectroscopic results, it was established that the iron contamination of the coal fly ash zeolites (CFAZs) was distributed in ionic positions of the zeolite lattice and as a finely dispersed iron oxide phase on the external surface of the supports. The formation of the NiFe alloy, not detectable by XRPD, was also evidenced on the impregnated samples. The catalysts were studied in the upgrading of levulinic acid (LA), derived from lignocellulosic biomass, to γ-valerolactone (GVL), in a batch reactor under 30 bar H2 pressure at 150 and 200 °C, applying water as a solvent. The NiCu/SOD and NiCu/X catalysts showed total LA conversion and a high GVL yield (>75%) at a reaction temperature of 200 °C. It was found that the textural parameters of the catalysts have less influence on the catalytic activity, but rather the stable dispersion of metals during the reaction. The characterization of the spent catalyst found the rearrangement of the support structure. The high LA conversion and GVL yield can be attributed to the weak acidic character of the support and the moderate hydrogenation activity of the Ni-Cu sites with high dispersion.

Impact of replacing dune sand with ground date palm on the performance of cement mortar: dispersion analysis

This study investigates the effects of substituting dune sand with ground date palm at varying proportions of 0.5% to 2% on the mechanical and thermal properties of cement mortar. The findings indicate that this substitution enhances both the thermal and mechanical performance of the mortar, thereby improving its insulation capabilities. Notably, significant variations in compressive strength are observed, particularly at an early age of 7 days, with a reduction in variability as the mortar matures. Additionally, a high dispersion in measurement results is recorded. The application of the Weibull model facilitates the quantification of this variability and the assessment of material reliability, emphasizing the necessity of considering these fluctuations in the evaluation of sustainable construction materials. This approach not only underscores the potential of utilizing ecological resources but also paves the way for innovative practices in the construction sector. Overall, the study highlights the promising implications of incorporating alternative materials for enhancing the performance and sustainability of cement-based composites.

Molecular gas stratification and disturbed kinematics in the Seyfert galaxy MCG-05-23-16 revealed by JWST and ALMA

Understanding the processes that drive the morphology and kinematics of molecular gas in galaxies is crucial for comprehending star formation and, ultimately, galaxy evolution. Using data from the Galactic Activity, Torus and Outflow Survey (GATOS) obtained with the James Webb Space Telescope (JWST) and the archival data from the Atacama Large Millimeter/submillimeter Array (ALMA), we study the behavior of the warm molecular gas at temperatures of hundreds of Kelvin and the cold molecular gas at tens of Kelvin in the galaxy MCG$-$05$-$23$-$16, which hosts an active galactic nucleus (AGN). Hubble Space Telescope (HST) images of this spheroidal galaxy, classified in the optical as S0, show a dust lane resembling a nuclear spiral and a surrounding ring. These features are also detected in CO(2$-$1) and H$_2$, and their morphologies and kinematics are consistent with rotation plus local inward gas motions along the kinematic minor axis in the presence of a nuclear bar. The H$_2$ transitions 0-0 S(3), 0-0 S(4), and 0-0 S(5), which trace warmer and more excited gas, show more disrupted kinematics than 0-0 S(1) and 0-0 S(2), including clumps of high velocity dispersion (of up to sim 160 km s$^ $), in regions devoid of CO(2$-$1). The kinematics of one of these clumps, located sim 350\,pc westward of the nucleus, are consistent with outflowing gas, possibly driven by localized star formation traced by polycyclic aromatic hydrocarbon emission at 11.3 mu m. Overall, we observe a stratification of the molecular gas, with the colder gas located in the nuclear spiral, ring, and connecting arms, and most of the warmer gas with a higher velocity dispersion filling the inter-arm space. The compact jet, approximately 200 pc in size, detected with Very Large Array (VLA) observations, does not appear to significantly affect the distribution and kinematics of the molecular gas, possibly due to its limited intersection with the molecular gas disk.

Fundamental Thermodynamic Aspects for the Effective Dispersion of Carbon Nanotubes and Improve Performance Grade of Bitumen

The application of carbon nanotubes to enhance bitumen properties is relevant due to the need to increase the durability of asphalt concrete pavements and reduce maintenance costs. Key areas requiring further study include the processes during ultrasonic dispersion, the selection of the optimal medium, and the stability of the resulting dispersions. This study examines dispersions containing multi-walled carbon nanotubes (MWCNTs) Taunit M (from 5·10−4 to 5·10−2%) and various hydrocarbon plasticizers. For the first time, the change in Gibbs free energy, enthalpy (interaction energy), and mixing and disordering entropy was calculated based on experimental data (surface tension, average cubic diameter of MWCNTs, molecular mass, etc.). The data were compared with the storage stability of polymer-modified binders (PMBs). It was found that mixing entropy plays a key role in forming thermodynamically stable dispersions, while the contribution of disordering entropy is minimal. High dispersion enthalpy of MWCNTs can reduce dispersion stability at high concentrations despite entropy growth. Systems with selective purification extracts showed the best PMB stability despite thermodynamic instability. The property changes after 3 days at 180 °C were no more than 5%. This suggests structural changes from component interactions are critical, highlighting the need for an integrated approach considering both thermodynamic and macroscopic properties.

On the catalytic nature of nitrided NiMo/γ-Al2O3 catalysts for dry reforming of methane

Nitrogen and phosphorus are one of the most common Group 15 elements. The chemistry of nitrogen and phosphorus is very important in the field of catalysis. Three types of nitride containing NiMo/γ-Al2O3 catalysts were synthesized using different loading-nitriding sequences and oxide precursor types for dry reforming of methane (DRM). The active components (Ni2Mo3N and Ni/Mo2N) firstly reacted with CO2, transforming into NiO and MoO2. They were then carburized with CH4 to produce Ni/Mo2C during the DRM process. From that point on, a redox cycle, viz. NiO/MoO2 ⇆ Ni/Mo2C, occurred during the DRM reaction. The low activity of nitriding-first NiMo nitride catalyst can be attributed to bulk oxidation. The observed gradual decline in performance of loading-first Ni/Mo nitride catalyst was due to coking. Noticeably, the loading-first NiMo nitride catalyst can demonstrate superiority in both activity and resistance to coking, which was due to its strong metal–Al2O3 interaction and high metal dispersion.