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In this study, a fluorocarbon chain was grafted on the surface of the alumina insulator through the molecule self-assembly of perfluorododecyl trichlorosilane to enhance the vacuum surface flashover voltage. A hydrocarbon chain with the same molecular structure, devoid of fluorine element, was also grafted through the self-assembly of dodecyl trichlorosilane to enable comparison. The surface state examination of the self-assembled alumina insulators shows that both the molecules are attached to the alumina surface. The arrangement of the molecules on the surface is regular. Surface property tests reveal that the fluorocarbon chain endows the surface of alumina with a lower secondary electron emission yield and a lower gas adsorption volume than the hydrocarbon chain. Correspondingly, the surface flashover voltage of the fluorocarbon chain grafted insulator is higher than that of the hydrocarbon chain. This implies that the surface flashover voltage can be improved through surface fluorination, which converts hydrocarbon bonds to fluorocarbon bonds. The study demonstrates this possibility at the molecule level. [ABSTRACT FROM AUTHOR]

The chemiresistive effect of an oxide significantly influences its electrical properties, which depend greatly on the interactions between the ambient gas molecules and the solid surface, including the gas adsorption and charge transfer still challenging to be clarified. In this work, we investigate the chemiresistive effect of the p-type delafossite CuScO2 microsheets by comparing their responses to various gaseous alcohols, which increase with an approximately linear relationship with the length of straight carbon chains from methanol to n-hexanol. A new mechanism is proposed to elucidate such a dramatic trend of observed chemiresistive change based on the first-principles calculations and test results. The increasing carbon chain length modulates the adsorption configuration and provides supplementary routes for electron transfer, which is assumed to account for the observed chemiresistive effect. This work may provide a novel perspective for the investigation and development of more advanced functional oxides for electrical applications. [ABSTRACT FROM AUTHOR]

While computational screening with density functional theory (DFT) is frequently employed for the screening of metal–organic frameworks (MOFs) for gas separation and storage, commonly applied generalized gradient approximations (GGAs) exhibit self-interaction errors, which hinder the predictions of adsorption energies. We investigate the Hubbard U parameter to augment DFT calculations for full periodic MOFs, targeting a more precise modeling of gas molecule–MOF interactions, specifically for N2, CO2, and O2. We introduce a calibration scheme for the U parameter, which is tailored for each MOF, by leveraging higher-level calculations on the secondary building unit (SBU) of the MOF. When applied to the full periodic MOF, the U parameter calibrated against hybrid HSE06 calculations of SBUs successfully reproduces hybrid-quality calculations of the adsorption energy of the periodic MOF. The mean absolute deviation of adsorption energies reduces from 0.13 eV for a standard GGA treatment to 0.06 eV with the calibrated U, demonstrating the utility of the calibration procedure when applied to the full MOF structure. Furthermore, attempting to use coupled cluster singles and doubles with perturbative triples calculations of isolated SBUs for this calibration procedure shows varying degrees of success in predicting the experimental heat of adsorption. It improves accuracy for N2 adsorption for cases of overbinding, whereas its impact on CO2 is minimal, and ambiguities in spin state assignment hinder consistent improvements of O2 adsorption. Our findings emphasize the limitations of cluster models and advocate the use of full periodic MOF systems with a calibrated U parameter, providing a more comprehensive understanding of gas adsorption in MOFs. [ABSTRACT FROM AUTHOR]

By employing a recently proposed Hubbard U density-corrected scheme within density functional theory, we provide design principles towards the design of materials exhibiting a spin crossover-assisted gas release. Small molecular fragments are used as case study to identify two main mechanisms behind the change in binding energy upon spin transitions. The feasibility of the proposed mechanism in porous crystals is assessed by correlating the change in binding energy of CO2, CO, N2, and H2, upon spin crossover, with the adiabatic energy difference associated with the spin state change of the square-planar metal in Hofmann-type clathrates (M = Fe, Mn, Ni). A few promising cases are identified for the adsorption of intermediate ligand field strength molecules such as N2 and H2. The latter stands out as the most original result as the strong interaction in low spin, as expected from a Kubas mechanism, results in a large change in binding energy. This work provides a general perspective towards the engineering of open-metal site frameworks exhibiting local environments designed to have a spin crossover upon adsorption of specific gas molecules. [ABSTRACT FROM AUTHOR]

Three new three-dimensional (3D) metal–organic frameworks [M2(ttdc)2(dabco)] (M = Zn(II), 1-Zn; Cu(II), 1-Cu; and Zn/Cu, 1-ZnCu) based on thieno[3,2-b]thiophene-2,5-dicarboxylate (ttdc2−) were synthesized and characterized by a combination of physicochemical methods (single crystal X-ray diffraction, powder X-ray diffraction, chemical and thermogravimetric analyses and IR spectroscopy). 1-Cu demonstrated permanent porosity (Vpore = 0.790 cm3 g−1 and SBET = 1725 m2 g−1) and significant CO2, CH4, C2H2, C2H4 and C2H6 gas uptakes under ambient conditions. The adsorption selectivities for gas mixtures, calculated by IAST, were 10.8 (10.7), 14.6 (9.4), 1.7 (1.6) and 1.5 (1.6) for the equimolar gas mixture compositions CO2/N2, C2H6/CH4, C2H6/C2H4 and C2H6/C2H2 at 1 bar and 273 K (298 K), respectively. The mixed-metal compound 1-ZnCu was prepared by a crystal-to-crystal ion exchange metathesis reaction from 1-Zn with a 52% degree of ion substitution, confirmed by energy-dispersive X-ray spectroscopy, optical microscopy and single crystal X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

The coalification process significantly influences the composition of coal material and the development of pore size, ultimately affecting the adsorption capacity of coal seams and the extraction of coalbed methane. This project aimed to assess the pore structure and gas adsorption capacity of coal samples from nine key sedimentary basins in China. The N 2 test results revealed that during the initial stage of coalification, micropore, transition pore, and mesopore dominate in order of magnitude. In the subsequent coalification stages, the development of mesopore is most significant during the second jump, while the transition pore becomes more prominent in the third jump. Additionally, the findings from nuclear magnetic resonance tests indicate that the proportion of adsorbed pore demonstrates a decreasing-then-increasing trend throughout the coalification process. The first and second coalification jumps primarily contribute to the development of adsorption pore and seepage pore, whereas the third jump mainly focuses on adsorption pore development. The gas adsorption capacity is influenced by various factors such as pore structure, material composition, and chemical structure. During the first coalification jump, gas adsorption mainly occurs in the adsorption pore. In the second jump, medium gas adsorption capacity is achieved due to the combined effects of enhanced adsorption pore development and reduced moisture and ash content. Finally, the third coalification jump exhibits highly developed adsorption pores, the lowest moisture and ash levels, and a sufficient aromatic structure in the chemical composition, resulting in high adsorption capacity. These findings contribute to a deeper understanding of the variations in coalbed methane enrichment across different basins in China, with coalification playing a crucial controlling role. • Three key stages in coal pore evolution identified. • Pore size distribution during coal thermal evolution in key basins studied. • Gas adsorption capacity of coal during coalification jumps studied. [ABSTRACT FROM AUTHOR]

LaNi 5 -based alloy is capable of storing and purifying hydrogen, however, it is susceptible to poisoning by impurities like O 2 and CO, ultimately diminishing its hydrogen storage performance. In this paper, a comprehensive study on the effect of oxygen on the gas adsorption properties of LaNi 4.25 M 0.75 (M = Co, Mn) and the effect of different oxygen concentrations and temperatures on LaNi 4. 25 Mn 0.75 was conducted. The results reveal that the gas adsorption capacity of LaNi 4.25 M 0.75 (M = Co, Mn) alloys increased from 150.73 ml/g and 136.51 ml/g to 186.37 ml/g and 165.04 ml/g, respectively, after introducing 1000 ppm oxygen during the initial exposure cycle. This augmentation is primarily attributed to the reaction between H 2 and O 2 , leading to the formation of H 2 O. As the number of poisoning cycles increases, the gas adsorption capacity of the alloys tends to decrease. Under varying oxygen concentrations, a higher oxygen content exerted more pronounced effects on LaNi 4. 25 Mn 0.75 , potentially linked to the accelerated rate of oxidation layer coverage with increasing oxygen levels. Regarding temperature variations, the LaNi 4. 25 Mn 0.75 alloy exhibited superior resistance to O 2 at higher temperatures compared to low temperatures. This is explained by the fact that impurity gases are more easily desorbed at elevated temperatures, thereby enhancing the likelihood of H 2 adsorption on the alloy surface. • Comprehensive O 2 on the hydrogenation/dehydrogenation performance of LaNi 4.25 M 0.75 (M = Co, Mn) alloys is systematically investigated. • The gas adsorption capacity of LaNi 4.25 M 0.75 (M = Co, Mn) alloys increased from 150.73 ml/g and 136.51 ml/g to 186.37 ml/g and 165.04 ml/g, respectively, after introducing 1000 ppm oxygen during the initial exposure cycle. • Under varying oxygen concentrations, a higher oxygen content exerted more pronounced effects on LaNi 4. 25 Mn 0.75. • The LaNi 4. 25 Mn 0.75 alloy exhibited superior resistance to O 2 at higher temperatures compared to low temperatures. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) show captivating performances in many large‐scale applications including gas adsorption and separation, heat reallocation, water production, or remediation which can overcome important drawbacks of the conventionally used porous materials in the industry. This raises, therefore, the commercial interest in MOFs which brings the necessity to decrease the cost of their production, calling for the synthesis optimization from small‐scale to large‐scale. However, the commercial availability, yet very limited, is highly dependent on their production cost. Thus, to promote the commercial development and availability of MOFs, many steps can be taken. In this work, the state‐of‐art of the large‐scale production of MOFs can be first outlined, before discussing the criteria of greener MOF synthesis processes. Besides, a critical evaluation of the available synthesis routes for large‐scale production can be given, taking into consideration their cost, environmental impact, safety, and feasibility. Moreover, since there are strong limitations to the use in the powder form, the shaping procedures can thus be discussed briefly to outline the prospects of MOFs for different industrial applications. Finally, yet importantly, the perspective for MOFs commercialization can be highlighted with an emphasis on the necessity of techno‐economic analyses and life‐cycle assessments. [ABSTRACT FROM AUTHOR]

Holmium based metal–organic frameworks (MOFs) are attractive due to their potential biomedical and radiotherapeutic applications. Two new three-dimensional MOFs consisting of holmium(III) and 3,3′,5,5′-azobenzenetetracarboxylate (H4abtc) were prepared. The microporous Ho(III) binuclear MOF (Ho2-abtc) with the chemical formula of [Ho2(abtc)1.5(DMF)4]·DMF exhibited a three-dimensional framework. A hexacluster (RE6X8) based three-dimensional MOF with the chemical formula ([Ho6(abtc)3(μ3-X)8]·DMA; X = OH−/F−, DMA = dimethyl ammonium) exhibited Ho6 clusters bridged by OH−/F− ions. The presence of hexaclusters in the holmium MOFs opens up the design of new MOFs for the holmium delivery with high holmium content. The crystal structures of the MOFs were solved. These MOFs are characterized by single-crystal X-ray diffraction (SC-XRD), powder XRD, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), 19F nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), gas adsorption analysis, and X-ray photoelectron spectroscopy (XPS). [ABSTRACT FROM AUTHOR]

Fluid inclusions are a window into deep geological fluids, providing unique access to their nature and composition. The isotopic composition of CO2 and CH4 hosted in fluid inclusions is a powerful proxy to assess the origin and transformation of deep geological fluids, giving insights into carbon sources, fluxes, and degassing in a wide variety of geodynamic settings. Over the last 5 decades, techniques have been developed to extract fluid inclusions from their host minerals and measure their bulk composition. These techniques are often challenged by analytical artifacts including high blank levels of CO2 and CH4, fluid re-speciation, gas adsorption, and diffusion. Since these processes may alter the pristine composition of gases liberated from fluid inclusions, rigorous protocols are needed in order to evaluate the isotopic integrity of the extracted volatile species. In this study, we introduce new protocols for bulk off-line fluid inclusion extraction for the analysis of δ13C-CH4 and δ13C-CO2 using a Cavity Ring-Down Spectroscopy (CRDS) analyser (Picarro G2201-i). Two mechanical fluid extraction techniques are compared: ball milling in ZrO2 jars and sample crushing in a stainless steel sealed tube under a hydraulic press. Blanks and isotopically labelled tests with the ball milling technique suggest that rotation speed, grinding stock filling degree and filling type alter the CH4 and CO2 concentrations and isotopic compositions measured by the CRDS analyser. In contrast, the crushing technique does not generate measurable quantities of blank CH4 and CO2. The protocols presented in this study allow to extract, detect, and analyse δ13C of CH4 and CO2 for concentrations above 10 and 1,000 ppm respectively. Interlaboratory experiments allowed to replicate previously measured δ13C-CH4 values in natural fluid inclusions within 1‰ with both extraction techniques. This study highlights the potential of combining simple bulk off-line fluid inclusion extraction techniques with a CRDS analyser for δ13C analysis of CO2 and CH4 without gas separation being required. [ABSTRACT FROM AUTHOR]

Two water‐stable indium metal‐organic frameworks, (NH2Me2)3[In3(BTB)4] ⋅ 12DMA ⋅ 4.5H2O (In‐MOF‐1) and (NH2Me2)9[In9O6(BTB)8(H2O)4(DMSO)4] ⋅ 27DMSO ⋅ 21H2O (In‐MOF‐2) (BTB=4,4′,4′′‐benzene‐1,3,5‐tribenzoate) with 3D interpenetrated structure has been constructed by regulating solvents. Structure analysis revealed that In‐MOF‐1 has a three‐dimensional (3D) structure with a single metal core, while In‐MOF‐2 features an octahedron cage constructed by three kinds of metal clusters to further form a 3D structure. The fluorescence investigations showed that In‐MOF‐1 and In‐MOF‐2 are potential MOF‐based fluorescent sensors to detect acetone and Fe3+ ions in EtOH or water with high sensitivity, excellent selectivity, recyclability and a low limit of detection. Moreover, the fluorescence mechanisms of In‐MOF‐1 and In‐MOF‐2 toward acetone and Fe3+ ions were further explained. In addition, In‐MOF‐2 has higher thermal and framework stability than In‐MOF‐1. The activated In‐MOF‐2 presents a high BET surface area of 998.82 m2g−1 and a pore size distribution of 8 to 16 Å. At the same time, In‐MOF‐2 exhibits high selective CO2 adsorption for CO2/CH4 and CO2/N2, respectively. Furthermore, the adsorption sites and adsorption isotherms were predicted using grand canonical Monte Carlo (GCMC) simulations, and the adsorption energy of the lowest‐energy adsorption configuration was calculated using molecular dynamics (MD) simulations. [ABSTRACT FROM AUTHOR]

Room temperature gas sensing is crucial for practical devices used in indoor environments. Among various materials, metal oxides are commonly used for gas sensing, but their strong insulating properties limit their effectiveness at room temperature. To address this issue, many studies have explored diverse methods such as nanoparticle decoration or conductive support, etc. Here, we report the emergence of gas-sensing functionality at room temperature with improved CO gas selectivity on SnO2 nanoparticles through sequential steps by using amorphous carbon (a-C) support and PtOx decoration. The SnO2 decorated on amorphous carbon shows enhanced gas adsorption compared to inactive gas sensing on SnO2 decorated carbon support. The higher Vo site of SnO2 on a-C induces gas adsorption sites, which are related to the higher sp2 bonding caused by the large density of C defects. The ambiguous gas selectivity of SnO2/a-C is tailored by PtOx decoration, which exhibits six values of sensing responses (Rg/Ra or Ra/Rg) under CO gas at room temperature with higher selectivity. Compared to PtOx/a-C, which shows no response, the enhanced CO gas sensing functionality is attributed to the CO adsorption site on PtOx-decorated SnO2 particles. This report not only demonstrates the applicability of CO gas sensing at room temperature but also suggests a strategy for using SnO2 and carbon compositions in gas sensing devices. [ABSTRACT FROM AUTHOR]

X-ray diffraction is used to study the sorption of CO and NO in two phthalocyanine nanoporous crystals (PNCs) with 4,4′ bipyridine or 4,4′ bipyrimidine trans coordinated to open Co2+ sites, demonstrating how the trans coordinated ligands influence the gas sorption properties and structures of the PNCs. [ABSTRACT FROM AUTHOR]

While understanding the competitive adsorption behavior of gas sensor is important, it is yet to be unraveled. Especially for the influence of water molecules to the gas adsorbed on 2D materials. This study explores the potential of layered 2D materials as a candidate material for gas sensing, employing non‐destructive measurement, and second harmonic generation (SHG). The investigation focuses on analyzing oxygen, ammonia, and water vapor adsorbed on a WS2 surface by studying the evolutions in electric dipole and electric field. Leveraging the simplified bond hyperpolarizability model (SBHM), a foundation is established for gas sensors utilizing high‐quality 2D materials. This approach facilitates the detection of material modifications in response to environmental influences, including the inevitable water molecules. The obtained hyperpolarizability from SBHM exhibits remarkable consistency with Langmuir's adsorption model, confirming the physical adsorption in the system. In addition, the competitive effects between gases are explored by comparing experimental results with theoretical predictions based on Boltzmann distribution and density functional theory (DFT) calculations. This highlights the effectiveness of SHG and SBHM in studying gas adsorption on layered van der Waals materials. [ABSTRACT FROM AUTHOR]

Single‐atom catalysts have garnered significant attention due to their exceptional atom utilization and unique properties. However, the practical application of these catalysts is often impeded by challenges such as sintering‐induced instability and poisoning of isolated atoms due to strong gas adsorption. In this study, we employed the mechanochemical method to insert single Cu atoms into the subsurface of Fe2O3 support. By manipulating the location of single atoms at the surface or subsurface, catalysts with distinct adsorption properties and reaction mechanisms can be achieved. It was observed that the subsurface Cu single atoms in Fe2O3 remained isolated under both oxidation and reduction environments, whereas surface Cu single atoms on Fe2O3 experienced sintering under reduction conditions. The unique properties of these subsurface single‐atom catalysts call for innovations and new understandings in catalyst design. [ABSTRACT FROM AUTHOR]

This research explores the production of activated carbon (AC) from cashew nut shells using a potassium hydroxide (KOH) activation method, with a focus on its application in high-pressure gas adsorption. Among the synthesized samples, AC850 demonstrated the highest efficiency, displaying a specific surface area of 1972 m2/g and total and micropore volumes of 0.847 cm3/g and 0.724 cm3/g, respectively. The bioorganic activated carbon exhibited significant sorption capabilities for H 2 , with uptake values of 13.34 mmol/g (2.69 wt%) at 10 bar and 25 °C, and a H 2 /CH 4 selectivity range between 43.4 and 2.6. Calculations were also conducted for selectivity in a mixture of three gases (H 2 , CO 2 , and CH 4) in industrial settings. Advanced characterization methods such as N 2 /CO 2 adsorption isotherms, FT-IR, Raman spectroscopy, SEM, and TGA were employed to analyze the structural and chemical properties of the produced AC, including its functional groups and molecular structure. The research underscores the potential of utilizing agricultural waste, particularly cashew nut shells, to develop efficient materials for H 2 storage and purification. The high-pressure adsorption capability and eco-friendly nature of the manufactured activated carbon make it suitable for both environmental and industrial applications. [Display omitted] • Activated carbon from cashew shells is explored for high-pressure H 2 adsorption. • A 1972 m2/g surface area is featured by AC850, excelling in H 2 sorption. • AC's structural, chemical traits are revealed, crucial for H 2 storage. • Exceptional H 2 sorption is demonstrated by the AC, with uptake reaching 13.34 mmol/g at 10 bar and 25 °C. • In industrial gas mixture separation, H 2 shows the highest selectivity, followed by CO 2 and CH 4. [ABSTRACT FROM AUTHOR]

Two-dimensional materials with chemical formula MA2Z4 are a promising class of materials for optoelectronic applications. To exploit their potential, their stability with respect to air pollution has to be analyzed under different conditions. In a first-principle study based on density functional theory, we investigate the adsorption of three common environmental gas molecules (O2, H2O, and CO2) on monolayer WSi2N4, an established representative of the MA2Z4 family. The computed adsorption energies, charge transfer, and projected density of states of the polluted monolayer indicate a relatively weak interaction between substrate and molecules resulting in an ultrashort recovery time of the order of nanoseconds. O2 and water introduce localized states in the upper valence region but do not alter the semiconducting nature of WSi2N4 nor its band-gap size apart from a minor variation of a few tens of meV. Exploring the same scenario in the presence of photogenerated electrons and holes, we do not notice any substantial difference except for O2 chemisorption when negative charge carriers are in the system. In this case, monolayer WSi2N4 exhibits signs of irreversible oxidation, testified by an adsorption energy of -5.5 eV leading to an infinitely long recovery time, a rearrangement of the outermost atomic layer bonding with the pollutant, and n-doping of the system. Our results indicate stability of WSi2N4 against H2O and CO2 in both dark and bright conditions, suggesting the potential of this material in nanodevice applications. [ABSTRACT FROM AUTHOR]

Context: The adsorptions of gas (CO, CO2, NH3) by metal (Au, Ag, Cu)-doped single layer WS2 are studied by density functional theory. The doping of metal atoms makes WS2 behave as n-type semiconductors. The final adsorption sites for CO, CO2, and NH3 are close to the atomic sites of the doped metal. The adsorptions of CO and NH3 gases on Cu/WS2, Ag/WS2, and Au/WS2 are dominated by chemisorption. The doped metal atoms enhance the hybridization of the substrate with the gas molecular orbitals, which contributes to the charge transfer and enhances the adsorption of the gas with the material surface. The adsorptions of CO and NH3 on Cu/WS2 and Ag/WS2 allow favorable desorption in a short time after heating. The single-layer Cu/WS2 is proved to have the potential to be used as a reliable recyclable sensor for CO. This work provides a theoretical basis for developing high-performance WS2-based gas sensors. Methods: In this paper, the adsorption energy, electronic structure, charge transfer, and recovery time of CO, CO2, and NH3 in the doped system have been investigated based on the CASTEP code of density functional theory. The exchange correlation function used is the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA). The TS (Tkatchenko-Scheffler) dispersion correction method was used to involve the effects of van der Waals interaction on the adsorption energies for all adsorption system. The ultrasoft pseudopotentials are chosen and the plane-wave cut-off energies are set to 500 eV. The k-point mesh generated by the Monkhorst package scheme is used to perform the numerical integration of the Brillouin zone and 5 × 5 × 1 k-point grid is used. The tolerances of total energy convergence, maximum ionic force, ionic displacement, and stress component are 1.0 × 10−5 eV/atom, 0.03 eV/Å, 0.001 Å, and 0.05 GPa, respectively. [ABSTRACT FROM AUTHOR]

The gas sweetening process is essential for removing harmful acid gases, such as hydrogen sulfide (H2S) and carbon dioxide (CO2), from natural gas before delivery to end-users. Consequently, chemical absorption-based acid gas removal units (AGRUs) are widely implemented due to their high efficiency and reliability. The most common solvent used in AGRU is monodiethanolamine (MDEA), often mixed with piperazine (PZ) as an additive to accelerate acid gas capture. The absorption performance, however, is significantly influenced by the solvent mixture composition. Despite this, solvent composition is often determined through trial and error in experiments or simulations, with limited studies focusing on predictive methods for optimizing solvent mixtures. Therefore, this paper aims to develop a predictive technique for determining optimal solvent compositions under varying sour gas conditions. An ensemble algorithm, Extreme Gradient Boosting (XGBoost), is selected to develop two predictive models. The first model predicts H2S and CO2 concentrations, while the second model predicts the MDEA and PZ compositions. The results demonstrate that XGBoost outperforms other algorithms in both models. It achieves R2 values above 0.99 in most scenarios, and the lowest RMSE and MAE values of less than 1, indicating robust and consistent predictions. The predicted acid gas concentrations and solvent compositions were further analyzed to study the effects of solvent composition on acid gas absorption across different scenarios. The proposed models offer valuable insights for optimizing solvent compositions to enhance AGRU performance in industrial applications. [ABSTRACT FROM AUTHOR]

This study investigates the modeling and experimental validation of cell morphology in microcellular-foamed polycaprolactone (PCL) using supercritical carbon dioxide (scCO2) as the blowing agent. The microcellular foaming process (MCP) was conducted using a solid-state batch foaming process, where PCL was saturated with scCO2 at 6 to 9 MPa and 313 K, followed by depressurization at a rate of −0.3 and −1 MPa/s. This study utilized the Sanchez–Lacombe equation of state and the Peng–Robinson–Stryjek–Vera equation of state to model the solubility and density of the PCL-CO2 mixture. Classical nucleation theory was modified and combined with numerical analysis to predict cell density, incorporating factors such as gas absorption kinetics, the role of scCO2 in promoting nucleation, and the impact of depressurization rate and saturation pressure on cell growth. The validity of the model was confirmed by comparing the theoretical predictions with experimental and reference data, with the cell density determined through field-emission scanning electron microscopy analysis of foamed PCL samples. This study proposes a method for predicting cell density that can be applied to various polymers, with the potential for wide-ranging applications in biomaterials and industrial settings. This research also introduces a Python-based numerical analysis tool that allows for easy calculation of solubility and cell density based on the material properties of polymers and penetrant gases, offering a practical solution for optimizing MCP conditions in different contexts. [ABSTRACT FROM AUTHOR]

Shale gas, mainly consisting of adsorbed gas and free gas, has served a critical role of supplying the growing global natural gas demand in the past decades. Considering that the adsorbed methane has contributed up to 80% of the total gas in place (GIP), understanding the methane adsorption behaviors is imperative to an accurate estimation of total GIP. Historically, the single-site Langmuir model, with the assumption of a homogeneous surface, is commonly applied to estimate the adsorbed gas amount. However, this assumption cannot depict the methane adsorption characteristics due to various compositions and pore sizes of shales. In this work, a multi-site model integrating the energetic heterogeneity in adsorption is derived to predict methane adsorption on shale. Our results show that the multi-site model is capable of addressing the heterogeneity of shales by a wide range of adsorption energy distributions (owing to the complex compositions and different pore sizes), which is different from the single-site model only characterized by single adsorption energy. Consequently, the multi-site model results have better accuracy against the experimental data. Therefore, applying the multi-site Langmuir model for estimating GIP in shales can achieve more accurate results compared with using the traditionally single-site model. [ABSTRACT FROM AUTHOR]

Dissolved gas analysis (DGA) is a vital method for the online detection of transformer operation state. The adsorption performance of a SnP3 monolayer modified by transition metal Cr regarding six characteristic gases (CO, C2H4, C2H2, CH4, H2, C2H6) dissolved in oil was studied. The study reveals the relevant adsorption and gas-sensing response mechanisms through calculations of the adsorption energy, density of states, differential charge density, energy gap, and recovery time. The results display a considerable increase in the adsorption effect of the Cr-SnP3 monolayer on six gases. The CO, C2H2, and C2H4 gases lead to chemical adsorption, and the CH4, H2, and C2H6 gases lead to physical adsorption. Combined with the recovery time, the Cr-SnP3 monolayer has a strong adsorption effect on CO and C2H2 gases at normal temperatures and even high temperatures, and the adsorption is stable. C2H4 gas can be rapidly desorbed from the Cr-SnP3 monolayer at 398 K. Therefore, the Cr-SnP3 monolayer can be expected to serve as a CO and C2H2 gas adsorbent and a resistive gas sensor for C2H4 gas. This research offers a theoretical foundation for the development of the Cr-SnP3 monolayer in gas-sensitive materials. [ABSTRACT FROM AUTHOR]

Great progress has been made in marine shale gas of Wufeng–Longmaxi formations in the Sichuan Basin. However, shale gas exploration in the complex structural belt around the Sichuan Basin still faces great challenges. In this study, shales of Wufeng–Longmaxi formations collected from the northern Guizhou were taken as the studied target, organic matter (OM) characteristics, mineral composition, pore structure, methane adsorption capacity and in situ desorption gas content were measured, and the controlling factors of shale gas content were further discussed. The results indicated that the sedimentary facies of Wufeng–Longmaxi formations in north Guizhou varies from shallow‐water shelf facies to deep‐water shelf facies from south to north, and organic‐rich shales are primarily distributed in Daozhen‐Xishui areas, with a maximum thickness of about 80–100 m. Organic‐rich shales are characterized by high total organic carbon (TOC) content, high thermal maturation and type I–II1 kerogens, which can be comparable with those in commercially produced shale gas field in Sichuan Basin. High‐quality shale gas reservoirs generally have a high content of brittle minerals, making them easier to be fractured. OM pores are the dominanted pore type in the studied shales, followed by intergranular pores associated with brittle minerals, dissolution pores within carbonate grains and microcracks, while clay mineral‐related pores are poorly developed. The Wufeng–Longmaxi Formation shales generally have strong methane adsorption capacities, but these vary greatly across different areas. Shale gas adsorption capacity is primarily controlled by TOC content and thermal maturation level. Similarly, total gas content, including desorption gas and lost gas, varies greatly in different areas, and it is obviously lower than that in Fuling and Luzhou shale gas field, due to the loss of shale gas and low‐pressure coefficient in the complex structural zone. It is worth explaining that shale gas is not always low in northern Guizhou, which is determined by burial depth and the distance of great fractures. Shale gas content is relatively high in LY1 well and DY1 well in Xishui‐Daozhen area, and it is extremely low in TY1 well and AY1 well in Tongzi‐Zheng'an area. Shale gas content in the same structural unit is primarily influenced by TOC content, OM pore development degree and water saturation. However, different structural units have different shale gas contents, due to the differences in preservation conditions. Shale reservoirs with good preservation conditions, that is, wide and gentle structure, far from a large fault and great burial depth, generally have high shale gas contents. [ABSTRACT FROM AUTHOR]

Carbon capture technologies are imperative for addressing climate change objectives. Among the available solutions, five post-combustion capture technologies stand out for their efficacy in trapping CO2 from flue gas emissions: chemical absorption, adsorption, membrane separation, cryogenic distillation, and electrochemical processes. Their implementation spans both laboratory investigations and pilot/commercial applications. This review systematically examines these five CO2 capture technologies, emphasizing their progression in industrial applications. Current research endeavors are explored, and pivotal challenges are underscored. When addressed, they can enhance both performance and economic feasibility. Comparative analyses indicate that while adsorption, membrane, and cryogenic processes have seen pilot/commercial applications, chemical absorption is the most cost-effective and established method, accounting for an operational capacity of approximately 50 million tons of CO2 annually. Remarkably, electrochemical devices have exhibited superior performance at the laboratory scale, achieving CO2 removal efficiencies exceeding 98% with a simple activation mechanism. Comprehensive strategies addressing operational costs and device configurations are essential to transition this technology to larger scales. [ABSTRACT FROM AUTHOR]

Heavy metal ions and antibiotic contamination have become a major environmental concern worldwide. The development of efficient recognition strategies of these pollutants at ultra‐low concentrations in aqueous solutions as well as the elucidation of the intrinsic sensing mechanism are challenging tasks. In this work, unique luminescent Ln‐MOF materials (NIIC‐3‐Ln) were assembled by rational ligand design. Among them, NIIC‐3‐Tb demonstrated highly selective luminescence quenching response toward Hg2+ and sulfadiazine (SDI) at subnanomolar concentrations in less than 7 s. In addition, a Hg2+ sensing mechanism through chelation was proposed on the basis of single‐crystal X‐ray diffraction analysis and Hg2+ adsorption study. The interaction mechanism of NIIC‐3‐Tb with SDI was revealed using a newly developed approach involving a (TD‐)DFT based quantification of the charge transfer of a MOF‐analyte supramolecular complex model in the ground and excited states. Effect of ultrasonic treatment on the surface morphology important for MOF sensing performance was revealed by gas adsorption experiments. The presented results indicate that NIIC‐3‐Ln is not only an advanced sensing material for the efficient detection of Hg2+ and SDI at ultra‐low concentrations, but also opens up a new approach to study the sensing mechanism at the molecular level at ultra‐low concentrations. [ABSTRACT FROM AUTHOR]

Fly ash (FA) contents and water-binder ratio (w/b) are the important factors influencing the mechanical characteristics of cement-based materials, meanwhile the porous structure of material plays a vital role. The compressive strength and water permeability of cement-based samples with high-volume FA contents (0%, 30%, 40%) and different w/b (0.3, 0.4, 0.5) were measured. The results demonstrated that higher FA contents or greater w/b led to lower compressive strength and higher water permeability at an early stage. The pore structure features of samples were obtained using mercury intrusion porosimetry and low-temperature nitrogen gas adsorption (LT-NGA). The pore size distributions (PSDs) and the matrix compressibility in cementitious materials were also analyzed, with the compression coefficient KC ranging from 11.919 to 1.249 × 10−4 MPa−1. Increasing the FA content and reducing the w/b resulted in an optimized pore structure of the samples, characterized by changing the main pore type from mesopores (10–50 nm) to micropores (< 10 nm). The pores and fractures in the samples also had distinct multifractal characteristics. The strongest negative correlation between the compressive strength and the width of the multifractal generalized spectrum was proved by Pearson correlation analysis, and the correlation coefficient (ρ) was − 0.93. Furthermore, the water permeability had the strongest positive correlation with porosity, with ρ of 0.91. The content of macropores (50–10 μm) had greater influence on its macroscopic properties. The dense structure accompanied by homogeneous PSDs is advantageous for enhancing the strength and anti-permeability properties of cement-based materials. [ABSTRACT FROM AUTHOR]

A novel metal–organic framework (MOF) denoted as CJLU-L1 has been successfully synthesized and characterized. This MOF was assembled by dicooper paddle-wheel Secondary Building Units (SBUs) and a ligand incorporating a phosphorous group. The structure was solved and analyzed through single crystal X-ray diffraction (SCXRD), revealing a framework with two types of cages with diameters of 5.79 and 6.20 Å. The void volume of CJLU-L1 is calculated to be 8130.5 Å3 per unit cell, which is 66% of the total crystal volume (12,321.4 Å3), as calculated by PLATON after remove of guest solvent in the pores. The Brunauer − Emmett − Teller (BET) surface areas also simulated by poreblazer software to be 1557 m2/g. The CJLU-L1 exhibits high hydrogen adsorption capacity at 77 K and 1 bar. This observation underscores the practical significance of CJLU-L1 in gas adsorption. Additionally, powder X-ray diffraction (PXRD) and infrared spectrum (IR) were performed to prove the phase purity of the CJLU-L1, and thermogravimetric analyses (TGA) was conducted to analyzed to the thermal stability of the CJLU-L1. [ABSTRACT FROM AUTHOR]

The injection of CO2 into deep, unmineable coal seams is an effective strategy for reducing greenhouse gas emissions. At depths greater than 800 m, the carbon dioxide transitions to the supercritical state (Sc-CO2). This study investigated the complex interactions between Sc-CO2 and coal, which substantially affected the pore structure, mineralogy, and permeability of the coal. We used low-pressure nitrogen gas adsorption (LP-N2GA) to assess the impact of Sc-CO2 on the pore characteristics of the coal. X-ray diffraction (XRD) was also used to determine the causal factors. We performed comparative triaxial permeability tests before and after Sc-CO2 exposure to evaluate the changes in permeability for various coal types. Our findings suggested that Sc-CO2 exposure markedly increased the complexity of the coal pore structure, which in turn affects coal-rock permeability. Specifically, a 10-day exposure period resulted in considerable increases of 43.5% and 50.9% in the pore volume and the specific surface area, respectively, along with a slight increase of 0.01 nm in the average pore diameter. Furthermore, there were notable decreases in the contents of minerals such as kaolinite, calcite, and pyrite, with decreases of 1.5%, 2.8%, and 2.2%, respectively, whereas the quartz content increased by 3%, indicating that significant mineral dissolution influenced the pore structure. A significant positive correlation was observed between the loss of coal mass and the increase in permeability. The effects of Sc-CO2 were most pronounced in coals with low permeabilities, particularly during the initial phase of saturation. Subsequent saturation cycles and prolonged exposure resulted in a reduced rate for permeability enhancement, which eventually reached a plateau. This study underscores the critical role of Sc-CO2 in long-term geological CO2 storage and improved efficiency for coalbed methane production. [ABSTRACT FROM AUTHOR]

The waste of resources associated with fruit decay is rapidly spreading globally, threatening the interests of relevant practitioners and the health of consumer groups, and demanding precise solutions. Controlling fruit ripening through ethylene regulation is one of the most important strategies for providing high‐quality fruits. However, current materials for ethylene regulation still have difficulty realizing their application potential due to high manufacturing costs and performance deficiencies. In this review, the ethylene‐controlled release materials for ripening based on molecular encapsulation and the ethylene scavengers for preservation based on mechanisms such as oxidation, photodegradation, and adsorption are presented. We discuss and analyze a wide range of materials in terms of mechanism, performance, potential of applicability, and sustainability. The ethylene release behavior of encapsulating materials depends on the form in which the ethylene binds to the material as well as on environmental factors (humidity and temperature). For ethylene scavengers, there are a variety of scavenging mechanisms, but they generally require porous materials as adsorption carriers. We highlight the great opportunity of designing soft crystalline porous materials as efficient ethylene adsorbent due to their unique structural properties. We present this review, including a summary of practical characteristics and deficiencies of various materials, to establish a systematic understanding of fruit quality assurance materials applied to ethylene regulation, anticipating a promising prospect for these new materials. [ABSTRACT FROM AUTHOR]

Context: The adsorptions of gas (CO, CO2, NH3) by metal (Au, Ag, Cu)-doped single layer WS2 are studied by density functional theory. The doping of metal atoms makes WS2 behave as n-type semiconductors. The final adsorption sites for CO, CO2, and NH3 are close to the atomic sites of the doped metal. The adsorptions of CO and NH3 gases on Cu/WS2, Ag/WS2, and Au/WS2 are dominated by chemisorption. The doped metal atoms enhance the hybridization of the substrate with the gas molecular orbitals, which contributes to the charge transfer and enhances the adsorption of the gas with the material surface. The adsorptions of CO and NH3 on Cu/WS2 and Ag/WS2 allow favorable desorption in a short time after heating. The single-layer Cu/WS2 is proved to have the potential to be used as a reliable recyclable sensor for CO. This work provides a theoretical basis for developing high-performance WS2-based gas sensors. Methods: In this paper, the adsorption energy, electronic structure, charge transfer, and recovery time of CO, CO2, and NH3 in the doped system have been investigated based on the CASTEP code of density functional theory. The exchange correlation function used is the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA). The TS (Tkatchenko-Scheffler) dispersion correction method was used to involve the effects of van der Waals interaction on the adsorption energies for all adsorption system. The ultrasoft pseudopotentials are chosen and the plane-wave cut-off energies are set to 500 eV. The k-point mesh generated by the Monkhorst package scheme is used to perform the numerical integration of the Brillouin zone and 5 × 5 × 1 k-point grid is used. The tolerances of total energy convergence, maximum ionic force, ionic displacement, and stress component are 1.0 × 10−5 eV/atom, 0.03 eV/Å, 0.001 Å, and 0.05 GPa, respectively. [ABSTRACT FROM AUTHOR]

Accurate shale gas reserves estimation is essential for development. Existing machine learning (ML) models for predicting gas isothermal adsorption are limited by small datasets and lack verified generalization. We constructed an "original dataset" containing 2112 data points from 11 measurements on samples from 8 formations in 3 countries to develop ML‐based prediction models. Similar to previous ML models, total organic matter, pressure, and temperature are characterized as the three most significant features using the mean impurity method. In contrast to previous ML models, the study reveals that these three features are inadequate to be used to make reasonable predictions for the datasets from the measurements different from those used to train the models. Instead, the extreme gradient boosting decision trees (XGBoost) model with two more features (specific surface area and moisture) exhibits good robustness, generalization, and precision in the prediction of gas isothermal adsorption. Overall, An XGBoost model with optimal input features is developed in this work, which exhibits both good performance in gas adsorption prediction and good potential for the estimation of gas storage in shale gas development. [ABSTRACT FROM AUTHOR]

Bilayer structure with functional overlayer has been commonly adopted to resolve the issue of moisture poisoning in chemiresistors. However, the conventional overlayers always suffer from blocking access of gas molecules to sensing layer due to lacking porosity and deteriorated adsorption capability. Herein, taking advantages of the well-defined porous structure and hydrophobic nature of pure silica zeolite, we assembled an overlayer of Pd-PdO clusters-encapsulated mesoporous silicalite-1 (MFI) zeolite (named M-S-1) on ZnO sensing layer, to prevent moisture poisoning, and enhance gas diffusion and adsorption capabilities. The inherent capability of MFI zeolite to incorporate monodispersed nanometric (ca. 3 nm) Pd-PdO cluster in its void space is of great importance for the NO2 adsorption. The Pd-PdO@M-S-1 overlayer can attain negligible moisture interference to the ZnO layer without significantly altering the gas selectivity and baseline resistance, and enhance gas response. Consequently, the Pd-PdO@M-S-1/ZnO bilayer sensor can ultra-selectively (Snitrogen dioxide/Sinterference gas > 4), and ultra-stably detect trace level of NO2 (9.5 ppb) at low temperature (370 K) under high levels of humidity (90% RH). This work exemplifies a next-generation solution to design bilayer sensors using zeolite overlayer for eliminating the humidity dependence of the gas-sensing properties. [ABSTRACT FROM AUTHOR]

Solid rocket motors (SRMs), frequently used as primary boosters in rockets, employ ammonium perchlorate as the oxidizer and aluminum powder as the fuel. Upon combustion, the exhaust products from composite propellants primarily include hydrochloric acid (HCl), carbon monoxide (CO), aluminum oxide, and hydrogen (H2). About 95% of the ammonium perchlorate undergoes conversion to HCl, constituting nearly 20% of the combustion product by weight, significantly contributing to air pollution. To address this environmental concern, we have developed a reusable MoS2 aerogel specifically engineered for absorbing HCl gas. The fabrication process is straightforward and cost‐effective, utilizing nontoxic reagents and standard equipment, enhancing its practicality. Characterization of the aerogel was conducted using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X‐ray Diffraction (XRD), X‐ray Photoelectron Spectroscopy (XPS), and Brunauer–Emmett–Teller (BET) analysis. The aerogel demonstrated a high absorptive capacity, achieving 65.88% absorption efficiency for HCl gas, which is noteworthy. Moreover, the aerogel samples exhibited exceptional recyclability over five cycles, highlighting their suitability for applications requiring HCl gas absorption. This research lays the foundation for advancing and scaling up innovative nanomaterial‐based aerogels, offering versatile solutions for a wide range of contemporary applications. [ABSTRACT FROM AUTHOR]

By utilizing density functional theory, we investigated the adsorption of gas molecules (NO2 and SO2) on Germanene nanosheets (GeNS). Our findings reveal that GeNS displays notably high reactivity toward these gas molecules, with adsorption energies exceeding 1.00eV. The stability of GeNS at elevated temperatures and the thermodynamics of the adsorption process have been thoroughly investigated. These findings point toward promising applications for GeNS in the development of metal-free catalysts. Furthermore, the comprehensive examination of gas molecules inactivation pathways on GeNS enhances the understanding of its properties and opens avenues for exploring its potential as both catalysts and gas sensors. [ABSTRACT FROM AUTHOR]

Hierarchical porous hypercrosslinked monoliths (PolyHIPE‐HCP) with ultrahigh specific surface areas are prepared via a solvent knitting strategy. Compared to previous work, the solvent knitting strategy is carried out in a relatively low air‐controlled atmosphere with gradient heating starting from low temperature while using DCM (Dichloromethane) as both a solvent and a cross‐linker, allowing for a slow and controlled cross‐linking process, thereby achieving a BET surface area ranging from 514 to 728 m2 g−1. Scanning electron microscopy (SEM) shows that the knitting process does not affect the presence of macroporous structure in the PolyHIPE. With the introduction of mesopores and micropores, these hierarchical porous monoliths exhibit significant potential for applications in gas adsorption and water treatment. Hence, a universal, simple and low‐cost method to synthesize polymeric monoliths with hierarchically porous structure and higher surface area is proposed, which has fascinating prospects in industrialization. [ABSTRACT FROM AUTHOR]

Chemical looping reforming of CH 4 coupled with CO 2 reduction stands out as a promising method for the syngas production. In this process, it is significant to design the oxygen carrier with high reactivity and stability. In this work, a highly efficient oxygen carrier is obtained by physically mixing Metal-modified ZSM-5 with LaFe 0.85 Ni 0.15 O 3 (LFN). The physical and chemical properties of the oxygen carriers are characterized by XRD, Raman, XPS, BET, TEM, NH 3 -TPD, CO 2 -TPD and CH 4 -TPD techniques. It is noted that mesoporous structures are formed over the Ni modified ZSM-5, due to that part of Ni elements replace Al in the silicaluminate framework. The structure change of the ZSM-5 promotes the gas adsorption capacity. CH 4 and CO 2 cannot be adsorbed on the surface of ZSM-5, while Ni-modified ZSM-5 enhances the adsorption capacity for CO 2 to a large degree. Moreover, Ni species are acted as active sites to facilitate the activation of CH 4 and CO 2 during the redox process. The aggregation-redispersion of Ni particles during the reduction-oxidation process inhibits the deactivation of Ni particles, which improves the stability of the oxygen carrier. Among all the obtained samples, LFN/10 wt% Ni-ZSM-5 exhibits the highest yields of syngas (8.38 mmol g−1) and CO (2.42 mmol g−1). [Display omitted] • Modifying ZSM-5 with Ni changed the pore structures and acid sites. • Ni-modified ZSM-5 promoted the adsorption capacity towards CO 2. • The activation of CH 4 and CO 2 could be improved over Ni-modified ZSM-5. • Ni particles maintained active by aggregation-redispersion under redox atmospheres. • LFN/10 wt% Ni-ZSM-5 exhibited high stability either in the activity or structure. [ABSTRACT FROM AUTHOR]

Understanding the structure in the nanoscopic region of water that is in direct contact with solid surfaces, so-called contact layer, is key to quantifying macroscopic properties that are of interest to e.g. catalysis, ice nucleation, nanofluidics, gas adsorption, and sensing. We explore the structure of the water contact layer on various technologically relevant solid surfaces, namely graphene, MoS2, Au(111), Au(100), Pt(111), and Pt(100), which have been previously hampered by time and length scale limitations of ab initio approaches or force field inaccuracies, by means of molecular dynamics simulations based on ab initio machine learning potentials built using an active learning scheme. Our results reveal that the in-plane intermolecular correlations of the water contact layer vary greatly among different systems: Whereas the contact layer on graphene and on Au(111) is predominantly homogeneous and isotropic, it is inhomogeneous and anisotropic on MoS2, on Au(100), and on the Pt surfaces, where it additionally forms two distinct sublayers. We apply hydrodynamics and the theory of the hydrophobic effect, to relate the energy corrugation and the characteristic lengthscales of the contact layer with wetting, slippage, the hydration of small hydrophobic solutes and diffusio-osmotic transport. Thus, this work provides a microscopic picture of the water contact layer and links it to macroscopic properties of liquid/solid interfaces that are measured experimentally and that are relevant to wetting, hydrophobic solvation, nanofluidics, and osmotic transport. [ABSTRACT FROM AUTHOR]

Using first-principles theory, this work purposes Ru-doped Janus WSSe (Ru-WSSe) monolayer as a potential gas sensor for detection of three typical gas species (CO, C2H2, and C2H4), in order to evaluate the operation status of the oil-immersed transformers. The Ru-doping behavior on the WSSe surface is analyzed, giving rise to the preferred doping site by the replacement of a Se atom with the formation energy of 0.01 eV. The gas adsorption of three gas species onto the Ru-WSSe monolayer is conducted, and chemisorption is identified for all three gas systems with the adsorption energy following the order: CO (−2.22 eV) > C2H2 (−2.01 eV) > C2H4 (−1.70 eV). Also, the modulated electronic properties and the frontier molecular orbital are investigated to uncover the sensing mechanism of Ru-WSSe monolayer upon three typical gases. Results reveal that the sensing responses of the Ru-WSSe monolayer, based on the variation of energy gap, to CO, C2H2, and C2H4 molecules are calculated to be 1.67 × 106, 2.10 × 105, and 9.61 × 103, respectively. Finally, the impact of the existence of O2 molecule for gas adsorption and sensing is also analyzed to uncover the potential of Ru-WSSe monolayer for practical application in the air atmosphere. The obtained high electrical responses manifest strong potential as a resistive sensor for detection of three gases. The findings hold practical implications for the development of novel gas sensing materials based on Janus WSSe monolayer. We anticipate that our results will inspire further research in this domain, particularly for applications in electrical engineering where the reliable detection of fault gases is paramount for maintaining the integrity and safety of power systems. [ABSTRACT FROM AUTHOR]

The pore fracture structure of deep coal reservoirs is crucial for evaluating the potential of deep coalbed methane resources, conducting exploration and development, and controlling coal mine gas disasters. Mercury intrusion porosimetry, the liquid nitrogen method, and the low-temperature carbon dioxide adsorption method were used to study the full pore size structure and pore fractal characteristics of different coal grades in deep coal and comprehensively characterize the pore structure of kilometer-level coal mining. The sponge, Frenkel–Halsey–Hill (FHH), and density function models were applied to comprehensively analyze the pore complexity of coal, and the influence of metamorphic degree on pore size structure was evaluated. The distribution relationship of pore volume in different stages of coal samples was macropore→mesopore→micropore, and macropores had the best connectivity. Micropores and mesopores had the largest specific surface area, and the development of micropores and microcracks controlled the deep gas adsorption performance. The micropore volume and specific surface area both revealed a nonlinear decreasing trend with the increase in volatile matter, and coal metamorphism promoted the development of micropores. The pore volume and specific surface area of mesopores and macropores decreased first and then increased in a "U" shape with increasing volatile matter. In contrast, the fractal dimension D1 revealed an inverted U shape with increasing volatile matter, followed by a decrease. The D2 value decreased nonlinearly with increasing volatile matter, whereas the D3 value increased nonlinearly with increasing volatile matter. The degree of metamorphism increased, and the microporous structure became more regular. [ABSTRACT FROM AUTHOR]

It is imperative to conduct experimental studies on the seepage behavior of gas-bearing coal under cyclic dynamic loading conditions. This paper focuses on the evolution of coal permeability under the combined effects of dynamic loading, static loading, and gas adsorption. The principal conclusions are as follows: (1) As the frequency and amplitude of dynamic loading increase, the development of pore and fissure structures within the coal body becomes increasingly pronounced during dynamic loading cycles, resulting in a gradual rise in permeability. Notably, as the coal approaches its yielding stage, the permeability can increase by up to 47%. (2) The permeability curve is divided into four regions: the compaction reduction zone, the oscillation zone, the gradual recovery zone, and the abrupt failure increase zone. Ultimately, in the failure phase, the permeability surges dramatically, potentially reaching four to five times the initial permeability. (3) When the static loading stage and dynamic load are constant, the rate of change in coal permeability decreases with increasing adsorption amounts. When the adsorption amount is constant, the rate of change in permeability of the coal under dynamic loading increases with the increase in the static loading stress stage, with the maximum increase reaching 75.2%. It can be concluded from the rate of change in permeability and the dynamic loading sensitivity coefficient that the permeability of coal is highly sensitive to cyclic dynamic loading, with increased sensitivity associated with larger static loading stages and decreased sensitivity with greater adsorption amounts. [ABSTRACT FROM AUTHOR]

Based on crystal engineering, three Zn/Cd-based metal--organic frameworks (MOFs) (FUM-153(Zn--H), FUM-167(Cd--H), and FUM-176(Cd--NH2)) were successfully prepared from rigid O-donor/flexible N-donor linkers (H2bdc (terephthalic acid) (L(O) H) or NH2-H2bdc (2-aminoterephthalic acid) (L(O) NH2) and bpfb (N,N'- 1,4-(phenylene) diisonicotinamide) (L(N))) with Zn/Cd ions. Structurally, the major difference among the FUMs is the various behaviors of the DMF solvent in the lattice or the coordination environment of the structures. This study investigated the effect of hydrogen bonding of NH2 substitution in 2-D layer linkers and its effect on the layer architecture. The results showed that hydrogen bonding indirectly affects the coordination of DMF solvent to the metal center and the porosity. To investigate the effect of the NH2 substitution in the presence or absence of the DMF solvent in the FUMs, the Cambridge Structural Database (CSD) was surveyed for similar structures with the L(O) H and L(O) NH2 linkers. Remarkably, the obtained data suggested that the existence of NH2 substitution may reduce the probability of the coordination of DMF to the metal centers. Theoretical studies were carried out to explore the gas adsorption performance of the title FUMs. A better CH4 adsorption compared to CO2 for all FUMs was observed. It is worth noting that CH4 and CO2 gas adsorption in FUM-176(Cd--NH2) is higher than that in FUM-153(Zn--H) and FUM-167(Cd--H). It can be deduced that the NH2 substitution in 2-D layer linkers prevented the entering of DMF molecules into the framework (lattice or coordinated solvent). Consequently, more accessible pores are provided for gas molecules. The work demonstrates the role of linker functionality in the crystal structure, pore size, and gas adsorption properties. [ABSTRACT FROM AUTHOR]

The high risk of CO poisoning justifies the need for indoor air quality control and warning systems based on the detection of low concentrations (ppm‐ppb) of CO. Cobalt corrole complexes selectively bind CO vs. O2, CO2, N2, opening new fields of applications. By combining the CO chemisorption properties of cobalt corroles with the known sorption capacity of MOFs, we hope to obtain high performance sensing materials for CO detection. In addition, the exposed metal sites of MOFs lead to CO2 physisorption, allowing the co‐detection of CO and CO2. In this work, PCN‐222, a stable Zr‐based MOF made from Ni(TCPP) with natural vacancies, has been used as a porous matrix for the grafting of electron‐poor metallocorroles. The materials were characterized by powder XRD, SEM and optical microscopy, BET analyses and gas adsorption measurements at 298 K. No degradation of the crystalline structure of PCN‐222 was observed. At 1 atm, the adsorbed CO(g) volumes measured for the best materials were 12.15 cm3 g−1 and 14.01 cm3 g−1 for CoCorr2@PCN‐222 and CoCorr3@PCN‐222 respectively, and both materials exhibited high CO chemisorption and selectivity against O2, N2, and CO2 at low pressure due to the highest energy of the chemisorption process vs physisorption. [ABSTRACT FROM AUTHOR]

Porous graphene structures continue to attract attention with their increasingly superior properties. Especially through carbon-based porous structures in a framework form have found applications in various fields such as gas storage. In this study, graphene fragments were utilized as pillars between graphene layers to create a novel framework structure, and geometry optimization was performed under different external pressures. Adsorptions of hydrogen, carbon dioxide, and methane gases, which need to be controlled for combating global warming, were investigated for the optimized structure. It is found that the structure which withstand deformations up to 5 GPa of external pressure could store 2.005 wt % hydrogen hydrogen at room temperature and 100 bar pressure. Moreover, capable to adsorb 6.426 and 8.776 mmol/g carbon dioxide and methane at room temperature and 1 bar pressure, respectively. In conclusion, alongside other potential applications like electrical and energy storage, its usability as a gas adsorbent for combating global warming have a great potential. • Graphene pillared porous graphene framework structure constructed. • Structure optimized under various external pressures. • The structure withstand up to 6 GPa selected for gas adsorption. • Hydrogen, Carbon dioxide and Methane stored inside. [ABSTRACT FROM AUTHOR]

To elucidate the relationship between internal nanopore structure parameters and pulverized size during coal pulverization, in this paper, we investigated the nanopore structure evolution law, fractal characteristics, different types of pore contribution rates, and related mechanisms of anthracite samples during pulverization by cryogenic N2 adsorption experiments. The results showed more pore volume (PV) and pore surface area (PSA) will be gradually exposed during coal pulverization, thus enhancing the adsorption performance. The sample size was negatively correlated with microporous PV proportion, and the contribution rate of micropores to total PV gradually increased with decreasing sample size, whereas the contribution rate of transition pores and mesopores gradually decreased. The sample size shows a similar law to the PSA proportion of corresponding pores. As sample sizes continue to be refined, D1 and D2 basically showed an increasing trend. In addition, it was confirmed that there is a risk of inaccuracy when a single fractal dimension (FD) metric is used to characterize changes in sample PSA. The increase of sample PV/PSA during pulverization is related to the gradual evolution of isolated closed pores and the increase of inter-particle pores. The research results can help researchers deeply understand the law and mechanism of mine gas outburst. [ABSTRACT FROM AUTHOR]

Nowadays, some fracking fluids can enable resourceful extraction of coalbed methane and reduce greenhouse gas emissions. However, their toxicity or corrosiveness will cause harm to downhole workers and pollute groundwater resources. Thus, five kinds of clean composite fracturing fluids were developed in this paper by using starch solution as the matrix and adding various preparations. The change rule of methane adsorption capacity by microstructure changes of coal samples was investigated systematically, and the optimal composite fracturing fluid was determined. The results showed that the new fracturing fluid increased the degree of aromatic ring condensation by 43.3% and the average pore size by 52.1%. Also, the adsorption constants of a value decreased by 11.6% and b value decreased by 23.9%, which can remarkably reduce the methane adsorption. The experimental results provide theoretical support for the clean production of coalbed methane. [ABSTRACT FROM AUTHOR]

Optical fiber sensor emerges as a highly promising technology for trace gas detection due to their high sensitivity, remote capability, and immunity to electromagnetic interference. However, the state‐or‐the‐art fiber‐optic gas sensors typically use lengthy optical fibers as gas absorption cells or coatings with functional materials to achieve more sensitive gas detection, which poses challenges such as slow response and/or poor selectivity, as well as limitations on their use in confined spaces. Here, an ultraminiature optical fiber‐tip photothermal gas sensor via direct 3D micro‐printing of a Fabry‐Pérot cavity on the end face of a standard single‐mode optical fiber is reported. It enables not only direct interaction between light and gas molecules at the fiber output but also remote interrogation through an interferometric read‐out scheme. With a low‐finesse microcavity of 66 µm in length, a noise equivalent concentration of 160 parts‐per‐billion acetylene gas is demonstrated with an ultra‐fast response time of 0.5 s. Such a small high‐performance photothermal gas sensor offers an approach to remotely detecting trace gases for a myriad of applications ranging from in‐reactor monitoring to medical diagnosis. [ABSTRACT FROM AUTHOR]

Catalytic transformation of CO2 into value‐added chemical products can provide an appropriate solution for the raising environmental issues. To date, various metal‐organic frameworks (MOFs) with transition metal ions have been explored for CO2 capture and conversion, but alkaline earth metal‐based MOFs are comparatively less studied. Metal ions like Sr(II) having relatively large radius give rise to a high coordination number resulting in higher stability of the MOFs. Moreover, the introduction of N‐rich functional group in organic linker like −NH2, −CONH− and triazole into MOF backbone enhance their CO2 capture and conversion efficiency. Herein, the effect of amine group on the catalytic efficiency of MOFs for CO2 cycloaddition with epoxides under solvent free and ambient conditions are presented. The di‐carboxylates, such as 5‐aminoisophthalate (AmIP) and 5‐bromoisophthalate (BrIP) were utilized to synthesize Sr(II) based MOFs. The Zn(II) MOF was synthesized using tetra‐carboxylate containing amide spacer (OAT) and 4‐amino‐4H‐1,2,4‐triazole (AMT). All three MOFs exhibited porous networks with guest available volume ranging from 15 to 58 %. The catalytic efficiency of the MOFs towards carbon dioxide fixation reaction was explored. The catalytic performances revealed that the presence of amine group in the channels enhances the catalytic efficiency of the MOFs. [ABSTRACT FROM AUTHOR]

The possibility of Fe loaded on BP (Fe@BP) as an efficient gas sensor for the detection of toxic gases such as NO2, NO, and CO is studied by the first‐principles calculation, and it is proposed that Fe@BP is an excellent gas‐sensitive material. The adsorption behaviors of gases on Fe@BP were analyzed in terms of adsorption configurations and electronic properties. It is found that all gases adsorbed on Fe@BP exhibit significantly enhanced interactions, and the adsorption intensity is much larger than that of molecules adsorbed on the surface of pure BP. Fe@BP has high selectivity for toxic and ambient gas molecules. In addition, the adsorption strength of NO2 and NO molecules on Fe@BP increases after compression strain is applied (within −3%), while the adsorption strength of CO decreases gradually. After the tensile strain is applied, the adsorption intensity of NO2 and NO is decreased, but that of CO is increased gradually. It is speculated that the strain causes changes in the electronic structure, which affects the adsorption behavior. The adsorption of NO has a stronger strain sensitivity. For these reasons, Fe@BP with high adsorption strength and strain selection is the ideal gas‐sensitive material. [ABSTRACT FROM AUTHOR]