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For metal-free low-dimensional ferromagnetic materials, a hopeful candidate for next-generation spintronic devices, investigating their magnetic mechanisms and exploring effective ways to regulate their magnetic properties are crucial for advancing their applications. Our work systematically investigated the origin of magnetism of a graphitic carbon nitride (Pca21 C4N3) monolayer based on the analysis on the partial electronic density of states. The magnetic moment of the Pca21 C4N3 originates from the spin-split of the 2pz orbit from special carbon (C) atoms and 2p orbit from N atoms around the Fermi energy, which was caused by the lone pair electrons in nitrogen (N) atoms. Notably, the magnetic moment of the Pca21 C4N3 monolayer could be effectively adjusted by adsorbing nitric oxide (NO) or oxygen (O2) gas molecules. The single magnetic electron from the adsorbed NO pairs with the unpaired electron in the N atom from the substrate, forming a Nsub-Nad bond, which reduces the system's magnetic moment from 4.00 μB to 2.99 μB. Moreover, the NO adsorption decreases the both spin-down and spin-up bandgaps, causing an increase in photoelectrical response efficiency. As for the case of O2 physisorption, it greatly enhances the magnetic moment of the Pca21 C4N3 monolayer from 4.00 μB to 6.00 μB through ferromagnetic coupling. This method of gas adsorption for tuning magnetic moments is reversible, simple, and cost-effective. Our findings reveal the magnetic mechanism of Pca21 C4N3 and its tunable magnetic performance realized by chemisorbing or physisorbing magnetic gas molecules, providing crucial theoretical foundations for the development and utilization of low-dimensional magnetic materials. [ABSTRACT FROM AUTHOR]

AbstractIn this study, we developed a transient convective heat and mass transfer model of an acoustically levitated slurry droplet evaporating in an atmosphere of air, water vapor, and soluble gas. The advanced model considers the effects of acoustic streaming, forced convection, non-isothermal gas absorption, and adsorption of dissolved gas on the evaporation rate of a liquid droplet containing small active solid particles. Adsorption of dissolved in a droplet soluble gas by solid particles leads to decreased dissolved gas concentration in a liquid droplet. A reduction in dissolved gas concentration in a liquid droplet causes an increase in the mass flux of active soluble gas from a gaseous phase to a slurry droplet, which causes a rise in the heating effect of absorption and an increase in evaporation rate of a droplet. The heat effect of adsorption also intensifies the evaporation rate. It is shown that the time of porous shell formation is essentially shorter when solid particles in slurry droplets are active compared to inert particles. [ABSTRACT FROM AUTHOR]

This work presents an extensive study for analyzing the adsorption mechanism of formaldehyde on pure and Pt-substituted rutile SnO2 (110) surfaces via the Density Functional Theory (DFT) method. Out of the two suitable surface sites for Pt-substitution, namely, Sn5c and Sn6c, the latter was found to be more suitable. Three formaldehyde configurations were considered, monodentate η1(O)-straight, monodentate η1(O)-tilted, and bidentate η2(O, C)-tilted. It was found that after Pt-substitution, the adsorption energies for η1(O)-tilted and η2(O, C)-tilted formaldehyde geometries were slightly improved. This improvement was found to be due to electron injection by Pt into the band gap of the surface combined with the stability of the formaldehyde orientation. Also, the overall adsorption energy values were better for the tilted configurations rather than those for the straight geometry. The changes in surface structure and bond lengths after optimization are seen to aid the adsorption mechanism by inducing steric effects and improved electrostatic interactions. Bader charge analysis shows two-fold interactions of charge transfer as well as only one-fold interaction in the cases of tilted and straight geometries respectively. Charge density difference (CDD) plots visually verified the above-stated results. The total density of states showed the injection of additional electronic states near zero energy (Fermi energy) level after Pt-substitution and an additional peak upon introduction of the gas molecule. PDOS plots were obtained to analyze the contribution of the orbitals of surface sites and the gas molecules to the gas adsorption mechanism. The recovery times for all the systems were obtained. [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]

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]

Direct capture of CO 2 from ambient air is technically feasible today, with commercial units already in operation. A demonstrated technology for achieving direct air capture (DAC) is chemical separation of CO 2 in a steam-assisted temperature-vacuum swing adsorption (S-TVSA) process. However, the potential to develop scalable solutions remains high, requiring a detailed understanding of the impact of both process design and operation on the performance of the DAC unit. Here, we address this knowledge gap by presenting a state-of-the-art process simulation tool for the purification of CO 2 from ambient air by a 5-step S-TVSA process. By considering the benchmark adsorbent APDES-NFC, we conduct multi-objective productivity/energy usage optimization of the DAC unit, subject to the requirement of producing a high purity CO 2 product ( ≥ 95 %). For the base case scenario, we find a maximum productivity of Pr max = 6.20 kg/m 3 /day and a minimum specific equivalent work of W EQ , min = 1.66 MJ/kg. While in reasonable agreement with published data, our results indicate that the description of both competitive adsorption and adsorption kinetics are key factors in introducing uncertainty in process model predictions. We also demonstrate that the application of formal optimization techniques, rather than design heuristics, is central to reliably assess the process performance limits. We identity that system designs employing moderate CO 2 sorption kinetics and contactors with low length-to-radius ratios yield the best performance in terms of system productivity. Finally, we find that moderate-high ambient relative humidities (50–75%) offer significantly favourable performance, and that a wide range of feed temperatures (5–30 ∘ C) can be accommodated via process optimization without a significant impact on performance. [ABSTRACT FROM AUTHOR]

Porous adsorbents, including activated carbons, zeolites, silicas, and newer materials such as metal–organic frameworks, have been investigated extensively for gas storage and separation applications. A key consideration is the performance of a material in terms of both its pure gas and multicomponent adsorption behavior, and so measuring accurate gas adsorption data is essential both to assess the suitability of an adsorbent for a given application and for process design and optimization. This article therefore provides an overview of the information required for gas storage and separation applications, the most common laboratory techniques used to obtain such data, with a focus on multicomponent equilibria measurements, and the main challenges associated with this process. We cover challenges for high pressure pure gas adsorption, multicomponent gas adsorption equilibria, kinetic gas adsorption and diffusion measurements, and the difficulty of accurately defining and calculating adsorption capacities. Recent developments, including porous reference materials for high pressure gas adsorption, and new techniques and apparatus for multicomponent gas adsorption equilibria measurements, are also highlighted. [ABSTRACT FROM AUTHOR]

Based on the generalized gradient approximation (GGA) under the density functional theory system,the first-principles method was used to investigate the effect of gas molecule adsorption on the adsorption energies,energy band structures and optical properties of the V-doped graphene.The band structure calculation showed that the band gap of V-doped graphene adsorbing NO2gas molecule is increased from 0 eV to 0.368eV,and its material property has also changed from metal to semiconductor.However,the band gaps of V-doped graphene adsorbing CO and NH3 molecules are almost unchanged.The adsorption energies of the three adsorption (NO2,CO,NH3) configurations are-8.499 eV,-2.05 eV and-2.01 eV, respectively, indicating that V-doped graphene has the best adsorption effect on NO2gas molecules.Furthermore,the optical properties of intrinsic and doped graphene when adsorbing NO2gas molecules were calculated.The results displayed that the dielectric absorption peak value of graphene is increased with V doping and adsorbing NO2gas,and the dielectric peak position is moved to the low energy region;Intrinsic graphene can only absorb ultraviolet light,and V-doped graphene can significantly improve the spectral range of light absorption after absorbing NO2molecules.The photoconductivity of graphene can be significantly enhanced by the doping and adsorption,and the photocurrent can be generated in the infrared and visible light regions.The above research results show that the electronic structures and optical properties of V-doped graphene adsorbing NO2have been significant changed,and it can be applied as an optical gas sensing material to detect NO2gas. [ABSTRACT FROM AUTHOR]

Toxic gases emitted by industries and vehicles cause environmental pollution and pose significant health risks which are becoming increasingly dangerous. Therefore, the detection of the toxic gases is crucial. The development of gas sensors with high sensitivity and fast response based on nanomaterials has garnered significant interest. In this work, we studied the adsorption behavior of B 9 − wheel structures of pristine and nitrogen functionalized borophene quantum dots for major hazardous environmental gases, such as NO2, CO2, CO, and NH3. The self-consistent-charge density-functional tight-binding method (SCC-DFTB) method was performed to investigate structural geometries, the most favorable adsorption sites, charge transfer, total densities of states, and electronic properties of the structures before and after adsorption of the gas molecules. Based on calculated results, it was found that the interaction between the borophene quantum dots and the gas molecules was chemisorption. The functionalized nitrogen atom contributed to impurity states, leading to higher adsorption energies of the functionalized borophene quantum dots compared to the pristine ones. Total densities of states revealed insights into electronic properties of gas molecules adsorbed on borophene quantum dots. The nitrogen-doped borophene quantum dots demonstrated excellent performance as a sensing material for hazardous environmental gases, especially CO2. [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 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]

Ionic liquid (IL)/metal–organic framework (MOF) (IL/MOF) nanocomposites have been shown to offer a broad potential in adsorption-based CO2 separation, especially at very low pressures. Selection of the most suitable ILs is crucial for synthesizing IL/MOF nanocomposites capable of achieving exceptionally high CO2 selectivities under more applicable conditions, such as at atmospheric pressure. However, the existence of a very wide range of IL-MOF pairs makes the design of such materials time-consuming when relying solely on experimental approaches. In this work, we employed a multitiered computational approach involving conductor-like screening model for realistic solvents, grand canonical Monte Carlo simulations, and density functional theory calculations. The goal was to screen 35,476 diverse ILs from various families to identify the IL that could boost the CO2 selectivity. Results of the computational screening highlighted 1-n-butyl-3-methylimidazolium tricyanomethanide ([BMIM]-[C-(CN)3]) as the promising IL candidate offering significant potential for separation of CO2 from N2 and CH4. We then experimentally incorporated this IL into a robust MOF, UiO-66, and characterized the resulting structure in deep detail. Testing of [BMIM]-[C-(CN)3]/UiO-66 for adsorption of CO2, N2, and CH4 demonstrated that the nanocomposite provides exceptional CO2 separation performance, offering an appreciable amount of CO2 uptake, while almost completely rejecting N2 and CH4 up to 1 and 0.3 bar, respectively, at 25 °C. Our results illustrated the importance of accurate selection of the IL for the design of IL/MOF nanocomposites with high performance for target gas separations. [ABSTRACT FROM AUTHOR]

Post‐modification of porous materials with molecular modulators has emerged as a well‐established strategy for improving gas adsorption and separation. However, a notable challenge lies in maintaining porosity and the limited applicability of the current method. In this study, we employed the mechanochemical “Cage‐on‐MOF” strategy, utilizing porous coordination cages (PCCs) with intrinsic pores and apertures as surface modulators to improve the gas adsorption and separation properties of the parent MOFs. We demonstrated the fast and facile preparation of 28 distinct MOF@PCC composites by combining 7 MOFs with 4 PCCs with varying aperture sizes and exposed functional groups through a mechanochemical reaction in 5 mins. Only the combinations of PCCs and MOFs with closely matched aperture sizes exhibited enhanced gas adsorption and separation performance. Specifically, MOF‐808@PCC‐4 exhibited a significantly increased C2H2 uptake (+64 %) and a longer CO2/C2H2 separation retention time (+40 %). MIL‐101@PCC‐4 achieved a substantial C2H2 adsorption capacity of 6.11 mmol/g. This work not only highlights the broad applicability of the mechanochemical “Cage‐on‐MOF” strategy for the functionalization of a wide range of MOFs but also establishes potential design principles for the development of hybrid porous materials with enhanced gas adsorption and separation capabilities, along with promising applications in catalysis and intracellular delivery. [ABSTRACT FROM AUTHOR]

An alternative synthesis route to obtain ultramicroporous zeolitic imidazolate framework‐8 (ZIF‐8) is reported that is rapid and does not require organic solvent or heating. The polyethylene glycol‐templated ZIF‐8 nanoparticles (<50 nm size) exhibited a high BET (Brunauer, Emmett and Teller) surface area of 1853 m2/g, a total pore volume of 0.73 cm3/g, and 0.54 nm ultramicropores. A new approach is introduced here to better understand gas adsorption in porous metal organic frameworks (MOFs) that combines theoretical and experimental isotherm data obtained for five gases with statistical physics modelling. The multiscale analytical model reveals that the gas molecules, irrespective of their structure, adsorb in a mixed orientation at low temperature, and a parallel multi‐molecular orientation at higher temperature. The number of gas molecules adsorbed per site ranged from 0.83–2.2 while the number of adsorbent layers ranged between 1.4–5.6, depending on the gas and the temperature. The multilayer adsorption processes involved adsorption energies from 2.85 kJ/mol–9.77 kJ/mol for all gases, consistent with physisorption via van der Waals and London dispersion forces. The initial adsorption energies were higher and therefore stronger. A particularly high capacity for CO2 of 1088 mg(CO2)/g at 298 K was observed while H2 adsorption was only 9 mg(H2)/g. The other gases adsorbed at 145 mg/g–245 mg/g at 298 K. Thermodynamic functions that governed the adsorption process such as the internal energy, the enthalpy, and Gibbs free energy, are also reported, as well as the adsorption entropies, for the 5 gases. [ABSTRACT FROM AUTHOR]

As an efficient and clean energy, coalbed methane development and utilization have deep significance in promoting energy conservation and emission reduction, reducing greenhouse gas emissions. Therefore, molecular simulation was utilized to study the influence of N2/CO2 on the adsorption and diffusion of methane in coal under different gas injection methods and to elucidate the influence of varying gas injection methods on the efficiency of coalbed methane extraction, which provides a basis for the efficient development of coalbed methane. The results show that the adsorption effect of gases in coal decreases with the increase of temperature and increases with the rise of pressure, and the adsorption performance of the three gases in coal shows the law of CO2 > CH4 > N2. In addition, the injection of CO2/N2 had an obvious inhibition effect on CH4 adsorption, and the inhibition effect of CO2 was more significant, and the inhibition effect on CH4 adsorption reached the maximum when the two gases were mixture injected. In terms of diffusion, compared with separate injection, mixed injection of N2 + CO2 promotes CH4 diffusion more effectively, which can be reflected in the relative concentration distribution and velocity distribution. The injection of N2 helps to increase the porosity of coal, and the injection of CO2 and N2 + CO2 will lead to the decrease of porosity, but the mixed gas injection has less effect than the injection of CO2 alone. [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]

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Abstract 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 As an efficient and clean energy, coalbed methane development and utilization have deep significance in promoting energy conservation and emission reduction, reducing greenhouse gas emissions. Therefore, molecular simulation was utilized to study the influence of N2/CO2 on the adsorption and diffusion of methane in coal under different gas injection methods and to elucidate the influence of varying gas injection methods on the efficiency of coalbed methane extraction, which provides a basis for the efficient development of coalbed methane. The results show that the adsorption effect of gases in coal decreases with the increase of temperature and increases with the rise of pressure, and the adsorption performance of the three gases in coal shows the law of CO2 > CH4 > N2. In addition, the injection of CO2/N2 had an obvious inhibition effect on CH4 adsorption, and the inhibition effect of CO2 was more significant, and the inhibition effect on CH4 adsorption reached the maximum when the two gases were mixture injected. In terms of diffusion, compared with separate injection, mixed injection of N2 + CO2 promotes CH4 diffusion more effectively, which can be reflected in the relative concentration distribution and velocity distribution. The injection of N2 helps to increase the porosity of coal, and the injection of CO2 and N2 + CO2 will lead to the decrease of porosity, but the mixed gas injection has less effect than the injection of CO2 alone.

The pore structure has a significant impact on the capability of coal seams to adsorb methane. But there is currently limited research on the features of adsorption pore structure in high-rank coal and its influence on methane adsorption capability. Taking the high-rank coal samples from Nuodong Coal Mine of Guizhou Xing'an Coal Industry Co., Ltd. as the research object, low-temperature N2 adsorption and low-temperature CO2 adsorption experiments are conducted. Combined with fractal theory, this paper studies the pore structure features of high-rank coal adsorption pores. Through high-pressure isothermal methane adsorption experiments, the influence of coal reservoir properties, pore structure features, and fractal dimension on methane adsorption capability is analyzed. The results show the following points. ① The pore morphology of high-rank coal reservoirs is relatively simple, mostly consisting of parallel plate pores and narrow slit pores with open ends. Micro pores dominate the pore structure of coal, with pore volume and pore specific surface area accounting for more than 98%, providing space for gas enrichment. ② The method calculates the comprehensive fractal dimension of high-rank coal pores based on the proportion of pore volume in different aperture segments, with micropore fractal dimension dominating the comprehensive fractal dimension. The pore structure of coal samples has obvious fractal features and strong heterogeneity of pores. ③ The Langmuir model can describe the adsorption behavior of high-rank coal. The physical properties, pore structure, and fractal dimension of coal reservoirs have a significant impact on methane adsorption capability. Langmuir volume is linearly positively correlated with maximum vitrinite reflectance, vitrinite content, ash content, and moisture content. It is linearly negatively correlated with inertinite content. The Langmuir volume is linearly positively correlated with the pore specific surface area and pore volume of the adsorption pores. The Langmuir volume is weakly linearly correlated with the fractal dimension. The research results can provide theoretical guidance for the exploration and development of high-rank coalbed methane and the prevention and control of coal mine methane disasters in southwestern Guizhou.

By using density functional theory (DFT), the adsorption behavior of gas molecules on defective graphene doped with manganese and nitrogen were investigated. The geometric structure, electronic structure, and magnetic properties of two substrates were calculated and the sensing mechanism was also analyzed. The results indicate that the MnSV-GP and MnN3-GP have stronger structural stability, in which Mn atoms and their coordination atoms will become the adsorption point for five gas molecules (CH2O, CO, N2O, SO2, and NH3), respectively. Moreover, at room temperature (298 K), the recovery time of the MnSV-GP sensor for N2O gas molecules is approximately 1.1 s. Therefore, it can be concluded that the MnSV-GP matrix as a magnetic gas sensor has a promising potential for detecting N2O. These results also provide a new pathway for the potential application of Mn-doped graphene in the field of gas sensors. [ABSTRACT FROM AUTHOR]

Graphitic nanoplatelets (GnPs), edge‐selectively carboxylated graphitic nanoplatelets (ECGnPs), are functionalized with a carboxylic acid at the edge increasing their surface area, and are highly dispersible in various solvents. However, there is a limit in that the basal plane remains intact because it is functionalized only in the part where the radical is generated at the edge. Here, we activate ECGnPs to have porous structures by flowing CO2 at 900 °C. Etching of the ECGnPs structure was performed through the Boudouard reaction, and the surface area increased from 579 m2 g−1 to a maximum of 2462 m2 g−1. In addition, the pore structure was investigated with various adsorption gases (CH4, Ar, CO2, H2, and N2) according to the reaction time. This study provides the overall green chemistry in that it utilizes CO2 from manufacturing to activation compared to the process of activating with conventional chemical treatment. [ABSTRACT FROM AUTHOR]

The development of nanoporous metal–organic frameworks (MOFs) capable of effectively separating and purifying CH4 is of significant importance. High surface polarity and suitable pore diameter are two key factors that can synergistically enhance separation performance. Herein, we report two hydroxyl-functionalized Al-MOFs (CAU-1-OH and CAU-1-(OH)2) for the separation and purification of natural gas. They both possess two different types of nanocages as well as a densely hydroxyl-functionalized surface. Significantly, CAU-1-(OH)2 demonstrated exceptional selectivity in separating C3H8/CH4 (50:50, v/v) and C2H6/CH4 (50:50, v/v), with selectivity values of 990 and 36, respectively, surpassing those of most reported porous materials. The dynamic breakthrough experiment of the ternary mixture can generate pure CH4 exceeding 3.46 mmol g–1, which adequately demonstrates the actual CH4 purification performance of CAU-1-(OH)2. Finally, molecular simulations and in situ infrared experiments verified that the high surface polarity and suitable pore diameter synergistically enhance the affinity of the frameworks toward C3H8 and C2H6, giving rise to the high loading capacity and selectivity for C3H8 and C2H6. These results support the significant potential of the double hydroxyl-modified nanomaterial CAU-1-(OH)2 for purifying methane from natural gas. [ABSTRACT FROM AUTHOR]

This study investigates the potential use of phosphomolybdic acid (POM) as an adsorbate for hazardous organic gases (CH3X, where X = F, Cl, and Br). Density functional theory (DFT) is employed to analyze the interaction between POM and the gases. Structural optimization using the TPSSh/Lanl2Dz level of theory is performed to determine the stable configurations. The adsorption energy of CH3X on POM is calculated to understand the adsorption capabilities and identify the most favorable complex. The results show that CH3F/POM has two optimal adsorption sites, while CH3Br/POM has a larger bond distance and stronger adsorption energy. CH3Cl/POM exhibits three bonding sites. The HOMO-LUMO energy difference decreases after binding, indicating improved conductivity. QTAIM, bond order, and NCI analysis reveal the inter- and intramolecular interactions and bond characteristics. Overall, POM is found to be suitable for adsorbing these gases, especially CH3Br. [ABSTRACT FROM AUTHOR]

Based on the generalized gradient approximation（GGA) under the density functional theory system, the first-principles approach was used to investigate the ability of SiGe nanowires along the [112] crystallographic orientation as molecular sensors to detect CO, CO2 and Cl2. The adsorption energies, energy band structures and optical properties before and after adsorption of gas molecules were mainly calculated. The calculation of geometric structure optimization shows that the absolute values of adsorption energy of CO, CO2 and Cl2 molecules on the [112] crystal orientation of SiGe nanowires with different SiGe compositions are between 0.001 eV and 1.36 eV, and the adsorption energy of Si24Ge36H32 for CO2 gas is maximum and gas sensing performance is the best. The energy band structure calculation shows that the energy band degeneracy of the [112] crystal-oriented SiGe nanowires adsorbed by CO and CO2 molecules is significantly reduced, and the band gap change is small. The impurity energy level is generated between the top of the valence band and the bottom of the conduction band after adsorption of Cl2 molecules, which reduces the band gap. The calculation of optical properties shows that the optical properties of Si24Ge36H32 nanowires after adsorptions of CO, CO2 and Cl2 molecules are obviously different, which is mainly reflected in the range of the absorption spectrum and the amplitude of the absorption peak. The above research results provide a theoretical basis for [112] Si24Ge36H32 nanowires as a sensitive material for gas sensors. [ABSTRACT FROM AUTHOR]

A type of foamed plastic insulation that improves thermal performance while maintaining the original durability by adding fillers with low radiation rates in foamed plastic insulation is investigated. The thermal conductivity of extruded polystyrene foam (XPS) adding graphite is reduced by 14% compared to without graphite additives. The study investigates that mechanism by comparing the properties of XPS and XPS containing graphite (graph XPS) through the gas isotherm method and 3D imaging analysis by X‐ray CT. First, the specific surface area of the insulation's resin is examined through the gas isotherm method using N2, H2O, and CO2. The results confirmed that graph XPS has a more increased specific surface area than XPS. Second, the internal structure of the insulation and its strut/pore distribution is confirmed through X‐ray CT, which showed an increase in surface area with a thinning of the strut. The improved thermal performance due to the addition of graphite may contribute to an increase in the surface area of the insulation. [ABSTRACT FROM AUTHOR]

Metal‐organic frameworks (MOFs) have emerged as versatile materials with exceptional properties, including high porosities, large surface areas, and remarkable stabilities, making them attractive for various applications. MOF‐5 stands out for its thermal stability and surface area, making it promising for diverse applications, including drug delivery and gas adsorption. This study explores the potential of amino acid MOF (AA‐MOF) composites, integrating phenylalanine, tryptophan, and tyrosine, for selective CO2 and CH4 adsorption using grand canonical Monte Carlo (GCMC) simulations. The impact of amino acid composition and spatial arrangement within MOF‐5 on selective CO2 and CH4 adsorption performance have been investigated. The results indicate that tryptophan‐MOF‐5 exhibits the highest CO2 uptake due to the interaction between CO2 and tryptophan, while phenylalanine‐MOF‐5 demonstrated the lowest affinity for gas adsorption. Radial distribution function (RDF) analysis reveals distinct gas distribution patterns within the composites, with tryptophan playing a dominant role in gas adsorption. Additionally, analysis of total energy, enthalpy of adsorption, and Henry's coefficient provide insights into the thermodynamic aspects of gas adsorption onto AA‐MOF composites. This study enhances the understanding of the fundamental mechanisms underlying CO2 and CH4 selective adsorption in amino acid MOF composites, facilitating the development of efficient gas separation technologies. [ABSTRACT FROM AUTHOR]

A novel class of crystalline porous materials has been developed utilizing multilevel dynamic linkages, including covalent B−O, dative B←N and hydrogen bonds. Typically, boronic acids undergo in situ condensation to afford B3O3‐based units, which further extend to molecular complexes or chains via B←N bonds. The obtained superstructures are subsequently interconnected via hydrogen bonds and π–π interactions, producing crystalline porous organic frameworks (CPOFs). The CPOFs display excellent solution processability, allowing dissolution and subsequent crystallization to their original structures, independent of recrystallization conditions, possibly due to the diverse bond energies of the involved interactions. Significantly, the CPOFs can be synthesized on a gram‐scale using cost‐effective monomers. In addition, the numerous acidic sites endow the CPOFs with high NH3 capacity, surpassing most porous organic materials and commercial materials. [ABSTRACT FROM AUTHOR]

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

The climate change is accelerating with the increase in the concentration of carbon dioxide (CO2) in the atmosphere. CO2 capture and conversion are effective strategies for stabilizing such environmental conditions. In this study, a series of melamine-based porous organic polymers (POPs), each incorporating different aromatic aldehydes as linkers, were synthesized. The POPs (MPOP-6C, MPOP-6N, MPOP-5N, and MPOP-5O) were characterized by Fourier-transform infrared spectroscopy, solid-state 13C nuclear magnetic resonance, X-ray diffraction, thermogravimetric analysis, and high-resolution field-emission scanning electron microscopy. The gas adsorption characteristics, including adsorption–desorption isotherms, pore size distribution, and adsorption at 298 and 323 K, were assessed through a Brunauer–Emmett–Teller analysis. The cycloaddition of CO2 with styrene oxide was performed using POPs as catalysts for conversion to styrene carbonate. Melamine-based POPs bearing heterocycles with high π-electron densities exhibited enhanced CO2 selectivity performances. MPOP-6N, which incorporated a pyridine motif, exhibited a notable enhancement in the conversion rate among the synthesized catalysts. [ABSTRACT FROM AUTHOR]

Two crystalline large‐sized porous organic cages (POCs) based on conical calix[4]arene (C4A) were designed and synthesized. The four‐jaw C4A unit tends to follow the face‐directed self‐assembly law with the planar triangular building blocks such as tris(4‐aminophenyl)amine (TAPA) or 1,3,5‐tris(4‐aminophenyl)benzene (TAPB) to generate a predictable cage with a stoichiometry of [6+8]. The formation of the large cages is confirmed through their relative molecular mass measured using MALDI‐TOF/TOF spectra. The protonated molecular ion peaks of C4A‐TAPA and C4A‐TAPB were observed at m/z 5109.0 (calculated for C336H240O24N32: m/z 5109.7) and m/z 5594.2 (calculated for C384H264O24N24: m/z 5598.4). C4A‐POCs exhibit I‐type N2 adsorption‐desorption isotherms with the BET surface areas of 1444.9 m2 ⋅ g−1 and 1014.6 m2 ⋅ g−1. The CO2 uptakes at 273 K are 62.1 cm3 ⋅ g−1 and 52.4 cm3 ⋅ g−1 at a pressure of 100 KPa. The saturated iodine vapor static uptakes at 348 K are 3.9 g ⋅ g−1 and 3.5 g ⋅ g−1. The adsorption capacity of C4A‐TAPA for SO2 reaches to 124.4 cm3 ⋅ g−1 at 298 K and 1.3 bar. Additionally, the adsorption capacities of C4A‐TAPA for C2H2, C2H4, and C2H6 were evaluated. [ABSTRACT FROM AUTHOR]

DFT calculations were employed to investigate the adsorption of gases produced from SF6 decomposition (SO2 and SO2F2) on pristine and Ti- -decorated single-walled carbon nanotubes (Ti-(8,0) SWCNT). All structures were relaxed and their structural and electronic properties were investigated before and after gas adsorption on the surface of the nanotubes. (Ti-(8,0) SWCNT) was found to have high chemisorption sensitivity to Ti, SO2F2 and SO2 adsorptions on its surface. The electronic properties of (8,0) SWCNT were altered from semiconductor to metallic upon decoration with Ti, as demonstrated by the calculated band structures and the density of states (DOS). SO2F2 and SO2 adsorption on the surface of (Ti-(8,0) SWCNT) from different sides transformed the conductor (Ti-(8,0) SWCNT) into a semiconductor nanotube. To more carefully study the nature of adsorption, partial density of states (PDOS) calculations were also made. Additionally, Ti decoration induced a magnetization of approximately 2.61 μB in (8,0) SWCNT, which disappeared after gas adsorption. [ABSTRACT FROM AUTHOR]

As a novel two-dimensional (2D) material, black phosphorene (BP) finds wide applications in gas adsorption and detection devices due to its distinctive optical, thermoelectric, and surface properties. However, numerous studies have demonstrated that BP exhibits strong selectivity towards gas adsorption and displays significant affinity towards gas molecules containing the element N, thereby greatly impeding its utilization in gas detection. To partially compensate for this deficiency, this study investigates the impact of halogen atom decoration on the adsorption behavior of BP towards CO2, H2O, and O2 molecules. Furthermore, a comparison is made between the variations in gas adsorption energy with and without decorated halogen atoms. The results showed that the adsorbates of CO2, H2O, and O2 molecules and halogen atoms (Cl, Br) adsorbed at the top (T) site of BP was much stronger than those at the bridge (B) and the hollow (H) sites of the P-P bond of BP, owing to their low adsorption energies. After the t position of BP is modified by the halogen (Cl, Br) atom, the optimal adsorption of CO2 changes from −0.85 eV to −1.70 eV (Cl) and −1.64 eV (Br), and the optimal adsorption of H2O changes from −0.72 eV to −1.48 eV (Cl) and −1.23 eV (Br), respectively. The adsorption properties were significantly enhanced. That is to say, the gas adsorption properties of BP have been largely improved by halogen Cl (Br) atoms decorating. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2) capture has become a hot topic in recent years because of global warming issues. However, most research has focused primarily on gas capture, with limited methods available for achieving both CO2 capture and conversion within a single material. Here, we synthesized FMU-101, a metal-organic framework (MOF) with metal-open sites, through the self-assembly of [1,1′-Biphenyl]-3,3′,5-tricarboxylic acid and lanthanide ions in a solvothermal environment. FMU-101 features hexagonal one-dimensional pores with a diameter of 1.4 nm. The presence of free dimethylamine cations and metal open sites in the channel contributes to its remarkable capability for selectively enriching CO2 from CO2/CH4 mixtures in dynamic breakthrough experiments. Furthermore, the metal-open sites in FMU-101 play a crucial role in CO2 fixation, serving as effective catalytic sites for converting the adsorbed CO2 into high-value chloropropylene carbonate, a versatile chemical intermediate. The segregation and conversion mechanisms were further elucidated through density-functional theory (DFT) calculations and Grand Canonical Monte Carlo (GCMC) simulations, which highlighted the critical role of metal-open sites in CO2 adsorption and transformation.

Abstract 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.

Gas adsorption and separation/desorption are two pivotal stages in gas capture, demanding additional energy for liberating gas molecules from the adsorbent. Hence, it’s essential to engineer an adsorbent with minimal energy consumption yet effective gas adsorption–desorption characteristics. Accordingly, this research introduces a carbon nano-network (CNN) material capable of inhaling and exhaling gases via self-deformation. Molecular dynamics simulations demonstrate that the gas adsorption–desorption capabilities of CNN can be efficiently regulated by its deformation. While the size of CNN minimally affects the gas sorption rate, a larger CNN necessitates a prolonged duration to achieve saturation under identical gas conditions. Incorporating elongated appendages in CNN enhances both its stability during contraction and its efficiencies in gas adsorption and desorption. We discerned that attaining a critical gas density within a confined space is imperative to initiate self-desorption of CNN. Specifically, if the gas density dips below this critical threshold–set at 5.2 times that of CO2 at room temperature (300 K) and atmospheric pressure (1 Bar)–CNN exhibits no self-desorption capability. Nevertheless, even a marginal elevation in gas density triggers and maintains self-desorption with a consistently surpassing desorption ratio of 98 %. This discovery offers valuable insights for designing automatic self-desorption materials or apparatuses.

Abstract 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.

The imidazolium-based supported ionic liquids (IL) in activated carbon (AC) is an exciting strategy for developing new adsorbents for H2S removal from biogas. In this work, the influence of IL on AC was discovered by examining the effect of ultrasonic stirring as an impregnation method, AC particle size and IL anion type. AC300μm-[Bmim]Cl-U5 demonstrated the highest H2S adsorption capacity of 8.25±0.38 mg H2S/g and was obtained through [Bmim]Cl impregnated on 300 μm AC size through the ultrasonic stirring for five minutes at room temperature. Adsorption/desorption study confirmed the regeneration ability of AC300μm-[Bmim]Cl-U5 up to three cycles with a maximum adsorption capacity of 14.24±0.43 mg H2S/g. The SEM images confirmed the presence of IL on the AC surface and were further explained through BET analysis. TGA measurement indicated the thermal stability of pristine IL, the fresh and exhausted adsorbent. Therefore, this study proves the potential of ultrasonic-assisted supported IL as a promising adsorbent for H2S removal from biogas that exhibit excellent properties in high adsorption capacity and thermal stability.

Considering the tremendous applications and purification requirement of acetylene (C2H2), seeking appropriate adsorbents with high capacity and selectivity is a vital task and remains an enduring challenge. Herein, we designed and synthesized a robust three-dimensional (3D) indium-organic framework ([(Me)2NH2][In(L6)0.5(IPA)0.5] dimethylammonium (DMA)2H2O (In-L6-IPA)) featuring two types of one-dimensional (1D) tubular channels. The activated In-L6-IPA displayed high loading for C2H2 (104.4 cm3·g−1, the second highest value among all reported indium-based metal-organic frameworks (MOFs)) and simultaneously selective adsorption for C2H2 over CO2, C2H6, and ethylene (C2H4) at 298 K under 100 kPa. Molecular modelling revealed that the porous wall of In-L6-IPA provides more and stronger multiple interactions for C2H2 than CO2, C2H6, and C2H4 containing C–H⋯π, C–H⋯O, and O⋯π interactions. Breakthrough experiments validated the actual separation ability for various ratios of binary C2H2/C2H4 and C2H2/CO2 mixtures as well as equimolar ternary C2H2/C2H4/CO2 and C2H2/C2H4/C2H6 mixtures with excellent reusability. [ABSTRACT FROM AUTHOR]

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

The imidazolium-based supported ionic liquids (IL) in activated carbon (AC) is an exciting strategy for developing new adsorbents for H2S removal from biogas. In this work, the influence of IL on AC was discovered by examining the effect of ultrasonic stirring as an impregnation method, AC particle size and IL anion type. AC300µm-[Bmim] Cl-U5 demonstrated the highest H2S adsorption capacity of 8.25±0.38 mg H2S/g and was obtained through [Bmim] Cl impregnated on 300 µm AC size through the ultrasonic stirring for five minutes at room temperature. The adsorption/desorption study confirmed the regeneration ability of AC300µm-[Bmim]Cl-U5 up to three cycles with a maximum adsorption capacity of 14.24±0.43 mg H2S/g. The SEM images confirmed the presence of IL on the AC surface and were further explained through BET analysis. TGA measurement indicated the thermal stability of pristine IL, the fresh and exhausted adsorbent. Therefore, this study proved the potential of ultrasonic-assisted supported IL as a promising adsorbent for H2S removal from biogas that exhibits excellent properties in high adsorption capacity and thermal stability. [ABSTRACT FROM AUTHOR]

To address the most significant environmental challenges, the quest for high-performance gas sensing materials is crucial. Among numerous two-dimensional materials, this study investigates the gas-sensitive capabilities of monolayer As, Sb, and Bi materials. To compare the gas detection abilities of these three materials, we employ first-principles calculations to comprehensively study the adsorption behavior of NO and NO2 gas molecules on the material surfaces. The results indicate that monolayer Bi material exhibits reasonable adsorption distances, substantial adsorption energies, and significant charge transfer for both NO and NO2 gases. Therefore, among the materials studied, it demonstrates the best gas detection capability. Furthermore, monolayer As and Sb materials exhibit remarkably high capacities for adsorbing NO and NO2 gas molecules, firmly interacting with the gas molecules. Gas adsorption induces changes in the material's work function, suggesting the potential application of these two materials as catalysts. [ABSTRACT FROM AUTHOR]

Context: Graphene-based nanomaterial was widely used in gas sensors, detection, and separation. However, weak adsorption and low selectivity of the pristine graphene used for gas sensors are major problems. Here, using density functional theory (DFT) calculations, we reported the significant increase of four gas molecules (N2, CO2, C2H2, and C2H4) adsorption on the transition metal ion (Fe3+, Co2+, Ni2+)–modified graphene complex (Fe3+/Co2+/Ni2+-G) comparing to be absorbed on the pristine graphene (G). Moreover, the Co2+-G is suitable for the selective separation of C2H4/C2H2 due to the larger adsorption energy difference (8.5 kcal/mol) between them. The addition of transition metal ions also decreased the HOMO–LUMO gap of the systems, which benefits the enhancement of electrical conductivity. This suggests that the transition metal ion–modified graphene can be used to distinguish the different gas molecule's adsorption, facilitating the design of graphene-based gas sensors and selective separation. Methods: All the density functional theory (DFT) calculations were performed by B3LYP with the GD3 dispersion method using Gaussian 16 software. The basis set 6-31G(d) was used for C, H, O, and N atoms, and Lanl2DZ was used for transition metal ions (Fe3+, Co2+, Ni2+). The DOS analysis and energy decomposition analysis were performed using the Multiwfn program. [ABSTRACT FROM AUTHOR]

Eu-MOFs have sparked widespread interest as a dependable, convenient, time-saving, highly sensitive, and specialised platform for analytical applications due to their strong skeletons, extremely high surface area, changeable pore sizes, easy functionalization, and great stability. This review will provide remarkable insight into the synthesis, structure, and properties of Eu-MOFs. Here, we will also focus on Eu-MOF applications as chemosensors, biosensors, selective gas adsorption, and chromatographic stationary phases in order to meet the needs of the materials used for analysis. Hence, this study will offer a comprehensive overview of existing research on the analytical applications of Eu-MOFs. We expect that this study will provide complete knowledge for researchers to recreate the procedures and contribute to future discoveries in this prominent field.

DFT calculations were employed to investigate the adsorption of gases produced from SF6 decomposition (SO2 and SO2F2) on pristine and Ti- -decorated single-walled carbon nanotubes (Ti-(8,0) SWCNT). All structures were relaxed and their structural and electronic properties were investigated before and after gas adsorption on the surface of the nanotubes. (Ti-(8,0) SWCNT) was found to have high chemisorption sensitivity to Ti, SO2F2 and SO2 adsorptions on its surface. The electronic properties of (8,0) SWCNT were altered from semiconductor to metallic upon decoration with Ti, as demonstrated by the calculated band structures and the density of states (DOS). SO2F2 and SO2 adsorption on the surface of (Ti-(8,0) SWCNT) from different sides transformed the conductor (Ti-(8,0) SWCNT) into a semiconductor nanotube. To more carefully study the nature of adsorption, partial density of states (PDOS) calculations were also made. Additionally, Ti decoration induced a magnetization of approximately 2.61 μB in (8,0) SWCNT, which disappeared after gas adsorption.

In order to further reveal the dynamic characteristics of coal with different degrees of metamorphism under different adsorption pressures, the self-developed TQY-2 precision adsorption instrument and infrared thermal imaging device were used to conduct macroscopic adsorption tests on lignite, coking coal and anthracite coal samples with a diameter of 8.5 mm at different pressures (0.2, 0.4, 0.6, 0.8, 1.0 MPa) and the adsorption test of the mesoscopic structure of the coal body with adsorption pressures of (0.3, 0.6, 0.9, 1.2, 1.5 MPa), using quasi-primary and quasi-secondary adsorption kinetic models such as intra-particle diffusion, Elovich and double constant analyze the law and mechanism of adsorption gas. The results show that compared with five adsorption kinetics models, the quasi-secondary adsorption kinetics model is suitable for characterizing the adsorption gas process of lignite and coking coal, while the optimal model for anthracite is the intra-particle diffusion model; with the increase of adsorption pressure, the quasi-secondary adsorption rate constant k2 of lignite and coking coal gradually increased, and the intra-particle diffusion rate constant kp of anthracite coal also gradually increased, all of which were positively correlated; adsorption pressure has little effect on the dynamic model suitable for coal samples; under the macroscopic adsorption experiment and the mesoscopic structure adsorption experiment of coal body based on infrared thermography, the dynamic models suitable for different degrees of metamorphism are consistent.

For metal-free low-dimensional ferromagnetic materials, a hopeful candidate for next-generation spintronic devices, investigating their magnetic mechanisms and exploring effective ways to regulate their magnetic properties are crucial for advancing their applications. Our work systematically investigated the origin of magnetism of a graphitic carbon nitride (Pca21 C4N3) monolayer based on the analysis on the partial electronic density of states. The magnetic moment of the Pca21 C4N3 originates from the spin-split of the 2pz orbit from special carbon (C) atoms and 2p orbit from N atoms around the Fermi energy, which was caused by the lone pair electrons in nitrogen (N) atoms. Notably, the magnetic moment of the Pca21 C4N3 monolayer could be effectively adjusted by adsorbing nitric oxide (NO) or oxygen (O2) gas molecules. The single magnetic electron from the adsorbed NO pairs with the unpaired electron in the N atom from the substrate, forming a Nsub-Nad bond, which reduces the system’s magnetic moment from 4.00 μB to 2.99 μB. Moreover, the NO adsorption decreases the both spin-down and spin-up bandgaps, causing an increase in photoelectrical response efficiency. As for the case of O2 physisorption, it greatly enhances the magnetic moment of the Pca21 C4N3 monolayer from 4.00 μB to 6.00 μB through ferromagnetic coupling. This method of gas adsorption for tuning magnetic moments is reversible, simple, and cost-effective. Our findings reveal the magnetic mechanism of Pca21 C4N3 and its tunable magnetic performance realized by chemisorbing or physisorbing magnetic gas molecules, providing crucial theoretical foundations for the development and utilization of low-dimensional magnetic materials.