Gallery Height Research Articles

Recent Advances in Layered Double Hydroxides Membranes: Insights into Multiple Mass Transport

AbstractLayered double hydroxides (LDHs) consist of metal cations with positive charges and anions located between their layers, resulting in a structured gallery height and a wide array of surface functionalities. In recent years, LDHs have garnered substantial attention due to their expanded application range through the development of LDHs membranes, bringing exciting possibilities across various fields. A deep understanding of mass transport mechanisms is essential for designing membrane materials effectively and enhancing separation processes. In this review, In this review, the strategies employed for creating continuous and well‐intergrown LDHs membranes are first elaborated. Subsequently, the study delves into a detailed discussion of the selective transport processes involving gas molecules, liquid molecules, and ions through LDHs membranes. Based on the interactions between permeated molecules and LDHs membranes, the mass transport mechanisms can be concluded in molecular sieving mechanism, solution‐diffusion mechanism and facilitated transport mechanism. Finally, the current challenges and future perspectives are outlined.

Analysis of AlN monolayer as a prospective cathode for aluminum-ion batteries

Developing cathode materials with high specific capability and excellent electrochemical performance is crucial for the advancement of aluminum-ion batteries, which leverage the high theoretical energy density of aluminum metal anodes. In this paper, we investigated the interaction of cluster and Al atom with AlN (−100) and (001) monolayer using density functional theory to assess the applicability of AlN as cathode material for aluminum-ion batteries. The results show that the AlN (001) monolayer is the most effective for adsorbing and accommodating clusters. Moreover, the AlN (001) monolayer maintains metallic behavior at different concentrations of the cluster, laying the foundation for its battery application. The theoretical storage capacity of the cluster is 105.93 which exceeds that of the Al/graphite battery. The formation energy of -intercalated AlN compounds is −2.74 eV, and the intercalant gallery height is moderate. Furthermore, the diffusion barrier of 0.19 eV for cluster between the AlN (001) monolayer provides high rate capability. The results indicate that AlN monolayer may be a potential cathode material for aluminum-ion batteries.

Tunable Ion Transport with Freestanding Vermiculite Membranes.

Membranes integrating two-dimensional (2D) materials have emerged as a category with unusual ion transport and potentially useful separation applications in both aqueous and nonaqueous systems. The interlayer galleries in these membranes drive separation and selectivity, with specific transport properties determined by the chemical and structural modifications within the inherently different interlayers. Here we report an approach to tuning interlayer spacing with a single source material─exfoliated and restacked vermiculite with alkanediamine cross-linkers─to both control the gallery height and enhance the membrane stability. The as-prepared cross-linked 2D vermiculite membranes exhibit ion diffusivities tuned by the length of the selected diamine molecule. The 2D nanochannels in these stabilized vermiculite membranes enable a systematic study of confined ionic transport.

Intercalation-Induced Ordered Nanostructure in the Interlayer Modified with Methylviologen by Molecular Dynamics Simulation.

Intercalation of phenol in montmorillonite, a representative layered material, has historically been investigated, and modification of the interlayer with methylviologen (Mont-MV) results in color change due to formation of a charge-transfer complex. Its detailed nanostructure, however, has yet been revealed owing to its small gallery height and poor crystallinity. In the present study, we performed molecular dynamics simulation to investigate structural changes in Mont-MV by the intercalation of phenol. The value of the basal spacing of Mont-MV was well consistent with that reported experimentally, and the MV cations were distributed horizontally. Successive intercalation of phenol revealed that the interlayer swelled nonlinearly and both the MV cations and phenol molecules were tilted, which were roughly parallel to each other. The obtained ordered nanostructure was similar to that reported in the charge-transfer complex crystal of the MV cation and the naphthol derivative. Thus, the parallel orientation in the interlayer was found to be the key for the color reaction. Combined with the fact that the phenol molecules interacted with the Mont layers, the role of the MV cation was found to be that of a pillar for providing sufficient gallery height, and the formation of the charge-transfer complex is the secondarily derived function.

Mesoporous nanohybrids of 2–D Cobalt–Chromium layered double hydroxide and polyoxovanadate anions for high performance hybrid asymmetric supercapacitors

An exfoliation-reassembling process is utilized to develop mesoporous intercalative nanohybrids of cationic 2-D cobalt-chromium-layered double hydroxide (Co–Cr-LDH) nanosheets and polyoxovanadate (POV) anions (Co–Cr-LDH-POV nanohybrids). The Co–Cr-LDH-POV nanohybrid displays a maximum specific capacity (SC) of 732 C g−1 at 1 A g−1, attributed to the layer-by-layer porous structures with expanded gallery height. An aqueous and solid-state hybrid asymmetric supercapacitor devices are fabricated by Co–Cr-LDH-POV nanohybrid as cathode and rGO nanosheets as an anode. An aqueous hybrid asymmetric supercapacitor (AHAS) device delivers an SC of 238.72 C g−1 at 0.8 A g−1 with a specific energy (SE) of 53.04 Wh kg−1 at 512 W kg−1 specific power (SP) and capacity retention of 85% over 10,000 cycles. Moreover, a solid-state hybrid asymmetric supercapacitor (SHAS) device displays a high SC of 148 C g−1 at 2.4 A g−1 with a SE of 27.59 Wh kg−1 at 2560 W kg−1 SP and capacity retention of 90.23% over 5000 cycles. Nevertheless, the obtained results suggest that such a new type of porous LDH-polyoxometalate (LDH-POM) based nanohybrids are useful as cathode for next-generation energy storage applications.

Surface modification and in situ carbon intercalation of two-dimensional niobium carbide as promising electrode materials for potassium-ion batteries

Potassium ion batteries (KIBs) have a great potential in large scale energy storage because of their cost advantages and similar working mechanism to lithium ion batteries (LIBs). However, the larger ionic radius of K+ presents great challenges to find suitable electrode materials for K+ insertion/extraction. Herein, the surface-modified and in-situ carbon-intercalated Nb2CTx MXene is rationally designed and synthesized as electrode for KIBs. The as-prepared Nb2C/C has larger effective interlayer distance (i.e. gallery height), higher specific surface area and electrical conductivity, and lower concentration of surface functional groups. As a result, Nb2C/C exhibits a significantly increased coulombic efficiency (67.6% for Nb2C/C, 28.5% for Nb2CTx) and its specific capacity is two times higher than that of Nb2CTx at 0.02 A·g−1, three times at 0.1 A·g−1. The Nb2C/C delivers an initial specific capacity of 397.9 mAh·g−1 at 0.02 A·g−1 and 338.1 mAh·g−1 at 0.1 A·g−1, and maintains 80.0% after 100 cycles at 0.02 A·g−1 and 76.2% after 200 cycles at 0.1 A·g−1, respectively. Notably, Nb2C/C possesses outstanding cyclic stability and rate performance at various current densities, outperforming most of reported MXene-based anodes for KIBs. The excellent potassium storage performance of Nb2C/C can be ascribed to the abundant active sites exposed to electrolyte, rapid diffusion kinetics of K+ and few side reactions at the electrode/electrolyte interface. This work proposes an effective strategy for the MXene-based materials to maximize their potential applications in various fields such as batteries, supercapacitors and catalysts.

Mesoporous Nanohybrids of 2D Ni‐Cr‐Layered Double Hydroxide Nanosheets Pillared with Polyoxovanadate Anions for High‐Performance Hybrid Supercapacitor

AbstractIn this study, the use of exfoliation‐restacking strategy to prepare mesoporous nanohybrids of 2D Nickel‐chromium‐layered double hydroxide (Ni‐Cr‐LDH) nanosheets pillared with polyoxovanadate (POV) anions (Ni‐Cr‐LDH‐POV) for a high‐performance hybrid supercapacitor (HSC) is demonstrated. The pillaring approach of Ni‐Cr‐LDH monolayers with POV anions via exfoliation‐restacking strategy yields mesoporous ordered layered structure with a high surface area and interconnected network morphology. The pillared hybridization of Ni‐Cr‐LDH with POV anions boosts the electrochemical performance of the pristine Ni‐Cr‐LDH, which is attributed to the development of layer‐by‐layer stacking structure with expanded gallery height and high surface area interconnected network morphology. The Ni‐Cr‐LDH‐POV nanohybrid electrode exhibits an improved specific capacity of 294.5 mAh g−1 as compared to pristine Ni‐Cr‐LDH electrode (98.9 mAh g−1) at 1 mA cm−2 with 82% capacity retention after 5000 charge‐discharge cycles. A full‐cell HSC composed of mesoporous Ni‐Cr‐LDH‐POV nanohybrid as a cathode and reduced graphene oxide (rGO) as an anode delivers a maximum specific energy of 57.78 Wh kg−1 and specific power of 1.59 kW kg−1 with 87% cyclic durability over 10 000 charge‐discharge cycles. The present study demonstrates the usefulness of the pillared Ni‐Cr‐LDH‐POV nanohybrids via exfoliation‐restacking strategy for exploring high‐performance HSC.

In Situ X-ray Diffraction of LiCoO2 in Thin-Film Batteries under High-Voltage Charging

LiCoO2 has been used as the cathode material employed in lithium-ion batteries since their development, and efforts to improve its performance are still in progress. For example, complete use of lithium provides a theoretical capacity as high as 274 mAh g–1; however, charge–discharge cycling with such a high capacity leads to rapid degradation. The degradation mechanism has been intensively studied in order to increase the practical capacity. Although phase transitions taking place in high-voltage charging have been considered to affect the cycling performance, side reactions induced by the high-voltage charging always overlap to blur the effects of phase transitions on the electrode properties. This study has unveiled the relation between the phase transition and electrode properties by employing a solid electrolyte that suppresses the side reactions efficiently. Electrochemical impedance spectroscopy combined with in situ X-ray diffraction shows clear correlation between phase transition from O3 to H1–3 and a drastic increase in the electrode resistance. The increasing resistance is attributable to formation of narrow interlayers with a gallery height of 4.2 Å that impede lithium-ion diffusion.

Combining Experiments and Theoretical Calculations to Investigate the Intercalation Behavior of Bis(trifluoromethanesulfonimide) Anion into Graphite Electrodes from Alkyl Phosphates.

In dual-ion batteries (DIBs) utilizing organic electrolyte solutions, the combinations of electrolyte salt and solvent serve as a determiner of the electrochemical performance of graphite electrode partially because solvent participates in the anion intercalation procedure. In this case, every solvated-anion@graphite intercalation compound possesses the characteristic intercalated gallery height. However, in Li/graphite DIBs with concentrated LiTFSI (lithium bis(trifluoromethanesulfonimide))-alkyl phosphates (ca. trimethyl, triethyl, tripropyl, tributyl phosphate) solutions, solvated-TFSI-@graphite intercalation compounds have the nearly identical intercalated gallery height of about 0.803 nm, which may be mainly attributed to both the big size of TFSI- anion and the rigid PO4 framework of these alkyl phosphate solvents.

Inhomogeneity of Organically Modified Montmorillonite Revealed by Molecular Dynamics Simulation.

The modification of an interlayer of layered materials by intercalation with an organoammonium ion has been a promising method to control the polarity of the two-dimensional nanospace. Montmorillonite is one of the best-known examples, and the modification with octadecyltrimethylammonium ion (Mont-C18) results in adsorption of anthracene and pyrene together with specific excimer emission, while the nanostructure is yet to be uncovered at the molecular level because the gallery height is only ca. 27 Å. We, herein, investigated the nanostructure of this nanocomposite by molecular dynamics (MD) simulation, combined with analysis of molecular orientations against the Mont layer. The gallery height of Mont-C18 was well consistent with the experimental value, which was linearly increased along with the intercalation of anthracene. Anthracene was segregated on the Mont layer with its short and long molecular axes vertical in the early and late stages, respectively. In contrast, C18 was initially rather horizontal, forming the so-called pseudotrimolecular layer. Pushed out by anthracene, distribution and orientation of C18 were gradually changed: the third molecular layer was distinctly observed in the center of the interlayer in the early stage, and the orientation was changed to vertical in the late stage. Thus, the continuous increase in the gallery height is ascribed to soft response of C18 to the intercalation. Summarizing the abovementioned results, it was concluded that Å-order inhomogeneity is introduced in the interlayer by the intercalation of anthracene, which is significant in ideal design of the two-dimensional nanospace.

Stage-number dependence of intercalated species for fluorosilicate graphite intercalation compounds: pentafluorosilicate vs. hexafluorosilicate

Most intercalated ions ever reported for graphite intercalation compounds (GICs) are singly charged, and the number of reports on GICs with doubly charged ions is limited. For fluorosilicate complex anions, only the intercalation of SiF5− was reported as stage-2 GICs, although SiF62− is more commonly known in inorganic compounds. In the present study, chemical states of fluorosilicate GICs (SiFy-GICs) are investigated along with the change in stage numbers. Syntheses of SiFy-GICs at various stage numbers (the mixtures of stage-5 and -4, stage-4 and -3, stage-3 and -2, and stage-3 and -2) clarify that SiFy-GICs at a low stage number have a larger gallery height than those at higher stage numbers. In addition, reactions of SiFy-GICs with PF5 formed PF6-GICs with large weight increase and stage-number decrease, which cannot be explained by the substitution of SiF4 with PF5 to intercalate PF6−. The model that SiF62− and SiF5− are present in GICs at high and low stage numbers, respectively (SiF62− for stage-n (n ≥ 3) and SiF5− for stage-2), can explain this phenomenon, suggesting intercalation of SiF62− into graphite for the first time and stage-number dependency of intercalated species for fluorosilicate GICs.

Intercalation of (η5‐Pentamethylcyclopentadienyl)trioxomolybdenum(VI) in a Layered Double Hydroxide

A Zn,Al layered double hydroxide (LDH) with [Cp*MoO3]– (Cp* = η5‐C5Me5) anions in the interlayer has been prepared by a direct coprecipitation method. The intercalated LDH and the mixed metal oxide (MMO) obtained after its calcination were characterized by elemental and thermogravimetric analyses, powder X‐ray diffraction (PXRD), FT‐IR and FT‐Raman spectroscopy, 13C and 27Al MAS NMR, and scanning electron microscopy. The observed basal spacing of 17.1 Å for the LDH Zn,Al‐Cp*MoO3 (corresponding to a gallery height of 12.3 Å) suggests that the guest anions self‐assemble into dimers via offset face‐to‐face Cp*···Cp* interactions, which facilitates hydrogen‐bonding interactions between the oxido ligands of the complexes and the layer hydroxyl groups, while positioning the hydrophobic aromatic rings towards the center of the galleries. Calcination of Zn,Al‐Cp*MoO3 at 550 °C under air gave an MMO comprising well‐dispersed ZnO, α‐ZnMoO4 and ZnAl2O4 (spinel) oxides in a molar of ca. 1.4:1.6:1. The MMO exhibited catalytic activity for the epoxidation of cis‐cyclooctene with tert‐butylhydroperoxide (TBHP) as terminal oxidant, with quantitative yield of the epoxide being achieved within 24 h at 85 °C.

Theoretical and experimental investigations of mesoporous C3N5/MoS2 hybrid for lithium and sodium ion batteries

Abstract The electrochemical properties of mesoporous C3N5 with a triazole-based C–N framework coupled with MoS2 as hybrid electrode materials for lithium and sodium ion batteries are investigated. The density functional theory (DFT) calculations suggest that the reversible adsorption of the lithium and sodium ions follows the order C3N5/MoS2 hybrid > C3N5 > g-C3N4. Bader charge analysis shows that the charge transferred from lithium and sodium ions is more distributed across the hybrid material as compared to the pure C3N5. It is experimentally found that the optimized mesoporous C3N5/MoS2 hybrid shows a 3.86 and 10.80 times increase in reversible capacities as compared to mesoporous g-C3N4 for lithium and sodium ion batteries, respectively. Based on the comparative mechanism studies, the limited intercalation kinetics and surface-derived ion storage hinder the application of the mesoporous g-C3N4 in lithium and sodium ion batteries, respectively. The synthesized mesoporous C3N5/MoS2 hybrids with mesopore channels, expanded gallery height and desired ion adsorption energies provide insights to improve the electrode performances of carbon nitrides-based materials for lithium and sodium ion batteries.

Facile In Situ Hydrothermal Synthesis of Layered Zirconium Phenylphosphonate Molecular Sieve Membranes with Optimized Microstructure and Superb H2/CO2 Selectivity.

Layered molecular sieve membranes containing uniform interlayer galleries have offered unprecedented opportunities to reach a performance far beyond the Robeson upper bound line. In this study, we took the initiative to prepare layered zirconium phenylphosphonate (ZrPP) molecular sieve membranes with optimized microstructure on tetragonal zirconia (t-ZrO2) buffer layer-modified porous α-Al2O3 substrates by facile in situ hydrothermal growth. Relying on the 3.2 Å-sized gallery height and preferential CO2 adsorption behavior, prepared ZrPP membranes showed exceptional H2/CO2 selectivity (>100) as well as considerable H2 permeability. Furthermore, extraordinary thermal, mechanical, and chemical stability of ZrPP membranes made them potentially attractive for long-term operations under harsh conditions.

Water removal in Polymer − Ca2+-Montmorillonite (Ca2+-Mon) composites prepared in colloidal System: DSC studies in low temperature range

Dehydration within low temperature range (30 °C − 100 °C) of Ca2+−Montmorillonite or Ca2+−Mon had caused water removal, where its endothermic from DSC curve reveals the heat of fusion H is about 336.96 J/g. Comparable endothermic within similar temperature range detected in PE-Mon, DPNR-Mon, ENR50-Mon and pPVC-Mon composite profile also indicates the present of interlayer water from Ca2+−Mon particles in the composites. The reduced H about 13% (DPNR-Mon), 32% (PE-Mon), 61% (ENR-50) and 70% (pPVC-Mon) suggests that water removal had occurred during composite fabrication in colloidal systems. XRD analysis however demonstrates that the clay interlayer structure in PE-Mon and DPNR-Mon remain unaffected with similar d001 = 1.46 nm as in pristine Ca2+−Mon. Structural effect from water removal can be seen in the case of ENR50-Mon and pPVC-Mon composites, where the reduced gallery height gives d001 = 1.29 nm and 1.34 nm respectively. Peak intensity behaviors as shown by hydroxyl ((∂HOH) and (νOH)) and silicate (Si-O) bands in FTIR spectra help to explain the observations, particularly the appearance of Si-O band (1017 cm−1) that proves the occurrence of water removal inside the clay composites.

Graphite as a Long-Life Ca2+-Intercalation Anode and its Implementation for Rocking-Chair Type Calcium-Ion Batteries.

Herein, graphite is proposed as a reliable Ca2+‐intercalation anode in tetraglyme (G4). When charged (reduced), graphite accommodates solvated Ca2+‐ions (Ca‐G4) and delivers a reversible capacity of 62 mAh g−1 that signifies the formation of a ternary intercalation compound, Ca‐G4·C72. Mass/volume changes during Ca‐G4 intercalation and the evolution of in operando X‐ray diffraction studies both suggest that Ca‐G4 intercalation results in the formation of an intermediate phase between stage‐III and stage‐II with a gallery height of 11.41 Å. Density functional theory calculations also reveal that the most stable conformation of Ca‐G4 has a planar structure with Ca2+ surrounded by G4, which eventually forms a double stack that aligns with graphene layers after intercalation. Despite large dimensional changes during charge/discharge (C/D), both rate performance and cyclic stability are excellent. Graphite retains a substantial capacity at high C/D rates (e.g., 47 mAh g−1 at 1.0 A g−1 s vs 62 mAh g−1 at 0.05 A g−1) and shows no capacity decay during as many as 2000 C/D cycles. As the first Ca2+‐shuttling calcium‐ion batteries with a graphite anode, a full‐cell is constructed by coupling with an organic cathode and its electrochemical performance is presented.

The stromatoporoidHabrostromain the upper Silurian (uppermost Pridoli)–Lower Devonian (Lochkovian) of North America, and the paleobiogeographic significance ofH.centrotum(Girty, 1895)

AbstractThree species ofHabrostromadominate stromatoporoid faunas in the Lower Devonian (Lochkovian) of five areas in North America: New York, Virginia, Maine, Bathurst Island, and Ellesmere Island. In addition, they occur in what could be the upper Silurian (uppermost Pridoli) of Virginia, and possibly New York. Measurements of nine morphologies from 127 specimens ofHabrostromawere subjected to an average linkage cluster analysis. Using average linkage between groups, three distinct clusters were revealed. Group assignments made from the cluster analysis were saved, and entered into a canonical discriminant analysis with the nine morphological variables. An overall Wilks’ lambda was calculated, and is statistically significant at alpha <0.001. The hit rate for classifying group 1 is 98%, that for group 2 is 100%, and that for group 3 is 97.9%; the total hit rate is 100%. The morphological variables contributing most to group membership are: (1) percent cystlike microlaminae, (2) microlaminae per mm, (3) gallery height, (4) laminae per mm, and (5) laminar thickness. The statistics confirm that there are three species:H.centrotum,H.microporum, andH.consimile.Habrostroma centrotumoccurs in all five areas. This is unusual because Virginia, New York, and Maine are part of the Eastern Americas Realm, and the arctic islands are part of the Old World Realm. Separation of the realms is based on a high percentage of unique genera in each. A breach in the inter-realm barrier is proposed to have existed across the Canadian Shield during the Lochkovian. The nature of the breach is determined to be a shallow-water filter, allowing the passage of a limited number of taxa.

Effect of molecular dimension on gallery height, release kinetics and antibacterial activity of Zn[sbnd]Al layered double hydroxide (LDH) encapsulated with benzoate and its derivatives

This paper outlines the encapsulation of benzoate and its two derivatives i.e. para-hydroxybenzoic acid (p-BZOH) and 2-chloro-5-nitrobenzoic acid (BZCN) having antibacterial activity in between the interlayer distance of ZnAl layered double hydroxides to form an antibacterial composite material. The three reagents were successfully intercalated in between ZnAl LDH via anion-exchange mechanism. The intercalation was successfully evaluated by the increase in the basal spacing from X-ray diffraction, FTIR and thermogravimetry (TG-DTA) analysis. By variation of incoming reagents, the nature of interlayer arrangement, the tendency of binding, kinetics of release of the reagent from the inorganic lamella and bactericidal effect differ. The novel nano-composites demonstrated a distinctly enhanced bactericidal effect towards both gram positive (Staphylococcus aureus, MTCC 96) and gram negative (Escherichia coli, MTCC 739) bacterial strains having diverse rate of killing. Also the diffusion of the active molecules out of the nano-composites was found to be very slow and in a sustained manner in case of BZCN as compared to other two. Therefore these newly designed organic-inorganic fusions may offer a promising antimicrobial elucidation to the society.

Synthesis and characterization of camptothecin-rhamnolipid-layered double hydroxide nanohybrid and its controlled release property

Camptothecin (CPT) is a kind of hydrophobic anticancer drug. The clinical application of CPT is limited by its poor water solubility and serious side effects. In this work, layered double hydroxide (LDH) nanosheets were prepared in an aqueous synthetic route, and rhamnolipid (RL) anions were assembled with LDH nanosheets to form a RL-LDH nanohybrid. A CPT-intercalated RL-LDH (CPT-RL-LDH) nanohybrid was then prepared via hydrophobic interaction in a saturated ethanol solution of CPT. A possible morphology of CPT molecules in the hydrophobic interlayer region of RL-LDH was proposed according to the size of CPT molecule and the gallery height of the RL-LDH. The obtained CPT-RL-LDH nanohybrid showed high thermal stability and controlled release of CPT. The diffusion of CPT through CPT-RL-LDH particles was the rate-limiting step of CPT release. The drug-RL-LDH nanohybrids can be used as potential drug delivery materials.

Potential Applications of Layered Double Hydroxides in Membrane-Based Separation and Anti-Corrosion

Layered double hydroxides (LDHs) are representative of inorganic layered compounds consisting of positively charged brucite-like sheets and charge compensating anions located in interlayer galleries. The high length-to-width ratio, uniform gallery height, flexible chemical compositions, active surface functionality and unique calcination properties of LDHs have inspired us to explore their potentials in gas separation. In the presentation we demonstrated that LDHs not only enabled to effectively separate hydrogen-containing gas mixtures relying on the uniform interlayer galleries, but also could serve as efficient perch, active heterogeneous nucleation center and qualified single metal source of MOF crystals for the preparation of high performance MOF membranes. In addition, potential applications of LDHs in anti-corrosion were further explored. Relying on the dense in-plane structure of LDHs, preferentially c-oriented NiAl-CO3 LDH coatings were prepared showing excellent anti-corrosion performance. In addition, well-intergrown MOF coatings exhibiting excellent anti-corrosion performance could be in situ grown on Al substrates further by simple solvothermal treatment of ZnAl-CO3 LDH buffer layers. To sum up, full utilization of both microstructural and physicochemical properties of LDHs had greatly expanded their potential applications in membrane-based separation and anti-corrosion.