Incisive amalgamation of open metal site (OMS) and functional group assisted pore decoration in metal-organic frameworks (MOFs) can accomplish selective capture and catalytic valorisation of carbon dioxide (CO2), where installation...

Due to the drawbacks in commercially known lithium-ion batteries (LIB) such as safety, availability, and cost issues, aluminum batteries are being hotly pursued in the research field of energy storage. Al being abundant, stable, and possessing high volumetric capacity has been found to be attractive among the next generation secondary batteries. Various unwanted side reactions in the case of aqueous electrolytes have shifted the attention toward nonaqueous electrolytes for Al batteries. Unlike LIBs, Al batteries are based on intercalation/deintercalation of ions on the cathode side and deposition/stripping of Al on the anodic side during the charge/discharge cycle of the battery. Hence, to provide a clear understanding of the recent developments in Al batteries, we have presented an overview concentrating on the choice of suitable cathodes and electrolytes involving aluminum chloride derived ions (AlCl 4 − , AlCl 2 + , AlCl 2+ , etc.). We elaborate the importance of innovation in terms of structure and morphology to improve the cathode materials as well as the necessary properties to look for in a suitable nonaqueous electrolyte. The significance of computational modeling is also discussed. The future perspectives are discussed which can improve the performance and reduce the manufacturing cost simultaneously to conceive Al batteries for a wide range of applications.

Atmospheric water harvesting, triphasic detection of water contaminants, and advanced antiforgery measures are among important global agendas, where metal–organic frameworks (MOFs), as an incipient class of multifaceted materials, can affect substantial development of individual properties at the interface of tailor-made fabrication. The chemically robust and microporous MOF, encompassing contrasting pore functionalization, exhibits an S-shaped water adsorption curve at 300 K with a steep pore-filling step near P/P 0 = 0.5 and shows reversible uptake–release performance. Density functional theory (DFT) studies provide atomistic-level snapshots of sequential insertion of H2O molecules inside the porous channels and also portray H-bonding interactions with polar functional sites in the two-fold interpenetrated structure. The highly emissive attribute with an electron-pull system benefits the fast-responsive framework and highly regenerable detection of four classes of organic pollutants (2,4,6-trinitrophenol (TNP), dichloran, aniline, and nicotine) in water at a record-low sensitivity. In addition to solid-, liquid-, and vapor-phase sensing, host–guest-mediated reversible fluoroswitching is validated through repetitive paper-strip monitoring and image-based detection of food sample contamination. Structure–property synergism in the electron transfer route of sensing is justified from DFT calculations that describe the reshuffling of molecular orbital energy levels in an electron-rich network by each organotoxin, besides evidencing framework–analyte supramolecular interactions. The MOF further delineates the pH-responsive luminescence defect repair via site-specific emission modulation, wherein reversibly alternated “encrypted and decrypted” states are utilized as highly reusable anticounterfeiting labels over multiple platforms and conceptualized as artificial molecular switches. Aiming at self-calibrated, advanced security claims, a NOR-OR coupled logic gate is devised based on commensurate fluorescence-cum-real-time synchronous detection of organic and inorganic (HCl and NH3) pollutants.

Aluminum dual-ion batteries (DIBs) have been identified as a possible future alternative for lithium-ion batteries, possessing several attractive properties like high abundance, high energy density, and environmental friendly. Graphite and graphitelike materials are being explored to improve the cathodic performance in Al DIBs. Very recently, several organic materials with p-type redox activity are also gaining attention due to their flexibility, low cost, and easy availability for usage as electrodes in DIBs. In this work, we have evaluated four lightweight polycyclic aromatic hydrocarbons (PAHs) (pyrene, perylene, triphenylene, and coronene) as prospective cathode materials for Al DIBs using firstprinciples calculation. Binding energy calculations show favorable intercalation of AlCl 4 − , maintaining its tetrahedral geometry inside the flexible lattices and subsequent charge transfer from the PAH systems displaying their redox activity. The charge transfer also initiates semiconducting to metallic transformation ensuring the electronic conductivity during the redox reactions in Al DIBs. Pyrene and coronene are found to deliver good electrochemical performance with ultrahigh specific capacity. Triphenylene also exhibits good voltage (∼1.9 V) even at a lower specific capacity. The flexible arrangement of PAH molecules is expected to compensate for a slightly higher diffusion energy barrier values due to subsequent expansion with increasing concentration of AlCl 4 − intercalation. These results motivate us toward use of PAH materials and further exploration of similar organic materials as cathodes for Al DIBs.

Two-dimensional chalcogenide-based materials of group 14 elements are predicted as potential thermoelectric (TE) materials, though the figure of merit (ZT) obtained requires improvement to be commercially accessible. Herein, we have computationally modeled synthesized γ-GeSe and reduced-dimension 2D layers (monolayer, bilayer, trilayer, and quad-layer) and subjected them to first-principles calculations to extract essential properties pertaining to TE. The ZT values obtained for the considered systems are found to be remarkably high (quad-layer: 2.8; trilayer: 3.1; bilayer: 3.8), even at a high temperature of 900 K. The dimensionality reduction (3D to 2D) as well as reducing layers (quad-layer to bilayer) improved the ZT considerably in comparison to that of bulk γ-GeSe (0.8 at 900 K). Even though the power factor decreases with decreasing layers, ultralow lattice thermal conductivities (k L) are responsible for the high ZT. Ultralow k L (>1 W m–1 K–1) was observed in 2D γ-GeSe at all temperature ranges, with the lowest k L observed in the bilayer (0.15 W m–1 K–1) and trilayer (0.17 W m–1 K–1) at 900 K. The low k L is also supported by the presence of high anharmonicity, high phonon scattering rates, low elastic constants, low group velocity, and low Debye temperature. We envisage that these findings will motivate investigations on similar low-dimensional materials for improved thermoelectric performance.

Dual-ion batteries (DIBs) are emerging as a highly attractive class of batteries as they try to address the shortcomings of the widely used lithium ion batteries. Among the various organic electrolytes used in DIBs, ethyl methyl carbonate (EMC) with LiPF6 salt is recently being considered as a better electrolyte in comparison to commercially used ethylene carbonate (EC). In this work, we have carried out a comparative study of EMC and EC solvent systems to address the greater stability of EMC in contact with aluminum (Al) and lithiated Al (LiAl) electrode as well as the effect of salt in the solid electrolyte interphase (SEI) formation process with the help of ab initio molecular dynamics (AIMD) simulations. We find that EMC can decompose via 1e– reduction due to limited charge transfer from the Al surface, whereas 2e– reduction becomes more favorable with lithiation of the Al anode surface. The limited decomposition observed in EMC compared to EC in contact with the Al electrode surface justifies the enhanced stability of EMC solvent in DIBs with an Al anode. However, the decomposition and SEI formation process can speed up in the presence of LiPF6 salt as it induces more charge transfer (1.11 |e| for Al and 2.86 |e| for LiAl) from the electrode surface. Nevertheless, the charge transfer is less than in the case of EC solvent (2.54 |e| for Al and 5.42 |e| for LiAl), further justifying the stability of EMC solvent. We also find that the charge transfer to the salt molecule from the electrode surface depends on the position of the salt rather than the composition of the electrode surface. Overall, our study shows that the EMC solvent–LiPF6 salt combination can serve as an efficient electrolyte for Al anode DIBs.

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With the limited number of studies available (mostly experimental), the field of aluminum−sulfur (Al−S) batteries is in urgent need of understanding their complex electrochemical reactions. Herein, the ab initio molecular dynamics (AIMD) simulations are used to obtain a detailed understanding of the involved charging and discharging processes in Al−S batteries by analysis of interfacial systems S 8 (001)/[EMIM]AlCl 4 and Al 2 S 3 (001)/[EMIM]AlCl 4 −electrolyte, respectively. We observe that during the discharging process, the reduction of S 8 follows a layer-by-layer mechanism and involves the formation of various cationic and anionic intermediate species, which drives the formation of Al polysulfides during the course of the discharging process. The evolution of the discharge voltage profile studied over a limited timescale shows two voltage domains: the first voltage domain (1.87−2.10 V) corresponds to the interface effects of surface−electrolyte and second the voltage domain of 1.38−1.50 V starts coinciding with the experimental value of 1.30 V and involves the reduction of S 8 to higher-order polysulfides. We also observe the diffusion of these higher-order Al polysulfides to the electrolyte, which is in accordance with the experimentally observed solvation of higher-order Al poylsulfides into the electrolyte. The evolution of the atomistic structure and reaction voltage during charging shows that the top atomic sublayer structural distortions are mainly limited to the layer where Al atoms are removed and not the other inner atomic layers, which could be the reason for the poor electrochemical reversibility and an increased overall charging voltage (1.75 V) in experimentally studied Al−S batteries. We believe that the new atomistic insights obtained about the formation of various intermediate species, competition of different reaction mechanisms, and importance of local Al concentration could help improve the understanding of the complex electrochemical processes observed in Al−S batteries.