Monthly Archives: September 2023

NiO/ZnO Composite Derived Metal‐Organic Framework as Advanced Electrode Materials for Zinc Hybrid Redox Flow Battery

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NiO/ZnO Composite Derived Metal-Organic Framework as Advanced Electrode Materials for Zinc Hybrid Redox Flow Battery

NiO/ZnO-derived MOF composite is used to modify carbon felt electrode. Alkaline zinc-based electrolyte is used as anolyte and catholyte and exhibits better redox reactions. The peak current ratio increases to 1.07 mA at 10 mA cm−2 for the as-prepared material.


Abstract

NiO/ZnO composite derived metal-organic framework (MOF) is used as to modify carbon felt (CF) via a conventional solid-state reaction followed by ultrasonication. The prepared electrode material is used in zinc-hybrid redox flow batteries (RFBs) due to their high redox activity of Zn2+/Zn. The electrochemical performance of composite modified CF and pre-treated CF was studied by cyclic voltammetry (CV) in 0.5 M aqueous zinc chloride with 5 M potassium hydroxide solutions showed clear confirmation for enhanced electrocatalytic activity. The unique porous structure of NiO/ZnO-derived MOF with increased surface area improves the battery behavior significantlyThe peak current ratio for the as-prepared material is about 3 times higher than that of the pre-treated CF due to more active sites. Zinc-based RFB with modified CF electrode exhibited better electrochemical performance with voltage efficiency (VE, 88 %), which is higher than true redox flow batteries.

Perspectives on Dual‐purpose Functional Nanomaterials for Detecting and Removing Fluoride Ion from Environmental Water

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Perspectives on Dual-purpose Functional Nanomaterials for Detecting and Removing Fluoride Ion from Environmental Water

Two-in-one: This review discusses recent developments in the area of functional nanomaterials that are capable of detecting and removing fluoride through the use of agglomeration, electrostatic, H-bonding, ion exchange, coordination and π-π stacking interactions. This unique approach provides an effective way to detect and remove fluoride from water in the environment.


Abstract

Fluoride (F−) is a unique analyte because when in small quantities, it is beneficial and harmful when in larger or negligible quantities, leaving it essential for dual-purpose detection and removal from a water sample to prevent fluoride-caused health risks. F− detection and removal using organic molecules and hybrid materials are extensively reported in the literature, but very few reports discuss dual-purpose detection and removal. Functional nanomaterials (FNM) based on nanoparticles, metal-organic frameworks, and carbon dots conjugated with fluorophore moiety are largely used for these purposes. Functional groups on nanomaterial surfaces exhibited various interactions such as agglomeration, electrostatic, hydrogen bonding, ion exchange, coordination and π-π stacking interactions, enabling dual-purpose detection and removal of F−. These materials offer unique properties such as tunable pore structure, size, and morphology coupled with large surface area and high thermal/chemical stability. Further, this perspective review discusses prospects for sustainable technologies and describes the advantages and disadvantages of using FNM based on its optical properties for detection and removal efficiency. We believe this is the first account that summarizes the single FNM that can be used for simultaneously the selective detection of F− in aqueous media and its efficient removal.

Influence of Coordination to Silver(I) Centers on the Activity of Heterocyclic Iodonium Salts Serving as Halogen‐Bond‐Donating Catalysts

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Influence of Coordination to Silver(I) Centers on the Activity of Heterocyclic Iodonium Salts Serving as Halogen-Bond-Donating Catalysts

Pyrazole-containing iodonium triflates and silver(I) triflate bind to each other, and such an interplay significantly affects the total catalytic activity of the mixture of these Lewis acids. The obtained results indicate that such a cooperation additionally results in prevention of decomposition of the organocatalysts during the reaction progress.


Abstract

Kinetic data based on 1H NMR monitoring and computational studies indicate that in solution, pyrazole-containing iodonium triflates and silver(I) triflate bind to each other, and such an interplay results in the decrease of the total catalytic activity of the mixture of these Lewis acids compared to the separate catalysis of the Schiff condensation, the imine–isocyanide coupling, or the nucleophilic attack on a triple carbon−carbon bond. Moreover, the kinetic data indicate that such a cooperation with the silver(I) triflate results in prevention of decomposition of the iodonium salts during the reaction progress. XRD study confirms that the pyrazole-containing iodonium triflate coordinates to the silver(I) center via the pyrazole N atom to produce a rare example of a pentacoordinated trigonal bipyramidal dinuclear silver(I) complex featuring cationic ligands.

Electrostatic Self Assembly of Metal‐Free Hexagonal Boron Nitride/Protonated Carbon Nitride (h‐BN/PCN) Nanohybrid: A Synergistically Upgraded 2D/2D Sustainable Electrocatalyst for Sulfamethazine Identification

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Electrostatic Self Assembly of Metal-Free Hexagonal Boron Nitride/Protonated Carbon Nitride (h-BN/PCN) Nanohybrid: A Synergistically Upgraded 2D/2D Sustainable Electrocatalyst for Sulfamethazine Identification

The present study illustrates the advantages of the synergistically upgraded, sustainable, metal-free h-BN/PCN electrocatalyst for sulfamethazine sensor towards real-world samples using highly sensitive electrochemical techniques with good recovery percentages. Thus, the best performance for the electrochemical sensing of SMZ was exhibited by the h-BN/PCN nanocomposite.


Abstract

In the scientific community, developing a non-enzymatic detection tool for highly reliable and sensitive identification of the targeted biomolecules is challenging. Sulfamethazine (SMZ), a bacterial inhibitor frequently used as an antibacterial medicine, can cause antimicrobial resistance (AMR) in humans if taken in excess. Hence, there is a need for a reliable and rapid sensor that can detect SMZ in food and aquatic environments. The goal of this study aims to develop a novel, inexpensive 2D/2D hexagonal boron nitride/protonated carbon nitride (h-BN/PCN) nanohybrid that can function as an electrocatalyst for SMZ sensing. The as-synthesized material‘s crystalline, structural, chemical, and self-assembly properties were thoroughly characterized by XRD, HR-TEM, XPS, HR-SEM, FT-IR, and ZETA potential and electrochemical sensing capacity of the suggested electrodes was optimized using CV, EIS, DPV, and i-t curve techniques. The above nanohybrid of h-BN/PCN-modified GCE exhibits improved non-enzymatic sulfamethazine sensing behaviour, with a response time of less than 1.83 s, a sensitivity of 1.80 μA μM−1 cm−2, a detection limit of 0.00298 μM, and a range of 10 nM to 200 μM. The electrochemical analysis proves that the conductivity of h-BN has significantly improved after assembling PCN due to the large surface area with active surface sites and the synergistic effect. Notably, our constructed sensor demonstrated outstanding selectivity over a range of probable interferents, and electrochemical studies indicate that the suggested sensor has improved functional durability, rapid response, impartial repeatability, and reproducibility. Furthermore, the feasibility of an h-BN/PCN-modified sensor to detect the presence of SMZ in food samples consumed by humans has been successfully tested with high recovery percentages.

Sterically Enhanced Control of Enzyme‐Assisted DNA Assembly

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Sterically Enhanced Control of Enzyme-Assisted DNA Assembly**

The sterically controlled, nuclease enhanced DNA assembly technique successfully assembles DNA structures containing multiple capture probes. Short (60 bp) DNA stands, with probes attached, are assembled with larger (1 kb) strands, overcoming the limitations of Gibson assembly, and offering a multiplex diagnostic tool.


Abstract

Traditional methods for the assembly of functionalised DNA structures, involving enzyme restriction and modification, present difficulties when working with small DNA fragments (<100 bp), in part due to a lack of control over enzymatic action during the DNA modification process. This limits the design flexibility and range of accessible DNA structures. Here, we show that these limitations can be overcome by introducing chemical modifications into the DNA that spatially restrict enzymatic activity. This approach, sterically controlled nuclease enhanced (SCoNE) DNA assembly, thereby circumvents the size limitations of conventional Gibson assembly (GA) and allows the preparation of well-defined, functionalised DNA structures with multiple probes for specific analytes, such as IL-6, procalcitonin (PCT), and a biotin reporter group. Notably, when using the same starting materials, conventional GA under typical conditions fails. We demonstrate successful analyte capture based on standard and modified sandwich ELISA and also show how the inclusion of biotin probes provides additional functionality for product isolation.

Linear Polymer Comprising Dual Functionalities with Hierarchical Pores for Lithium Ion Batteries

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Linear Polymer Comprising Dual Functionalities with Hierarchical Pores for Lithium Ion Batteries

Polymers for batteries: A linear polymer with micro and Nano pores with azo and carbonyl functionalities renders increased accessibility to Li ions after preconditioning. During charge-discharge experiment Azo-Carb-PDI electrode had impressive discharge capacity of 469 mA h/g after 500 cycle which is almost 15 times higher than the monomer (Azo-PDI-Azo, 30 mA h/g after 100 cycle).


Abstract

Organic materials with carbonyl, azo, nitrile and imine moieties are widely used in lithium batteries. The solubility of these materials in battery electrolytes is an issue. Aggregation of the organic molecules can suppress the solubility, but the accessibility of lithium-ion is hindered. Therefore, insoluble porous organic materials are desired. Herein, we synthesized a linear polymer with carbonyl and azo functionalities. Due to the presence of easily isomerizable azo moiety, a porous polymer was obtained. The polymer showed nano and micropores. The battery with the porous polymer showed an impressive specific capacity of 400 mA h/g at 0.2 A/g. If the battery is pre-conditioned, the specific capacity increased to 615 mA h/g at the same current density. The post-mortem analysis of the battery confirmed that the polymer didn't dissolve in the battery electrolyte. The control material is a small molecule with carbonyl and azo moieties that showed a poor specific capacity of 40 mA h/g indicating the necessity to have a hierarchically porous dual-functional polymer.

An Efficient Approach for Quantifying the Mechanical Degradation of Ni‐Rich NMC‐based Cathodes for Lithium‐Ion Batteries using Nano‐XCT Analysis

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An Efficient Approach for Quantifying the Mechanical Degradation of Ni-Rich NMC-based Cathodes for Lithium-Ion Batteries using Nano-XCT Analysis

Nano-XCT analysis for batteries: This study compares scanning electron microscopy images and nano X-ray computed tomography scans of pristine and cycle-aged battery electrodes. Structural changes over the cycle life are determined, and a quantitative analysis of the active material‘s gray scale value distribution reveals severe degradation near the separator interface, with a reciprocal relationship to particle radius.


Abstract

LiNi0.8Co0.1Mn0.1O2 has emerged as a promising electrode material for automotive lithium-ion batteries due to its high specific discharge capacity, cost-effectiveness, and reduced cobalt content. However, despite all mentioned beneficial attributes, the widespread adoption of this material class is impeded by active material degradation during cycling operation, which is linked to performance loss. This study compares scanning electron microscopy images and nano X-ray computed tomography scans with a 3D reconstruction of pristine and cycle-aged battery electrodes to determine structural changes over cycle life. Although a very moderate current rate was chosen for the cycle test, which suggests a homogeneous load across the entire electrode, particle fracture varied across electrode thickness and particle size. A quantitative analysis of the active material‘s gray scale value distribution reveals severe degradation near the separator interface with a reciprocal relationship to particle radius. Remarkably, particle shape and size remain relatively unchanged despite cracking, eliminating the need to adjust these parameters in aging simulations. Moreover, it underscores the practical significance of particle cracking, as it can significantly impact the electrode‘s performance. Thus, analyzing changes in particle shape and size alone is insufficient, and a comprehensive exploration of the particle interior using nano-XCT is necessary.

Why DFT‐Based Tight Binding Gives a Better Representation of the Potential at Metal‐Solution Interfaces than DFT Does

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Why DFT-Based Tight Binding Gives a Better Representation of the Potential at Metal-Solution Interfaces than DFT Does

The inner potential φ experienced by an ion differs greatly from the average electrostatic potential as calculated by DFT. The problem is caused by the divergence of the potential at the sites of the nuclei. DFT-based tight binding gives results in line with values estimated from experiment or from other models, and allows a uniform quantum-mechanical modeling of electrode and solution.


Abstract

In modelling electrochemical interfaces it is important to treat electrode and electrolyte at the same level of theory. Density functional theory, which is usually the method of choice, suffers from a distinct disadvantage: The inner potential is calculated as the average of the total electrostatic potential. This includes the highly localized potential generated from the nuclei. The resulting inner potential is far too high, of the order of 3.5 V, and not relevant for electrochemistry. In the density functional based tight binding (DFTB) method the electrostatic potential is much smoother, as it stems from atomic charge fluctuations with respect to neutral reference atoms. The resulting values for the electrochemical inner potential are much lower and compare well with those obtained by other, elaborate methods. Thus DFTB recommends itself as a method for treating the electrochemical interface including the inner potential.

Heterogeneous Photocatalysts for Light‐Mediated Reversible Deactivation Radical Polymerization

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Heterogeneous Photocatalysts for Light-Mediated Reversible Deactivation Radical Polymerization

Heterogeneous photocatalysis can increase the sustainability of photochemistry by providing simple means for catalyst recovery and reuse. This review explores four prevalent classes of these materials: Photocatalytic Nanoparticles, polymer networks, metal organic frameworks (MOFs), and immobilized photocatalysts on solid supports in their use for light-mediated reversible deactivation radical polymerization.


Abstract

Heterogeneous photocatalysis combines the benefits of light-mediated chemistry with that of a catalytic platform that facilitates re-use of (often expensive) photocatalysts. This provides significant opportunities towards more economical, sustainable, safe, and user-friendly chemical syntheses of both small and macromolecular compounds. This contribution outlines recent developments in the design of heterogenous photocatalysts and their use to mediate polymerizations. We outline four classes of heterogeneous photocatalysts in detail: Nanoparticles, conjugated and non-conjugated polymer networks, metal-organic frameworks (MOFs), and functionalized solid supports.

Halide Complexes of 5,6‐Dicyano‐2,1,3‐Benzoselenadiazole with 1:4 Stoichiometry: Cooperativity between Chalcogen and Hydrogen Bonding

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The [M4–Hal]– (M = the title compound; Hal = Cl, Br, and I) complexes were isolated in the form of salts of [Et4N]+ cation and characterized by XRD, NMR, UV-Vis, DFT, QTAIM, EDD, and EDA. Their stoichiometry is caused by a cooperative interplay of σ-hole-driven chalcogen (ChB) and hydrogen (HB) bondings. In the crystal, [M4–Hal]– are connected by the π-hole-driven ChB; overall, each [Hal]– is six-coordinated. In the ChB, the electrostatic interaction dominates over orbital and dispersion interactions. In UV-Vis spectra of the M + [Hal]– solutions, ChB-typical and [Hal]–-dependent charge-transfer bands are present; they reflect orbital interactions and allow identification of the individual [Hal]–. However, the structural situation in the solutions is not entirely clear. Particularly, the UV-Vis spectra of the solutions are different from the solid-state spectra of the [Et4N]+[M4–Hal]–; very tentatively, species in the solutions are assigned [M–Hal]–. It is supposed that the formation of the [M4–Hal]– proceeds during the crystallization of the [Et4N]+[M4–Hal]–. Overall, M can be considered as a chromogenic receptor and prototype sensor of [Hal]–. The findings are also useful for crystal engineering and supramolecular chemistry.