Formation Of Chemical Bonds Research Articles

Structure engineering and heteroatom doping-enabled high-energy and fast-charging dual-ion batteries

Sodium dual-ion batteries (SDIBs) have attracted extensive attention due to the high working voltage and low cost. Nevertheless, lack of robust anode materials that can achieve highly efficient insertion/extraction of sodium ions still remains a huge challenge to develop the high-performance SDIBs. Herein, we exhibited excellent long-cycling performance (capacity retention of 85 % over 2000 cycles) with large reversible capacity (1788 mA h g−1 under 0.2 A/g) as well as superior rate capability (721 mA h g−1 under 10 A/g) for sodium-ion storage by encapsulating red phosphorus within nitrogen-doped mesoporous graphene particles. And the structural stability of composite during sodiation was directly demonstrated using in-situ transmission electron microscopy. The results of density functional theory reveal that nitrogen doping and formation of PC chemical bonds within graphene matrix may improve the adsorption energy of P atoms and promote the sturdy contact. The adsorption energies of nitrogen-doped graphene for Na+ and PF6− are −2.12 and −3.62 eV, respectively, which shows that the doping of N element is beneficial to the adsorption of Na+ and PF6−. Upon pairing with nitrogen-doped mesoporous graphene particles as cathode, an innovative SDIBs with high energy-power-density of 324 W h kg−1 at 331 W kg−1 and 187 W h kg−1 at 2665 W kg−1 were manufactured. This study opens up an effective strategy towards high-performance SDIBs for electric vehicles and other applications.

Bond Formation at C8 in the Nucleoside and Nucleotide Purine Scaffold: An Informative Selection.

This paper presents methods for the introduction and exchange of substituents in a nucleobase and its nucleosides and nucleotides with emphasis on the C8-position in the purine skeleton. The nucleobase is open for electrophilic and nucleophilic chemistry. The nucleophilic chemistry consists mainly of displacement reactions when the C8-substituent is a good leaving group such as a halogen atom. The heteroatom in amines, sulfides, or oxides is a good nucleophile. Halides are good reaction partners. Metal-promoted cross-coupling reactions are important for carbylations. Direct oxidative metalation reactions using sterically hindered metal amides offer chemo- and regio-selectivity besides functional tolerance and simplicity. The carbon site is highly nucleophilic after metalation and adds electrophiles resulting in chemical bond formation. Conditions for metal-assisted reactions are described for nucleobases and their glycosides.

Mechanisms of acrylamide biosorption by Lactobacillus plantarum ATCC8014 peptidoglycan

This study extracted peptidoglycan (PG) from Lactobacillus plantarum ATCC8014, its acrylamide (AA) adsorption behavior was evaluated by creating adsorption models, and its binding characterizations were investigated by physicochemical methods. The kinetics and isothermal model revealed that the biosorption of AA by PG conformed to Langmuir, Freundlich equations, and the second-order kinetic model, confirming that the adsorption process involved both physisorption and chemisorption. Fourier transform infrared spectroscopy and chemical blocking of functional groups confirmed that carboxyl, amino and hydroxyl groups were involved. Meanwhile, a new peak was generated in the proton nuclear magnetic resonance spectrum of PG upon adsorption, and the water contact angle was significantly reduced, indicating that hydrogen bonds and hydrophobic force were involved in the biosorption. Besides, energy dispersive spectroscopy and X-ray photoelectron spectroscopy results have important findings, suggesting that amide bonds might be formed during the adsorption process. Subsequently, this speculation was confirmed by the identification results of amidase. Overall, our results indicated that the mechanism of adsorption is complex and involves hydrogen bonding, hydrophobic forces and the formation of chemical bonds.

Unveiling the interaction mechanisms of cold atmospheric plasma and amino acids by machine learning

AbstractPlasma medicine has attracted tremendous interest in a variety of medical conditions, ranging from wound healing to antimicrobial applications, even in cancer treatment, through the interactions of cold atmospheric plasma (CAP) and various biological tissues directly or indirectly. The underlying mechanisms of CAP treatment are still poorly understood although the oxidative effects of CAP with amino acids, peptides, and proteins have been explored experimentally. In this study, machine learning (ML) technology is introduced to efficiently unveil the interaction mechanisms of amino acids and reactive oxygen species (ROS) in seconds based on the data obtained from the reactive molecular dynamics (MD) simulations, which are performed to probe the interaction of five types of amino acids with various ROS on the timescale of hundreds of picoseconds but with the huge computational load of several days. The oxidative reactions typically start with H‐abstraction, and the details of the breaking and formation of chemical bonds are revealed; the modification types, such as nitrosylation, hydroxylation, and carbonylation, can be observed. The dose effects of ROS are also investigated by varying the number of ROS in the simulation box, indicating agreement with the experimental observation. To overcome the limits of timescales and the size of molecular systems in reactive MD simulations, a deep neural network (DNN) with five hidden layers is constructed according to the reaction data and employed to predict the type of oxidative modification and the probability of occurrence only in seconds as the dose of ROS varies. The well‐trained DNN can effectively and accurately predict the oxidative processes and productions, which greatly improves the computational efficiency by almost ten orders of magnitude compared with the reactive MD simulation. This study shows the great potential of ML technology to efficiently unveil the underpinning mechanisms in plasma medicine based on the data from reactive MD simulations or experimental measurements.

Unraveling Enyne Bonding via Dehydrogenation–Hydrogenation Processes in On‐Surface Synthesis with Terminal Alkynes

AbstractOn‐surface reactions of terminal alkynes in ultrahigh vacuum have attracted widespread attention due to their high technological promise. However, employing different precursors and substrate materials often intricate reaction schemes appear far from being well‐understood. Thus, recent investigations of alkyne coupling on noble metal surfaces suggest non‐dehydrogenative scenarios, contradicting earlier reports. Herein, the study employs noncontact atomic force microscopy (nc‐AFM) with high spatial resolution to conclusively characterize exemplary alkyne coupling products. Contrary to initial interpretations proposing dehydrogenative homocoupling on Ag(111), bond‐resolved AFM imaging reveals the expression of enyne motifs. Based on complementary, extensive density functional theory calculations, the pertaining reaction mechanisms are explored. It is proposed that enyne formation initiates with a direct carbon–carbon coupling between two alkyne groups, followed by surface‐assisted dehydrogenation‐hydrogenation processes. Thereby consecutive steps of atomic hydrogen cleavage, surface migration and recombination to a different carbon atom enable bridging via carbon–carbon double bonding. The new results shed light on subtle, but crucial surface‐mediated hydrogen transfer processes involved in the chemical bond formation, which are suggested to be of general relevance in on‐surface synthesis.

Zr4+-mercaptosuccinate MOF for the uptake and recovery of gold nanoparticles and gold ions under batch and continuous flow conditions

The increasing use of nanomaterials in commercial products has raised concerns regarding their potential effects on water quality and living organisms. So far, most sorbents available for removing nanosized inorganic pollutants from water rely on electrostatic interactions or entrapment in the sorbent pores. However, this limits their applicability in real wastewater samples containing nanomaterials with variable surface properties and sizes, along with high concentrations of competitive species such as inorganic salts and organics. Little attention has also been paid to the recovery of nanoparticles after sorption. In this work, a Zr4+-mercaptosuccinate metal organic framework (MOF) with free thiol groups was investigated as a sorbent for the removal of Au nanoparticles and Au3+ ions from water. Sorption occurs on the surface of the MOF via the formation of strong metal-thiolate chemical bonds enabling the fast uptake of noble metal nanoparticles and noble metal ions from water (within <1 h). The maximum sorption capacity was found to depend on the size of the Au nanoparticles and ranged from 8 to 41.5 mg/g. The surface functionalization of nanoparticles did not influence sorption performance, which was also maintained in natural waters of variable matrix complexity. The material was also efficient in fixed bed columns with an estimated maximum Au sorption capacity of approximately 7 mg/g, which is significantly higher than the environmental concentrations of Au nanoparticles and adequate for their removal from industrial wastewater. Importantly, the sorbed nanoparticles could be quantitatively recovered (>90 %), at the expense of material degradation, enabling their potential reuse.

Computational investigations on the performance of transition metal carbide (MXene) for methylene blue dye adsorption and remediation from wastewater

MXenes are receiving a lot of attention as adsorbents for environmental contaminants, due to their distinct characteristics, and the adsorption abilities were toughly influenced by the surface terminal groups. In this research the adsorption ability of free-standing Ti3C2 for methylene blue (MB) dye as a major hazardous contaminant in the watery environment is investigated and compared with the O and OH terminated MXene counterparts using computational material tools. DFT simulations are carried out to explore the structural properties and electronic structures, thermodynamic stability, and adsorption behavior of MB on the considered MXenes surface. The Ti3C2 monolayer is observed to behave as superior adsorbent for MB with strong interaction characteristic which is typical for the chemisorption followed by the Ti3C2(OH)2 and Ti3C2O2 MXenes with hydrogen bonding (strong physisorption) and electrostatics attractions, respectively. Meanwhile the DFTB-MD simulation of MB/MXene in ambient conditions reveals a strong ability of Ti3C2 monolayer in MB adsorption by chemical bond formation between N/C atom of MB and surface Ti atom followed by hydrogen bond formation in MB/Ti3C2(OH)2 system. The superior adsorption behavior of free-standing Ti3C2 monolayer in aqueous solution, make this novel monolayer a promising adsorbent for MB adsorption and removal from watery contaminants. The present findings will be beneficial for the design of suitable nanoadsorbents for remediation of hazardous organic contaminants from wastewater.

MoS2-poly(sodium4-styrenesulfonate) nanocomposite-based humidity sensor for monitoring wound healing

In this paper, a humidity sensor with high response, high stability and fast response recovery based on MoS2-PSS hybridized sensitive materials was designed, and preliminarily explored for application in noninvasive monitoring of human wound healing. The modification of PSS promoted the increase of S vacancy defects in the MoS2-PSS hybrid materials, which facilitated the rapid adsorption of water molecules and charge transfer. The edge dangling bonds and PSS in MoS2-PSS hybrid materials jointly enhanced the water molecule adsorption capacity and promoted the rapid formation of chemisorbed water layer on materials surface. The formation of chemical bond between MoS2 and PSS makes the hybrid material more stable in structure. The prevents the loss of hydrophilic material caused by the sensor working in high humidity environment for a long time and improves the stability of the sensor. MoS2-PSS humidity sensor exhibites high response (11097), short response/recovery time (5/6 s), low humidity hysteresis (1.6%), and high stability in the 11%-95% RH range. This study not only promotes the development of high-performance sensors, but may also provide a viable option for noninvasive monitoring of wound healing.

Effects of photo-oxidation and transition metals on the formation of reactive oxygen species from aromatic compounds using spectroscopic method

Particulate matter (PM) can cause adverse health effects by overproducing reactive oxygen species (ROS). Although the ability of PM to induce ROS generation depends on its composition and environmental factors. This study explores how photo-oxidation affects ROS generation from aromatic compounds (ACs, including catechol (CAT), phthalic acid (PA), and 4,4′-oxydibenzoic acid (4,4′-OBA)) and their mixtures with transition metals (TMs, including Fe(II), Mn(II), and Cu(II)) using Fourier-transform infrared (FTIR) and Ultraviolet-visible spectroscopy (UV–Vis). Results showed that photo-oxidation facilitated ROS generation from ACs. CAT-Fe(II)/Cu(II) showed synergistic effects, but 4,4′-OBA-Fe(II)/Cu(II) showed antagonistic effects. ACs-Mn(II) and PA-Fe(II)/Cu(II) exhibited synergistic effects first and then showed antagonistic effects. The different interactions were due to complexation between ACs and TMs. The photo-oxidized ACs-TMs significantly enhanced ROS generation compared with ACs-TMs. The study suggested the photo-oxidation mechanism involved that the transfer of π-electrons from the ground to an excited state in benzene rings and functional groups, leading to the breakage and formation of chemical bonds or easier π-electron transfer from ACs to TMs. The former could generate ROS directly or produce polymers that promoted ROS generation, while the latter promoted ROS generation by transferring π-electrons to dissolved oxygen quickly. Our study revealed that both interactions among components and photo-oxidation significantly influenced ROS generation. Future studies should integrate broader atmospheric factors and PM components to fully assess oxidative potential and health impacts.

Boosting the electroreduction of CO2 to liquid products via nanostructure engineering of Cu2O catalysts

The electrochemical reduction of CO2 presents a promising pathway for storing intermittent renewable energy in the form of chemical bonds, thereby mitigating CO2 emissions and enabling the production of sustainable fuels. In this work, we demonstrate nanoscale engineering of oxygen vacancy and morphology simultaneously on Cu2O catalysts for electrochemical reduction of CO2 to liquid products (formate and ethanol). By comparing the performance of cube- and tetrakaidecahedron-like Cu2O catalysts, we have demonstrated that the flower-like Cu2O catalyst, enclosed with rich oxygen vacancy defects, exhibited superior performance in the reduction of CO2 to liquid products. Moreover, the synergetic role of Cu+ also contributed to the enhanced activity by promoting CO2 adsorption and facilitating C–C coupling. As a result, the peak Faradaic efficiency (FE) for liquid products of 95.5 % was obtained, associated with a high ethanol FE of 52.6 % and formation rate of 23.8 μmol h−1 cm−2 within a H-cell. Furthermore, within a flow cell configuration, we have observed a significant improvement in the generation of formate, maintaining FE values above 70 % even under high current densities of up to 400 mA cm−2. In-situ Raman spectroscopic measurements allow us to identify and track key intermediates involved in the CO2 reduction to formate and ethanol. This detailed understanding of the reaction pathways adds to our fundamental knowledge and provides valuable insights for the development of morphology-controlled electrocatalysts targeting efficient conversion of CO2 into liquid products.

Enhanced production of hydrogen via catalytic methane decomposition on a Pt7-Ni (110) substrate: a reactive molecular dynamics investigation

Abstract Numerous researchers in the energy field are engaged in a competitive race to advance hydrogen as a clean and environmentally friendly fuel. Studies have been conducted on the different aspects of hydrogen, including its production, storage, transportation and utilization. The catalytic methane decomposition technique for hydrogen production is an environmentally friendly process that avoids generating carbon dioxide gas, which contributes to the greenhouse effect. Catalysts play a crucial role in facilitating rapid, cost-effective and efficient production of hydrogen using this technique. In this study, reactive molecular dynamics simulations were employed to examine the impact of Pt7 cluster decoration on the surface of a Ni (110) catalyst, referred to as Pt7-Ni (110), on the rates of methane dissociation and molecular hydrogen production. The reactive force field was employed to model the atomic interactions that enabled the formation and dissociation of chemical bonds. Our reactive molecular dynamics simulations using the Pt7-Ni (110) catalyst revealed a notable decrease in the number of methane molecules, specifically ~11.89 molecules per picosecond. The rate was approximately four times higher than that of the simulation system utilizing a Ni (110) catalyst and approximately six times higher than that of the pure methane, no-catalyst system. The number of hydrogen molecules generated during a simulation period of 150 000 fs was greater on the Pt7-Ni (110) surface than in both the Ni (110) and pure methane systems. This was due to the presence of numerous dissociated hydrogen atoms on the Pt7-Ni (110) surface.

Enhanced interfacial bonding of AF/PEEK composite based on CNT/aramid nanofiber multiscale flexible-rigid structure

The application of aramid fiber (AF)/polyetheretherketone (PEEK) composites is currently hindered by the inert surface and poor wettability of AF, resulting in weak interfacial adhesion and poor mechanical properties. Surface coating and the introduction of nanostructures have been proven to be effective approaches to address this problem. Herein, a simple hybrid sizing agent has been developed to modify the AF surface, consisting of soluble polyimide (PI) as a compatibilizer, carboxyl-functionalized carbon nanotubes (CNT-COOH) as a rigid unit, and aramid nanofibers (ANF) as a flexible component. The synergetic effects of PI and the multiscale flexible-rigid structure (CNT-COOH/ANF) contribute to the formation of chemical and physical bonds between AF and PEEK matrix, further improving the interfacial adhesion and stress transfer efficiency. Attributed to the enhanced wettability and roughness of AF, compared with unsized AF, the flexural strength (220.97 MPa), modulus (13.26 GPa), ILSS (13.36 MPa), and storage modulus (12.93 GPa) of the AF/PEEK composite increase by 132.60 %, 99.00 %, 18.97 %, and 82.70 % respectively. Additionally, the flexible-rigid nanonetwork facilitates the penetration of the PEEK resin into pore spaces. This simple and effective approach exhibits promising potential in enhancing the interfacial bonding of AF/PEEK composites.

Exfoliation of Metal-Organic Frameworks to Give 2D MOF Nanosheets for the Electrocatalytic Oxygen Evolution Reaction.

The structure and properties of materials are determined by a diverse range of chemical bond formation and breaking mechanisms, which greatly motivates the development of selectively controlling the chemical bonds in order to achieve materials with specific characteristics. Here, an orientational intervening bond-breaking strategy is demonstrated for synthesizing ultrathin metal-organic framework (MOF) nanosheets through balancing the process of thermal decomposition and liquid nitrogen exfoliation. In such approach, proper thermal treatment can weaken the interlayer bond while maintaining the stability of the intralayer bond in the layered MOFs. And the following liquid nitrogen treatment results in significant deformation and stress in the layered MOFs' structure due to the instant temperature drop and drastic expansion of liquid N2, leading to the curling, detachment, and separation of the MOF layers. The produced MOF nanosheets with five cycles of treatment are primarily composed of nanosheets that are less than 10 nm in thickness. The MOF nanosheets exhibit enhanced catalytic performance in oxygen evolution reactions owing to the ultrathin thickness without capping agents which provide improved charge transfer efficiency and dense exposed active sites. This strategy underscores the significance of orientational intervention in chemical bonds to engineer innovative materials.

Exfoliation of Metal–Organic Frameworks to Give 2D MOF Nanosheets for the Electrocatalytic Oxygen Evolution Reaction

AbstractThe structure and properties of materials are determined by a diverse range of chemical bond formation and breaking mechanisms, which greatly motivates the development of selectively controlling the chemical bonds in order to achieve materials with specific characteristics. Here, an orientational intervening bond‐breaking strategy is demonstrated for synthesizing ultrathin metal–organic framework (MOF) nanosheets through balancing the process of thermal decomposition and liquid nitrogen exfoliation. In such approach, proper thermal treatment can weaken the interlayer bond while maintaining the stability of the intralayer bond in the layered MOFs. And the following liquid nitrogen treatment results in significant deformation and stress in the layered MOFs’ structure due to the instant temperature drop and drastic expansion of liquid N2, leading to the curling, detachment, and separation of the MOF layers. The produced MOF nanosheets with five cycles of treatment are primarily composed of nanosheets that are less than 10 nm in thickness. The MOF nanosheets exhibit enhanced catalytic performance in oxygen evolution reactions owing to the ultrathin thickness without capping agents which provide improved charge transfer efficiency and dense exposed active sites. This strategy underscores the significance of orientational intervention in chemical bonds to engineer innovative materials.

Synergy of oxygen vacancies, Lewis acid sites, and interfacial chemical bonds on ZnSnO3/AgI for photodegradation of tetracycline

Chemically bonded Z-scheme ZnSnO3/AgI composites rich in oxygen vacancies (OVs) and Lewis acid sites were prepared successfully and showed excellent photocatalytic activities. Especially, ZnAg-2 degraded 96.1% tetracycline under visible light irradiation for 15 min. OVs contributed to Lewis acid sites production and interfacial chemical bonds formation through weakening the metal−O bonding. Lewis acid sites favored the adsorption of electron-rich tetracycline. Interfacial chemical bonds together with Z-scheme structure accelerated electron transfer and retained the high redox ability of ZnSnO3 and AgI. OVs contributed to singlet oxygen (1O2) production through facilitating the energy transfer from triplet exciton to O2. ZnSnO3/AgI composites possess good reusability and show great practical application potential. Based on ROSs generation and photoreduction experiment, the photocatalytic mechanism of the ZnAg composites was proposed. The possible degradation pathway was deduced and the biological toxicity was evaluated based on detected degradation intermediates. This work highlights the significant roles of OVs, Lewis acid sites, and chemical bonding in improving the photocatalytic activity of Z-scheme composites and provides new insight into designing high efficient photocatalysts.

PREPARATION AND JUSTIFICATION OF NANOFIBRES-LOADED MAFENIDE USING ELECTROSPINNING TECHNIQUE TO CONTROL RELEASE

Objective: The primary objective was to fabricate a novel drug delivery system capable of providing a controlled and prolonged release of antibiotics. Methods: The experimental design was formulated using Design-Expert® software (version 13), enabling systematic and efficient fabrication process optimization. The study involved the preparation of various nanofiber formulations with different ratios of the three polymers to assess their impact on drug release behavior. Mafenide, a widely used antibiotic, was chosen as the model drug for this investigation. The electrospinning process allowed for producing uniform and fine nanofibers with a high surface area, ensuring a large drug-loading capacity. The synthesized nanofibers were characterized using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) to evaluate their morphology, chemical interactions, and thermal properties. The drug release kinetics of the antibiotic-loaded nanofibers were studied under different physiological conditions to assess their sustained release behavior. Results: The final nanofiber formula was successfully prepared using the electrospinning technique. The Fourier Transform Infrared Spectroscopy (FTIR) analysis was achieved to confirm the possibility of chemical interaction and bond formation between mafenide and the polymers. Present. The SEM picture of the optimized nanofiber formula showed the homogeneity and excellent entanglement of the electrospun nanofibers at a resolution of 5 µm. PVA/chitosan/HPMC and mafenide pure drug have been successfully fabricated with sufficient strength to resist swelling after absorbing wound exudate. The polymer network becomes more compact when chitosan and Hydroxypropyl Methyl Cellulose (HPMC) are combined with polyvinyl alcohol (PVA), enabling regulated swelling during solvent ingress. The polymer composite's three-dimensional network influenced how quickly the medication was released from the matrix. Sample 2's polymer network traps the medication, gradually releasing after controlled swelling, resulting in a sustained release profile compared to blank sample according to the cumulative release (%) study of mafenide loaded nanofiber and mafenide drug blank sample. Conclusion: This research successfully demonstrated the fabrication of sustained-release antibiotic nanofibers using electrospinning and three biocompatible polymers. The systematic optimization approach using Design-Expert® software proved effective in tailoring the drug release behavior of nanofibers. The developed drug delivery system holds great promise for pharmaceutical applications, particularly in improving antibiotic therapies and patient care.

Heavy Metal Ions Removal from Aqueous Solution using NiZnFe2O4/TiO2 Nanocomposites Adsorbent

This research explores the adsorption effectiveness of NiZnFe2O4/TiO2 nanocomposites regarding Cr(VI). The nanocomposites were effectively synthesized utilizing coprecipitation and Stöber methods, incorporating diverse molar ratios of TiO2. The samples were subjected to characterization using methods such as X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy-energy dispersive X-ray (SEM-EDX), Fourier-transform infrared (FTIR), vibrating sample magnetometer (VSM), and ultraviolet-visible spectroscopy (UV-Vis). These analyses were conducted to evaluate the crystal structure, morphology, chemical bond formation, optical properties, magnetic properties, and removal efficiency of the specimens. XRD results showed that NiZnFe2O4 and TiO2 have a cubic and tetragonal structure. The crystallite size decreased as the TiO2 concentration increased. TEM image of NiZnFe2O4 reveals the formation of clusters, indicating uneven dispersion under agglomerated conditions. The average particle size is measured at (10.6 ± 0.8) nm. The Fourier-transform infrared (FTIR) analysis demonstrated the presence of functional groups O-H, C-H, and H-O-H, indicating the successful synthesis of the material. Moreover, the identification of MO-octahedral, MO-tetrahedral, and Ti-O functional groups suggested the formation of NiZnFe2O4/TiO2 nanocomposites. The incorporation of TiO2 had an impact on both the saturation magnetization and coercivity values, which fell within the ranges of 12.4 to 22.9 emu/g and 47 to 55 Oe, respectively. This finding indicates the presence of advantageous magnetic properties. The absorbance spectrum of these nanocomposites displayed a shift to the right (redshift), allowing them to absorb ultraviolet rays. The band gap of these nanocomposites ranges from (2.85 ± 0.02) to (3.29 ± 0.02) eV. Notably, NiZnFe2O4/TiO2 nanocomposites with a concentration ratio of 1:5 exhibit effective Cr(VI) removal efficiency, achieving a degradation value of 65.6%. The pseudo-kinetic model was first investigated to describe kinetic data and Cr(VI) removal determination. The SEM-EDX adsorbent results after adsorption showed the presence of Cr(VI) in the nanocomposites. Therefore, these results can promote NiZnFe2O4/TiO2 nanocomposites as a promising candidate in the removal of heavy metal waste.

Density functional theory study on the enhanced adsorption mechanism of VOCs by Cu4 cluster decorated UiO-66

Volatile organic compounds (VOCs) are a class of air pollutants that greatly harm human health and the ecological environment, convenient and effective treatment of VOCs has become a challenge. This work proposed a transition metal cluster decorated UiO-66 (a typical type of metal-organic framework) as the effective adsorbent for the purification of VOCs with typical functional groups based on density functional theory (DFT) calculations. The results show that the VOCs adsorption energy on the modified UiO-66 increased significantly, especially for Cu4 cluster-modified UiO-66, and the adsorption energy of trichloroethene is greater than that of the other considered VOCs, which may be induced by halogens or carbon-carbon double bond in trichloroethene. We compared chloromethane, chloroethylene, and ethylene and found that VOCs with carbon-carbon double bond have stronger adsorption energy, increasing with the number of chlorine atoms. The density of states (DOS), Hirshfeld charge analysis, and orbital distribution further confirm the charge distribution in UiO-66 after the decoration of the Cu4 cluster. Cu4 cluster can act as a bridge to promote the formation of chemical bonds between UiO-66 and VOCs molecules. Therefore, Cu4 cluster-modified UiO-66 can be a promising VOCs adsorption material, especially for vinyl chloride molecules.

Bio‐inspired acid‐sensitive polyurethane woven artificial muscle nanofibers with tunable mechanical properties via electrostatic spinning

AbstractPolyurethane (PU) is a traditional chemical known for its chemical stability and mechanical performance. Inspired by the similarity between the formation and breakage of chemical coordination bonds and the energy storage and release of muscle fibers, muscle‐like electrostatically spun fibers with acid‐responsive energy storage and release were prepared by introducing bio‐inspired elastic energy storage groups and bio‐active degradation groups (PU‐BPY‐Fe) in the main chain of PU, taking advantage of the good mechanical properties of PU. The fabricated electrospinning film PU‐BPY‐Fe can respond to external stimulation, which generated high strain (32 MPa), stretch of 206%, outperforming the nanofiber membrane before stimulation, similar and even higher than the biological muscles. The variable mechanical properties and elastic energy storage capacity of PU‐BPY‐Fe were attributed to the reversible hydrogen bonding and the destabilization of metal coordination bonds (Fe3+ to Fe2+) within the material under acidic stimulation. Cytotoxicity testing of the synthesized fibers indicated a degree of biocompatibility, suggesting potential for in vivo applications. This method of storing and releasing elastic energy was demonstrated and has endowed the PU‐BPY‐Fe with stimuli‐responsibility and muscle‐like mechanical properties, which may inspire the design of soft muscles materials for robots and tissue engineering applications.

Interactions of Acetylene-Derived Thioester Collectors with Gold Surfaces: A First-Principles Study

The high reactivity of the acetylene group enables the formation of strong chemical bonds with active sites on mineral surfaces, thereby improving the flotation performance of gold minerals. This study utilized density functional theory (DFT) to analyze the quantum chemical parameters of structure, Mulliken population, and the frontier orbitals of a thioester collector containing an acetylene group, PDEC (prop-2-yn-1-yl diethylcarbamodithioate). PDEC was compared with analogous thioester collectors Z-200 and Al-DECDT. The interaction mechanism of PDEC on the Au(1 1 1) surface was simulated, followed by empirical validation through adsorption experiments. The findings indicate that the S atom of PDEC in the carbon–sulfur group exhibits shorter covalent bond lengths, and has reduced carbon–sulfur double bonds and Mulliken population, resulting in enhanced electron localization. This confers greater selectivity to PDEC during its adsorption on mineral surfaces. Frontier orbital analysis shows that the electrons of the acetylene group possess a notable electron-accepting capacity, significantly influencing the frontier orbital energy of PDEC and playing a pivotal role in the bonding interaction with mineral surfaces. Both the S atom in the carbon–sulfur group and its acetylene group establish stable adsorption structures with the A(111) surface in a single coordination mode. The adsorption energy sequence is PDEC &gt; Al-DECDT &gt; Z-200. Partial density of states demonstrates that the S 3p orbit of the carbon–sulfur group hybridizes with the Au 5d orbit, while the C 2p orbit of the acetylene group engages in weaker back-donation bonding with the Au 5d orbit. This is corroborated by the electron density difference and post-adsorption Mulliken population analyses, revealing that the S atom of the carbon–sulfur group in PDEC donates electrons to the Au atom, forming dominant positive coordination bonds, whereas the acetylene group accepts partial electrons from the Au atom, resulting in weaker back-donation bonds. The adsorption experiments align with the DFT adsorption energy results.