Electronegative Groups Research Articles

Regulating defect density of iron based metal–organic frameworks by defective ligands functionalization to enhance fenton-like activity and stability

Generating defect sites in iron based metal–organic frameworks (Fe-MOFs) by introducing defective ligands has recently emerged as an effective approach to optimize Fenton-like activity, but the structure–activity relationship between defective ligands and Fenton-like reaction is still not fully understood. Herein, a series of defective MIL-100(Fe), i.e., Dx-MIL-100(Fe), were constructed via introducing defective ligands with various functional groups including -N,–NO2,-Cl and –OH. It was observed that defect density and Fenton-like activity of DX-MIL-100(Fe) is positively correlated with the electronegativity of functional groups in defective ligands. With the increasing defect density, the stability and recyclability of DX-MIL-100(Fe) in Fenton-like reaction was not decreased, which is attributed to increasing coordination bond energy between defective ligands and Fe-O cluster. The high defect density results in the increase of electron density of Fe and rate of FeⅢ reduction. Therefore, DN-MIL-100(Fe) possessing highest defect density exhibited superior Fenton-like activity with the pseudo-first-order kinetic constant up to 0.089 min−1 for Bisphenol A degradation, which is 148.3 times than that of perfect MIL-100(Fe). Meanwhile, DN-MIL-100(Fe) showed excellent pH adaptability, anti-interference ability and cycle stability. This work unravels the role of functional groups in defective ligands on regulating defect density, Fenton-like activity and stability for the first time, which can provide a novel platform for precisely designing Fe-MOFs as promising Fenton-like catalyst.

Regulating the electronic microenvironment of adsorption sites in nanofiber for promoting In(III) capture performance

Enhancing adsorbent-adsorbate interactions via rational construction of adsorption sites is essential for the capture of the strategic metal indium. Herein, a nanofiber (PCA-Nanofiber) was successfully fabricated for In(III) ions recovery by introducing an electronegative fluorine-containing group to modulate the electronic structure of adsorption sites. Adsorption experiments exhibited that the maximum adsorption of PCA-Nanofiber for In(III) ions (116.3 mg/g) was 3.3 times higher than that of the pre-regulated nanofiber, exceeding most of the reported adsorbents. The PCA-Nanofiber maintained stable performance in five consecutive adsorption–desorption experiments and exhibited excellent selectivity. Furthermore, advanced spectroscopic characterization revealed that the adsorbed complex presented in a six-coordinated octahedral configuration, resembling an anti-triangular prism configuration centered on In(III) ions. The density functional theory demonstrates that the excellent adsorption performance benefits from the electronegative F atoms modulating the electronic microenvironment of the adsorption sites and optimizing the band-gap energy for charge migration, resulting in efficiently driven charge transfer. This work offers ideas for the rational design of adsorption sites in nanofiber from the perspective of regulation of electronic microenvironmental.

Adsorption performance of the functional COFs for removal of bisphenol A: Molecular dynamic simulations

The inherent structural features of the covalent organic frameworks (COFs) play a crucial role in determining their adsorption performances for bisphenol A (BPA). The computational methods were advantageous in unraveling intrinsic molecular properties about their performances. Herein, some COFs with different functional groups (–COOH, –NH2, –NO2 and –CF3) were designed to demonstrate the efficacy of the functional COFs for adsorbed BPA in gas phase and aqueous solution. The density functional theory (DFT) and Grand Canonical Monte Carlo (GCMC) methods were used to analyze the interaction energy between COFs and BPA, structure properties, and adsorption performances etc.. The results indicated that the addition of strong electronegative functional groups in COFs increased these COFs’ isosteric heat of adsorption (Qst) (TpBD-(COOH)2 > TpBD-(CF3)2 > TpBD-(NH2)2 > TpBD-(NO2)2 > TpBD) for gas phase BPA, but their introduction also reduced the pore size of COFs (TpBD > TpBD-(COOH)2 > TpBD-(NH2)2 > TpBD-(CF3)2 > TpBD-(NO2)2). However, these functional COFs demonstrated the stronger the adsorption capacity for gas phase BPA (At 298 K and 1 bar, the BPA uptake of TpBD-(COOH)2, TpBD-(NH2)2, TpBD, TpBD-(NO2)2 and TpBD-(CF3)2 was 242.52, 232.43, 219.31, 206.64 and 197.73 mg/g, respectively.). The amount of BPA adsorbed by functional COFs was the result of the synergistic effect of the electronegativity of functional groups and the pore size. Molecular dynamic (MD) simulation performed the same phenomenon for BPA in aqueous solution. In addition, the higher temperature will decrease the adsorption amount of BPA by COF, but increase its desorption ability.

Multifunctional Asymmetric Separator Constructed by Polyacrylonitrile-Derived Nanofibers for Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries hold great promise as next-generation high-energy storage devices owing to the high theoretical specific capacity of sulfur, but polysulfide shuttling and lithium dendrite growth remain key challenges limiting cycling life. In this work, we propose a polyacrylonitrile-derived asymmetric (PDA) separator to enhance Li-S battery performance by accelerating sulfur redox kinetics and guiding lithium plating and stripping. A PDA separator was constructed from two layers: the cathode-facing side consists of polyacrylonitrile nanofibers carbonized at 800 °C and doped with titanium nitride, which can achieve rapid polysulfide conversion via electrocatalysis to suppress their shuttling; the anode-facing side consists of polyacrylonitrile oxidized at 280 °C, on which the abundant electronegative groups guide uniform lithium ion plating and stripping. Li-S batteries assembled with the PDA separator exhibited enhanced rate performance, cycling stability, and sulfur utilization, retaining 426 mA h g-1 capacity at 1 C over 1000 cycles and 632 mA h g-1 at 4 C over 200 cycles. Attractively, the PDA separator showed high thermal stability, which could mitigate the risk of internal short circuits and thermal runaway. This work demonstrates an original path to addressing the most critical issues with Li-S batteries.

Accelerating the discovery of N-annulated perylene organic sensitizers via an interpretable machine learning model

A data-driven strategy was proposed by combining machine learning (ML) model and first-principles verification to rapidly quarry efficient and synthesizable candidate organic sensitizers from the vast chemical space of dye-sensitized solar cell (DSSC) sensitizers. We built interpretable machine learning models using easy-to-obtain descriptors and obtained 50 candidates which could be synthesized and have the overall power conversion efficiency (PCE) greater than 13 %. Especially, the density functional theory (DFT) and time-dependent density functional theory (TD-DFT) showed that top 2 candidates had better open-circuit Voltage (Voc) and PCEs than C281. And the PCE predicted by the ML model was roughly consistent with the ones calculated by quantum chemistry. Model analysis revealed that Cobalt-based electrolyte was the better option. Paid attention to the electronegativity and molecular weight of doner of N-annulated perylene organic sensitizers (N-P sensitizers), appropriately increased the electronegativity group of accepter fragment. Hopefully, this data-driven approach is expected to provide further creativity for the practical application of other advanced energy materials.

Engineering a localized electrostatic environment to enhance hydroxyl activating for electrocatalytic biomass conversion

The 5-hydroxymethylfurfural electrocatalytic oxidation reaction (HMFOR) is a sustainable and efficient route for converting biomass platform molecules into high-value chemicals. The HMFOR process involves the simultaneous oxidation of hydroxyl and aldehyde groups. Optimizing the reaction pathways by modulating the adsorption behavior of 5-Hydroxymethylfurfural molecules toward a higher conversion rate is vital for achieving an efficient HMFOR. In this study, the HMFOR electrocatalytic performance of NiO was enhanced by regulating the surface microenvironment through the decoration of NiO nanosheets with polypyrrole (PPy). Operando Fourier transform infrared spectroscopy, density functional theory calculation, and electrochemical behavior characterizations demonstrated that electropositive PPy can optimize the adsorption behavior of electronegative hydroxyl groups and modulate the reaction pathway toward the formation of 2,5-diformylfuran intermediates. By modulating the local microenvironment, the designed NiO-PPy catalyst showed excellent HMFOR performance with a threefold increase in current density. This study emphasizes the significance of the surface microenvironment in modulating reaction pathways to achieve selective biomass electrocatalytic conversion.

Aquatic toxicity, ecological effects, human exposure pathways and health risk assessment of liquid crystal monomers

Liquid crystal monomers (LCMs), one of the key materials for liquid crystal displays, have been considered as emerging pollutants in recent years. However, the environmental behaviors of LCMs have not yet been well investigated. The toxicity data of 1173 LCMs were calculated by integrated computational simulation methods in this study. It showed that 64.6% LCMs exhibited PBT (persistent, bioaccumulative, and toxic) properties. Based on the results, 1173 LCMs were identified as molecules possessing the highest level of acute toxicity to aquatic organisms. Among which, and a human health risk priority control list about LCMs was generated in this study, among which 435 were classified as requiring priority control LCMs. It was confirmed that LCMs could eventually accumulate in the human body along the aquatic food chain or penetrate the bloodstream through the dermis, thereby causing harm to health by identifying the exposure pathways of LCMs in humans. Additionally, the electronegativity of the side chain group of LCMs is the main factor causing toxicity differences; therefore, the LCMs containing halogens presented significant acute and chronic toxic effects. This study provided a more comprehensive understanding of LCMs for the public and scientific strategies for controlling LCMs.

Hydrogen bond recombination regulated by strongly electronegative functional groups in demulsifiers for efficient separation of oil–water emulsions

Tight oil extraction and offshore oil spills generate large amounts of oil–water emulsions, causing serious soil and marine pollution. In such oil–water emulsions, the resin molecules are bound by π–π stacking and bind to interfacial water molecules via hydrogen bonds, which impede the aggregation between water droplets and thereby the separation of the emulsion. In this study, strongly electronegative oxygen atoms (in ethylene oxide, propylene oxide, esters, and hydroxyl groups) were introduced through poly(propylene glycol)-block-polyether and esterification with acrylic acid to attract negative charges in order to form electron-rich regions and enhance interfacial hydrogen bond recombination. The potential distribution in the demulsifier molecules and their space occupancy were regulated by the polymerization reaction to destroy the π–π stacking interaction between resin molecules. The results show that the binding energies (binding free energy and hydrogen bonding energy) of oxygen-containing demulsifier molecules with water molecules were higher than those of resin molecules with water molecules, resulting in the fission of the hydrogen bonds between resin and water molecules. The introduction of demulsifier molecules that occupied large interfacial space reduced the binding energy between resin molecules from −2176.06 to −110.00 kJ·mol−1. Noteworthy, the binding energy between demulsifier molecules and resin molecules was −1076.36 kJ·mol−1 lower than that between resin molecules (−110.00 kJ·mol−1), indicating the adsorption of the surrounding interfacial resin molecules by the demulsifier molecules and destruction of the π–π stacking between them, thus favoring the collapse of the interfacial structure of the oil–water emulsion and achieving its separation. This study provides important theoretical support for the treatment of oil-contaminated soil and offshore oil spill pollution.

Novel insights of structure evolution between ZIF and hydroxide via controlled doses of ammonium bifluoride and applications on battery supercapacitor hybrids

Metal organic framework is often post-treated to increase electrical conductivity and electroactivity for application on battery supercapacitor hybrids (BSH). An in-situ modification is previously proposed to replace post-treatments via incorporating ammonium fluoride (NH4F) during synthesizing zeolitic imidazolate framework-67 (ZIF67) to develop derivatives with excellent energy storage ability. Inspired by structure directing ability of ammonium group, high electronegativity of fluorine-based group, and time and money-saving process of in-situ modification, a novel structure directing agent (SDA), ammonium bifluoride (NH4HF2), is proposed in this study to design ZIF67 derivatives via the facile one-step solution process for the first time. The amounts of NH4HF2 and 2-methylimidazole are varied to fabricate a series of ZIF67 derivatives, and the SDA effects on physical and electrochemical properties are investigated. The highest specific capacitance (CF) of 1116.7 F/g and the capacity of 217.1 mAh/g are achieved for the optimal ZIF67 derivative at 20 mV/s, because of the thinnest layers with large surface area and abundant electrolyte contacts. The ZIF67 derivative and carbon electrodes are applied to fabricate a BSH, which displays a CF retention of 84.8% and Coulombic efficiency of 96.1% after measuring the charge/discharge curves at 1.0 A/g for 10,000 cycles, as well as the maximum energy density of 7.3 Wh/kg at the power density of 714.3 W/kg.

Atomic-level insights into the mechanism by which synthetic organic fibers enhance the tensile strength of concrete

Improving tensile strength has always been a hot research topic in the field of concrete. Synthetic organic fibers are usually used to enhance the tensile strength of concrete, so it is important to understand its strengthening mechanism. However, there are few reports revealing its mechanism at the atomic scale. To fill this gap, we selected three typical synthetic organic fibers (Polypropylene (PP), Polyacrylonitrile (PAN), and Polyvinyl alcohol (PVA)) to prepare fiber-reinforced concrete (FRC) and investigated the influence mechanism on splitting tensile strength. The influence of fibers on concrete strength were studied and fibers’ state in concrete were observed. Molecular models of fibers and concrete hydration products (calcium hydroxide (CH) and calcium silicate hydrate (CSH)) were established to study the adsorption energy between fiber and hydration products. The chemical properties of fibers were investigated by first principles calculation. Results show that the adsorption energy is positively correlated with the splitting tensile strength of concrete. The adsorption energy of fiber to calcium hydroxide is stronger than that of calcium silicate hydrate. The electronegative groups of fibers are functional groups that increase the tensile strength of concrete splitting. These findings can provide a theoretical basis for fiber modification and serve as a valuable reference for strengthening the strength of the transition zone of concrete.

Various Techniques for the Synthesis of 2-Nitrophenylamino-1,4-naphthoquinone Derivatives

Nitrated products are important since they are intermediates in the synthesis of other compounds, such as explosives, perfumes, dyes and plastics, among others, and they have an easy capacity to convert into other functional groups. The synthesis of compounds with biological activity that have a nitro group in their structure is relevant to improving and/or enhancing their effect. In this work, different methodologies for the nitration of naphthoquinone derivative compounds are presented. The nitration of 3-R-2-(phenylamino)-1,4-naphthoquinone derivatives was carried out with nitric acid and sulfuric acid; milder reaction conditions were also established by diluting the acids or performing the reaction with weaker acids. Other methodologies were tested using nitrate salts for mononitrate product synthesis. We used a solvent-free reaction with oxalic acid using 3-R-2-(phenylamino)-1,4-naphthoquinones (R=H, Br or Cl), noting that the electronegativity of the chlorine group is decisive for achieving nitration with good yields. Finally, a Michael addition was performed with some nitrated anilines. To obtain denitrated compounds in the ortho and para positions, the reaction with strong acids is feasible; however, for the formation of mononitrated products, the Michael-type addition is more convenient.

Effects of MOFs size and functional group on the pore structure and performance of thin-film nanocomposite membranes

Incorporation of nanomaterials into the selective layer during the interfacial polymerization process was an effective way to improve the perm-selectivity of the membranes. In this study, the piperazine enriched templates assisted interfacial polymerization method was proposed to enhance the salts rejection of thin-film nanocomposite (TFN) membranes. The mono-dispersed UiO-66 type MOFs with high amine adsorption ability were utilized as templates to increase the reaction region and promote the participation of piperazine (PIP) during the interfacial polymerization reaction, resulting in a denser polyamide (PA) layer with weaker surface electronegativity and higher nitrogen-containing group contents. The TFN membranes prepared with 236 nm UiO-66-OH and PIP concentration of 0.35 w/v% exhibited smaller mean pore size (0.636 nm) and reduced surface zeta potential (−26.0 mV) compared to the pristine TFC membranes (0.667 nm and −31.1 mV). Consequently, the rejection of 10 mM MgCl2, MgSO4 and Na2SO4 was increased from 44.7%, 97.7% and 98.3% to 84.3%, 99.2% and 99.5%, respectively, while the pure water flux was slightly decreased from 53.5 L m−1 h−1 to 37.4 L m−1 h−1 at 0.3 MPa. In addition, the size and functional group of the MOFs were found to have significant impacts on the pore structure and performance of the TFN membranes. The increasing of reaction region with relatively large MOFs and higher absorption ability were beneficial to obtain a thicker PA layer, while strong interaction between MOFs and PA oligomers was unfavorable for PA chain packing. Therefore, the TFN membranes prepared with UiO-66-NO2 exhibited a much narrow size distribution and high rejection to all salts, whether by divalent cationic salt or divalent anion salts, i.e., MgCl2 of 95.5%, MgSO4 of 98.9% and Na2SO4 of 99.1%, and the pure water flux was 28.6 L m−1 h−1 at 0.3 MPa. These results illustrated the influences of MOFs size and functional group on the interfacial polymerization process, which was crucial for the TFN membranes preparation.

Fluorinated polyimide with triphenyl pyridine structure for 5G communications: Low dielectric, highly hydrophobic, and highly transparent

With the rapid development of 5G communications, the traditional interlayer dielectric material polyimide (PI) requires modification due to its intrinsically high dielectric constant (Dk), high dielectric loss (Df), and high moisture absorption, which make it difficult to meet the needs of the high-frequency communications industry. In this paper, a new strategy for the preparation of novel PI with intrinsically low Dk and Df is proposed from the perspective of molecular structure design, the modification effect of superimposing bulky triphenyl pyridine structures and strong electronegativity groups, combined with long-chain anhydride to reduce the density of the imide structure. Therefore, three bulk diamine monomers (BPAB, PBAB3F, PBAB6F) containing triphenyl pyridine structures were designed in this paper and polymerized with 4,4′-(4,4′-isopropyldiphenoxy) phthalic anhydride (BPADA) to obtain three new PIs (PI-H, PI-CF3, PI-2CF3) with different fluorine contents, focusing on the relationship between structure and properties, especially the effect of fluorine content on dielectric properties. The results of the study show that the dielectric and hygroscopic properties of PI improve with increasing fluorine content. Among them, PI-2CF3 has the best overall performance, showing low dielectric (Dk = 2.72@10 GHz & Df = 0.00233@10 GHz), high transparency (Cut-off wavelength (λ0) = 389 nm, Maximum transmittance (Tvia) = 89%) and low hygroscopicity (Water absorption (Ma) = 0.246%, Contact angle (Ca) = 111°).

Single-ion conductors functionalized graphene oxide enabling solid polymer electrolytes with uniform Li-ion transport toward stable and dendrite-free lithium metal batteries

The utilization of poly(ethylene oxide) (PEO)-based solid polymer electrolytes (SPEs) has long been deemed promising for the application of state-of-the-art lithium metal metals (LMBs), but still severely impeded by the insufficient Li-ion transporting channels and inhomogeneous Li deposition. Herein, the design of single-ion conductors (PSLi) modified graphene oxide nanosheets (GO-PSLi)-reinforced PEO-based SPEs to address these long-standing issues is proposed. The electronegative sulfonate-rich groups with lithiophilic features on GO-PSLi surface not only effectively enhance the dispersion of nanoparticles within the PEO matrix, but also provide fast Li-ion diffusion pathways. Meanwhile, introducing PSLi chains is also favorable to highly reducing the crystallization of composite SPEs through hydrogen interactions derived from the desired amide functional groups. This, in turn, facilitates segmental relaxation of the PEO backbone, leading to accelerates the Li-ion migration. As a proof of concept, the as-prepared composite SPEs demonstrate a good ionic conductivity of 2.2 × 10−4 S cm−1 and a high lithium transference number of 0.53, significantly outperforming the pure PEO SPEs (1.0 × 10−4 S cm−1 and 0.28, respectively) at 60 °C. In addition, the symmetrical Li||Li cells based on the composite SPEs show excellent reversible lithium plating/stripping performances with dendrite-free uniform lithium deposition over 1100 h under a current of 0.1 mA cm−2 at 60 °C. The Li||LiFePO4 batteries also achieve an impressive capacity of 120.2 mAh g−1 at a high current density of 4C and deliver remarkable cycling abilities with 84.6% retention after 250 cycles under 1C at 60 °C. This study offers a facile and practical strategy to develop advanced composite PEO-based SPEs for safe and dendrite-free solid-state LMBs.

DFT-based analysis of siderophore-metal ion interaction for efficient heavy metal remediation.

Siderophores have great application potential in metal pollutant remediation because of their effective cost and friendly impact on the environment. However, the practical use of siderophores in the remediation of specific metals is rather limited because of the weak nonspecific interactions between the siderophores and different metals. Thus, screening for a siderophore with optimal interaction with a specific metal would be necessary. In this study, the interaction between metal ions and moieties that donate the oxygen ligands for the coordination of four types of siderophore (hydroxamates, catecholates, phenolates, and carboxylates) was modeled and analyzed. As revealed by DFT-based analysis, the four types of siderophore generally exhibited selection preference for different metal ions in the order Ga3+ > Al3+ > Fe3+ > Cr3+ > Ni2+ > Cu2+ > Zn2+ > Co2+ > Mn2+ > Hg2+ > Pb2+ > Cd2+, which was determined mainly by the electronegativity of the siderophore functional groups, the electronegativity of the metals, and the ionic radius of the metals, as well as the interaction between the siderophores and the metals. Moreover, the effect of linear or nonlinear (cyclic) structure on the affinity of each siderophore for different metal ions was evaluated. In most situations, metal-bound cyclic siderophores were found to be more stable than their linear counterparts. Thus, proper siderophores for the remediation of metal pollution may be rapidly screened using this model.

Carbonate modified polyester nanofiltration membrane: Separation performance and mechanism investigation

The development of loose nanofiltration (LNF) membranes with high water flux and excellent separation performance is of great significance for wastewater treatment and resource recovery. As a green polyphenol with high molecular weight, tannic acid (TA) is an attractive aqueous monomer to prepare LNF membranes via interfacial polymerization (IP) with trimesoyl chloride (TMC). To the best of our knowledge, this work first reports a facile and delicate method to regulate reaction sites of the aqueous monomer by oxidizing a certain proportion of hydroxyl groups under weak alkaline condition caused by carbonate to tailor the morphology of polyester layer. The resulted nanobubbles generated by the reaction of carbonate with H+ produced during the IP reaction (which also promoted the IP process) rendered polyester layer nanovoids structure. Compared with the pristine membrane, the tailored morphology of active layer decreased 93.24% membrane resistance and significantly improved water flux up to 13.55 times, while maintained effective dye/salt separation. Furthermore, the polyester NF membrane possessed high electronegativity and abundant oxygen-containing functional groups, which could effectively remove heavy metal ions Pb2+, Cu2+ and radionuclide uranium (U(VI)) from water through Donnan effect and adsorption, with the rejection rates of above 95.39%, 94.71% and 99.35%, respectively. This work provides a noteworthy modification idea for the preparation of high-performance multifunctional LNF membranes derived from green polyphenols to deal with some challenges such as dye separation, heavy metal ions and radionuclide removal.

Three-Step Method to Teach Inductive Effect

The inductive effect is one of the very important concepts of electronic effects in organic chemistry. In traditional teaching methods, only the origin, transmission mode, and decay of the inductive effect are introduced briefly, which is not conducive to students’ complete understanding of the inductive effect. This work developed a new method to teach inductive effect, named the “Three-step Method” (TsM): (1) establishing the concept of inductive effect; (2) evaluating the transmission distance of inductive effect qualitatively; and (3) determining the attenuation factor of inductive effect quantitatively. In the TsM, the group electronegativity, nuclear magnetic resonance chemical shift of H atom, and data fitting method are employed to discuss the origin, transmission mode, transmission distance, and attenuation factor of the inductive effect. The TsM of this paper is intuitive and simple, and takes less than 10 minutes in the classroom, which can help students to understand the concept of inductive effect in-depth and to cultivate students’ molecular structure–property reasoning ability.

Halogenation effect on physicochemical properties of Ti3C2 MXenes

Halogenated MXenes have been experimentally demonstrated to be promising two-dimensional materials for a wide range of applicability. However, their physicochemical properties are largely unknown at the atomic level. In this study, we applied density functional theory (DFT) to theoretically investigate the halogenation effects on the structural, electronic, and mechanical characteristics of Ti3C2, which is the most studied MXene material. Three atomic configurations with different adsorption sites for four kinds of halogen terminals (fluorine, chlorine, bromine, and iodine) were considered. Our DFT results reveal that the adsorption site of terminals has a considerable impact on the properties of MXene. This can be ascribed to the different coordination environments of the surface Ti atoms, which change d-orbital splitting configurations of surface Ti atoms and the stabilities of systems. According to the density of states, crystal orbital Hamilton population, and charge analyses, all the considered halogenated MXenes are metallic. The electronic and mechanical properties of the halogenated MXenes are strongly dependent on the electronegativity of the halogen terminal group. The Ti–F bond has more ionic characteristics, which causes Ti3C2F2 mechanically behave in a more ductile manner. Our DFT results, therefore, suggest that the physicochemical properties of MXenes can be tuned for practical applications by selecting specific halogen terminal groups.

Accelerated Fe(II) regeneration on Fe-doped oxidized carbon nanotube enabling highly-efficient electro-Fenton process for pollutants removal

Heterogeneous electro-Fenton (e-Fenton) is considered a prospective technology for persistent organic contaminants removal that relies on the strongly oxidizing •OH. However, the efficiency of e-Fenton is still low as the sluggish Fe(II) regeneration caused by the difficulty modulating the electronic structure of Fe(III) center. Herein, the Fe-doped oxidized carbon nanotube catalysts (OCNT-Fe) is prepared to accelerate Fe(II) regeneration by introducing electronegative oxygen-containing groups and inducing local charge distribution of Fe(III) center. The OCNT-1Fe exhibits an excellent e-Fenton performance for phenol degradation with a kinetic rate of 0.11 min−1 at pH 6.5, which is the highest among reported state-of-the-art e-Fenton catalysts. Moreover, OCNT-1Fe catalyst is demonstrated to be more energy efficient in coking wastewater treatment with an energy consumption of 6.5 kW h kgCOD−1 than other e-Fenton systems of 9.2–29.7 kW h kgCOD−1. This work offers a new perspective on the high-performance e-Fenton catalysts design by rationally modulating the electronic structure for organic pollutants removal.

Insight into the addition reactions of stannylenoid H2SnLiF with ethylene.

Tetrylenoids, R2EXM (E = Si, Ge, and Sn; X = electronegative group; M = alkali metal), have electrophilic and nucleophilic properties just like carbenoid. As the products of carbenoid compounds with olefins, the cyclopropane fraction has been found to be biologically active in many natural and artificial compounds. Can carbenoid analogues of stannylenoid facilitate similar cyclopropanation reactions? Addition reaction of the stannylenoid compound H2SnLiF with ethylene was investigated using density function theory (DFT) at the M062X/def2-TZVP level. The single-point energy calculations were performed on the basis of QCISD/def2-TZVP level. Two possible pathways were found for the addition reaction of H2SnLiF (R1) with ethylene (R2). The most favorable path is the two successive reactions of H2SnLiF and ethylene through the ternary ring product c-H2Sn(CH2)2 (P1) and then the formation of the five-membered ring product (P2). Solvation-related studies have shown that addition reactions are more likely to occur in the presence of THF solvents. This work provides theoretical support for the reactions of stannylenoid with olefins.