Experimental and Quantum Chemical Calculations on the High-Efficiency Transesterification of Dimethyl Carbonate with Alcohol Catalyzed by Calcium Oxide.

Typical catalysts used in dimethyl carbonate (DMC) transesterification encounter challenges in terms of environmental sustainability and economic viability. Calcium oxide (CaO), being an environmentally friendly and cost-effective catalyst, exhibits favorable compatibility with the criteria above. It has been conclusively demonstrated that CaO performs high efficiency as a catalyst for the transesterification between alcohols and DMC. The optimal conditions for the CaO-catalyzed transesterification of DMC and 1-octanol were determined (90 °C, 17 h, and CaO/1-octanol/DMC molar ratio = 0.3:1.0:40.0), under which the conversion of 1-octanol reaches 98.3%, while the yield and selectivity of methyl octyl carbonate are 98.1 and 99.9%, and CaO has been proven to have the efficient ability to be recycled three times. Meanwhile, the CaO-catalyzed reaction mechanism of the transesterification of DMC with alcohol is illustrated in the quantum chemical method based on the M06-2X functional, and the structures of the corresponding transition states are simultaneously derived. The activation energy barrier is proven to be effectively decreased by the catalytic effect of CaO. In addition, the electrostatic potential diagram verifies the proposed reaction sites. This research constructs the theoretical basis for CaO-based DMC chemistry and expands the green catalysts available for the synthesis of dialkyl carbonates.

Tf2O-Mediated Tandem Reaction of Enaminones for the Synthesis of Functionalized Conjugated-Enals/ß-Naphthalaldehydes.

A highly efficient and regioselective method for constructing functionalized conjugated enals via the Tf2O-mediated tandem reaction of enaminones with thiophenols has been described. Chain products with excellent stereoselectivity could be obtained through substrate regulation. Additionally, a feasible method for synthesizing ß-naphthalaldehydes through PhSO2Na/DABCO promoting hydrogen atom transfer process has also been reported here. Mechanism studies have shown that 2-formyl vinyl triflate 8 and sulfonylated enal 9 were the key intermediates in this process.

Bi-modified Cu-Based Catalysts for Acetylene Hydrogenation: Leveraging Dispersion and Hydrogen Spillover.

Removing trace acetylene from the ethylene stream through selective hydrogenation is a crucial process in the production of polymer-grade ethylene. However, achieving high selectivity while maintaining high activity remains a significant challenge, especially for nonprecious metal catalysts. Herein, the trade-off between activity and selectivity is solved by synergizing enhanced dispersion and hydrogen spillover. Specifically, a bubbling method is proposed for preparing SiO2-supported copper and/or bismuth carbonate with high dispersion, which is then employed to synthesize highly dispersed Bi-modified CuxC-Cu catalyst. The catalyst displays outstanding catalytic performance for acetylene selective hydrogenation, achieving acetylene conversion of 100% and ethylene selectivity of 91.1% at 100 °C. The high activity originates from the enhanced dispersion, and the exceptional selectivity is due to the enhanced spillover capacity of active hydrogen from CuxC to Cu, which is promoted by the Bi addition. The results offer an avenue to design efficient catalysts for selective hydrogenation from nonprecious metals.

CdBi2S4-Decorated Aminated Polyacrylonitrile Nanofiber for Photocatalytic Treatment of Cr(VI) and Tetracycline Wastewater.

The significant threat posed by the high toxicity of heavy metals and antibiotics in water pollutants has prompted a growing emphasis on the development of highly efficient removal methods for these pollutants. In this paper, flexible electrospinning polyacrylonitrile (PAN) nanofiber-supported CdBi2S4 was synthesized via a hydrothermal method, followed by amination treatment with diethylenetriamine (DETA). The as-prepared CdBi2S4/NH2-PAN nanofiber, enriched with sulfur vacancies, demonstrated outstanding visible-light trapping ability and a suitable band gap, leading to efficient separation and transport of photogenerated carriers, ultimately resulting in exceptional photocatalytic capability. The optimal 3-CdBi2S4/NH2-PAN nanofiber achieved impressive reduction rates of 92.26% for Cr(VI) and 96.45% for tetracycline hydrochloride (TCH) within 120 min, which were much higher than those for CdS/NH2-PAN, Bi2S3/NH2-PAN, and CdBi2S4/PAN nanofibers. After five cycles, the removal rate of the CdBi2S4/NH2-PAN nanofiber consistently remained above 90%. Their ease of separation and recovery from the application environment contributes to their practicality. Additionally, compared with conventional suspended particle catalyzers, the composite nanofiber exhibited remarkable flexibility and self-supporting properties.

Ultrathin LayCoOx Nanosheets with High Porosity Featuring Boosted Catalytic Oxidation of Benzene: Mechanism Elucidation via an Experiment-Theory Combined Paradigm.

Designing transition-metal oxides for catalytically removing the highly toxic benzene holds significance in addressing indoor/outdoor environmental pollution issues. Herein, we successfully synthesized ultrathin LayCoOx nanosheets (thickness of ∼1.8 nm) with high porosity, using a straightforward coprecipitation method. Comprehensive characterization techniques were employed to analyze the synthesized LayCoOx catalysts, revealing their low crystallinity, high surface area, and abundant porosity. Catalytic benzene oxidation tests demonstrated that the La0.029CoOx-300 nanosheet exhibited the most optimal performance. This catalyst enabled complete benzene degradation at a relatively low temperature of 220 °C, even under a high space velocity (SV) of 20,000 h-1, and displayed remarkable durability throughout various catalytic assessments, including SV variations, exposure to water vapor, recycling, and long time-on-stream tests. Characterization analyses confirmed the enhanced interactions between Co and doped La, the presence of abundant adsorbed oxygen, and the extensive exposure of Co3+ species in La0.029CoOx-300 nanosheets. Theoretical calculations further revealed that La doping was beneficial for the formation of oxygen vacancies and the adsorption of more hydroxyl groups. These features strongly promoted the adsorption and activation of oxygen, thereby accelerating the benzene oxidation processes. This work underscores the advantages of doping rare-earth elements into transition-metal oxides as a cost-effective yet efficient strategy for purifying industrial exhausts.

Imparting Outstanding Dispersibility to Nanoscaled 2D COFs for Constructing Organic Solvent Forward Osmosis Membranes.

In the context of thin-film nanocomposite membranes with interlayer (TFNi), nanoparticles are deposited uniformly onto the support prior to the formation of the polyamide (PA) layer. The successful implementation of this approach relies on the ability of nanoparticles to meet strict requirements regarding their sizes, dispersibility, and compatibility. Nevertheless, the synthesis of covalent organic frameworks (COFs) that are well-dispersed, uniformly morphological, and exhibit improved affinity to the PA network, while preventing agglomeration, remains a significant challenge. In this work, a simple and efficient method is presented for the synthesis of well-dispersed, uniformly morphological, and amine-functionalized 2D imine-linked COFs regardless of the ligand composition, group type, or framework pore size, by utilizing a polyethyleneimine (PEI) shielded covalent self-assembly strategy. Subsequently, the as-prepared COFs are incorporated into TFNi for the recycling of pharmaceutical synthetic organic solvents. After optimization, the membrane exhibits a high rejection rate and a favorable solvent flux, making it a reliable method for efficient organic recovery and the concentration of active pharmaceutical ingredient (API) from the mother liquor through an organic solvent forward osmosis (OSFO) process. Notably, this study represents the first investigation of the impact of COF nanoparticles in TFNi on OSFO performance.

Hydroxyl-Decorated Pt as a Robust Water-Resistant Catalyst for Catalytic Benzene Oxidation.

In catalytic oxidation reactions, the presence of environmental water poses challenges to the performance of Pt catalysts. This study aims to overcome this challenge by introducing hydroxyl groups onto the surface of Pt catalysts using the pyrolysis reduction method. Two silica supports were employed to investigate the impact of hydroxyl groups: SiO2-OH with hydroxyl groups and SiO2-C without hydroxyl groups. Structural characterization confirmed the presence of Pt-Ox, Pt-OHx, and Pt0 species in the Pt/SiO2-OH catalysts, while only Pt-Ox and Pt0 species were observed in the Pt/SiO2-C catalysts. Catalytic performance tests demonstrated the remarkable capacity of the 0.5 wt % Pt/SiO2-OH catalyst, achieving complete conversion of benzene at 160 °C under a high space velocity of 60,000 h-1. Notably, the catalytic oxidation capacity of the Pt/SiO2-OH catalyst remained largely unaffected even in the presence of 10 vol % water vapor. Moreover, the catalyst exhibited exceptional recyclability and stability, maintaining its performance over 16 repeated cycles and a continuous operation time of 70 h. Theoretical calculations revealed that the construction of Pt-OHx sites on the catalyst surface was beneficial for modulating the d-band structure, which in turn enhanced the adsorption and activation of reactants. This finding highlights the efficacy of decorating the Pt surface with hydroxyl groups as an effective strategy for improving the water resistance, catalytic activity, and long-term stability of Pt catalysts.

Nitrogen-doped carbon frameworks decorated with palladium nanoparticles for simultaneous electrochemical voltammetric determination of uric acid and dopamine in the presence of ascorbic acid.

A glassy carbon electrode (GCE) was modified with nitrogen-enriched carbon frameworks decorated with palladium nanoparticles (Pd@NCF/GCEs). The modified GCE is shown to be a viable tool for determination of uric acid (UA) and dopamine (DA) in the presence of ascorbic acid (AA). The Pd@NCF was fabricated though one-step pyrolysis and characterized by X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy and nitrogen-adsorption/desorption analysis. The Pd@NCF/GCE was characterized by differential pulse voltammetry (DPV). Both UA and DA have pronounced oxidation peaks (at 360 mV for UA and 180 mV for DA, all vs. Ag/AgCl) in the presence of AA. Response is linear in the 0.5-100 µM UA concentration range and in the 0.5-230 µM DA concentration range. The detection limits are 76 and 107 nM, respectively (at S/N = 3). This electrode is stable, reproducible and highly selective. It was used for UA and DA determination in spiked serum samples. Graphical abstractSchematic representation of nitrogen-enriched carbon frameworks decorated with palladium nanoparticles co-modified glassy carbon electrode for simultaneous determination of dopamine and uric acid in the presence of ascorbic acid.

Droplet Motion on a Shape Gradient Surface.

We demonstrate a facile method to induce water droplet motion on an wedge-shaped superhydrophobic copper surface combining with a poly(dimethylsiloxane) (PDMS) oil layer on it. The unbalanced interfacial tension from the shape gradient offers the actuating force. The superhydrophobicity critically eliminates the droplet contact line pinning and the slippery PDMS oil layer lubricates the droplet motion, which makes the droplet move easily. The maximum velocity and furthest position of droplet motion were recorded and found to be influenced by the gradient angle. The mechanism of droplet motion on the shape gradient surface is systematically discussed, and the theoretical model analysis is well matched with the experimental results.

Directional Self-Transportation of Droplets on Superwetting Wedge-Shaped Surface in Air and Underliquid Environments.

The directional self-transportation of droplets has aroused great attention in microfluidic systems. However, most reported surfaces are mainly designed for driving water droplets to move in air, displaying low adaptability in complex environments. This work presents a wedge-shaped surface with multiple superwettability, i.e., superhydrophilicity/superoleophilicity and underwater superoleophobicity/underoil superhydrophobicity, fabricated by electrodeposition of a metal-organic framework on a copper sheet. This surface exhibited excellent performance for driving droplet self-transportation, regardless of the droplet type (water or oil) and environmental media (air or underliquids). In air, the wedge-shaped surface with wedge angle of 9.2° could move droplets of water and dodecane up to 24.5 mm and 17.9 mm, respectively. The movement of water droplet under dodecane, however, dropped from 24.5 mm to 22.1 mm, while the dodecane droplet underwater increased from 17.9 mm to 20.3 mm in moving displacement, indicating the underliquid environment is in favor of manipulation of oil droplets. Furthermore, the droplet convergence, transportation, and separation were achieved on the well-designed multiple wedge tracks in air with a total movement distance up to 60.0 mm. The test of micro-oil droplets collecting under water demonstrated that a sponge with two wedges has 2.1 times the oil droplet collection capacity over that of the sponge only, providing a new strategy for efficient treatment of the micro-oil droplets contaminated water.

A superwetting stainless steel mesh with Janus surface charges for efficient emulsion separation.

Design of charged materials for demulsification of ionic surfactant-stabilized oil-in-water emulsions is emerging in recent years. Herein, a superwetting stainless steel mesh with Janus surface charges (Janus SSM) was prepared by respectively brush-coating polyethyleneimine/aminated carbon nanotubes (PEI/CNTs-NH2) coating and polyacrylic acid (PAA) coating on its two sides. Two demulsification mechanisms, i.e., electrostatic attraction-repulsion and electrostatic repulsion-attraction based on the synergism of two oppositely charged sides were proposed. Combined with the superwettability and optimized pore size, the Janus SSM can successfully be used to demulsify, coalesce and separate emulsions. In detail, the Janus SSM exhibited separation efficiencies of up to 99.29%, 97.12% for SDS- and DTAC-stabilized oil-in-water emulsions respectively under the electrostatic attraction-repulsion mechanism, and up to 97.10%, 98.57% under the electrostatic repulsion-attraction mechanism. The results indicated that the electrostatic attraction-repulsion mechanism proposed in this study is conductive to achieving higher efficiency in emulsion separation. Furthermore, excellent durability extend the operation life of Janus SSM. This Janus SSM, which combines opposite charges on its two sides, may advance the development of charged materials for emulsion separation.

A novel Janus sponge fabricated by a green strategy for simultaneous separation of oil/water emulsions and dye contaminants.

A novel Janus sponge with the ability to remove complex contaminants from water is reported. Firstly, a superhydrophilic sponge (PA@PEI-sponge) is prepared via synthesizing negatively charged phytic acid@polyethyleneimine (PA@PEI) nanoparticles and assembling them on the surface of polydopamine (PDA) and PEI-modified polyurethane (PU) sponge through electrostatic adsorption. The Janus sponge is generated by modifying one side of the PA@PEI-sponge with PDMS, which exhibits superior separation efficiency and high filtration flux toward both water-in-oil and oil-in-water emulsions due to its multiplex selective wettability and the interconnected and tortuous 3D porous channels. The numerous negatively charged active sites of PA@PEI nanoparticles and PDA layer impart the superhydrophilic PA@PEI-sponge with the removal efficiency of 39.95 ± 0.27% for malachite green (MG) via simple flow-through filtration, which can be improved to 99.92 ± 0.07% by Janus modification. More importantly, the Janus sponge exhibits an excellent treatment capacity for complex mixtures containing emulsified oil and dye, with the separation efficiency above 99.59%. The Janus sponge also demonstrates the effective separation of real industrial wastewater collected from an acrylic dyeing plant. Together with a facile and green preparation strategy, this Janus sponge shows excellent application potential for simultaneous dye removal and oil/water emulsion separation.

An efficient NiCu@C/Al2O3 catalyst for selective hydrogenation of acetylene.

The development of non-noble metal catalysts for selective hydrogenation still remains a challenge. Herein, NiCu@carbon core-shell nanoparticles supported on Al2O3 (NiCu@C/Al2O3) were prepared, which showed enhanced catalytic performance of acetylene-selective hydrogenation in comparison with NiCu/Al2O3 without carbon encapsulation. In detail, NiCu@C/Al2O3 displayed high ethylene selectivity (>86%) even at an acetylene conversion of 100% and excellent stability (>90 h). Thus, NiCu@C/Al2O3 exhibited great potential as an alternative to Pd-based catalysts for acetylene-selective hydrogenation.

Room-temperature fabrication of superhydrophobic covalent organic framework (COF) decorated cotton fabric for high-flux water-in-oil emulsion separation.

We report the preparation of a two-dimensional superhydrophobic covalent organic framework (COF)-coated cotton fabric via a rapid one-step method at room temperature. The COF-coated fabric was found to have stable superhydrophobicity and remarkable water-in-oil emulsion separation capacity with ultra-high flux under only gravity.

Stable Zr-UiO-67 constructed through polymeric network assisted post-synthetic modification and its wettability modulation.

Stable Zr-UiO-67 is prepared by introducing a fluorine-containing layer on its surface through a polymeric network assisted post-synthetic modification (PSM) strategy. The stability of the MOFs in acidic, alkaline and saline environments is improved because of the existence of a protective layer. The MOFs are superlyophobic towards liquids with a surface tension threshold of over 48 mN m-1, making them a potential choice for separating various liquid-liquid mixtures and emulsions.

Novel flexible bifunctional amperometric biosensor based on laser engraved porous graphene array electrodes: Highly sensitive electrochemical determination of hydrogen peroxide and glucose.

Polyimide-laser-engraved porous graphene (LEPG) are hopeful electrode modification materials for flexible electrochemical sensing based on its high-efficiency preparation and low cost. Herein, a flexible, multi-patterned, and miniaturized electrode was fabricated via a simple and novel direct laser engraving. 3D LEPG with porous network structure can selective decorated with Pt nanoparticles (Pt NPs) by in situ electrochemical depositions (Pt-LEPG) as sensitively H2O2 sensors with a wide range of linear (0.01-29 nM) and high sensitivity (575.75 µA mM-1 cm-2). Subsequently, a glucose biosensor was successfully constructed through immobilized glucose oxidases (GOD) onto Pt-LEPG electrode. New-designed GOD/Pt-LEPG glucose sensor exhibited a noteworthy lower limit of detection (0.3 µM, S/N = 3) and high sensitivity (241.82 µA mM-1 cm-2), as much a wide-range of linear (0.01-31.5 mM) at near-neutral pH conditions, enabling detect glucose in real human serum specimens with satisfactory results. Predictably, these outstanding performance sensors have great potential in terms of flexible and wearable electronics.

Fabrication of superhydrophilic PVDF membranes by one-step modification with eco-friendly phytic acid and polyethyleneimine complex for oil-in-water emulsions separation.

Superhydrophilic membranes with simultaneous underwater superoleophobicity are highly desirable and worth exploring for separation of emulsified oil from water. In this work, combining the strong negative charges of phytic acid (PA) and the high cationic charge density of polyethyleneimine (PEI), an eco-friendly PA@PEI polyelectrolyte complex was synthetized in aqueous solution. And then the polyelectrolyte complex was deposited onto hydrophobic PVDF membranes through a one-step assembly approach with high convenience, endowing the membranes with superhydrophilic and underwater superoleophobic property. The as-prepared PA@PEI/PVDF membrane shows outstanding static and dynamic water stability, and was successfully used to separate multiple oil-in-water emulsions, with an average rejection rate exceeding 98.5% and a water flux up to 12203.6 L m-2∙h-1∙bar-1. Furthermore, the water flux can be recovered to a high level after four separation-washing cycles, showing excellent antifouling performance and recovery capability. Together with its natural raw materials and environmentally friendly preparation strategy, the PA@PEI/PVDF membrane shows great potential in practical treatment of emulsified oily wastewater.

A durable superwetting clusters-inlayed mesh with high efficiency and flux for emulsion separation.

How to rapidly and efficiently separate surfactant-stabilized emulsions has been a great challenge for oil/water separation materials. In this work, a durable superwetting copper mesh with high efficiency and flux for gravity-driven emulsion separation was fabricated by subtly inlaying polydopamine/polyethyleneimine@aminated carbon nanotubes (PDA/PEI@CNTs-NH2) clusters in the mesh pores. The porous clusters with abundant cationic groups render the mesh with superwettability, submicron permeation channels and positive charges, so as to achieve strong demulsification ability. Based on the superwettability and the strong demulsification ability, the PDA/PEI@CNTs-NH2 clusters-inlayed copper mesh (PPC-CM) exhibited high separation efficiency of over 99.5% for various anionic surfactant-stabilized oil-in-water emulsions. Meanwhile, the permeation flux of PPC-CM solely driven by gravity is as high as 3946.3 L m-2 h-1. The strong demulsification ability and high permeation flux of the superwetting mesh are due to the synergistic action of charge-screening effect of -NH3+ and size-sieving effect of optimized pore size. Furthermore, the resultant mesh exhibited excellent durability that it could resist serious physical abrasion and chemical corrosion. Especially the mesh after repeated separation can recover its positive charge by a simple acid treatment. These excellent performances highlight the superwetting mesh a promising potential for sustainable separation of highly stabilized oil/water emulsions.

Microwave-Assisted Solvothermal Synthesis of Covalent Organic Frameworks (COFs) with Stable Superhydrophobicity for Oil/Water Separation.

COFs were synthesized by a microwave-assisted solvothermal route, with the building blocks containing 1,3,5-tris(4-aminophenyl) benzene and 2,3,5,6-tetra-fluoroterephthalaldehyde (or 1,4-phthalaldehyde). The -F groups introduced into the benzene ring promoted hydrophobicity and stability of the COFs. The universality and long effectiveness of oil adsorption can be realized when applying COFs as adsorbent. The powder also exhibited excellent water-in-oil emulsions separation performance, with the separation efficiency no lower than 99.5%. In this work, the use of microwave solvothermal synthesis of superhydrophobic COFs is potential to replace the conventional synthesis process and more suitable for industrial scale-up production. Furthermore, the findings provide a new strategy for solving the problem of oil spill treatment and industrial water-in-oil emulsions separation by using the emerging 2D COFs.

Hard-and-Soft Integration Strategy for Preparation of Exceptionally Stable Zr(Hf)-UiO-66 via Thiol-Ene Click Chemistry.

UiO-66 metal-organic frameworks (MOFs) are unstable in some harsh aqueous environments, which limit their practical applications. We demonstrate a postsynthetic modification methodology to transform hydrophilic Zr(Hf)-UiO-66 into superhydrophobic Zr(Hf)-UiO-66-SH-y (SH = thiol, y = fluoroalkyl) by introducing long fluoroalkyl chains into organic linkers through a thiol-ene click reaction. Water contact angles of the four modified UiO-66 MOFs are all larger than 150°. The grafted low-surface-energy fluorine-containing groups become an effective protective shield for the MOFs, making them exhibit remarkable stability in extreme conditions such as alkaline (pH = 12), saturated HCl, and high concentration of NaCl solution (20 wt %). The Zr-UiO-66 MOFs grafted with 1H,1H,2H-perfluoro-1-hexene have high CO2 adsorption contents of 1.54 and 2.88 mmol·g-1 at 298 and 273 K, respectively. Moreover, the superhydrophobic MOFs also showed potential application in oil/water separation.