Langmuir最新文献

Tribocatalysis,which converts mechanical energy into chemicalenergy, offers a green route for water treatment, yet efficient, recoverable,and durable tribocatalysts remain scarce. Herein, a magnetic Fe₃O₄/Au nanocomposite was developed for organic dyedegradation. Although Fe₃O₄/Au has been widelystudied in photocatalysis and Fenton-like systems, its tribocatalyticapplication is largely unexplored. The composite was synthesized bya solvothermal method using polyethylenimine as a scaffold, followedby grafting dithiocarbamate and self-assembling AuNPs (5–20nm) onto Fe₃O₄ hollow microspheres (∼200nm). Characterization (XRD, TEM, SEM, XPS, BET, VSM) confirmed a stableheterostructure with mesoporous features (21.3 m²/g) andstrong superparamagnetism (66.84 emu/g), enabling magnetic recoverywithin 15 s. XPS revealed a +0.07 eV shift of Fe 2p_3/2 uponAu loading, evidencing interfacial electron transfer from Fe₃O₄ to Au and formation of a Schottky barrier that promotescharge separation. Under optimized stirring (500 rpm, 5 h), Fe₃O₄/Au achieved 100% degradation of (RhB) (5 mg/L,50 mL) with a rate constant of 0.7751 h^–1, outperformingpure Fe₃O₄ and AuNPs. The near-neutral pH condition(pH ≈ 7) was found to be optimal for the tribocatalytic performance.Radical scavenger and EPR experiments identified ^•OH as the primary active species and ^•O₂^– as secondary. TOC analysis showed 71% mineralization.The catalyst retained 97.47% efficiency after five cycles with negligibleFe (<0.006 ppm) and Au (<0.001 ppm) leaching, and preservedmorphology. RhB degraded faster than Methylene Blue, Crystal Violet,Acid Orange 7, and Methyl Orange, correlating with molecular bondstrengths. This work demonstrates a novel mechanical-to-chemical energyconversion pathway for sustainable water treatment.

Hemihydrate calcium sulfate nanocrystals hold promisingpotentialin biomedical and industrial applications. Conventional synthesismethods typically necessitate high temperatures/pressures, acidic/alkalinemedia, or expensive organic reagents. This study proposes a facileapproach: when dripping CuSO₄ aqueous solution into CaCl₂ ethanol solution, driven by SO₄^2–, CuSO₄ droplets are immediately transformed into numerousSO₄^2–-enriched instantaneous microdomains,where Ca²⁺ and SO₄^2– undergoa confined reaction and aggregate into calcium sulfate crystals, whileethanol suppresses crystal growth, thereby yielding hemihydrate calciumsulfate nanocrystals. Under optimized conditions, the prepared pure-phasecalcium sulfate crystals belong to the α-hemihydrate phase andthe trigonal space group P3₂21, havingdiameters of 30–80 nm and lengths of 100–350 nm. Theprocess enables the cost-effective and environmentally friendly preparationof calcium sulfate nanocrystals under mild ambient conditions withoutacid or base, while allowing ethanol recycling and CuCl₂ byproduct recovery.

Mechanicallyexfoliable oxide membranes on mica are promising forflexible optoelectronics, but the actual fracture pathway during oxide/micadelamination remains unclear. Here, β-Ga₂O₃ thin films were epitaxially grown on mica by pulsed laser deposition,and their tape-assisted exfoliation behavior was investigated. Althoughthe films could be transferred onto adhesive supports, mica-relatedresidues were repeatedly detected on the backside of the exfoliatedβ-Ga₂O₃ films. Combined XRD, SEM/EDS line-scan,XPS, and rocking-curve results show that exfoliation does not occurthrough clean separation at the β-Ga₂O₃/mica interface, but instead involves cleavage within the mica substrate.First-principles calculations show that the β-Ga₂O₃/mica adhesion energy reaches 40.6 meV Å^–2, approximately 40% higher than the mica interlayer cleavage energyof 28.9 meV Å^–2, supporting the preferentialmica-interlayer fracture pathway. Energy decomposition further revealsthat the DFT-D3 dispersion term accounts for 46.5% of the calculatedβ-Ga₂O₃/mica work of separation, challengingthe simplified assumption of a purely vdW-bonded oxide/mica interface.This work identifies a mica-interlayer-mediated exfoliation mechanismand provides guidance for controlled transfer and interfacial cleanlinessof flexible β-Ga₂O₃ membranes.

Thecopresence of copper (Cu²⁺) and cadmium (Cd²⁺) in water poses a serious threat to aquatic ecosystems dueto their combined toxicity, persistence, and potential for bioaccumulation.Because of the hazardous effects of both ions, the simultaneous removalof Cu²⁺ and Cd²⁺ in aquatic environments isof great significance. Herein, novel sulfide-modified nanozerovalentiron (S-nZVI)/MXene composites were prepared by in situ embeddingS-nZVI nanoparticles into an MXene lamellar structure. Different characteristictechniques such as SEM, HRTEM, XRD, FTIR, XPS, and BET suggest thatS-nZVI was evenly anchored to the MXene layers, effectively mitigatingtheir clustering. Nitrogen adsorption-desorption showed that the specificsurface area of S-nZVI@MXene was approximately 29.77 m²/g, which is 1.64 times more than that of MXene (17.84 m²/g). Batch experiments demonstrated that S-nZVI@MXene exhibits excellentremoval efficiency for Cu²⁺ and Cd²⁺ in a binarysolution. At pH = 5.4, the maximum adsorption capacities of S-nZVI@MXenefor Cu²⁺ and Cd²⁺ were 67.85 and 56.33 mg/g,respectively. The pseudo-second-order kinetic model and Langmuir isothermmodel were more suitable for describing the adsorption, implying thenature of single-layer chemical adsorption. Results of experimentaland density functional theory (DFT) calculations jointly indicatedion-exchange reactions and surface complication. After three reuses,S-nZVI@MXene maintained removal efficiencies of 97.8% and 62.54% forCu²⁺ and Cd²⁺, respectively. S-nZVI@MXene showsgreat potential as an adsorbent for simultaneously removing Cu²⁺ and Cd²⁺ from wastewater.

DevelopingFe–N–C electrocatalysts with high activesite utilization remains a key challenge for the oxygen reductionreaction (ORR), primarily because of the limited accessibility ofFe-Nx sites. Herein, a hierarchically porous Fe–N–C(HP-Fe–N–C) catalyst is constructed via a ZnO-templatedstrategy combined with urea-assisted secondary pyrolysis, enablingthe simultaneous regulation of the pore structure and Fe-Nx site density.The ZnO template governs the formation of mesoporous architectures,and concurrently, the pyrolysis of urea releases gaseous species thatfacilitate the enlargement and interconnection of mesoporous channels.Notably, the balanced micromesoporous structure derived from the ZnOtemplate facilitates efficient mass transport and enhances site accessibility,while urea regulates the nitrogen species to promote the formationof dense Fe-Nx moieties. As a result, the HP-Fe–N–Ccatalyst delivers a high half-wave potential of 0.90 V, along withnear four-electron selectivity and excellent durability. The Zn-airbattery assembled with the HP-Fe–N–C cathode achievesan open-circuit voltage of 1.52 V, a specific capacity of 745.6 mAhg^–1, and favorable charge–discharge stabilityexceeding 800 h. This work reveals the balance between hierarchicalporosity and active site density in the Fe–N–C catalystfor the high-performance ORR.

Omniphobic antiwetting surfaces could play an essentialrole inenhancing performance in certain nonaqueous electrochemical systems,and a possible route to achieve durable repellency is the scalablefabrication of metallic re-entrant microstructures. This study systematicallyinvestigates the microstructure-wettability relationships of arraysof electrodeposited copper micromushrooms. Singly and doubly re-entrantarchitectures were fabricated using a combination of photolithographyand electrodeposition. The impact of geometric parameters, includingpillar diameter, center-to-center spacing, and overhang width, onthe measured contact angle was evaluated across a range of solventswith varying surface tensions. An optimized singly re-entrant geometrymaximized contact angle for high- and intermediate-surface-tensionliquids but failed to prevent the wetting of low-surface-tension solventslike methanol. Synergistic effects were observed when combining thesemicrostructures with perfluoroalkyltrichlorosilane coatings, whichsignificantly reduced surface energy and enabled repellency for evenlow-surface-tension fluids. While doubly re-entrant structures weresuccessfully fabricated, their rounded cap morphology limited additionalantiwetting benefits compared to singly re-entrant designs. Thesefindings provide design guidelines for developing robust, scalable,and conductive antiwetting surfaces suitable for gas diffusion electrodesand other electrochemical applications.

Pickeringemulsions offer superior stability and eco-friendlypropertiesacross multiple industries due to solid particle stabilization atoil–water interfaces. However, the design and synthesis ofultrafine nanoparticles capable of stabilizing Pickering emulsionshave always been a challenging problem. Herein, ultrafine silica nanoparticleswhich have a diameter of 20–30 nm, were prepared based on amicroemulsion method. The ultrafine silica nanoparticles have excellentdispersion properties in water. The benzyl-modified amphiphilic silicananoparticles were synthesized by grafting benzyl groups onto thenanoparticle surface using the Pickering emulsion template methodafter modification with 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane.The benzyl-modified silica nanoparticles have excellent interfacialactivity, with a three-phase contact angle close to 90°, andcan reduce the interfacial tension of the kerosene/water system. Theresulting Pickering emulsions stabilized by benzyl-modified silicananoparticles have excellent long-term stability (stable for at least200 days). Additionally, benzyl-modified silica nanoparticles canalso be used as Pickering emulsifiers for soybean oil, sunflower oil, n-hexadecane, and mineral oil, and they exhibit potentialapplication scenarios in fields such as the food and cosmetics industry,catalytic synthesis, and sustained drug release.

The electrosynthesis of acetamide in alkaline conditionsvia thecoupling reduction of NO and CO₂ establishes a sustainable,efficient platform that enables simultaneous valorization of majoratmospheric pollutant and primary greenhouse gas. However, limitedcatalytic activity and an unclear reaction mechanism in alkaline mediaremain critical challenges. Herein, in this study density functionaltheory (DFT) calculations systematically investigate a series of transitionmetal (TM) doped MoS₂ catalysts to elucidate the mechanismof acetamide electrosynthesis. Among the fourth-period TM dopants,Ni–MoS₂ exhibits the highest catalytic activity.Electronic structure analysis shows that Ni doping increases interfacialelectron density and promotes surface reactivity. Ni–MoS₂ exhibits strong synergistic adsorption of NO (−0.44eV) and CO₂ (−0.58 eV), accompanied by enhancedorbital hybridization and interfacial bonding interactions. Reactionpathway analysis reveals that Ni–MoS₂ facilitatesthe efficient formation of key intermediates (NH₂OH andCH₃CHO), shortens the overall reaction pathway, and suppressescompeting side reactions, thereby improving both activity and selectivity.These intermediates subsequently undergo thermodynamically favorableC–N coupling on the Ni–MoS₂ surface, enablingefficient acetamide production with a limiting potential of −1.23V. Overall, this work reveals a mechanistic relationship between theelectronic properties of active sites, reaction energetics, and acetamideelectrosynthesis performance, providing theoretical insights for therational design of high-performance electrocatalysts.