Langmuir最新文献

Hastelloy fiber paper(HAP) can be used as the oxygenevolutionreaction porous transport layer (PTL) without using a catalyst layerin anion exchange membrane water electrolysis. It is combined withRu on nickel fiber paper (NFP) (hydrogen evolution reaction PTL) toform an asymmetric Ru/NFP(−)//HAP(+) single-cell system. Theexperimental results for electrodeposited Co(OH)₂ on HAPare also demonstrated for comparison. At 70 °C, the cell delivers725.67 mA cm^–2 at 1.8 V under cathode-wet conditionsand maintains 701.34 mA cm^–2 under cathode-dry operation.A 5000-cycle accelerated stress test (AST) confirms the good operationalstability of the system under dynamic cycling conditions. In addition,the effect of Co(OH)₂ electrodeposition on the HAP anodewas further investigated to show the current density decreases to485.59 mA cm^–2 at 1.8 V when operated at 70 °C.The AST stability also degrades with Co(OH)₂ deposition.Further analysis indicates that the electrodeposited Co(OH)₂ coating may alter the pore structure and surface wettability ofthe catalyst layer, leading to mass-transport limitations at highcurrent densities, including hindered ion transport and inefficientoxygen bubble removal.

Nitride ferroelectrics are among the emerging materialswith promisingpotential for a wide range of electronic, optoelectronic, and memoryapplications because of their high remanent polarization, low growthtemperature, and complementary metal-oxide-semiconductor (CMOS) compatibility.Growth of wurtzite-structured nitride ferroelectrics on bottom electrodesor Si substrates has resulted in defective and amorphous interfaces.Epitaxial growth on wide bandgap nitride substrates, such as galliumnitride (GaN), is preferred to achieve sharp interfaces and improvedintegration in semiconductor devices. However, the formation of inversiondomains (IDs) on these substrates degrades the electrical properties.Here, an epitaxial aluminum boron scandium nitride (Al_0.78(BSc)_0.22N) ferroelectric thin film grown on an n-typeGaN substrate is characterized using scanning transmission electronmicroscopy (STEM) to determine the formation mechanism of IDs. Integrateddifferential phase contrast (iDPC) imaging directly exhibits the Al–Ndumbbell orientation across an inversion domain boundary (IDB) andorientation discontinuity close to the Al_0.78(BSc)_0.22N/GaN interface. Four-dimensional scanning transmissionelectron microscopy (4D-STEM) strain mapping reveals the role of substrate-inducedpinning in the formation of the IDs. This demonstrates local shearstrain variations along IDBs. This study highlights the importanceof STEM-based techniques in directly correlating the local latticevariations with the polarization and switching behavior of this classof wurtzite ferroelectric films.

Hypothesis:Contact line pinning on heterogeneous surfaces governswetting dynamics across scales. While classical theory treats defectsas point-like forces, this assumption breaks down at the nanoscale,where the finite physical width of a defect becomes significant. Wehypothesize that this finite width determines both the pinning strengthand the resulting contact line dynamics, enabling the determinationof key mechanical parameters from the defect geometry and system dimensionswithin the framework of the present model. Simulations: We performlarge-scale molecular dynamics (MD) simulations of a liquid bridgeconfined between two parallel solid plates. The plates move at a constantvelocity in opposite directions along the x-axis.A single, well-defined nanoscale defect with finite width is introducedon the top plate. By systematically varying the defect size and thesystem length, we measure the full two-dimensional contact line morphology,effective contact line stiffness, maximum pinning force, and the completetime-resolved trajectory of the contact line apex x_p(t) during the pinningand depinning processes. Findings: A theoretical model is derivedbased on a Gaussian pinning potential, which yields an analyticalcontact line morphology that bridges a parabolic near-field and alogarithmic far-field. The present framework yields an effective globalstiffness K and a closed-form expression for theposition-dependent pinning force F_pinn(x_p). These resultsenable a reduced Langevin equation for the apex dynamics, whose predictionsare validated quantitatively by MD simulations without adjustableparameters. Furthermore, by inverting this relationship, we demonstratethat temporal wetting dynamics can be programmed through spatiallyengineered defect patterns.

Efficient hydrogenation of furfural (FAL) to tetrahydrofurfurylalcohol (THFA) under mild conditions using non-noble-metal catalystsremains challenging because it requires the hydrogenation of boththe carbonyl group and the furan ring. In this work, a CoNi alloyconfined within hollow mesoporous silica spheres (CoNi@hw-mSiO₂) was developed as an efficient catalyst for FAL hydrogenation.Comprehensive characterization results demonstrate the successfulformation of a CoNi alloy with strong electronic interactions, whichis uniformly dispersed within the hollow mesoporous framework. Undermild conditions (100 °C, 2 MPa H₂, 2 h), CoNi@hw-mSiO₂ achieved a THFA yield of 96.2% with excellent recyclability.The outstanding performance is attributed to the electronic synergyof the CoNi alloy and the structural advantages of the hollow mesoporousstructure. The CoNi alloy provides favorable active sites for thesequential hydrogenation of the C═O and C═C bonds, whilethe hollow structure helps stabilize active species, suppresses metalmigration and leaching, and facilitates efficient mass transfer. Thiswork demonstrates an effective strategy for designing efficient non-noble-metalcatalysts for biomass hydrogenation.

The catalytic roleof heteroatom dopants in Sn-based electrocatalystsremains elusive because the dynamic evolution of surface states underelectrochemical conditions is rarely considered. Herein, density functionaltheory calculations combined with pH-dependent microkinetic simulationsreveal that hydrogen affinity governs the evolution of catalytic surfacestates in Sn-based single-atom alloys (SAAs) during electrochemicalCO₂ reduction to formate. We demonstrate that hydrogenpreferentially occupies either dopant or neighboring Sn sites dependingon the electronic structure of the dopant and identify simple electronicdescriptors based on the dopant d-band and p-band centers that enablethe screening of preferential H adsorption sites. Surface Pourbaixanalysis further reveals that Sn-based SAAs tend to evolve into nearlymonolayer hydrogen-covered surfaces under practical CO₂RR conditions, indicating that the catalytic performance should beevaluated on reconstructed rather than pristine surfaces. By incorporatingdipole–field interactions, explicit potential of zero charge,and pH-dependent electric-field effects into microkinetic modeling,a predictive pH-dependent activity volcano is established, showingexcellent agreement with experimental benchmarking. The resultingframework identifies promising catalysts with distinct pH-dependentactivity windows and, more importantly, establishes hydrogen affinityas a fundamental descriptor governing surface-state evolution andthereby influencing catalytic performance, providing a general strategyfor the rational design of p-block-metal-based electrocatalysts.

The poor conductivity and severe volume effect of siliconanodeslead to sluggish lithiation/delithiation kinetics and electrode pulverization,largely impeding the cyclability of the batteries. A multifunctionalbinder system that can simultaneously address these issues is highlydemanded. Herein, we report a conductive interpenetrating gel network(marked as CGP) constructed by cationic guar gum and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS) through dynamic H-bonds and Coulombic interactions, whichfurther donates self-healing capability to accommodate volume expansion.The lone-pair electrons of the oxygen and sulfur heteroatoms abundantin CGP coordinate with Li⁺ to optimize ion diffusion, whilethe conductive PEDOT:PSS facilitates electron transport, togetherachieving stable solid electrolyte interphases and enhanced reactionkinetics. Consequently, the Si@CGP electrode delivers a high initialdischarge capacity of 3997.8 mAh g^–1 at 0.5 A g^–1 with a Coulombic efficiency of 84.1% and retainsa reversible capacity of 1973.8 mAh g^–1 after 100cycles. Notably, it still retains a high capacity of 1428.4 mAh g^–1 at 4.0 A g^–1, indicating its excellentcyclability and rate performance. The design of a conductive, self-healingbinder may broaden the way toward efficient binder systems for high-performancesilicon anodes.

Perfluorooctanesulfonate(PFOS) is a highly persistent and toxicper- and polyfluoroalkyl substance (PFAS) widely recognized for itsserious risks to both environmental and human health. In this work,an electrochemical impedance spectroscopy (EIS)-based sensor was developedfor PFOS detection by integrating a MIL-101(Cr) metal–organicframework (MOF) sensing layer on the working electrode and a nickelhexacyanoferrate (NiHCF)-modified counter electrode. This simple andpractical two-electrode system utilizes the large pore size, highsurface area, and chromium center of MIL-101(Cr) to enable strongelectrostatic and host–guest interactions with PFOS, leadingto pronounced changes in pore resistance upon adsorption. The fabricatedsensor exhibits a linear relationship between PFOS concentrationsand pore resistance, with the limit of detection reaching 10.13 ppt.Selectivity tests demonstrate that excess amounts of common PFAS analogs,humic acid, and inorganic salts do not significantly interfere withthe PFOS signal. This was further validated by statistical analysisusing one-way ANOVA followed by Dunnett’s test, which confirmedthat most interference conditions are not significantly differentfrom PFOS alone. The sensor also shows stable performance over repeatedmeasurements and operates effectively within the pH range of 5–8.Lastly, sensing experiments involving real water samples verify theapplicability of the device for the detection of PFOS in complex matrices.