High Surface Energy Research Articles

Multifunctional Aluminum Pre-treatments from End-Functionalized Phosphonic Acid Self-Assembled Monolayers.

Aluminum alloys are used in advanced engineering applications as they possess a combination of favorable properties, including high strength, lightweightness, good corrosion resistance, machineability, and recyclability. Such applications often require forming the sheets into the final components, which is typically aided by an oil-based lubricant, followed by joining them using adhesives, which is hampered by residual lubricant. In this work, aluminum surfaces were modified with different self-assembled monolayers (SAMs), with the goal of significantly reducing the amount of lubricant while simultaneously improving friction properties, forming, and bonding performance. Our results show that SAMs terminated with hydrophilic and nucleophilic end groups give rise to high-energy surfaces with wetting properties that are stable over time. These surfaces showed significantly improved surface wetting by the lubricant, which in turn resulted in an improved forming performance at reduced lubricant coat weights. Moreover, the nucleophilic SAM termination provided outstanding performance in adhesive bonding tests under corrosive conditions.

Barrier-Induced Rupture Front Disturbances during the 2023 Morocco Earthquake

Abstract Seismic waveforms, including teleseismic body waves, contain information about the irregular behavior of rupture propagation, which is essential for understanding the evolution process of large earthquakes. Here, a high-degree-of-freedom source inversion is applied to the teleseismic P waves of the 2023 moment magnitude 6.8 Morocco earthquake to reveal the irregular rupture behavior during earthquake growth. The resulting total moment tensor solution is an oblique focal mechanism that exhibits reverse faulting with a strike-slip component. There are two distinct peaks at 2 and 4 s in the moment rate function. The reverse fault component dominates at the beginning of the rupture, but then the strike-slip component increases to the second peak and then decreases. The main rupture propagates first in an east-northeast direction, then both up- and down-dip. The down-dip propagating rupture diminishes shortly, whereas the up-dip propagating rupture becomes dominant. The main rupture propagating in the up-dip direction is temporarily suppressed around a point located at 19 km depth and 10 km east-northeast of the hypocenter (region B). After the rupture propagates surrounding region B, the rupture propagates into region B, where a relatively fast slip rate is observed. It is confirmed that the irregular rupture propagation associated with region B is reproduced even when the model settings and the data sampling interval are slightly changed. The irregular rupture propagation obtained in this study suggests that a barrier with high apparent strength (e.g., high fracture surface energy) can cause the rupture to be initially suppressed within the barrier region, followed by delayed rupture propagation through the apparent barrier. The high-frequency seismic motions caused by such an irregular rupture propagation may have contributed to the increase in earthquake-related damage.

Transient co-tuning of atomic Fe and nanoparticle facets for self-relaying Fenton-like catalysis

Fenton-like catalysts are important materials for degrading refractory organic pollutants, however, they still suffer from limited oxidizing ability. Although single atoms and nanoparticles with high-index facets are commonly used in catalysis, their high surface energy hinders controllable synthesis. Here, we construct an iron-based material containing both isolated single atoms and high-index faceted nanoparticles by carbon-assisted Flash Joule heating for organic pollutant remediation. The current-induced thermal shock benefits the excitation of iron atoms and subsequent trapping by graphene defects. At ultrahigh temperatures, the thermodynamic limitations are overcome, leading to nanoparticles with high-index facets. Density functional theory calculations indicate that hydroxyl radical production can be enhanced by self-relay catalysis via the ensemble effect between single atoms and high-index facet nanoparticles. The derived materials exhibit dramatically improved performance in terms of antibiotic removal and medical micropolluted water. Thus, this method presents an effective strategy for designing smart materials for organic wastewater purification.

Morphology design and electronic configuration of MoSe2 anchored on TiO2 nanospheres for high energy density sodium-ion half/full batteries

Molybdenum selenide (MoSe2) has shown potential sodium storage properties due to its large layer spacing (0.646 nm) and high theoretical capacity and narrow band gap. However, as the anode material of sodium ion batteries (SIBs), the MoSe2’s performance is not ideal, especially due to the layer agglomeration and stacking caused by volume expansion and low intrinsic conductivity. Hence, morphology design and electronic configuration of MoSe2 is proposed via building MoSe2 nanosheets and auxiliary sulfur doping on the surface of the TiO2 hollow nanosphere (S-MoSe2@TiO2). The hierarchical shaped S-MoSe2@TiO2 effectively overcomes the shortcomings of high surface energy and weak interlayer van der Waals force of MoSe2. As anode for SIBs, S-MoSe2@TiO2 delivers enhanced cycling life and rate capability (308 mAh/g at 10 A/g after 1000 cycles) with the comparison of MoSe2@TiO2 or pure MoSe2 and TiO2. Such excellent sodium storage performance is due to the fast diffusion kinetics of Na+. When it is applied in sodium ion full batteries, the S-MoSe2@TiO2 anode based cell can reach a high energy density of 187.8 W h kg−1 at 148.3 W kg−1. The design of the new MoSe2-based hybrid provides a novel scheme for the preparation of advanced anode in SIBs.

Spontaneous adsorption effect of graphitic carbon nitride nanosheets to improve sintering behavior of yttria-stabilized zirconia microbeads

Yttria-stabilized zirconia (YSZ) is a ceramic material in which the zirconium dioxide structure is stabilized at room temperature by adding yttrium oxide. However, the YSZ formed by the thick film process on a pre-sintered dense substrate suffers from sintering problems such as different sintering shrinkage rates due to phase transitions and thermal conductivity. This in turn can lead to de-bonding, cracking, delamination, and abnormal growth. We prepared a spherical YSZ green body of approximately 38 μm diameter formed by an organic binder based on a sintered YSZ seed with 15 to 20 μm diameter. In addition, the application of two-dimensional g-C3N4 nanosheets that can be adsorbed on the surface and pores of the green body before the sintering process was evaluated. The YSZ green body with adsorbed surface-modified g-C3N4 nanosheets could be synthesized by stable spontaneous adsorption due to zeta-potential attraction onto the surface of zirconia particles in an aqueous solution. Consequentially, the formation of large grains due to abnormal grain growth was reduced as g-C3N4 was adsorbed. The spontaneous adsorption of nanosheets controls the surface diffusion mechanism by sequentially lowering the energy from a high surface energy in the initial stage of sintering. Uniform grain growth thus can be induced according to the activation energy level of the controlled surface diffusion.

Anomalous texture developments, new two-dimensional primary growth modeling, and fully [formula omitted]-textured electrical steels

Various anomalous texture developments have been investigated in C-free and AlN-free electrical sheets, and new two-dimensional (2D) primary growth modeling has been carried out to understand them. In one-stage cold-rolled sheets, the primary (001) texture pole intensity (TPI) increases with decreasing bulk sulfur content and sheet thickness. The high-index hkl and (001) TPIs increase concurrently with increasing annealing time. In other case, the (001) TPI increases to a maximum after which it rather decreases. In two-stage cold-rolled sheets showing the primary 001+(110) texture, the (001) TPI increases with decreasing sheet thickness and second-stage cold-rolling ratio (CRR). The final (001) grain size is determined by the combination between sheet thickness, bulk sulfur content, CRR, heating rate, and MnS precipitation reaction. New 2D primary growth modeling supports strongly that the higher surface energy grains as well as the lower surface energy ones can grow, although their growth is transient and peripheral. Several unique concepts implied in the 2D growth maps well explain the various anomalous texture developments. The (111) island grains in electrical sheets fully (001)-textured after final annealing are always consumed with further annealing, regardless of the grain size. However, the (110) island grains may grow or not, which depends on the grain size and the number of neighboring ones. Fully developed (110)[001] Goss or (001) texture can be obtained from electrical sheets of the same composition, depending on the processing variables. Fully (001)-textured electrical sheets of high magnetic properties were developed through the experimental results and the 2D growth modeling.

Surface Redox Reaction for the Synthesis of NiPt Catalysts for the Upgrading of Renewable Ethanol/Methanol Mixtures

Mixtures of ethanol and methanol being synthesized from CO2 and green H2 can serve as sustainable base chemicals for a number of chemical processes. Amongst these processes, the catalytically supported synthesis of CO2-neutral C4 to C10 alcohols is of increasing importance as, e.g., iso-butanol can be used as a drop-in fuel or after dehydration to produce iso-butene as a feedstock for the synthesis of plastics. 2-ethyl-hexanol can be further refined into solvents, tensides, or monomers. In this respect, NiPt alloys on an activated carbon support were found to be active and stable catalysts for the synthesis of iso-butanol following the Guerbet reaction scheme. In this study, two different routes are applied to the synthesis of these NiPt catalysts: a more conventional one based on the impregnation of Ni and Pt salts and an advanced path with a surface redox reaction between elemental Ni on the support and Pt ions in a polar solution. The experimental evaluation shows that the Pt particles from the surface redox reaction being exposed on the Ni particles are more active than those on the impregnated catalysts due to their high surface energy. Their specific space-time yields are 10–20 times higher.

CS/CoFe2O4 nanocomposite as a high-effective and steady chainmail catalyst for tetracycline degradation with peroxymonosulfate activation: performance and mechanism.

Tetracycline becomes a crucial measure for managing and treating communicable diseases in both human and animal sectors due to its beneficial antibacterial properties and cost-effectiveness. However, it is important not to trivialize the associated concerns of environmental contamination following the antibiotic's application. In this study, cobalt ferrate (CoFe2O4) nanoparticles were loaded into chitosan (CS), which can avoid the agglomeration problem caused by high surface energy and thus improve the catalytic performance of cobalt ferrate. And it can avoid the problem of secondary contamination caused by the massive leaching of metal ions. The resulting product was used as a catalyst to activate peroxymonosulfate (PMS) for the degradation of tetracycline (TC). To determine the potential effects on TC degradation, various factors such as PMS dosing, catalyst dosing, TC concentration, initial solution pH, temperature, and inorganic anions (Cl-, H2PO4- and HCO3-) were investigated. The CS/CoFe2O4/PMS system exhibited superior performance compared to the CoFe2O4-catalyzed PMS system alone, achieving a 92.75% TC removal within 120 min. The catalyst displayed high stability during the recycling process, with the efficiency observed after five uses remaining at a stable 73.1%, and only minor leaching of dissolved metal ions from the catalyst. This confirms the high stability of the catalyst. The activation mechanism study showed that there are free radical and non-free radical pathways in the reaction system to degrade TC together, and SO4•- and 1O2 are the primary reactive oxygen radicals involved in the reaction, allowing for effective treatment of contaminated water by TC.

SurfFlow: High-throughput surface energy calculations for arbitrary crystals

We introduce SurfFlow, an open-source high-throughput workflow package designed for automated first-principles calculations of surface energies in arbitrary crystals. Our package offers a comprehensive solution capable of handling multi-element crystals, nonstoichiometric compositions, and asymmetric slabs, for all potential terminations. To streamline the computational process, SurfFlow employs an efficient pre-screening method that discards surfaces with suspected high surface energy before conducting resource-intensive density functional theory computations. The results generated are seamlessly compiled into an optimade-compliant database, ensuring easy access and compatibility. Additionally, a user-friendly web interface facilitates workflow submission and management, provides result visualization, and enables the examination of Wulff shapes. SurfFlow represents a valuable tool for researchers looking to explore surface energies and their implications in a diverse range of systems.

Geometrically Amplified Wetting of Silver Nanosolder on a Rough Diamond Surface.

The wetting behavior of silver at the nanoscale on a textured diamond substrate is not absolutely roughness-dependent in printing diamond chips, tough bioimplant coating, and joining for cutting tool industries. This study uses a molecular dynamics simulation to capture the stochastic wetting behavior toward precision for given geometries. It is deduced that the metalophilic character of molten silver is increased with an increase in roughness on sinusoidal contoured diamond substrates rather than orthogonal pillars of the same roughness until an equilibration time of 210 ps at a temperature of 950 K. Increasing the roughness after the equilibrium time causes a supermetalophilic angle of 13° for the sinusoid at 500 ps, and the orthogonal design causes the Wenzel state. Therefore, wetting states are metastable and ultimately depend upon the wetting time and geometry rather than the roughness only. A high joining strength creates a long-lasting coating, owing to the high surface energy of the textured surface. This study presents effective thin seam development in the least possible time of 230 ps and silver consumption at the nanoscale for supermetalophilic and metalophobic coatings in electronic packaging.

Amphiphobic PTFE membrane as functional covering membrane to hinder ammonia emission during the composting process

Composting is a process of converting potentially harmful organic matter into harmless organic fertilizer through microbial fermentation. This process enables the rational use of resources and represents an embraced technology marked with sustainable development features. Hindering ammonia emissions during composting is vital, as ammonia is a valuable resource and harmful if emitted excessively. Polytetrafluoroethylene (PTFE) membranes are often used as functional covering membranes to prevent ammonia produced by composting from releasing due to its hydrophobicity. However, they are susceptible to oily aerosols in oily composting, which affects microbial decomposition in aerobic composting. Thus, the development of amphiphobic PTFE membrane is necessary and meaningful. For the amphiphobic PTFE membrane, an important issue is the amphiphobic stability of the membrane, especially in the special alkaline environment of composting. Herein, we suggest the use of the polymer to wrap around nanoparticles and PTFE membrane fibers to prepare stable amphiphobic membranes as functional covering membranes for oil-containing composting. Poly(methyl-3,3,3-trifluoropropylsiloxane) (PTFPMS) and 1H, 1H, 2H, 2H-perfluorodecyltrichlorosilane (PFTS) entangled with each other and then wrapped the nanoparticles and membrane fibers to form stable amphiphobic membranes with high roughness and low surface energy. The prepared membrane had high liquid repellency to water (～152.8°), diiodomethane (～127.5°), and n-hexadecane (～127.0°). This membrane also possessed a high anti-oil fouling. Moreover, the membrane amphiphobicity exhibited a high stability. This is attributed to the stable fixation of nanoparticles on PTFE membrane fibers with PFTS/PTFPMS. Therefore, the amphiphobicity of the membrane was not affected by ammonia. As for the ammonia filtration efficiency, the amphiphobic membrane had a filtration efficiency of 77.4 % within 10 min, an increase of 6.8 % compared to the PTFE membrane, demonstrating the potential of the membrane we developed toward hindering ammonia emission. This work provides a new way of developing high-performance membrane for the oily composting process.

Experimental Study on Hypersonic Double-Wedge Induced Flow Based on Plasma Active Actuation Array

The double-wedge configuration is a typical characteristic shape of the rudder surface of high-speed aircraft. The impact of the shock wave/boundary layer interaction and the shock wave/shock wave interaction resulting from the double wedge on aircraft aerodynamics cannot be ignored. The aerodynamic performance of the aircraft would be seriously affected. Accordingly, to reduce the wave drag, and to relieve the thermal load and pressure load, flow control is required for the shock wave/shock wave interaction and the shock wave/boundary layer interaction induced by the double-wedge configuration. In this paper, double-wedge shock wave/shock wave interaction is controlled by a high-energy surface arc discharge array and observed by high-speed schlieren flow field measurement at Mach 8. The 30-channel discharge array is set on the primary wedge plane, and actuation is generated. Hypersonic V shock wave/shock wave interaction is effectively controlled by the shock wave array induced by the high-energy surface arc discharge array, which makes the shock wave/shock wave interaction structure disappear or intermittent. The potential control mechanism is to reduce strong shock wave interaction by transforming the type of shock wave interaction. Therefore, the ability of plasma array actuation to control complex shock wave/shock wave interaction is verified, which provides a new method for hypersonic shock wave/shock wave interaction control.

A magnetic-enhanced FRET biosensor for simultaneous detection of multiple antibodies

Accurate, rapid and sensitive detection of specific immunoglobulin G (IgG) and immunoglobulin M (IgM) antibodies in human samples is crucial for preventing and assessing pandemics, especially in the case of recent COVID-19 outbreaks. However, simultaneous and efficient detection of IgG and IgM in a single system remains challenging. Herein, we developed a multicolor nanosystem capable of quantitatively analyzing anti-SARS-CoV-2 IgG and IgM with high sensitivity within 20 ​min. The detection system consists of core-shell upconversion nanoparticles (csUCNPs), secondary antibodies labeled with fluorescent dyes (sab), and magnetic nanocrystals (PMF). By leveraging the Förster resonance energy transfer (FRET) effect, the photoluminescence (PL) intensity of blue and green regions is restored for IgG and IgM detection, respectively. Inspiringly, owing to the introducing of PMF, the limits of detection (LODs) of IgG and IgM tested are improved to 89 ​fmol ​L−1 and 19.4 ​fmol ​L−1, representing about 416-folds and 487-folds improvement over only-dye dependent system, respectively. Mechanistic investigations reveal that the high collective effect and surface energy transfer efficiency from csUCNPs to PMF contribute to the enhanced detection sensitivity. The assay enables us to quantify clinical vaccinated samples with high specificity and precision, suggesting our multicolor platform can be a promising alternative for clinical point-of-care serological assay.

Thermal Stability of Au Rhombic Dodecahedral Nanocrystals Can Be Greatly Enhanced by Coating Their Surface with an Ultrathin Shell of Pt.

Rhombic dodecahedral nanocrystals have been considered particularly difficult to synthesize because they are enclosed by {110}, a low-index facet with the greatest surface energy. Recently, we demonstrated the use of seed-mediated growth for the facile and robust synthesis of Au rhombic dodecahedral nanocrystals (AuRD). While the unique shape and surface structure of AuRD are desirable for potential applications in plasmonics and catalysis, respectively, their high surface energy makes them highly susceptible to thermal degradation. Here we demonstrate that it is feasible to greatly improve the thermal stability with some sacrifice to the plasmonic properties of the original AuRD by coating their surface with an ultrathin shell made of Pt. Our in situ electron microscopy analysis indicates that the ultrathin Pt coating can increase the thermal stability from 60 up to 450 °C, a trend that is also supported by the results from a computational study.

Reactivity and Durability of TiO2 Photoanodes with Dominant High-Energy (211) Facets

Owing to a large band gap and high surface energy via theoretical calculation, anatase TiO2 with dominant (211) facets can be expected to serve as one of the candidates for...

A mini-review on wrinkled nanofibers: Preparation principles via electrospinning and potential applications

Tailoring the surface morphology of nanofibers determines its application to an excessive extent. At present, different structures of nanofibers have been produced such as wrinkled, grooved, porous, rough, etc. Amongst them, wrinkled nanofibers have attracted the attention of researchers due to their exceptional structure and properties such as coarse surface, high surface energy, high specific surface area, excellent mechanical properties, and good piezoelectricity resulting in serving successfully in various fields such as energy harvesting, air filtration, water filtration, gas sensors, biomedical applications, fuel cells, and energy storage. Therefore, this work aims to spotlight the importance of the wrinkled structure, methods, and strategies used for producing electrospun wrinkled nanofibers of various materials. This review focuses on the materials, preparation methods, and applications of the electrospun wrinkled nanofibers. This review can serve as an essential reference for the materials, formation methods, and applications of wrinkled nanofibers prepared via electrospinning.

Transition metal oxide clusters: advanced electrocatalysts for a sustainable energy future.

The comprehensive utilization of sustainable green energy is essential to face the global energy and environmental crisis. The oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and electrocatalytic urea synthesis (EUS) are the pivotal electrocatalytic processes, necessitating the development of low-cost electrocatalysts with high efficiency. Small-sized transition metal oxide (TMO) clusters have attracted a lot of attention because of their exceptional qualities, such as exhibiting a dense array of low-coordinated metal active sites (e.g. abundant metal cation defects and oxygen vacancy), amorphous structures with high surface energy, high atom utilization efficiency, and cost-effectiveness. Furthermore, the synergistic actions between metal clusters and TM-Nx single atom active sites remarkably boost up the electrocatalytic performances, corroborated by density functional theory (DFT). More efforts in this comprehensive feature article are expected to achieve insights into the fundamental understanding of electrocatalytic reaction mechanisms in our lab and serve as a guide for creating cutting-edge electrocatalysts of transition metal oxide clusters.

Phase-field simulation of sintering process of ceramic composite fuel

Due to the limitation of existing experimental techniques, it is difficult to observe the evolution of microstructure in the sintering process in real time, resulting in a lack of in-depth understanding of the sintering mechanism of two-phase composite fuels. Therefore, it is greatly important to carry out theoretical simulation studies in the sintering process of composite fuels. In this work, a phase-field model of the two-phase sintering process of ceramic composite fuel is established, and the sintering process of UN-U<sub>3</sub>Si<sub>2</sub> composite fuel is simulated by using this method. The simulation results show that during the formation of sintering neck, the surface deformation of the grains with higher surface energy is significant. The size of the final equilibrium dihedral angle formed by the two-phase double grains depends on the ratio of the grain boundary energy to the surface energy of the two phases. The phenomenon of large grains swallowing small grains does not occur between the two unequal double grains. Subsequently, the pore shrinkage and the properties of the trident grain boundary among the two-phase three grains are investigated in the sintering process. It is found that the angle of the trident grain boundary formed by the two-phase three grains deviates from 120°. The high-energy barrier at the grain boundary hinders the diffusion of the pore vacancies along the grain boundary, resulting in a slow shrinkage rate of the pore vacancies at the trident grain boundary. In addition, the simulation results of the microstructure evolution of two-phase polycrystalline sintered tissue with different volume fraction ratios show that the grain boundary diffusion plays a major role in the two-phase sintering process. The grain growth of the phase with a higher volume fraction is dominant, and there exists a hindrance to the migration of grain boundaries between two-phase grains. The phenomenon of grain migration exists between grains of the same phase.

In situ self-assembled near-infrared phototherapeutic agent: unleashing hydrogen free radicals and coupling with NADPH oxidation.

Investigation of electron transfer (ET) between photosensitizers (PSs) and adjacent substrates in hypoxic tumors is integral to highly efficient tumor therapy. Herein, the oxygen-independent ET pathway to generate hydrogen free radicals (H˙) was established by the in situ self-assembled phototherapeutic agent d-ST under near-infrared (NIR)-light irradiation, coupled with the oxidation of reduced coenzyme NADPH, which induced ferroptosis and effectively elevated the therapeutic performance in hypoxic tumors. The higher surface energy and longer exciton lifetimes of the fine crystalline d-ST nanofibers were conducive to improving ET efficiency. In hypoxic conditions, the excited d-ST can effectively transfer electrons to water to yield H˙, during which the overexpressed NADPH with rich electrons can power the electron flow to facilitate the generation of H˙, accompanied by NADP+ formation, disrupting cellular homeostasis and triggering ferroptosis. Tumor-bearing mouse models further showed that d-ST accomplished excellent phototherapy efficacy. This work sheds light onto the versatile electron pathways between PSs and biological substrates.

Effects of peening duration on surface and wear properties of aircraft graded AA2017 alloy

This investigation addresses the effects of peening duration during SP on surface properties of AA2017 alloy. SP performed with different durations (0, 70, 140 and 210 s) and imparts the modification in the surface region. Alloy strength and structural parameters like crystallite size (D), dislocation density (ρ) microstrain (ε) and lattice constant (a) are increased with SP duration till 140 s. After 210 s, these properties declined due to the effect of softening caused by rise in surface temperature through over peening duration, and exhibited dynamic recovery. Severe plastic deformation developed by SP, created rough surface in all SPed samples and shows responsible for low wettability, high contact angles and low surface energy in comparison with AR sample. The SP140 exhibited maximum hardness (234 ± 7.1 HV) and maximum residual compressive stress (RCS) (−51 MPa) as compared with that of AR sample shown 70 ± 2.1 HV and 20 MPa respectively. Also, the cross-sectional measurements over a thickness of 200 μm confirmed their improvement. These results favoured for SP140 sample to yield lower wear rate about 0.776 mm3/ KN-m compared to AR sample (1.046 mm3/ KN-m). Further increase in shot peening duration to 210 s induces softened layer by rise in surface temperature and presence of Cu as major alloying element in AA2017 exhibits superior thermal conductivity and resulted in detrimental effect on wear resistance. The combination of several factors such as structural parameters, RCS and hardness in the surface region of SP140 sample are responsible to develop the wear resistance of AA2017 alloy.