The 50 most-cited articles in Langmuir, 2021

In this work, a set of experimental electrophoretic mobility (μ e ) data was used to show how inappropriate selection of the electrokinetic model used to calculate the zeta potential (ζ-potential) can compromise the interpretation of the results for nanoparticles (NPs). The main consequences of using ζ-potential values as criteria to indicate the colloidal stability of NP dispersions are discussed based on DLVO interaction energy predictions. For this, magnetite (Fe 3 O 4 ) NPs were synthesized and characterized as a model system for performing electrokinetic experiments. The results showed that the Fe 3 O 4 NPs formed mass fractal aggregates in solution, so the ζ-potential could not be determined under ideal conditions when μ e depends on the NP radius. In addition, the Dukhin number (Du) estimated from potentiometric titration results indicated that stagnant layer conduction (SLC) could not be neglected for this system. The electrokinetic models that do not consider SLC grossly underestimated the ζ-potential values for the Fe 3 O 4 NPs. The DLVO interaction energy predictions for…

Fluid flow in porous systems driven by capillary pressure is one of the most ubiquitous phenomena in nature and industry, including petroleum and hydraulic engineering as well as material and life sciences. The classical Lucas-Washburn (LW) equation and its modified forms were developed and have been applied extensively to elucidate the fundamental mechanisms underlying the basic statics and dynamics of the capillary-driven flow in porous systems. The LW equation assumes that fluids are incompressible Newton ones and that capillary channels all have the same radii. This kind of hypothesis is not true for many natural situations, however, where porous systems comprise complicated pore and capillary channel structures at microscales. The LW equation therefore often leads to inaccurate capillary imbibition predictions in such situations. Numerous studies have been conducted in recent years to develop and assess the modifications and extensions of the LW equation in various porous systems. Significant progresses in computational techniques have also been attained to further improve our…

The design of photocatalysts with hierarchical pore sizes is an effective method to improve mass transport, enhance light absorption, and increase specific surface area. Moreover, the construction of a heterojunction at the interface of two semiconductor photocatalysts with suitable band positions plays a crucial role in separating and transporting charge carriers. Herein, ZIF-8 and urea are used as precursors to prepare hierarchically porous ZnO/g-C 3 N 4 S-scheme heterojunction photocatalysts through a two-step calcination method. This S-scheme heterojunction photocatalyst shows high activity toward photocatalytic H 2 O 2 production, which is 3.4 and 5.0 times higher than that of pure g - C 3 N 4 and ZnO, respectively. The mechanism of charge transfer and separation within the S-scheme heterojunction is studied by Kelvin probe, in situ irradiated X-ray photoelectron spectroscopy (ISI-XPS), and electron paramagnetic resonance (EPR). This research provides an idea of designing S-scheme heterojunction photocatalysts with hierarchical pores in efficient photocatalytic hydrogen…

Much contemporary research considers the development of novel sorbents for the removal of toxic contaminants. Whilst these studies often include experimental adsorption kinetics, modelling is normally limited to application of the pseudo-second order (PSO) rate equation, which provides no sensitivity towards changes in experimental conditions and thus no predictive capability. We demonstrate a relatively simple modification of the PSO model, with the final form dqt/dt = k’C t (1-(q t /q e ))^2 where k’=k 2 *(q e *^2)/C 0 *. We demonstrate that unlike the PSO model, this new rate equation provides first-order dependence upon initial sorbate concentration (observed experimentally as x̄=0.829±0.417), whilst rate constant k’ is significantly less sensitive to changes in C 0 and C s than PSO rate constant k 2 . We demonstrate that this model improves predictive capacity towards changes in C 0 and C s , particularly when q e is calculated using the Langmuir or Freundlich adsorption isotherm. Finally, we explore how the new rate constant, k’, responds to changes in sorbent morphology,…

This work presents the facile synthesis of heteroatom-doped fluorescent carbon quantum dots (C-dots), which could serve as an antioxidant. Herein, nitrogen, phosphorous, and sulfur codoped carbon dots (NPSC-dots) have been synthesized by a single-step hydrothermal strategy. Owing to the radical scavenging activity of the NPSC-dots, they were tested against several methods as well as in practical applications. The antioxidant ability of the NPSC-dots was efficiently utilized on plastic films by coating with these NPSC-dots. For the very first time, NPSC-dots were immobilized onto nonpolar plastic films (polypropylene) via photochemical covalent grafting to extend the shelf life of food items or storage without affecting the quality of plastic films. The NPSC-dot-coated PP film with negligible deterioration of transparency was extensively studied using scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared (FTIR) analysis, X-ray photoelectron spectroscopy (XPS), contact angle measurement, and thermogravimetric analysis (TGA). The fluorescent…

The synthesis of high entropy oxide (HEO) nanoparticles (NPs) possesses many challenges in terms of process complexity and cost, scalability, tailoring nanoparticle morphology, and rapid synthesis. Herein, we report the synthesis of novel single-phase solid solution (Mn, Fe, Ni, Cu, Zn) 3 (O) 4 quinary HEO NPs produced by a flame spray pyrolysis route. The aberration-corrected scanning transmission electron microscopy (STEM) technique is utilized to investigate the spinel crystal structure of synthesized HEO NPs, and energy-dispersive X-ray spectroscopy analysis confirmed the high entropy configuration of five metal elements in their oxide form within a single HEO nanoparticle. Selected area electron diffraction, X-ray diffraction, and Raman spectroscopy analysis results are in accordance with STEM results, providing the key attributes of a spinel crystal structure of HEO NPs. X-ray photoelectron spectroscopy results provide the insightful understanding of chemical oxidation states of individual elements and their possible cation occupancy sites in the spinel-structured HEO NPs.

Microbubbles are very fine bubbles that shrink and collapse underwater within several minutes, leading to the generation of free radicals. Electron spin resonance spectroscopy (ESR) confirmed the generation of hydroxyl radicals under strongly acidic conditions. The drastic environmental change caused by the collapse of the microbubbles may trigger radical generation via the dispersion of the elevated chemical potential that had accumulated around the gas-water interface. The present study also confirmed the generation of ESR signals from the microbubble-treated waters even after several months had elapsed following the dispersion of the microbubbles. Bulk nanobubbles were expected to be the source of the spin-adducts of hydroxyl radicals. Such microbubble stabilization and conversion might be caused by the formation of solid microbubble shells generated by iron ions in the condensed ionic cloud around the microbubble. Therefore, the addition of a strong acid might cause drastic changes in the environment and destroy the stabilized condition. This would restart the collapsing…

With the rapid development of bionic science and manufacturing technology, superhydrophobic surfaces have received extensive attention and research. However, the cumbersome steps, high cost, fluorine pollution, and poor durability greatly restrict its commercial promotion and application. Here, a simple spraying method is used to construct wear-resistant superhydrophobic coatings on various substrates such as glass, filter paper, copper sheets, and polyethylene terephthalate films, using an integrated fluorine-free suspension consisting of silica micropowder, nanofumed silica, epoxy resin, and polydimethylsiloxane. The prepared superhydrophobic coating can withstand 75 sandpaper abrasion cycles and can still maintain good superhydrophobic performance after other physical tests (e.g., hand kneading and tape peeling after knife scraping). In addition, the coating is extremely water-repellent under harsh conditions such as strong UV irradiation and extreme chemical corrosive media. In the buoyancy test, the coated filter paper can bear 39 times its own gravity. This water-repellent…

Gallium-based alloys have garnered considerable attention in the scientific community, particularly as they are in an atypical liquid state at and near room temperature. Though physical parameters, such as thermal conductivity, electrical conductivity, viscosity, yield stress, and surface tension, of these alloys are broadly known, the surface tension (surface free energy) of the oxide skin remains intangible due to the high yield stress of the oxide skin. In this article, we propose to employ gradually attenuated vibrations to obtain equilibrium shapes, which are analyzed along the lines of the puddle height method. The surface tension of the oxide skin was determined on quartz glass and liquid metal-phobic diamond coating to be around 350-365 mN/m, thus independent of the substrate surface or employed liquid metal (i.e., eutectic Ga-In (EGaIn) and galinstan). The similarity of the surface tension for different alloys was ascribed to the composition of the oxide skin, which predominantly comprises gallium oxides due to thermodynamic constraints. We envision that this method can…

We review existing explanations for drop pinning and the origin of the force required to initiate the sliding of a drop on a solid surface (depinning). Theories that describe these phenomena include de Gennes', Marmur's, Furmidge's, the related Furmidge-Extrand's, and Tadmor's theory. These theories are all well cited but generally do not address each other, and usually papers that cite one of them ignore the others. Here, we discuss the advantages and disadvantages of these theories and their applicability to different experimental systems. Thus, we link different experimental systems to the theories that describe them best. We describe the force laws that can be deduced should these theories be united and the major open problems that remain. We describe a physical meaning that can be extracted from retention force measurements, specifically, the interfacial modulus that describes the tendency of a solid to conform to the liquid. This has implications for various wetting phenomena such as adhesion robustness, drug penetration into biological tissues, and solid robustness/resilience…

Surfactant adsorption to fluid interfaces is ubiquitous in biological systems, industrial applications, and scientific fields. Herein, we unravel the impact of the hydrophobic phase (air and oil) and the role of oil polarity on the adsorption of surfactants to fluid interfaces. We investigated the adsorption of anionic (sodium dodecyl sulfate), cationic (dodecyltrimethylammonium bromide), and non-ionic (polyoxyethylene-(23)-monododecyl ether) surfactants at different interfaces, including air and oils, with a wide range of polarities. The surfactant-induced interfacial tension decrease, called the interfacial pressure, correlates linearly with the initial interfacial tension of the clean oil-water interface and describes the experimental results of over 30 studies from the literature. The higher interfacial competition of surfactant and polar oil molecules caused the number of adsorbed molecules at the interface to drop. Further, we found that the critical micelle concentration of surfactants in water correlates to the solubility of the oil molecules in water. Hence, the nature of…

Lipid nanoparticles (LNPs) containing short-interfering RNA (LNP-siRNA systems) are a promising approach for silencing disease-causing genes in hepatocytes following intravenous administration. LNP-siRNA systems are generated by rapid mixing of lipids in ethanol with siRNA in aqueous buffer (pH 4.0) where the ionizable lipid is positively charged, followed by dialysis to remove ethanol and to raise the pH to 7.4. Ionizable cationic lipids are the critical excipient in LNP systems as they drive entrapment and intracellular delivery. A recent study on the formation of LNP-siRNA systems suggested that ionizable cationic lipids segregate from other lipid components upon charge neutralization to form an amorphous oil droplet in the core of LNPs. This leads to a decrease in intervesicle electrostatic repulsion, thereby engendering fusion of small vesicles to form final LNPs of increased size. In this study, we prepared LNP-siRNA systems containing four lipid components (hydrogenated soy phosphatidylcholine, cholesterol, PEG-lipid, and 1,2-dioleoyl-3-dimethylammonium propane) by…

Bio-based aerogels serve as potential materials in separation of oil/water mixtures. Nevertheless, there remain some key challenges, including expensive/toxic organic cross-linkers, unpromising reusability, and poor performance in emulsion separation. Hereby, a novel, robust, and superhydrophobic sodium alginate/graphene oxide/silicon oxide aerogel (SA/GO/SiO 2 -M) was fabricated by simple calcium ion cross-linking self-assembly, freeze-drying, and chemical vapor deposition methods based on the renewable and abundant raw materials. The as-prepared SA-based aerogel possesses high absorbency for varieties of organic solvents and oils. Importantly, it shows high efficiency in the separation of surfactant-stabilized water-in-oil emulsions. SA/GO/SiO 2 -M aerogels display excellent reusability in both absorption and separation because of their good mechanical properties in the air and oil phase, and the mechanism in emulsion separation is discussed. This study shows that SA/GO/SiO 2 -M aerogels are a promising material in treating oil contaminants from different fields.

This work establishes that static contact angles for gallium-based liquid metals have no utility despite the continued and common use of such angles in the literature. In the presence of oxygen, these metals rapidly form a thin (∼1-3 nm) surface oxide "skin" that adheres to many surfaces and mechanically impedes its flow. This property is problematic for contact angle measurements, which presume the ability of liquids to flow freely to adopt shapes that minimize the interfacial energy. We show here that advancing angles for a metal are always high (>140°)-even on substrates to which it adheres-because the solid native oxide must rupture in tension to advance the contact line. The advancing angle for the metal depends subtly on the substrate surface chemistry but does not vary strongly with hydrophobicity of the substrate. During receding measurements, the metal droplet initially sags as the liquid withdraws from the "sac" formed by the skin and thus the contact area with the substrate initially increases despite its volumetric recession. The oxide pins at the perimeter of the…

The demand for industrially produced cellulose nanocrystals (CNCs) has been growing since 2012, when CelluForce Inc. opened its inaugural demonstration plant with a production capacity of 1 tonne per day. Currently, there are 10 industrial CNC producers worldwide, each producing a unique material. Thus, academic researchers and commercial users alike must consider the properties of all available CNCs and carefully select the material which will optimize the performance of their desired application. To support these efforts, this article presents a thorough characterization of four new industrially produced CNCs including sulfated CNCs from NORAM Engineering and Constructors Ltd. (in cooperation with InnoTech Alberta and Alberta-Pacific Forest Industries Inc.) and Melodea Ltd., as well as carboxylated CNCs from Anomera Inc. and Blue Goose Biorefineries Inc. These materials were benchmarked against typical lab-made, sulfated CNCs. While all CNCs were similar in size, shape, crystallinity, and suspension quality, the sulfated CNCs had a higher surface charge density than their…

Abstract In the present study, cobalt manganese phosphate (H-CMP-series) thin films with different compositions of Co/Mn are prepared on stainless steel (SS) substrate via a facile hydrothermal method and employed as binder-free cathode electrodes in a hybrid supercapacitor. The XRD study reveals a monoclinic crystal structure, and the FE-SEM analysis confirmed that H-CMP-series samples displayed a nano/microarchitecture (microflowers to nanoflakes) on the surface of SS substrate with excess available surfaces and unique sizes. Interestingly, the synergy between cobalt and manganese species in the cobalt manganese phosphate thin film electrode demonstrates a maximum specific capacitance of 571 F g–1 at a 2.2 A g–1 current density in 1 M KOH. Besides, the nano/microstructured cobalt manganese phosphate was able to maintain capacitance retention of 88% over 8000 charge–discharge cycles. More importantly, the aqueous/all-solid-state asymmetric supercapacitor manufactured with the cobalt manganese phosphate thin film as the cathode and reduced graphene oxide (rGO) as the anode displays…

Bulk nanobubbles (NBs) have received considerable attention because of their extensive potential applications, such as in ultrasound imaging and water management. Although multiple types of experimental evidence have supported the existence and stabilization of bulk NBs, the underlying mechanism remains unclear. This study numerically investigates the bulk NB stabilization with molecular dynamics (MD) methods: the all-atom (AA) MD simulation is used for NBs of several nanometers diameter; the coarse-grained (CG) MD simulation is for the NBs of about 100 nm. The NB properties are statistically obtained and analyzed, including the inner density, inner pressure, surface charge, interfacial hydrogen bond (HB), and gaseous diffusion. The results show that the gas inside an NB has ultrahigh density (tens of kilograms per cubic meter). A double-layer surface charge exists on the NB. The inner/outer layer is positively/negatively charged, and the electrostatic stress can counteract part of the surface tension. In addition, the interfacial HB is weakened by the interaction between gas and…

Graphitic carbon nitride quantum dots (CNQDs) are a new class of nanomaterial with an extraordinary photoluminescent property. Here, three highly water-soluble and photoluminescent CNQDs are synthesized through a green and facile one-step hydrothermal approach, with urea as the nitrogen source and citric acid and its salts as carbon sources. The photoluminescence (PL) performance demonstrated that the fluorescence emission peak was altered by neither the structures nor the molar ratio of urea to the carbon source. Three highly luminescent CNQDs with a quantum yield of 40% were obtained when the molar ratio of urea to sodium citrate, citric acid, and ammonium citrate was 6:1, 18:1, and 18:1, which have average sizes of 4.1, 4.6, and 6.3 nm, respectively. Moreover, the possibility of using CNQDs as potential probes to determine the concentration of iron is also discussed. The results show that the as-prepared CNQDs has high selectivity for Fe 3+ ions. The quenching mechanism of CNQDs by iron is connected with the nitrogen functional groups on the surface of CNQDs. Results showed…

We developed a novel metal–organic framework (MOF)@covalent–organic framework (COF) hybrid with a hierarchical nanostructure and excellent photoactivity, which further acted as the bifunctional platform of a dual-mode photoelectrochemical (PEC) and electrochemical (EC) biosensor for detecting HIV-1 DNA via immobilizing the HIV-1 DNA probe. First, the presynthesized Cu-MOF nanoellipsoids were used as the template for the in situ growth of the COF network, which was synthesized using copper-phthalocyanine tetra-amine (CoPc-TA) and 2,9-bis[ p -(formyl)phenyl]-1,10-phenanthroline as building blocks through the Schiff base condensation. In view of the large specific surface area, abundant reserved amino group, excellent electrochemical activity, and high photoactivity, the obtained Cu-MOF@CuPc-TA-COF heterostructure not only can serve as the sensitive platform for anchoring the HIV-1 DNA probe strands but also can be utilized as the signal transducers for PEC and EC biosensors. Thereby, the constructed biosensor shows the sensitive and selective analysis ability toward the HIV-1 target…

Based on the energy conservation approach, this study develops a universal model to predict the maximum spreading factor of liquid droplet impact on a smooth solid surface. Validated with the present simulations and experiments in the literature, this model effectively overcomes the limitation of previous models in the viscous regime and greatly reduces the computing errors from over 30% to below 6%. It is demonstrated that the underestimated maximum spreading factor by previous models results from the overestimation of viscous dissipation. By replacing the conventional model of spreading time, t m = 8 D 0 /3 U 0, with a more precise one, t m = 1.47 τ i We – 0.44, the formulation to compute the viscous dissipation of entire spreading is improved. Finally, we examine the applicability of present model in the capillary regime and good performance is also shown.

Photocatalysts play an increasingly important role in environmental remediation polluted by industrial wastewater. However, the preparation of adsorbents and catalysts with high activity by simple and easy methods is still a great challenge. Here, sandwich-like composite catalyst Cu 2 O/TiO 2 /Ti 3 C 2 was prepared by an easily available solvent reduction measure for the highly efficient catalytic nitro compounds. In particular, sandwich-like composite catalyst Cu 2 O/TiO 2 /Ti 3 C 2 exhibits excellent catalysis for 2-nitroaniline (2-NA) and 4-nitrophenol (4-NP), and its pseudo-first-order reaction rate constants ( k ) are 0.163 and 0.114 min –1, respectively. Interestingly, even after eight consecutive cycles of catalytic experiments, the conversion rates of catalytic 2-NA and 4-NP are still greater than 95 and 92%, respectively, demonstrating that the obtained catalyst has excellent catalytic capability and a high reutilization rate. The excellent catalytic performances of Cu 2 O/TiO 2 /Ti 3 C 2 can be attributed to the fact that Ti 3 C 2 provides a greater reaction site for the…

The quest for interesting properties and phenomena in liquid crystals toward their employment in nondisplay application is an intense and vibrant endeavor. Remarkable progress has recently been achieved with regard to liquid crystals in curved confined geometries, typically represented as enclosed spherical geometries and cylindrical geometries with an infinitely extended axial-symmetrical space. Liquid-crystal emulsion droplets and fibers are intriguing examples from these fields and have attracted considerable attention. It is especially noteworthy that the rapid development of microfluidics brings about new capabilities to generate complex soft microstructures composed of both thermotropic and lyotropic liquid crystals. This review attempts to outline the recent developments related to the liquid crystals in curved confined geometries by focusing on microfluidics-mediated approaches. We highlight a wealth of novel photonic applications and beyond and also offer perspectives on the challenges, opportunities, and new directions for future development in this emerging research area.

Fabrication of high-performance artificial antioxidant enzyme (AAE) systems based on a single nanozyme possessing multi-enzymatic activities is fascinating but challenging. Here, polyvinylpyrrolidone (PVP)-platinum-copper nanoparticle clusters (PVP-PtCuNCs) are prepared by a facile one-pot chemical coreduction method. PVP-PtCuNCs possess efficient superoxide dismutase (SOD)-like, peroxidase (POD)-like, and catalase (CAT)-like activities, and the multi-enzymatic activities depend on the bimetal component and cluster structure. Compared with individual platinum nanoparticle clusters (PVP-PtNCs), PVP-PtCuNCs can effectively eliminate reactive oxygen species (ROS) including superoxide anions, hydrogen peroxide, and hydroxyl radicals. The doping of copper not only reduces the usage of Pt content but also improves the catalytic efficiency and versatility effectively through the synergistic effect of bimetal components and the nanocluster structure. The results not only demonstrate that a single bimetallic nanozyme has the potential as an efficient AAE system in the biomedical application…

Among heterogeneous electrocatalysts, gold comes closest to the ideal reversible electrocatalysis of CO 2 electrochemical reduction (CO2RR) to CO and, vice versa, of CO electroxidation to CO 2 (COOR).The nature of the electrolyte has proven to crucially affect the electrocatalytic behavior of gold.Herein, we expand the understanding of the effect of the widely employed bicarbonate electrolytes on CO2RR using gold monocrystalline electrodes, detecting the CO evolved during CO2RR by selective anodic oxidation.First, we show that CO2RR to CO is facet dependent and that Au(110) is the most active surface.Additionally, we detect by in situ FTIR measurements the presence of adsorbed CO top only on the Au(110) surface.Second, we highlight the importance of acid-base equilibria for both CO2RR and COOR by varying the electrolyte (partial pressure of CO 2 and the concentration of the bicarbonate) and voltammetric parameters.In this way, we identify different regimes of surface pH and bicarbonate speciation, as a function of the current and electrolyte conditions.We reveal the importance of…

New advanced adsorbents are a crucial driver for the development of energy and environmental applications. Tremendous potential is provided by machine learning and data mining techniques, as these approaches can identify the most appropriate adsorbent for a particular application. However, the current scientific reporting of adsorption isotherms in graphs and figures is not adequate to reproduce original experimentally measured data. This report proposes the specification of a new standard adsorption information file (AIF) inspired by the ubiquitous crystallographic information file (CIF) and based on the self-defining text archive and retrieval (STAR) procedure, also used to represent biological nuclear magnetic resonance experiments (NMR-STAR). The AIF is a flexible and easily extended free-format archive file that is readily human and machine readable and is simple to edit using a basic text editor or parse for database curation. This format represents the first steps toward an open adsorption data format as a basis for a decentralized adsorption data library. An open format…

Both a superhydrophobic structure and layered double hydroxide (LDH) coating were effective to improve the corrosion resistance of alloys. In this study, a superhydrophobic composite coating based on LDHs was constructed on Mg alloy by laser treatment, in situ growth of Mg-Al LDHs, and modification with octadecyl-trimethoxy-silane (OTS). The so-obtained composite coating was coded as L-LDHs-OTS, where L stands for laser treatment. Results showed that the L-LDHs-OTS composite coating presented the best anti-corrosion performance and the corrosion current density was reduced by about 5 orders of magnitude compared with that of the Mg alloy substrate. The excellent corrosion resistance was related to the superhydrophobicity of the composite coating, the compactness and ion-exchange capacity of the LDH layer, and the dense Si-O-Si network within the OTS layer. Moreover, the L-LDHs-OTS composite coating was still effective after 20 days of immersion tests, showing good long-term corrosion resistance due to the existence of hydrophobicity of the composite coating and the self-healing…

As the main component of the municipal waste, waste cardboard has caused a host of environmental problems. Therefore, the reasonable disposal of waste cardboard is of great significance to global sustainable development and green economics. Herein, using waste cardboard as the raw material, a superhydrophobic aerogel has been developed with a unique three-dimensional porous network structure, which exhibits excellent selective oil absorption capacities. The aerogel was made by combining Ca 2+ cross-links and postmodification with stearic acid. Superhydrophobic aerogels can absorb various organic solutions and its maximum absorption capacity can reach 47 times its own weight. Meanwhile, the size of aerogels has been further expanded, with a diameter of 21.2 cm and a height of 3.2 cm, which can absorb 34 times its own weight of kerosene. More importantly, the aerogel can also absorb oil droplets in oil/water emulsions with an adsorption efficiency of over 98.5%. Moreover, the aerogel can be employed multiple times without significantly reducing the adsorption capacity via distillation…

Here, poly(vinyl alcohol) (PVA) with numerous hydroxyl groups has been applied as a suitable substrate for efficient formation of zinc oxide (ZnO) nanoparticles with a flower shape (confirmed by electron-scanning microscopy), silver iodide (AgI) nanoparticles, and chlorophyll (Chl), as a natural-based photocatalyst (PVA/ZnO/AgI/Chl). First, an efficient preparation route for the PVA/ZnO/AgI/Chl nanophotocatalyst is presented starting from the extraction of Chl from fresh spinach. Then, the catalytic role of the prepared composite is precisely investigated in degradation of methylene blue (MB). The effects of visible-light irradiation, different contact times, and the employed ingredients on the architecture of the PVA/ZnO/AgI/Chl are screened in the degradation process of MB. It is demonstrated that the best result (MB removal efficiency ca. 95.5%) is achieved by applying the visible-light irradiation using a LED lamp (70 W, λ = 425 nm) for a 60 min duration. Moreover, the photocatalytic performance of PVA/ZnO/AgI/Chl has been further confirmed by degradation of Congo red (CR) (ca.…

This work aims to synthesize a core–shell material of CeO 2 @SiO 2 based on rice husk as a novel hybridized adsorbent for antibiotic removal. The phase structures of CeO 2 @SiO 2 and CeO 2 nanoparticles that were fabricated by a simple procedure were examined by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), and Fourier transform infrared (FT-IR) spectroscopy, while their interfacial characterizations were performed by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), the Brunauer–Emmett–Teller (BET) method, and ζ-potential measurements. The removal efficiency of the antibiotic amoxicillin (AMX) using CeO 2 @SiO 2 nanoparticles was much greater than that using SiO 2 and CeO 2 materials in solutions of different pH values. The optimum conditions for AMX removal using CeO 2 @SiO 2 including contact time and adsorbent dosage were 120 min and 5 mg/mL, respectively. The maximum AMX removal using CeO 2 @SiO 2 reached 100% and the adsorption capacity was 12.5 mg/g. Adsorption isotherms of AMX onto CeO 2 @SiO 2 were fitted by…

Nanobubbles (NBs) in liquid exhibit many intriguing properties such as low buoyancy and high mass transfer efficiency and reactivity as compared to large bulk bubbles. However, it remains elusive why or how bulk NBs are stabilized in water, and particularly, the states of internal pressures of NBs are difficult to measure due to the lack of proper methodologies or instruments. This study employed the injection of high-pressure gases through a hydrophobized ceramic membrane to produce different gaseous NBs (e.g., N 2, O 2, H 2, and CO 2 ) in water, which is different from cavitation bubbles with potential internal low pressure and noncondensed gases. The results indicate that increasing the injection gas pressure (60–80 psi) and solution temperatures (6–40 °C) both reduced bubble sizes from approximately 400 to 200 nm, which are validated by two independent models developed from the Young–Laplace equation and contact mechanics. Particularly, the colloidal force model can explain the effects of surface tension and surface charge repulsion on bubble sizes and internal pressures. The…

The cycloaddition of carbon dioxide (CO 2 ) with epoxides to yield highly value-added cyclic carbonates is an effective way to chemically utilize and convert CO 2 . Here, a heterogeneous catalyst of imidazole ionic liquid-decorated covalent organic framework with polyoxometalates (POM@ImTD-COF) was constructed by the covalent modification of ionic liquids to COFs and the electrostatic interaction between POMs and ionic liquids. The obtained POM@ImTD-COF shows high catalytic activity for CO 2 cycloaddition reaction under mild conditions (1 atm and 80 °C) in the presence of a co-catalyst, and the catalytic activity of POM@ImTD-COF has no obvious decrease during reusing five times. The excellent catalytic performance is mainly attributed to the synergistic effect of ionic liquids, POMs, and COFs. In the cycloaddition process, ionic liquids and the co-catalyst weaken the C–O bond of epoxides and promote the ring opening of epoxides. POMs as the Lewis acids facilitate the insertion of CO 2 to form reaction intermediates. The multiple activation effect of ionic liquids and POMs together…

When two or more droplets coalesce on a superhydrophobic surface, the merged droplet can jump spontaneously from the surface without requiring any external energy. This phenomenon is defined as coalescence-induced droplet jumping and has received significant attention due to its potential applications in a variety of self-cleaning, anti-icing, antifrosting, and condensation heat-transfer enhancement uses. This article reviews the research and applications of coalescence-induced droplet jumping behavior in recent years, including the influence of droplet parameters on coalescence-induced droplet jumping, such as the droplet size, number, and initial velocity, to name a few. The main structure types and influence mechanism of the superhydrophobic substrates for coalescence-induced droplet jumping are described, and the potential application areas of coalescence-induced droplet jumping are summarized and forecasted.

Metal oxide semiconductor (MOS) gas sensors show poor selectivity when exposed to mixed gases. This is a challenge in gas sensors and limits their wide applications. There is no efficient way to detect a specific gas when two homogeneous gases are concurrently exposed to sensing materials. The p–n nanojunction of x SnO 2 – y Cr 2 O 3 nanocomposites (NCs) are prepared and used as sensing materials ( x / y shows the Sn/Cr molar ratio in the SnO 2 –Cr 2 O 3 composite and is marked as Sn x Cr y for simplicity). The gas sensing properties, crystal structure, morphology, and chemical states are characterized by employing an electrochemical workstation, an X-ray diffractometer, a transmission electron microscope, and an X-ray photoelectron spectrometer, respectively. The gas sensing results indicate that Sn x Cr y NCs with x / y greater than 0.07 demonstrate a p-type behavior to both CO and H 2, whereas the Sn x Cr y NCs with x / y < 0.07 illustrate an n-type behavior to the aforementioned reduced gases. Interestingly, the Sn x Cr y NCs with x / y = 0.07 show an n-type behavior to H 2 but…

A Ag 3 PO 4 /GO/UiO–66–NH 2 (AGU) composite photocatalyst was prepared by an ultrasonic-assisted in situ precipitation method. The optical property, structure, composition, and morphology of photocatalysts were investigated using UV–vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, electrochemical impedance spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, energy-dispersive spectrometry, transmission electron microscopy, Fourier transform infrared spectroscopy, and charge flow tracking by photodeposition of Pt and PbO 2 nanoparticles. In comparison with Ag 3 PO 4 and Ag 3 PO 4 /UiO–66–NH 2 (AU), the AGU composite photocatalyst showed heightened photocatalytic performance for the degradation of levofloxacin hydrochloride (LVF). The AGU photocatalyst (dosage: 0.8 g/L) with 1% mass content of graphene oxide (GO), the mass ratio of Ag 3 PO 4 and UiO–66–NH 2 (U66N) reached 2:1, showed the highest photodegradation rate of 94.97% for 25 mg/L LVF after 60 min of visible light irradiation at pH = 6. The formation of a…

In this work, lignin/chitosan nanoparticles (Lig/Chi NPs) with controlled structures were synthesized in a simple and scalable microfluidic system. When the positively charged chitosan and the negatively charged lignin solution were blended in a microreactor, Lig/Chi NPs were rapidly formed via the electrostatic coassembly between the amino groups of chitosan and the carboxyl groups of lignin. The ζ potential changes from negative (-13 mV) to positive (+54.5 mV) for Lig NPs and Lig/Chi NPs, respectively. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results demonstrated that Lig/Chi NPs have an average particle size of about 180 nm, which can be used as nanocarriers for drug delivery. The anticancer drug nanoparticles with docetaxel (DTX) and curcumin (CCM) were prepared by coassembly with Lig/Chi NPs in a microreactor, which had good drug loading efficiency, biocompatibility, and can release drugs in response to pH in the weakly acidic environment of the tumor. The drug release amounts in acidic solutions that simulated the tumor microenvironment…

Self-healing superhydrophobic coatings have a wide potential for practical applications by prolonging their lifespan, but still suffer from some shortcomings, for example, difficulty in repairing microstructure damage, limited self-healing cycles, and more importantly the inability to self-heal while in service. Herein, we present the fabrication of superhydrophobic coatings having photothermal self-healing chemical composition and microstructure for the high performance anticorrosion of Mg alloy. The coatings contain a shape-memory polymer (SMP) primer and an upper superhydrophobic coating composed of fluorinated polysiloxane-modified multiwalled carbon nanotubes (PF-POS@MWCNTs). The coatings have good superhydrophobicity, photothermal effect, and anticorrosion performance. The coatings show excellent self-healing performance in response to chemical and microstructure damage, such as rapid self-healing under 1 sun irradiation in 10 min, complete self-healing after serious damage (e.g., 10 damage and self-healing cycles and complex microstructure damage), and even self-healing under…

Responsive hydrogels have found widespread applications in biomedical science and engineering fields, especially for drug delivery. Despite the superior performance of responsive hydrogels, challenges still exist in drug-delivery efficiency when environmental stimuli are weak. Recently, the demand in the design of hydrogel-based drug delivery systems has stimulated considerable interest in the search for new strategies, for instance, the application of nanocomposite hydrogels for reinforcing the versatility and flexibility in controlled drug delivery. In this study, a novel and effective nanocomposite hydrogel microcapsule drug delivery system, which is composed of poly( N -isopropylacrylamide) (PNIPAM) and alginate interpenetrating polymer and GO–Fe 3 O 4 nanomaterials, is developed to achieve NIR light-, magneto-, and pH-responsive drug release. The GO–Fe 3 O 4 nanomaterials embedded in the interpenetrating polymer enable the PNIPAM hydrogel deswelling by raising temperature above the lower critical solution temperature under NIR light and alternating magnetic field, thus…

The geometric structure of carbon electrodes affects their electrochemical behavior, and large-scale surface roughness leads to thin layer electrochemistry when analyte is trapped in pores. However, the current response is always a mixture of both thin layer and diffusion processes. Here, we systematically explore the effects of thin layer electrochemistry and diffusion at carbon fiber (CF), carbon nanospike (CNS), and carbon nanotube yarn (CNTY) electrodes. The cyclic voltammetry (CV) response to the surface-insensitive redox couple Ru(NH 3 ) 6 3+/2+ is tested, so the geometric structure is the only factor. At CFs, the reaction is diffusion-controlled because the surface is smooth. CNTY electrodes have gaps between nanotubes that are about 10 μm deep, comparable with the diffusion layer thickness. CNTY electrodes show clear thin layer behavior due to trapping effects, with more symmetrical peaks and Δ E p closer to zero. CNS electrodes have submicrometer scale roughness, so their CV shape is mostly due to diffusion, not thin layer effects. However, even the 10% contribution of thin…

In nature, many plants have evolved various wettability surfaces to survive and thrive in diverse environments. For example, the superhydrophobic surface of lotus can keep itself clean, while the rose petals can retain droplets for a long time. The former is referred to the "lotus effect," and the latter is known as the "rose petal effect." This research proposes a method to fabricate magnetic-responsive superhydrophobic magnetorheological elastomers (MREs) which could reversibly and instantly transition their surface wetting state between the "lotus effect" and the "rose petal effect." These surfaces with controllable wettability could find applications in the manipulation of liquids in biological and chemical systems. The MREs are cured by applying a uniform magnetic field to form "mountain-like" microstructures on their surfaces. This initial surface is rough and exhibits the lotus leaf effect. Because of the nonuniform magnetically induced deformation, the surface micromorphology and roughness can be altered by an applied magnetic field. The state of water droplets on its…

Slippery liquid infused porous surfaces (SLIPS) are an important class of repellent materials, comprising micro/nanotextures infused with a lubricating liquid. Unlike superhydrophobic surfaces, SLIPS do not rely on a stable air-liquid interface and thus can better manage low surface tension fluids, are less susceptible to damage under physical stress, and are able to self-heal. However, these collective properties are only efficient as long as the lubricant remains infused, which has proved challenging. We hypothesized that, in comparison to a nanohole and nanopillar morphology, the "hybrid" morphology of a hole within a nanopillar, namely a nanotube, would be able to retain and redistribute lubricant more effectively, owing to capillary forces trapping a reservoir of lubricant within the tube, while lubricant between tubes can facilitate redistribution to depleted areas. By virtue of recent fabrication advances in spacer defined intrinsic multiple patterning (SDIMP), we fabricated an array of silicon nanotubes and equivalent arrays of nanoholes and nanopillars (pitch, 560 nm;…

High Resolution Image Download MS PowerPoint Slide The study of Langmuir monolayers incorporating biomimetic and bioactive substances plays an important role today in assessing the properties and quality of the molecular films for potential biomedical applications. Here, miscibility of binary and ternary monolayers of phospholipid (dioleoyl phosphatidylcholine, DOPC), immunosuppressant (cyclosporine A, CsA), and antioxidant (lauryl gallate, LG) of varying molar fractions was analyzed by means of the Langmuir technique coupled with a surface potential (Δ V ) module at the air–water interface. The surface pressure–area per molecule (π– A ) isotherms provided information on the physical state of the films at a given surface pressure, the monolayer packing and ordering, and the type and strength of intermolecular interactions. Surface potential–area (Δ V – A ) isotherms revealed the molecular orientation changes at the interface upon compression. In addition, the apparent dipole moment of the monolayer-forming molecules was determined from the surface potential isotherms. The obtained…

Among the most reliable techniques for exfoliation of two-dimensional (2D) layered materials, sonication-assisted liquid-phase exfoliation (LPE) is considered as a cost-effective and straightforward method for preparing graphene and its 2D inorganic counterparts at reasonable sizes and acceptable levels of defects. Although there were rapid advances in this field, the effect and outcome of the sonication frequency are poorly understood and often ignored, resulting in a low exfoliation efficiency. Here, we demonstrate that simple mild bath sonication at a higher frequency and low power positively contributes to the thickness, size, and quality of the final exfoliated products. We show that monolayer graphene flakes can be directly exfoliated from graphite using ethanol as a solvent by increasing the frequency of the bath sonication from 37 to 80 kHz. The statistical analysis shows that ∼77% of the measured graphene flakes have a thickness below three layers with an average lateral size of 13 μm. We demonstrate that this approach works for digenite (Cu9S5) and silver sulfide (Ag2S),…

Metal ion-induced peptide assembly is an interesting field. As compared to traditional antibacterial Ag +, rare earth metal ions possess the advantage of antibacterial performance with photostability and low toxicity. Herein, a new peptide Fmoc-FFWDD-OH was designed and synthesized, which could form a stable hydrogel induced by rare earth metal ions, including Tb 3+, Eu 3+, and La 3+ . The mechanical properties were characterized by rheological measurements, and they exhibited elasticity-dominating properties. Transmission electron microscopy (TEM) images showed a large number of nanoscale fiber structures formed in the hydrogel. Circular dichroism (CD) spectra, Fourier transform infrared (FT-IR) spectra, ThT assays, and X-ray diffraction (XRD) pattern illustrated the formation mechanism of the fiber structure. The rare earth ion-induced peptide hydrogel was proved to possess good antibacterial performance on Escherichia coli ( E. coli ) with excellent biocompatibility. The introduction of rare earth metal ions may have some potential applications in the biological antibacterial and…

The real-time application of piezoelectric nanogenerators (PNGs) under a harsh environment remains a challenge due to lower output performance and poor durability. Thus, the development of flexible, sensitive, and stable PNGs became a topic of interest to capture different human motions including gesture monitoring to speech recognition. Herein, a scalable approach is adapted where naphthylamine bridging a [Cd(II)-μ-I 4 ] two-dimensional (2D) metal–organic framework (MOF)-reinforced poly(vinylidene fluoride) (PVDF) composite nanofibers mat is prepared to fabricate a flexible and sensitive composite piezoelectric nanogenerator (C-PNG). The needle-shaped MOF was successfully synthesized by the layering and diffusion of two different solutions. The incorporation of single-crystalline 2D MOF ensures a large content of electroactive phases (98%) with a resultant high-magnitude piezoelectric coefficient of 41 pC/N in a composite nanofibers mat due to the interfacial specific interaction with −CH 2 –/–CF 2 – dipoles of PVDF. As an outcome, C-PNG generates high electrical output…

To reduce the corrosion of Q235 steel, environment-friendly and efficient N-doped carbon dots (N-CDs) were synthesized using 4-amino salicylic acid (4-ASA) and l -histidine ( l -His) as precursors. The corrosion inhibition behavior of N-CDs for Q235 steel in 1 M HCl solution was systematically investigated using a weight-loss experiment, an electrochemical test, and corrosion morphology. Results showed that N-CDs could effectively inhibit the corrosion of Q235 steel, and the inhibitory efficiency reached 93% at 50 mg L –1 . Quantum chemistry and molecular dynamics were used to study the inhibition mechanism of N-CDs. The results demonstrated that N-CDs exhibited a strong adsorption force on metal and the adsorption process followed the Langmuir adsorption isotherm, indicating physical/chemical mixed adsorption.

We report the formation of coacervate-supported phospholipid membranes by hydrating a dried lipid film in the presence of coacervate droplets. Coacervate-supported membranes were characterized by fluorescence imaging, polarization, fluorescence recovery after photobleaching of labeled lipids, lipid quenching experiments, and solute uptake experiments. Our findings are consistent with the presence of lipid membranes around the coacervates, with many droplets fully coated by what appear to be continuous lipid bilayers. In contrast to traditional giant lipid vesicles formed by gentle hydration in the absence of coacervates, the coacervate-templated membrane vesicles are more uniform in size, shape, and apparent lamellarity. Due to their fully coacervate model cytoplasm, these simple artificial cells are macromolecularly crowded and can be easily pre-loaded with high concentrations of proteins or nucleic acids. Within the same population, in addition to coacervate droplets having intact lipid membrane coatings, other coacervate droplets are coated with membranes having defects or pores…

The interface of nanobio science and cancer nanomedicine is one of the most important current frontiers in research, being full of opportunities and challenges. Ultrasmall fluorescent metal nanoclusters (MNCs) and carbon quantum dots (CQDs) have emerged as promising fluorescent nanomaterials due to their unique physicochemical and optical properties, facile surface functionalization, good photostability, biocompatibility, and aqueous dispersity. These characteristics make them advantageous over conventional fluorophores such as organic dye molecules and semiconductor quantum dots (QDs) for the detection, diagnosis, and treatment of various diseases including cancer. Recently, researchers have focused on the biofunctionalization strategy of the MNCs and CQDs which can tailor their physicochemical and biological properties and, in turn, can empower these biofunctionalized nanoprobes for diverse applications including imaging, drug delivery, theranostics, and other biomedical applications. In this invited feature article, we first discuss some fundamental structural and physicochemical…

Precise tailoring of two-dimensional nanosheets with organic molecules is critical to passivate the surface and control the reactivity, which is essential for a wide range of applications. Herein, we introduce catechols to functionalize exfoliated MXenes (Ti 3 C 2 T x ) in a colloidal suspension. Catechols react spontaneously with Ti 3 C 2 T x surfaces, where binding is initiated from a charge-transfer complex as confirmed by density functional theory (DFT) and UV–vis. Ti 3 C 2 T x sheet interlayer spacing is increased by catechol functionalization, as confirmed by X-ray diffraction (XRD), while Raman and atomic force microscopy-infrared spectroscopy (AFM-IR) measurements indicate binding of catechols at the Ti 3 C 2 T x surface occurs through metal–oxygen bonds, which is supported by DFT calculations. Finally, we demonstrate immobilization of a fluorescent dye on the surface of MXene. Our results establish a strategy for tailoring MXene surfaces via aqueous functionalization with catechols, whereby colloidal stability can be modified and further functionality can be introduced,…

A novel metal-free all-solid-state z-scheme g-C 3 N 4 /NCDs/WO x photocatalyst was fabricated using nitrogen-doped carbon dots (NCDs) as the electron mediator. As-prepared sandwich-structured composites displayed enhanced visible and NIR light photocatalytic activity. Under visible light irradiation, the hydrogen evolution rate reached 3.27 mmol g –1 h –1, which increased to roughly seven times higher than that of pure g-C 3 N 4 and roughly twice that of g-C 3 N 4 /NCDs or g-C 3 N 4 /WO x binary heterojunctions. The apparent quantum efficiency is 7.58% at 420 nm. The localized surface plasmon resonance effect of WO x and the up-converted photoluminescence property of NCDs enhanced the utilization efficiency of NIR light together. In addition, the matched energy band structures of WO x and g-C 3 N 4 as well as the effective electron conductor (NCDs) between them accelerate electron transfer at the interface. The all-solid-state z-scheme g-C 3 N 4 /NCDs/WO x photocatlyst was confirmed by a series of characterizations and experiment results. This report offered new insights into…

The phase transfer of ions is driven by gradients of chemical potentials rather than concentrations alone (i.e., by both the molecular forces and entropy). Extraction is a combination of high-energy interactions that correspond to short-range forces in the first solvation shell such as ion pairing or complexation forces, with supramolecular and nanoscale organization. While the latter are similar to the long-range solvent-averaged interactions in the colloidal world, in solvent extraction they are associated with lower characteristic lengths of the nanometric domain. Modeling of such complex systems is especially complicated because the two domains are coupled, whereas the resulting free energy of extraction is around k B T to guarantee the reversibility of the practical process. Nevertheless, quantification is possible by considering a partitioning of space among the polar cores, interfacial film, and solvent. The resulting free energy of transfer can be rationalized by utilizing a combination of terms which represent strong complexation energies, counterbalanced by various…