Surface Of Foam Research Articles

Development of surface modified PU foam with improved oil absorption and reusability via an environmentally friendly and rapid pathway

Although the commercial polyurethane (PU) foams are hydrophobic in nature, they generally show low degree of reusability for oil and organic solvent absorption. In this work, we proposed a solvent-free and rapid surface functionalization approach based on chemical vapor deposition (CVD) process to improve the surface characteristics of PU foam, increasing not only its reusability but also its absorption capacity. Among the monomers used to functionalize the surface of foam, our results showed that only hexamethyldisiloxane (HMDSO) and 2,2,3,4,4,4-hexafluorobutyl acrylate (HFBA) were promising to increase the absorption performance of the control PU foam, owing to the enhanced foam’s surface hydrophobicity (with contact angle increased from ~106° to 120–135°) without altering the foam’s porosity. These promising features are attributed to the formation of ultrathin highly hydrophobic yet uniform layer on the foam surface. Further investigation indicated that the modified foams outperformed the control foam for the multicycle cyclohexane and crude oil absorption (up to 10 cycles) by showing significantly higher absorption capacity. The reusability of the modified foams could be further improved when ethanol was employed to rinse the saturated foam after each absorption cycle. Such solvent rinsing help in maintaining the foam absorption capacity. In conclusion, the proposed greener surface modification method clearly demonstrated its effectiveness in functionalizing the PU foam, leading to higher absorption capacity against cyclohexane and crude oil as well as higher degree of reusability.

Synthesis of hierarchical hetero-composite of graphene foam/α-Fe2O3 nanowires and its application on glucose biosensors

In this study, graphene foam/hematite (GF/α-Fe2O3) nanowire arrays hetero-structured nanocomposite (HNC) electrode was synthesized in a hierarchical manner where each constituent had its own function. The synthesis of continuous, high crystallinity and intact graphene layers on the surface of Ni foam was carried out via chemical vapor deposition (CVD) and there was no significant deterioration after Ni removal. Acting as an active backing layer, the GF provided a large surface area with high charge transfer capacity, thus facilitating the high electron transfer rate and increased electrochemical response. Hydrothermal synthesis yielded α-Fe2O3 nanowires with an average length of 400–450 nm. XPS results showed that the HNC sample was mostly composed of α-Fe2O3 phase. Finally, HNC electrode was applied for the construction of an electrochemical glucose biosensor. The increased surface area of the electrode facilitated immobilization of large amounts of glucose oxidase (GOx). Based on the active surface area of the electrode, the limit of detection and sensitivity of the biosensor were calculated to be 71.6 μM and 20.03 μAmM−1cm−2, respectively. The high sensitivity and selectivity of HNC for the detection of glucose demonstrated that the synthesized nanocomposite material is a promising material to construct high sensitive biosensors for the detection of biologically relevant molecules.

Flexible polyurethane foams surface-modified with FeOOH for improved oil-water separation and flame retardancy

In this work, the flexible polyurethane foam modified with FeOOH (FPU/FeOOH) was successfully fabricated by hydrothermal method with ferric chloride hexahydrate and urea as raw materials. FPU/FeOOH foams were characterized by X-ray diffraction (XRD), Scanning electron (SEM), X-ray energy dispersive spectroscopy (EDS) and Contact angle (CA), showing a large amount of FeOOH nanoparticles were uniformly distributed on the surface of FPU foams. The introduction of FeOOH significantly boosted the hydrophobicity and oleophilicity of FPU foams, and the maximum adsorption capacity for various oil products and organic solvents had achieved 44 times of its own weight. Moreover, the modified FPU foams still had excellent reusability and stability. Not only that, the flammability of FPU/FeOOH foams was estimated by cone calorimeter test (CCT) and direct combustion test, the values of peak heat release rate (PHRR), total heat release (THR), peak smoke production rate (PSPR) and total smoke production (TSP) decreased dramatically, indicating the introduction of FeOOH nanoparticles remarkably boosted the flame retardant property of FPU foams. Therefore, due to its facile fabrication technique, excellent absorption performances, reusability and flame retardancy, the FPU/FeOOH foams hold great promise for potential applications in oil/water separation.

Lithiophilic NiF2 coating inducing LiF-rich solid electrolyte interphase by a novel NF3 plasma treatment for highly stable Li metal anode

A three-dimensional lithiophilic skeleton is an effective strategy that is widely studied due to its large specific surface area and the lithiophilicity for suppressing the growth of dendrites on Li metal anodes. However, there are few studies on the lithiophilicity of the metal fluoride. In this study, we employ a novel NF3 plasma fluoridized strategy to fabricate a NiF2 coating on Ni foams for the first time. Due to the lithiophilic NiF2 layer, the Li+ flux tends to deposit preferentially on the sites of NiF2 and homogeneously distributes around the surface of the Ni foam, leading to a smooth and dense Li deposition. Moreover, the LiF-rich solid electrolyte interphase layer generated from the reaction between Li and NiF2 significantly improves the interfacial stability. The fluoridized Ni foam exhibits a highly stable cycling performance of over 2000 cycles at 2 mA cm−2 and over 1600 h at 1 mA cm−2. In addition, the fluoridized Ni foam@Li || LiFePO4 full cell delivers a capacity retention of 93% after 250 cycles at 1C. This work provides a safe and simple plasma strategy to construct a lithiophilic metal fluoride coating for strengthening the solid electrolyte interphase and suppressing the growth of Li dendrites.

Scalable Synthesis of NiFe‐LDH/Ni9S8/NF Nanosheets by Two‐Step Corrosion for Efficient Oxygen Electrocatalysis

AbstractScalable synthesis of non‐noble‐metal‐based electrocatalysts achieved by energy‐saving and cost‐effective strategies towards efficient oxygen evolution is primary significant for the practical application of water splitting, however, it is still a great challenge. In this work, a two‐step corrosion engineering is proposed to construct ultrathin NiFe‐LDH and high‐conductivity Ni9S8 composites (denoted as NiFe‐LDH/Ni9S8/NF) at room temperature. By ingeniously using the corrosion reaction between nickel foam (NF) and S2O32− under acidic condition, Ni9S8 was firstly formed on the surface of Ni foam. Then, ultrathin NiFe‐LDH nanosheets were precipitated on the Ni9S8 surface through an ultrafast Fe2+ ions‐assisted corrosion treatment. Featured with fast electron/mass transfer rates, sheet‐stacked structure, and superior hydrophilicity, NiFe‐LDH/Ni9S8/NF exhibits an enhanced oxygen evolution reaction (OER) activity with low overpotentials of 223 and 265 mV at 10 and 100 mA cm−2, respectively. Such feasible, economical, and scale‐up synthesis method might open a new avenue for the wide‐scale fabrication of materials for various electrochemical applications.

Effect of polysaccharide polymers on the surface and foam properties of aqueous film-forming foam

Three kinds of polysaccharide polymers were used as the proposed foam stabilizers in aqueous film-forming foam (AFFF). The effect of polysaccharide polymers on viscosity, surface tension, foaming ability and foam stability of AFFF was discussed by various analytical methods. The results shows that the addition of polysaccharide polymers slightly increases the surface tension of foam solution, while the combination of xanthan gum and gelatin presents the least negative influence on the surface tension of foam solution. Especially, the addition of gelatin improves the foaming ability of AFFF while both xanthan gum and sodium alginate decrease the foaming ability of AFFF. The combination of xanthan gum and gelatin can effectively balance the foaming ability and foam stability of AFFF, which is ascribed to the increases of viscosity that enhances the surface strength of foam liquid film and decreases the diffusion of water in the liquid film, thus effectively slowing down the drainage rate and bubbles coarsening of foam.

Preparation of CuWO4 foam and its use as a heterogeneous catalyst for dimethyl sulfoxide oxidation in a scale-up microreactor

BackgroundMetal foam has been demonstrated numerous advantages in fine chemistry when used as catalyst support. In this research, a novel strategy for the fabrication of copper tungstate (CuWO4) foam as heterogeneous catalysis to conduct dimethyl sulfoxide (DMSO) oxidation reaction in a scale-up microreactor was proposed. MethodsA series of three-dimensional skeleton CuWO4 foams were prepared by a continuous sintering approach. The obtained CuWO4 catalysis inherited the porous structure from the copper foam and had a high loading density of CuWO4 crystal particles. Afterwards, DMSO oxidation was employed as a probe reaction to explore the catalytic performance of CuWO4 foam. Significant findingsCuWO4 foam showed prefect catalytic activity in a scale-up microreactor. The average crystallite size of CuWO4 were increased from 52.8 to 57.7 nm with extension of sintering time. Under the optimum condition (residence time was 40 min, CuWO4 catalyst was CuWO4F-5 and reaction temperature was 80 oC), a high dimethyl sulfone yield of 65.4% was obtained. The yield of MSM reached nearly 65.3% in the run time of 1 h and showed a value of 50.4% even in the run time of 4 h. Higher reaction contact surface and larger crystal particles of CuWO4 foam are conducive to enhancing the catalytic performance of CuWO4 foam. This research indicates the potential opportunity to apply CuWO4 foam in a scale-up microreactor.

Rational design of PdCu nanoparticles supported on a templated Ni foam: The cooperation effect of morphology and composition for electrocatalytic oxidation of ethanol

In this study, with the goal of the production of a cost effective anode for ethanol oxidation, the surface of Ni foam is covered with templated PdCu nanoparticles via the galvanic replacement reaction. The use of the templating method results in the uniform formation of the spongiform bimetallic structure on the surface of Ni foam. The role of the templating method in the synthesis of a stable catalyst towards dealloying process is considered by the electrochemical pretreatment of t-PdCu/NF and PdCu/NF in H2SO4 solution. The excellent stability of t-PdCu/NF for ethanol oxidation in the alkaline media is proved by the achievement in the steady state after 14 s with survival of 60% current density and 12% increase in the current density after 100 consecutive cycles. The electrochemical impedance spectroscopy gives evidence that the templating method and elemental composition cooperate in the improvement of the reactant diffusion and charge transfer on the surface of the synthesized catalyst. Finally, the mechanism of the ethanol oxidation and the effect of morphology and composition on this mechanism are studied using the cyclic voltammetry and chronoamperometry methods.

Synchronously enhanced thermal properties and fracture toughness of epoxy composites through melamine foam templated dispersion of carbon nanofibers

Fabricating the thermally conductive composites through incorporating fillers into polymer matrix is usually at the sacrifice of the fracture toughness. To resolve such contradiction, this work proposed a feasible but highly efficient method of constructing the thermally conductive path in the epoxy composite at extremely low filler content. The polyvinylpyrrolidone (PVP) modified carbon nanofibers (P-CNFs) were coated on the three-dimensional (3D) framework surface of the melamine foam (MF), then the epoxy resin was impregnated into the MF@P–CNF. The results showed that the assembled structure of MF@P-CNFs could be well reserved in the epoxy composite. Consequently, at extremely low P–CNF content (0.8 wt%), the MF@P–CNF/EP sample shows the largely enhanced thermal conductivity (0.4 W/m·K) and glass transition temperature (167 °C) compared with the pure epoxy sample (0.2 W/m·K and 162 °C). Specifically, the composite sample also shows the apparently enhanced fracture toughness. Therefore, it is believed that coating CNFs on the 3D interconnected framework of MF is a promising way to prepare the epoxy composites with good comprehensive properties.

A novel perspective on interfacial interactions between polypyrrole and carbon materials for improving performance of supercapacitors

Using carbon-based materials as substrates or additives is an effective strategy for the improvement of electrochemical properties of polypyrrole (PPy) in supercapacitors, while the interfacial interactions between them is not exactly clear, which limits the rational design of composite electrodes. Herein, the interfacial interactions are investigated by forming novel freestanding composite electrodes via depositing PPy on the surface of carbon foam (CF). After combination, the capacitance increases from 37.3 mF cm−2 to 364.0 mF cm−2. Moreover, a superior capacitance retention (99.6%) can be achieved, after 10,000 charging/discharging cycles. Density functional theory (DFT) results show that the introduction of different oxygen-containing functional groups will lead to the difference of adsorption energy between carbon materials and PPy, thus affecting the cycling stability of composite materials. Moreover, the intermolecular interaction also affects redox properties of composite electrodes by changing the composition and energy of frontier orbits of the interfacial complexes involved in redox reactions. This study will provide a new perspective for purposeful regulating the electrochemical performance of composite electrodes.

Cobalt Boride/g-C3N4 Nanosheets-Assisted Electrocatalytic Oxidation of 5-Hydroxymethylfurfural into 2,5-Furandicarboxylic Acid

The electrochemical production of 2,5-furandicarboxylic acid (FDCA) from 5-(hydroxymethyl)furfural (HMF) is receiving growing attention. The FDCA-based polyethylene 2,5-furan dicarboxylate (PEF) polymer is a green candidate for substituting polyethylene terephthalate. This work demonstrated a highly efficient CoB/g-C3N4 nanosheet on the surface of the nickel foam as an electrode for the HMF electrooxidation reaction. Electrolysis at a constant potential combined with liquid chromatography showed the formation of FDCA with a yield of 97% with an excellent faradaic efficiency of near 95%. CoB/g-C3N4 achieved a current density of 20 mA cm−2 for HMF oxidation in 1.0 M KOH with 10 mM HMF at 1.37 V vs. RHE before the competing oxygen evolution reaction. The electrocatalyst was effectively reused up to three times without compromising efficiency. This work demonstrates a cheap and active electrocatalyst material for the electrochemical formation of FDCA from HMF and gives perception into the reaction mechanism.

Fabrication of super-wetting copper foam based on laser ablation for selective and efficient oil-water separation

Oil pollution has caused damage to the ecological environment and human health, which cannot be ignored in industrial production and marine economic. It is very vital to explore a simpler and easier to manufacture oil-water separation method. In this work, the super-wetting copper foam with superhydrophobicity or superhydrophilicity on was fabricated based on low-cost nanosecond laser ablation combined chemical modification. The surface of copper foam was covered with fluffy microstructures and smaller nanoparticles after laser ablation, which greatly enhances the hydrophobicity, with a maximum contact angle of 156°. The droplet could rebound many times after being compressed in a cake shape on the superhydrophobic surface but spread rapidly on the superhydrophilic surface. Analysis of chemical composition verified the fluorine-containing long-chain greatly reduces surface energy, while the oxygen group of graphene oxide is the opposite. Based on the oil permeability of the superhydrophobic copper foam and the water permeability of the superhydrophilic copper foam, the separation of heavy oil and light oil can be selectively achieved. The separation efficiency of different oil-water mixtures could be higher than 99%, and the recyclability was better after multiple separations. It provides a convenient and selective way for oil-water separation.

Electrodeposited Co–W–P ternary catalyst for hydrogen evolution reaction

In order to reduce the overpotential of hydrogen evolution reaction (HER), the ternary coating Co–W–P was deposited on the surface of the nickel foam by electrochemical deposition to obtain a highly active electrode. Based on the measured double layer capacitance (C dl) and HER activity, there is volcanic behavior between the intrinsic activity of Co–W–P and the Co:W ratio in the electrolyte. W and P play different roles in the formation of nanoparticles, and work together to achieve the large electrochemical surface area and excellent activity. When applied to the modification of other catalysts (Ni–P and Fe–P), the higher intrinsic activity was obtained after the introduction of W.

One-step synthesis of 2D vertically-aligned hybrid CuSe@NiSe nanosheets for high performance flexible supercapacitors

An in-situ one-step hydrothermal method is used to prepare hybrid CuSe@NiSe nanosheets with vertical orientation and interpenetrating structure on the surface of copper foam (S-CuSe@NiSe). The S-CuSe@NiSe has excellent electrochemical performance and outstanding cycling performance. The specific capacitance of the S-CuSe@NiSe is 1478 F g-1 at a current density of 1 A g-1 and stabilizes at 990 F g-1 at 8 A g-1. The specific capacitance retention of S-CuSe@NiSe is 81.7% after 10,000 cycles. The all-solid-state flexible capacitors prepared with S-CuSe@NiSe as electrode (S-CuSe@NiSe-SFCs) also exhibit excellent flexibility, superior electrochemical performance and cycle stability. Its capacitance reaches 333 F g-1 at a current density of 1 A g-1. Capacitance retention of 79.3% has been obtained after 10,000 charge-discharge cycles at 2 A g-1.

Cubic KNiFe(CN)6/C loaded on nickel foam for rechargeable liquid/flexible Zn-air batteries

KNiFe(CN)6/C/NF catalyst is prepared by a simple hydrothermal reaction. In this catalyst, the cubic structure of KNiFe(CN)6 grows on the surface of the nickel foam (NF) to form a three-dimensional network structure. The formation of KNiFe(CN)6 is based on the substitution of K+ by Ni2+ in K3[Fe(CN)6]. During this substitution process, some K+ vacancies will be formed in KNiFe(CN)6, so that the catalytic activity can be improved. The KNiFe(CN)6/C/NF catalyst shows exhibited efficient electrocatalytic activity for oxygen evolution reaction, requiring low overpotentials of 69 and 231 mV to achieve 10 and 100 mA cm−2 current densities in 1.0 M KOH solution. When it is used as a catalyst for ZABs, KNiFe(CN)6/C/NF shows excellent high stability within 1000 cycles with a charge-discharge overpotential gap of 0.85 V at 5 mA cm−2. The flexible battery assembled based on the KNiFe(CN)6/C/NF catalyst also has excellent performance, which can maintain stable charge and discharge within 50 cycles at a current density of 5 mA cm−2.

High-Strength and Low-Cost Biobased Polyurethane Foam Composites Enhanced by Poplar Wood Powder Liquefaction.

An environmentally friendly liquefaction of wood powder was prepared by atmospheric pressure liquefaction technology to replace the non-renewable petroleum polyols in the preparation of polyurethane foam composites. The liquefaction time varied from 0 min to 140 min. The composition of liquefied products and the effects of liquefaction time on the morphology, apparent density and mechanical properties of polyurethane foam composites were investigated. The results showed that the optimal process time for the preparation of wood powder liquefaction products, which could replace traditional petroleum polyols, was 110 min. At this time, polyether polyols are the main liquefaction products, with an average molecular weight in Mn reaching 237 and average molecular weight in Mw reaching 246. The functional group of the liquefied product consisted mainly of hydroxyl, with the highest content of 1042 mg KOH/g and the lowest acid number of 1.6 mg KOH/g. In addition, the surface of the polyurethane foam based on poplar wood is dominated by closed cell foam; thus its foam has good heat insulation and heat preservation properties. At 110 min liquefaction time, the apparent density of polyurethane foam is 0.164 g/cm3 and the compression strength is 850 kPa, which is higher than that of traditional polyurethane foam (768 kPa), which is without wood powder modification. Replacing petroleum polyol with renewable wood powder liquefaction products to prepare biomass-based polyurethane foam composite materials, researching complex chemical changes in different liquefaction stages, and finding the best liquefaction conditions are of great significance to optimize the performance of polyurethane, address the shortage of resources and reduce environmental pollution.

Effects of carbothermal reduction of iron oxide on microstructures and electrochemical properties of the carbon foams

This work developed novel surface-modified carbon foams (SMCFs) with high heteroatom contents and a certain amount of iron oxide particles via the carbothermal reduction reaction between iron oxide and the cyanate resin-based carbon foam. The effects of carbothermal reduction of iron oxide on microstructures and electrochemical properties of the carbon foams have been studied systematically using TG, XRD, FESEM, BET, and XPS. Results show that the carbothermal reduction greatly influences the microstructures of carbon foams when the temperature is higher than 600 °C. The generated iron oxide particles were embedded into the surface of carbon foams. With the increase of temperature, the surface became porous and rough with a certain graphitic structure. When the temperature arrives at 1000 °C, the as-prepared SMCF-1000 has a highest specific capacitance of 212.42 F g−1 at 1 A g−1, and the specific capacitance maintains 107% of the initial value after 10,000 charge-discharge cycles. In addition, the SMCF-1000 exhibits a maximum compressive strength of 2.52 MPa, which is expected to be a novel three-dimensional self-supporting electrode material.

The facile conversion of iron foam into copper-coated 3D porous cobalt ferrite/iron foam for high-performance asymmetric hybrid supercapacitor

In this work, copper-coated CoFe2O4/iron foam (Cu@CoFe2O4/Fe) is synthesized with a facile method, including the growth of the copper film on the surface of iron foam via a displacement reaction between iron foam and Cu(II), and the subsequent partial conversion of the interior iron to CoFe2O4via a hydrothermal reaction by heating the copper-coated iron foam (Cu@Fe) in the aqueous solution of cobalt nitrate. Iron foam is used as the self-sacrificial template not only for the synthesis of cobalt ferrite foam but also the synthesis of the copper film. The high porosity of Cu@CoFe2O4/Fe facilitates the mass and charge transport at the solution/electrode interface, while the coating of the CoFe2O4 with copper film effectively hinders the volume expansion of CoFe2O4 and subsequently prevents the falling off of CoFe2O4 during the vigorous charging/discharging process, as evidenced by the high areal capacity, good rate capacity and extraordinary cycling stability of Cu@CoFe2O4/Fe.

Facile Synthesis of Coral Reef-Like ZnO/CoS2 Nanostructure on Nickel Foam as an Advanced Electrode Material for High-Performance Supercapacitors

Nanocomposite electrodes receive much attention because of their excellent energy storage nature. Electrodes for supercapacitors have come a major source of interest. In this pursuit, the current work elucidates binder-free coral reefs resembling ZnO/CoS2 nanoarchitectures synthesized on the surface of Ni foams employing the cost-effective hydrothermal route. The Zno/CoS2 nanocomposite demonstrated excellent battery-type behavior, which can be employed for supercapcitor application. Various analyses were carried out in the current study, such as X-ray diffraction and high-resolution scanning electron microscopy, which allowed defining the crystalline nature and morphology of surface with ZnO/CoS2 nanoarchitectures. Electrochemical measures such as cyclic voltammetry, galvanostatic charge discharge, and potentiostatic impedance spectroscopy confirmed the battery-type behavior of the material. The synthesized precursors of binder-free ZnO/CoS2 nanostructures depicted an excellent specific capacity of 400.25 C·g−1 at 1 A·g−1, with a predominant cycling capacity of 88. 2% and retention holding of 68% at 10 A·g−1 and 2 A·g−1, even after 4000 cycles, representing an improvement compared to the pristine ZnO and CoS2 electroactive materials. Therefore, the electrochemical and morphological analyses suggest the excellent behavior of the ZnO/CoS2 nanoarchitectures, making them promising for supercapacitors.

Measurement bruise volume of olive during impact test using FEM and quality evaluation of extracted olive oil.

Mechanical damage is a phenomenon that always occurred in the postharvest process. Due to the inappropriate harvest and postharvest process of Olive that lead to the bruise phenomenon, the quality of the extracted olive oil reduces. In this study, the effect of olive damage on bruising volume and quality characteristics was investigated. Three different varieties of Yellow, Oily, and Fishemi in three stages of unripe, semiripe, and ripped were used. Also, three kinds of the surface of rubber, nylon, and foam for the drop test were considered. The tests were performed in laboratory mode and simulated. For all tests, with increasing maturity, the amount of stress and internal energy were decreased and the bruise volume was increased. The amount of bruise volume and bruise susceptibility were obtained, and the experimental and simulated conditions were compared. On the other hand, the quality characteristics of olive oil including free fatty acid (FFA), peroxide value (PV), k232 and K270 coefficients, total chlorophyll, total carotenoid, total phenol, and total flavonoid were measured. The results showed that the finite element and chemometric methods are acceptable methods for predicting the generated energy of the fruit during impact, the amount of bruising volume, as well as evaluating the quality of the extracted oil.