Abstract
Electrospinning is a powerful and versatile technique to produce efficient, specifically tailored and high-added value anodes for lithium ion batteries. Indeed, electrospun carbon nanofibers ...(CNFs) provide faster intercalation kinetics, shorter diffusion paths for ions/electrons transport and a larger number of lithium insertion sites with respect to commonly employed powder materials. With a view to further enhance battery performances, red phosphorous (RP) is considered one of the most promising materials that can be used in association with CNFs. RP/CNFs smart combinations can be exploited to overcome RP low conductivity and large volume expansion during cycling. In this context, we suggest a simple and cost effective double-step procedure to obtain high-capacity CNFs anodes and to enhance their electrochemical performances with the insertion of red phosphorous in the matrix. We propose a simple dropcasting method to confine micro- and nanosized RP particles within electrospun CNFs, thus obtaining a highly efficient, self-standing, binder-free anode. Phosphorous decorated carbon mats are characterized morphologically and tested in lithium ion batteries. Results obtained demonstrate that the reversible specific capacity and the rate capability of the obtained composite anodes is significantly improved with respect to the electrospun carbon mat alone.
Carbon nanofibers (CNFs) have witnessed extensive application in lithium-ion batteries (LIBs) over the last decade. CNFs are characterized by its one-dimensional nanosized structure and excellent ...mechanical and electrical properties. They are desirably assembled into porous, flexible and robust platforms, on which a variety of anode and cathode active materials are loaded resulting in a promising family of LIB electrodes. Structures of the as-fabricated CNF-based composites have been verified to be of great importance to electrochemical performance. Therefore, this review aims at elaborating the relation between the structures and the electrochemical performance of CNF-based composites. Specifically, the review is sectioned by the morphology of CNFs, i.e., solid, porous and hollow, the type of active materials and the morphology of active materials. In addition, some thoughts for future progress are provided.
•A comprehensive collection of carbon nanofiber-based composites for lithium-ion batteries.•A deep insight into the relation between structures and electrochemical performance of carbon nanofiber-based composites.•Constructive suggestions on a route toward high electrochemical performance for carbon nanofiber-based composites.
Superoleophobic thin films have many potential applications including fluid transfer, fluid power systems, stain-resistant and antifouling materials, and microfluidics. Transparency is also desired ...with superhydrophobicity for numerous applications; however, transparency and oleophobicity are almost incompatible with each other from the point of view of surface structure. Oleophobicity requires a rougher structure on the nano–microscale than hydrophobicity, and this rough structure brings light scattering. So far, there are few reports of compatible transparency and superoleophobicity. In this report, we propose see-through-type fabrics having nanoparticle-based hierarchical structure thin films to improve both oleophobicity and transparency. The vacant space between the fibers of the fabric has two important roles: to allow light to pass through and to induce an air layer to produce a Cassie state of a liquid droplet on the resulting thin film. To realize a low surface energy and nanoscale rough structured surface on fabric fibers, we used a spray method with perfluoroalkyl methacrylic copolymer, silica nanoparticles, and volatile solvent. Scanning electron microscopy images revealed that hierarchical nanoparticle structures were uniformly formed on the fabrics. The transparency of the obtained thin film was approximately 61 %, and the change of transparency between the non-coated and coated fabrics was 11 %. The contact angles of oil (rapeseed oil and hexadecane) and water droplets on the fabricated film were observed to be over 150° during investigation of its surface wettability.
► The layer-by-layer process was applied to the surface of TiO2 nano particles. ► This method can control the particle's aggregation and can generate micro-scale rough structure. ► Micro–nano scale ...rough structure using LBL process shows the high oleophobicity. ► This method may have industrial advantages because it is aqueous based.
The layer-by-layer (LBL) adsorption technique has potential for controlling the surface wettability. In this study, we controlled surface wettability between “superhydrophobic and oleophobic” and “hydrophobic and oleophilic” by LBL process on TiO2 nanoparticle with hydrophobic polymer and hydrophilic polymer. From the cast coating with LBL process on TiO2 nanoparticle, the surface showed “superhydophobic and oleophobic” when the top surface was hydrophobic polymer, on the other hand, the surface showed “hydrophobic and oleophilic” when the top surface was hydrophilic polymer. The LBL process also affected to the structure of TiO2 nanoparticle/polymer composite, and TiO2 nanoparticle were aggregated with polymers in LBL process. In the condition of the aggregated diameter of TiO2 nanoparticle/polymer composite around 10μm in solution, the oleohobicity of spray coated film was enhanced with its hierarchical structure (static contact angles of rapeseed oil of 150° and hexadecane of 145°) “Superhydrophobic and high oleophobic” surfaces generated from all water-based dispersions are expected for application in technologies that need to avoid organic solvents.
We report the different attenuated shear vibrations of hydrophilic quartz crystal microbalance (QCM) by attached small viscous liquids and this technique enabled us to measure the viscosity of ...various 5 μL solutions. Covering entire area of QCM surface by a liquid was important for stable damping time measurement and accordingly we induced silica/polyelectrolyte hydrophilic coating on QCM with using Layer by Layer (LbL) self assembly method for enhanced wettability and saving viscous materials. We examined the relationship between damping time and viscosity of polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP) or glycerol aqueous solutions. We also applied this technique for estimating blood coagulation behaviors.
We report a new approach for fabricating a super-hydrophobic nanofibrous zinc oxide (ZnO) film surface. The pure poly(vinyl alcohol) (PVA) and composite PVA/ZnO nanofibrous films can be obtained by ...electrospinning the PVA and PVA/zinc acetate solutions, respectively. After the calcination of composite fibrous films, the inorganic fibrous ZnO films with a reduced fiber diameter were fabricated. The wettability of three kinds of fibrous film surfaces were modified with a simple coating of fluoroalkylsilane (FAS) in hexane. The resultant samples were characterized by field emission scanning electron microscopy (FE-SEM), water contact angle (WCA), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). It was found that the pure PVA fibrous films maintained the super-hydrophilic surface property even after the FAS modification. Additionally, the WCA of composite fibrous films was increased from 105 to 132° with the coating of FAS. Furthermore, the surface property of inorganic ZnO fibrous films was converted from super-hydrophilic (WCA of 0°) to super-hydrophobic (WCA of 165°) after the surface modification with FAS. Observed from XPS data, the hydrophobicity of FAS coated various film surfaces were found to be strongly affected by the ratio of fluoro:oxygen on the film surfaces.
Antifouling coatings are important in fields such as mobility, architecture, power generation devices, and medical devices, where energy efficiency is required to be maximized. Slippery ...liquid-infused porous surfaces (SLIPS) are an antifouling approach inspired by nature from the pitcher plant, and have recently received widespread attention in many fields. SLIPS can repel various liquids, including organic solvents with low contact angle hystereses, but require further development to extend their application. We previously reported a fast and straight-forward process for preparing SLIPS called Gel-SLIPS. SLIPS were prepared by the non-solvent-induced phase separation (NIPS) of a poly(vinylidene fluoride- co -hexafluoropropylene) (PVDF–HFP)/di- n -butyl phthalate solution. In the current study, SLIPS were prepared by electrospinning to give nanofiber SLIPS. These exhibited high scattering (50%), high total transmittance (93.2%), and a low sliding angle (≤10°). These properties resulted from the nanofiber non-woven structure of the PVDF–HFP. Nanofiber SLIPS provide control over scattering by altering the under layer density, all while maintaining the total transparency. These characteristics are useful for energy efficient optical devices such as solar cells and street lighting.
Natural systems contain surfaces with unique wettability that enable functionalities such as directional liquid transport. Such systems typically rely on nano/microscale structural anisotropy and/or ...chemical structures, which induce a directional friction at solid–liquid interfaces. Here, the origin of the solid–liquid interfacial tribo‐dynamics of the skin of Lampropeltis pyromelana (Arizona Mountain Kingsnake) is examined. Continuous and directional water transport phenomenon is found on its hydrophobic slippery ventral skin. Liquid is continuously supplied and spread on its skin in a rear to front direction although the surface is slippery. X‐ray tomography and spectroscopy reveal that the skin surface is composed of an asymmetric wrinkle structure and a homogeneous hydrophobic lipid layer. Owing to this surface feature, the rear directional water spreading is restricted by slant reentrant pinning, whereas the front directional water spreading is promoted by liquid bridging, which continued as long as water is supplied. Because this system type relies on a superhydrophilic sticky surface, it is expected that related biological design principles can be used to develop artificial mass fluid transport systems without undesirable adhesion losses.
Continuous and directional water transport on the hydrophobic slippery ventral skin of Lampropeltis pyromelana is reported. The phenomenon is due to the asymmetric wrinkle structure and the homogeneous hydrophobic lipid layer. This hydrophobic liquid transport principle could be used to develop artificial mass fluid transport systems without undesirable adhesion losses.
The ZnO nanorod growth mechanism during liquid-phase deposition (LPD) has been investigated, with results considered in the context of phase stabilization, LPD chemical processes, and Gibbs free ...energy and entropy. Zinc oxide (ZnO) possesses unique optical and electronic properties, and obtaining ZnO species with high specific surface area is important in ZnO applications. Highly c-axis-oriented ZnO films are expected to be utilized in future optical and electrical devices. ZnO nanorods were synthesized using an aqueous solution deposition technique on a glass substrate with a free-standing ZnO nanoparticle layer. ZnO nanorod growth was easily controlled on the nanoscale by adjustment of the immersion time (15-210 min). X-ray diffraction, field-emission scanning electron microscopy (FE-SEM), and film thickness measurements were used to characterize the crystalline phase, orientation, morphology, microstructure, and growth mechanism of the ZnO nanorods. FE-SEM images were analyzed by image processing software, which revealed details of the of ZnO nanorod growth mechanism.
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