One-step Solution-immersion Process Research Articles

“Soapy water” transformation of the “condenser” with self-cleaning ability and antibacterial activity

Superhydrophobic materials exhibit diverse application potential in various fields due to their excellent self-cleaning properties. However, it is still challenging to prepare bionic superhydrophobic materials employing the green methods. In this study, the “condenser” (simulated by a red copper spiral tube) with excellent self-cleaning properties and antibacterial activity has been prepared by a simple one-step “soapy water” immersion process without introducing any other reagents. The results demonstrate that the Cu[CH3(CH2)10COO]2 lamellar nanostructures are formed on the surface of “condenser” owing to the oxidation of copper upon immersion in the sodium laurate aqueous solution. The as-formed nanostructures exhibit excellent self-cleaning performance and can significantly inhibit the growth and proliferation of Escherichia coli and Staphylococcus aureus, which is significant for the upgradation of the safety and comfort features of the new generation air-conditioners. Moreover, the ruptured superhydrophobic coating on the copper tube can be effectively restored by a facile re-soaking process. Therefore, the present approach, with simple one-step solution-immersion process, low cost, short immersion period, environmental friendliness and optimal applicability to a variety of metal structures of different shapes, represents a promising strategy for fabricating the low-cost superhydrophobic surfaces applicable to the condenser and heat transfer systems, thereby, promoting the development of the self-cleaning and antibacterial smart devices.

Eco-friendly and one-step modification of poly(vinylidene fluoride) membrane with underwater superoleophobicity for effective emulsion separation

In this study, poly(vinylidene fluoride) (PVDF) microfiltration membrane was modified by an eco-friendly and low-cost mussel-inspired method for applications in oil/water separation. Catechol (CA) and polyamines, instead of dopamine (DA), were utilized to modify the membranes based on a facile one-step solution-immersion process. Similar to the oxidation polymerization of DA, polyamines can react with CA via Schiff base/Michael addition reaction. A homogeneous coating with micro-nano structures and superior hydrophilicity can be formed on the surface of the membrane and the inner walls of its holes. The membrane with a water contact angle of nearly 0° and a water flux above 8000 L/m2 h was obtained after being modified with 5 mM CA and tetraethylene pentaamine (TEPA) for 24 h. The micro-nano scale roughness and the superior hydrophilicity contributed to an excellent underwater superoleophobicity with oil contact angles larger than 150° and low adhesion to various oils. The as-prepared membrane was applied to separate a series of oil-in-water emulsions, and a high separation efficiency larger than 99.4 % as well as extraordinary antifouling property without discernible decay after ten cycle tests were demonstrated. Moreover, the functional coating shows good stability in acid and alkali environment with the pH values between 0 and 11, and has few impacts on the mechanical and thermal properties of the pristine membrane. Therefore, the proposed facile and low-cost preparation of the underwater superoleophobic microfiltration membrane shows great potential in practical oily wastewater treatment.

Facile synthesis of TiO2-supported Al2O3 ceramic hollow fiber substrates with extremely high photocatalytic activity and reusability

TiO2 oxide was deposited on a microstructured α-Al2O3 ceramic hollow fiber substrate by a simple one-step solution-immersion process with tetraethyl orthosilicate (TEOS) as a binder. The effects of the starting coating solution's composition on the photocatalytic properties of TiO2 powders deposited on a substrate was determined by using TiO2-supported Al2O3 ceramic hollow fiber substrates fabricated from coating solutions with different compositions and examining the substrates' effect on the methylene blue (MetB) degradation reaction under ultraviolet light. A strong correlation was observed between the initial coating solution compositions and the final photocatalytic characteristics of the TiO2-supported Al2O3 ceramic hollow fiber substrates. Under optimal conditions, the MetB removal efficiency reached about 91% in a few minutes. To the best of our knowledge, this is the highest and most rapidly attained MetB removal efficiency reported for TiO2-supported Al2O3 ceramic hollow fiber substrates. Furthermore, apart from attaining an extremely high photocatalytic activity within minutes, the fabricated TiO2-supported Al2O3 ceramic hollow fiber substrates exhibited high photocatalytic stability even after several cycles.

Micrometer-sized spherulites as building blocks for lotus leaf-like superhydrophobic coatings

Micropapillae covered by nanometer-sized wax crystals are essential building blocks of lotus leaf surface for repelling water and self-cleaning. It is generally time-consuming and complex to construct similar artificial micropapillae covered by nanometer-sized protuberances in the fabrication of superhydrophobic coatings without the aid of nanomaterials or special materials. We develop a cost-efficient strategy to simplify the fabrication process of lotus leaf-like superhydrophobic coatings by using micrometer-sized spherulites as building blocks. Well-controlled lotus leaf-like superhydrophobic coatings were prepared from hydrogenated castor oil spherulites through a one-step solution-immersion process. The result coatings have water contact angles over 150° and water shedding angles below 10°. It was demonstrated that micrometer-sized spherulites originated from common material could easily form lotus leaf-like superhydrophobic coatings on different materials through simple crystallization process.

One-Step Preparation of Highly Hydrophobic and Oleophilic Melamine Sponges via Metal-Ion-Induced Wettability Transition

Hydrophobic and oleophilic absorbent materials have received wide attention in recent years for potential applications in pollutant removal from accidental spills of oil or organic chemicals. In this work, we report a metal-ion-induced hydrophobic melamine sponge (MII-HMS) prepared by a one-step solution immersion process. The commercial melamine sponge (intrinsically superhydrophilic with a water contact angle of ∼0°) is immersed in an aqueous solution of transition metal ions (e.g., FeCl3, Fe(NO3)3, Zn(NO3)2, Ni(NO3)2, and Co(NO3)2) for a short period, followed by drying. This simple process renders the transition of the superhydrophilic melamine sponge to become highly hydrophobic (a water contact angle of ∼130°). Results from X-ray photoelectron spectroscopy and infrared spectroscopy suggest that the unprecedented transition is likely due to the formation of metal complexes during immersion. The MII-HMS is also oleophilic, exhibiting excellent oil absorption capabilities, ∼71-157 times of its weight, for a wide range of oils and organic solvents. Our work offers a simple, scalable, and economical approach to fabricate highly efficient absorbent materials for potential applications in oil spill recovery and environmental remediation.

Silver-nickel oxide core-shell nanoparticle array electrode with enhanced lithium-storage performance

We demonstrate the synthesis of Ag-NiO core-shell nanoparticle arrays via a one-step solution-immersion process and subsequent RF-sputtering technique. The Ag nanoparticle arrays on copper substrate are firstly prepared by a displacement reaction at mild temperature of 303K. Then, a NiO layer is deposited onto the surface of the Ag nanoparticles via RF-sputtering technique. When evaluated as an anode for lithium-ion batteries, the Ag-NiO core-shell electrode shows higher capacity and better cycling performance than the planar NiO electrode. The in-situ synthesized Ag nanoparticles can enhance the interfacial strength between the active material and substrate, andimprove the electrical conductivity of the electrode, which may be responsible for the enhanced performance.

Silver–nickel oxide core–shell nanoflower arrays as high-performance anode for lithium-ion batteries

We demonstrate the synthesis of Ag–NiO core–shell nanoflower arrays via a one-step solution-immersion process and subsequent RF-sputtering method. The aligned Ag nanoflower arrays on copper substrate are prepared by a facile displacement reaction in absence of any surfactant at a mild temperature. When used as anode materials for lithium-ion batteries, the Ag–NiO core–shell nanoflower arrays show better cycling performance and higher capacity than the planar NiO electrodes. The improved performance should be attributed to the core–shell structures that can enhance the conductivity and accommodate the volume change during the charge–discharge process.

Superhydrophobic surfaces created by a one-step solution-immersion process and their drag-reduction effect on water

A simple one-step process was developed to fabricate superhydrophobic surfaces on copper alloy substrates.

Fabrication of non-flaking, superhydrophobic surfaces using a one-step solution-immersion process on copper foams

Non-flaking superhydrophobic surfaces were prepared using a simple one-step solution-immersion process on commercially obtained copper foam substrates. Copper foams were immersed in a 0.05M ethanolic stearic acid solution at room temperature for several days. This formed coverage of copper stearate with micro- and nano-scale hierarchical surface morphology. The surface of the copper foam after 4 days of immersion demonstrates superhydrophobicity with a water contact angle of 156°. A sliding angel of 4° for a 5μL droplet indicates excellent non-sticking behavior. Compared with a flat copper plate, the superhydrophobic surfaces based on copper foams are much more robust and mechanically stable. This work provides a promising strategy for scalable fabrication of superhydrophobic surfaces on 3D porous structures.

Facile Fabrication of Superhydrophobic Cu(OH)2 Nanorod and CuO Nanosheet Arrays on Copper Surface

Cu(OH)2 nanorod and CuO nanosheet arrays have been successfully grown on the copper surfaces by a simple one-step solution-immersion process at ambient temperature and pressure. After the chemical modification with 1H, 1H, 2H, 2H-Perfluorodecyltriethoxysilane, the wettability of the copper substrate changed from superhydrophilic to superhydrophobic. Meanwhile, the sliding angle of the superhydrophobic surface is less than 5 degrees. It is confirmed that both the synergic effect of the surface morphology and the surface free energy contribute to this unique surface water repellence. Furthermore, the as-prepared surfaces were stable even after a long-term storage, and retained good superhydrophobicity for corrosive liquids. Such special superhydrophobic properties will greatly extend the applications of copper in many other important industrial fields.

Nanometric Multiscale Rough CuO/Cu(OH)2 Superhydrophobic Surfaces Prepared by a Facile One-Step Solution-Immersion Process: Transition to Superhydrophilicity with Oxygen Plasma Treatment

An inexpensive and facile one-step method to develop a superhydrophobic coating on the copper surface is reported. Superhydrophobic CuO/Cu(OH)2 surfaces were prepared by a simple solution-immersion process at room temperature, without using a low surface energy material. The structure and composition of as-prepared CuO/Cu(OH)2 hierarchical structure were confirmed by X-ray diffraction, micro-Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The growth stage was carefully examined by field emission scanning electron microscopy (FESEM), and it was observed that initially Cu(OH)2 nanoneedle arrays were formed on the copper surface and subsequently the CuO microflowers formed on the nanoneedle arrays. The contact angle as a function of immersion time was studied using a contact angle goniometer. The correlation between the microstructure of the immersed copper surface and the contact angle was examined carefully using FESEM and atomic force microscopy (AFM). Our results based on FESEM and AFM studies show that the CuO/Cu(OH)2 coatings demonstrate superhydrophobicity only for an optimal combination of the solid region (i.e., microflowers and nanoneedles) and air pockets (i.e., voids). The maximum static water contact angle on the prepared surface was 159°. The wettability transition of the CuO/Cu(OH)2 surface from superhydrophobicity to superhydrophilicity was studied by the alteration of oxygen plasma treatment and dark storage. The FESEM, AFM, and XPS studies showed that this transformation was mainly due to the morphological changes that occur in addition to the chemical changes taking place on the CuO/Cu(OH)2 surface under the influence of oxygen plasma. XPS analysis demonstrated that the incorporation of oxygen species by oxygen plasma activation accounted for the highly hydrophilic character of the surface.

Intrinsic dew-enhancing ability of SiO 2/PODS materials

A superhydrophobic polymerized n-octadecylsilane (PODS) surface with a highly ordered lamellar structure was obtained via a one-step solution immersion process. The PODS surface had water contact and sliding angles of 159° and ∼0°, respectively. A hydrophilic/superhydrophobic surface was then obtained by chemically bonding nano-SiO 2 onto the PODS surface. This SiO 2/PODS layer exhibited dew-enhancing ability, similar to that of the surface of the stenocara beetle. Vapor condensation occurring heterogeneously on the SiO 2/PODS surface is proposed to explain the dew-enhancing property, and these hydrophilic/superhydrophobic surfaces may have applications in enhanced heat transfer.

Fabrication of functionalized aluminum compound petallike structure with superhydrophobic surface

AbstractThe petallike structures, similar to that of a lotus leaf, were directly fabricated on the surface of aluminum sheets by a simple one‐step solution‐immersion process. It was found that the width of the nanoflakes ranges from 20 to 500 nm, and the length of the flakes is about several micrometers. The wettability of the surface with a hierarchical structure was changed from superhydrophilicity to superhydrophobicity by chemical modification with perfluorodecyltriethoxysilane (PDES). The static contact angles (CAs) for water on both of the modified surfaces were larger than 150° , which was closely related to the chemical modification and hierarchical structure. Furthermore, the surfaces retained good superhydrophobic stability in long‐term storage as well, which should be critical to the application of aluminum materials in engineering. Copyright © 2010 John Wiley & Sons, Ltd.

Fabrication of Functionalized Copper Compound Hierarchical Structure with Bionic Superhydrophobic Properties

Hierarchical structure of flower-like CuO standing on Cu(OH)2 nanorod arrays, similar to that of a lotus leaf, was directly fabricated on the surface of copper foils by a simple one-step solution-immersion process. It was found that the diameter of the nanorods ranges from 100 to 500 nm, and the length of the rods is about tens of micrometers. Synchronously, flower-like CuO with a diameter of about 3−5 μm was also deposited from the bulk solution during the growth of nanorod arrays. The wettability of the surface with hierarchical structure was changed from surperhydrophilicity to superhydrophobicity by chemical modification with stearic acid (STA) or 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PDES). The static contact angles (CAs) for water on both of the modified surfaces were larger than 160°, which was closely related to the chemical modification and hierarchical structure. Compared with the STA-modified surface, the PDES-modified surface had a lower CA hysteresis (CAH) and adhesion for water droplets...