Excellent Self-cleaning Properties Research Articles

Superhydrophobic PCTFE-based microporous membrane for water/oil emulsion separation in various environments

The separation of oil from oily water is a critical endeavor owing to the escalating global oil pollution. Membrane separation technology has gained widespread adoption for oily water treatment. Inspired by the vertical segregation phenomenon in drying multi-component suspensions, this study proposed an evaporation-induced stratification coupled with sacrificial template method to prepare superhydrophobic polychlorotrifluoroethylene (PCTFE) membrane for fast gravity-driven oil/water separation. The precursor of PCTFE microporous membranes, PCTFE/fluoroelastomer/hydrophobic silica nanoparticles (PCTFE/FR/SiO2) composite films, were fabricated via a solvent-assisted method. Induced by solvent evaporation, the pre-fabricated composite films exhibited a stratified structure, where SiO2 nanoparticles enriched near the top surfaces, making it easily tailor the surficial wettability. For the matrix, PCTFE-rich domains and FR-rich domains intersected, forming a bicontinuous structure. After sacrificing FR, PCTFE porous membranes were obtained. Meanwhile, the PCTFE-based porous skeletons combining with surface enriched SiO2 nanoparticles constructed a multi-level roughness, thus achieving superhydrophobicity. The optimized membrane possessed an average pore size of ∼1.84 μm, a porosity of ∼60 %, and a WCA above 155°, owning excellent self-cleaning properties and efficient oil/water separation ability. The membrane exhibited remarkable capability in various oil/water mixtures, including emulsified water-in-oil. The separation flux and oil recovery purity for water-in-dichloromethane emulsion were up to 2843 ± 84 L/(m2·h) and 99.95 wt%, respectively. Furthermore, though being immersed into various organic solvents for 7 days or experiencing 15 separation cycles, the performances of the membranes hardly changed. Accordingly, this work provides a practical approach for tailoring surficial wettability and fabricating PCTFE-based membranes suitable for oil/water separation fields.

Innovative Treatment of Ancient Architectural Wood Using Polyvinyl Alcohol and Methyltrimethoxysilane for Improved Waterproofing, Dimensional Stability, and Self-Cleaning Properties

This study introduced a novel two-step treatment to enhance the waterproofing, dimensional stability, and self-cleaning capabilities of ancient architectural wood. The process was initiated with the immersion of wood in an organic hybrid sol, composed of an acidic methyltrimethoxysilane (MTMS)-based silica sol and polyvinyl alcohol (PVA), which effectively sealed the wood’s inherent pores and cracks to mitigate degradation effects caused by aging, fungi, and insects. Subsequently, the treated wood surface was modified with an alkaline MTMS-based silica sol to form a functional superhydrophobic protective layer. The modification effectiveness was meticulously analyzed using advanced characterization techniques, including scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The results demonstrated substantial improvements: the modified wood’s water contact angle (WCA) reached 156.0°, and the sliding angle (SA) was 6.0°. Additionally, the modified wood showed a notable reduction in water uptake and moisture absorption, enhancing its dimensional stability. The superhydrophobic surface endowed the wood with excellent self-cleaning properties and robust resistance to pollution. Enhanced mechanical durability of superhydrophobic surface was observed under rigorous testing conditions, including sandpaper abrasion and tape peeling. Furthermore, the modification improved the thermal stability, compressive strength, and storage modulus of the wood. Collectively, these enhancements render this modification a potent methodology for the preservation and functional augmentation of historic architectural woodwork.

Self-cleaning of metal-organic framework membranes achieved by photocatalytic ZIFs for dye and antibiotic separation

The progress of membrane-based applications is hindered by widespread membrane fouling, which leads to a significant decrease in separation effectiveness and lifespan, even though membrane separations have shown great potential in the treatment of dye wastewater. The metal-organic framework MOFs (ZIF-8) display strong thermal and chemical stability and an exceptional capacity to degrade organic molecules under visible light, making them extremely promising for the development of self-cleaning membranes. In this investigation, a ZIF-8/L-DOPA/PVDF mixed matrix membrane with excellent self-cleaning properties was constructed using the in-situ growth technique. The characterization results confirmed the formation of a continuous ZIF-8 coating layer, considerably increasing the surface roughness of the composite membrane from 22.9nm to 76.3nm compared to L-DOPA/PVDF substrates. The ZIF-8 layer deposited on the L-DOPA/PVDF membrane surface reduced the contact angle from 75.71° to 40.94°. The highest-performing ZIF-8/L-DOPA/PVDF membranes show a higher water permeability of 159.63 (L·m−2 h−1 bar−1) and superior dye rejection rates (Congo red: 97.3%, Methylene Blue: 98.32%, Methyl Blue: 98.62%), along with enhanced removal of antibiotics (e.g., Tetracycline: 95.3% and Ciprofloxacin: 93.34%), and long-term nanofiltration stability. Furthermore, the treated membrane recovers almost all of its initial separation efficacy after exposure to visible light due to the successful removal of attached dyes from the membrane surface through photocatalysis. This work presents the potential to fabricate membranes with advantageous photocatalytic properties and effectively treat dye wastewater using self-cleaning membranes.

Radiative cooling and indoor light management enabled by a transparent and self-cleaning polymer-based metamaterial

Transparent roofs and walls offer a compelling solution for harnessing natural light. However, traditional glass roofs and walls face challenges such as glare, privacy concerns, and overheating issues. In this study, we present a polymer-based micro-photonic multi-functional metamaterial. The metamaterial diffuses 73% of incident sunlight, creating a more comfortable and private indoor environment. The visible spectral transmittance of the metamaterial (95%) surpasses that of traditional glass (91%). Furthermore, the metamaterial is estimated to enhance photosynthesis efficiency by ~9% compared to glass roofs. With a high emissivity (~0.98) close to that of a mid-infrared black body, the metamaterial is estimated to have a cooling capacity of ~97 W/m2 at ambient temperature. The metamaterial was about 6 °C cooler than the ambient temperature in humid Karlsruhe. The metamaterial exhibits superhydrophobic performance with a contact angle of 152°, significantly higher than that of glass (26°), thus potentially having excellent self-cleaning properties.

Superhydrophobic finishing of cotton fabric via nonsolvent-induced phase separation of polystyrene–perfluoropolyether block copolymer

This paper reports synthesis of polystyrene–perfluoropolyether block copolymer@cotton fabric (PS–PFPE@CF) with a rough structure through nonsolvent-induced phase separation. The factors affecting the hydrophobicity of the coating, such as solvent quality, the molecular weight of the PS segments, and the volume ratio of tetrahydrofuran/1,3-di(trifluoromethyl)benzene (THF/DTFMB) and THF–MeOH, were all investigated, and the relation between the coating structure and hydrophobicity was also analyzed. In the THF–DTFMB system, PS–PFPE@CF (4 h, 80 mg/mL) appeared as a secondary structure with the superposition of small spheres on large spheres. For this structure, the water-contact angle reached 156.2° ± 0.5° and the sliding angle was 9.5° ± 1.5°. Furthermore, scanning electron microscopy, energy-dispersive X-ray spectroscopy, atomic force microscopy, and thermogravimetric analysis confirmed that PS–PFPE coated the cotton fabric. Finally, application tests were performed to assess the application prospects of PS–PFPE@CF. Oil-water separation, self-cleaning, and antifouling applications were studied, and the experimental results showed that the separation efficiency of the superhydrophobic fabric was nearly constant, from 99.4 % to 98.3 % after 10 oil-water separation tests. PS–PFPE@CF exhibited excellent self-cleaning properties and performed well in the sandpaper abrasion and tape peeling tests. This research thus used a degradable PFPE block copolymer to produce cotton fabrics with excellent hydrophobicity, self-cleaning, and wear resistance.

Role of coating techniques and low surface energy materials on long-term performance of superhydrophobic titanium

This study, for the first time, compares the performance of robust superhydrophobic (SHP) titanium (CP-Ti) surfaces developed by two different coating methods, (i) dip / immersion coating and (ii) spin coating, using two different low surface energy materials, (i) stearic acid and (ii) polydimethylsiloxane (PDMS). A facile two-step method for the fabrication of SHP Ti surface is followed, wherein the CP-Ti was first anodized and followed by the coating. The anodization of CP-Ti increased its surface roughness by developing a homogeneous coverage of randomly distributed micro-clusters, whose chemical composition was TiO2-xCly. Subsequent low surface energy organic coatings did not alter the surface morphology. The XPS analysis of stearic acid coated SHP Ti showed that the molecular structure of stearic acid is retained intact whereas the PDMS coated sample showed a partial modification of PDMS molecular structure with the presence of additional -[Si(O)2-O]- bonds apart from the inherent -[Si(CH3)2-O]- bonds. The water contact angle (WCA) and sliding angle (SA) values of SHP Ti were 170±5° and 6±2°, respectively. The SHP Ti showed excellent self-cleaning properties for both hydrophobic and hydrophilic contaminants. The adhesion test of the coatings showed the detachment of coating was within 5%. The coatings prepared by dip / immersion method retained their superhydrophobicity for an abrasion distance of about twice the length, (75±25 cm), due to a higher coating thickness, as compared to those obtained by the spin coating technique (40±20 cm). Further, the stearic acid-coated CP-Ti showed a better abrasion resistance while the stability of the PDMS-coated samples in different pH and Cl- environments was better. Nevertheless, both the stearic acid and PDMS-coated SHP CP-Ti samples showed excellent long-term stability against ambient atmosphere and UV exposure.

Construction of wear resistant superhydrophobic structure without degrading the surface mechanical properties of alloy layer

The vulnerability of superhydrophobic surface structures frequently leads to a loss of their superhydrophobicity under friction, significantly restricting their broad-scale applicability. The preparation of alloy layers emerges as an effective strategy to enhance the mechanical properties of metal surfaces. The construction of superhydrophobic structures without loss of mechanical properties of alloy layer is expected to lead to the preparation of superhydrophobic surface with excellent wear resistance. In this study, a superhydrophobic surface with excellent hardness and wear resistance was successfully prepared by a two-step process of electrospark deposition and anodization. The superhydrophobic surface maintained superhydrophobicity under long distance friction. Firstly, alloy layer with micron bulges and excellent mechanical properties was constructed on the metal surface by electrospark deposition, which was then slightly anodized to create hierarchical micro-nano bulges rather favourable to superhydrophobicity, and anodization did not degrade mechanical properties of the surface. The surface is provided with excellent superhydrophobicity after modification with fluorosilane. SEM, 3D profilometer and roughness tester were adopted to explore microscopic morphology of the sample surfaces. XPS and FTIR were used to explore chemical components of the sample surfaces. The element distribution of the sample surfaces was analysed through EDS, and wettability of the sample surfaces was explored through the contact angle test. The hardness test and wear test were applied to explore mechanical properties of the sample surfaces. It was proved through linear friction, droplet impact, hammering and knife scratch that the superhydrophobic surface could maintain good superhydrophobicity under multiple forms of mechanical destruction, while the neutral salt spray test, electrochemical tests and acid and alkali soaking test proved the excellent property of corrosion resistance of the superhydrophobic surface. In addition, the prepared superhydrophobic surface also features an excellent self-cleaning property.

In situ wrapping carbon dots towards robust, durable and transparent tri-layer films with precise spectral conversion and excellent self-cleaning properties

Based on solid-state fluorescent emission CDs, PDMS and hydrophobic fumed silica, the robust and transparent tri-layer films with UV-to-red spectral conversion and excellent superhydrophobic self-cleaning properties were designed and fabricated.

C3N4-BiOBr/PVC photocatalytic submerged membrane for oil-in-water emulsion separation with visible light-driven self-cleaning performance

Membrane separation has been widely used for oil-in-water separation, but the fouling of oil droplets on the membrane surface is still a challenge. Coating a photocatalyst layer on the membrane surface is an effective method for the regulation of hydrophobicity, degradation of stuck oil, and boosting the self-cleaning properties of the membranes. Thus, in this work, a heterostructure photocatalyst of carbon nitride-bismuth oxybromide (C3N4-BiOBr) with different proportions was coated on a polyvinyl chloride (PVC) layer and the performance of the resultant membrane was studied in the separation of oil-in-water emulsion under visible light. The experimental results exhibited that the membrane with C3N4 to BiOBr ratio of 40:10 coating had the lowest water contact angle of 42°, the maximum light harvesting, the lowest surface roughness, and the low recombination rate of charge carriers. The correlations drawn between surface morphology and fouling behavior of this membrane led to the maximum flux of 65 L·m−2·h−1, 99% separation efficiency, 100% Total Organic Carbon (TOC) removal, and excellent self-cleaning properties (flux recovery ratio of 93.8%). Therefore, this study provides a novel design strategy for multifunctional membranes that achieve effective treatment of oil-in-water emulsion wastewater.

Highly efficient electromagnetic interference shielding composite with excellent superhydrophobic and photothermal/electrothermal effects

With the development of communication facilities, electromagnetic pollution has become more problematic in modern society. Outdoor electromagnetic devices such as signal stations and radar units are the main source of electromagnetic pollution. Therefore, it is urgent to develop electromagnetic interference (EMI) shielding composites for outdoor applications. Meanwhile, the accumulation of ice on the surfaces of these facilities often has serious effects, especially in winter and cold areas. To this end, the Polydimethylsiloxane/Graphite/Carbon black-Polydimethylsiloxane/Fe3O4@Multi-walled carbon nanotube-Aramid paper@Ag (PDMS/GP/CB-PDMS/Fe3O4@MWCNTs-AgP) laminated composite was prepared by combining spraying, scraping and electroless plating techniques to enable the coordination of EMI shielding and de-icing. Through the rational design of the absorbing and conducting layers, the PDMS/GP/CB-PDMS/Fe3O4@MWCNTs-AgP composite has a shielding effectiveness of 31.35 dB in the X-band and an ultra-high absorption coefficient (A) of 0.9. It is worth noting that, due to the rough structure and the low surface energy of the surface layer, the composite exhibits excellent superhydrophobicity (158° ± 1°). Importantly, the PDMS/GP/CB-PDMS/Fe3O4@MWCNTs-AgP composite exhibits stable electrothermal properties, with a fast response and high-speed de-icing capability. At 0.1 W/cm2 input electrical power, ice completely melts in 210 s. And the composite shows excellent photothermal properties, with the ice completely melts within 180 s at 1 sun. The composite also shows excellent self-cleaning properties and acid-alkali resistance. This multifunctional EMI shielding composite provides a new strategy for the safe and long-term use of all-weather outdoor devices.

Superhydrophobic multi-response actuator with high strength

Superhydrophobic actuators that are capable of moving on water surface under external stimuli has broad application prospects in various fields such as robots, environmental protection, sensors and freight transportation. However, the film actuators with soft materials as skeleton frames are easily deformed and destroyed when subjected to heavy loads, which severely restricts its further applications. Herein, we proposed a general and efficient strategy to fabricate a high-strength double-layer actuator composed of a metal/glass-based superhydrophobic substrate and a polymer superhydrophobic coating by combining the laser ablation and spraying techniques. The superhydrophobic coating not only possessed high adhesive strength with the ablated substrates, but also showed excellent self-cleaning, anti-ultraviolet irradiation and anti-stripping properties. Additionally, the addition of light and magnet response materials endowed the superhydrophobic coating with excellent photothermal and magnetic response properties, which supported the application of superhydrophobic actuators in different fields, such as freight collection and transportation.

Performance study of a superhydrophobic nanocellulose membrane on the surface of a wood-based panel prepared via the sol-gel method

The scarcity of wood resources in China has led to the development of wood-based panels. However, wood-based panels often exhibit hydrophilicity and require veneering. This paper presents a solution to this problem in which a composite membrane is prepared using nanocellulose (CNF) and polyvinyl alcohol (PVA) through the hot pressing method. The surface of the composite membrane is then coated with silica nanoparticles using the sol-gel method to achieve a superhydrophobic effect. The coating has a surface hardness of 5H, adhesion of 0, gloss of 20% Gu, colour difference of 3.11, and impact resistance of 19 kg.cm. The resulting modified wood-based panel has a contact angle of 166.8° and a sliding angle of 5.3°, indicating excellent self-cleaning properties and chemical stability. This innovation promotes the use of wood-based panels in high-humidity environments and offers new research avenues for the high-value utilization of nanocellulose.

Fabrication of superhydrophobic cauliflower-like Cu[sbnd]Co coating with anti-corrosion and anti-fouling properties on B10 copper–nickel alloy welded joint

A superhydrophobic CuCo coating is successfully applied to the surface of a B10 copper–nickel (CuNi) alloy welded joint via electrodeposition and modification using a low-surface-energy material (stearic acid). The static water contact angle is measured to be 162.2 ± 1°, and the roll off angle is 2.1°. Various techniques, including scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier-transform infrared absorption spectroscopy are employed to characterize the chemical composition and phase structure of the samples before and after electrodeposition and modification. The corrosion resistance of the superhydrophobic samples is evaluated via electrochemical impedance spectroscopy, potentiodynamic polarization, and scanning Kelvin probe microelectrochemistry. The results indicate that the superhydrophobic coating exhibits greater charge transfer resistance, lower self-corrosion current density, and higher surface work function, thus effectively enhancing the corrosion resistance of the B10 CuNi alloy welded joint. Furthermore, the micro-nano rough structure with low surface energy on the superhydrophobic sample surface traps air and forms an air layer, thereby reducing the contact between the corrosive medium and welded joint as well as minimizing corrosion. The superhydrophobic coating demonstrate thermal stability as well as excellent self-cleaning and mechanical properties, based on comprehensive testing and analysis.

Photothermal Superhydrophobic Cotton Fabric Based on Silver Nanoparticles Cross-Linked by Polydopamine and Polyethylenimide.

Photothermal materials that can convert solar energy into heat energy through photothermal conversion have attracted extensive attention, but these materials are easily polluted by the environment. Here, we propose a simple and effective strategy for constructing photothermal superhydrophobic cotton fabrics with self-cleaning ability. The PDA@PEI@GA@Ag@PDMS-coated cotton fabric can achieve good superhydrophobicity (water contact angle: 159.6°) by a simple dipping method and mussel-inspired dopamine surface modification, which is regulated by the mass of dopamine, the mass of silver nitrate, and the concentration of polydimethylsiloxane (PDMS). The coated cotton fabric has good physical and chemical stability. Meanwhile, the coated cotton fabric has excellent self-cleaning and antifouling properties. The superhydrophobic PDA@PEI@GA@Ag@PDMS fabric exhibits excellent and stable photothermal properties, with the surface temperature reaching 70.4 °C under simulated sunlight with a current of 20 A. This photothermal superhydrophobic fabric with self-cleaning properties is expected to be applied in the field of photothermal conversion.

Biomimetic nanonet membranes with UV-driven self-cleaning performance for water remediation

Water pollution caused by industrial and natural contaminants has placed a significant burden on environment and human health. The present filtration membranes, however, suffer from a series of issues involving low permeation fluxes and easy fouling issue during long-term water remediation, which seriously restricts their practical applications. Herein, inspired by royal water lily leaf, we construct biomimetic nanonet membranes (BNMs) composed of fractal network and mastoid structures by one-step phase inversion of PVDF/TiO2 solution using electrospun fibrous membrane as substrates. Benefit from the distinct structures, the BNMs show sub-micro pores, high porosity, and intriguing hydrophilicity, which result in excellent removal performance for 0.3 μm solid particle (efficiency of 99.88%, permeation flux of 3439 L m−2 h−1), E. coli (log reduction value = 8.39, permeation flux of 1242 L m−2 h−1), and oil-in-water emulsions (efficiency of 99.0%, permeation flux of 8312 L m−2 h−1). Importantly, the presence of TiO2 nanoparticles with UV-driven catalytic activity effectively endows the BNMs with desirable biocidal efficiency (LRV = 8.5) and excellent self-cleaning properties (flux recovery ratio of 98.1%). The synthesis of such membranes may open new avenues in the design of high-performance filtration membranes for remediation of large volumes of wastewater.

A stretchable slippery surface fabricated by femtosecond laser direct writing

Surface conditions of flexible electronic devices can affect their accuracy, so it is necessary to keep surfaces clean and stable to ensure their correct-long-term operation. The Nepenthes-inspired slippery surface has excellent self-cleaning, stability, and self-healing properties. A slippery surface with stretching durability is significant for application to a flexible sensors surface. As an advanced micro-nanomanufacturing method, femtosecond laser has become an effective method for preparing porous structures to process a slippery surface. In this study, a femtosecond laser was used to prepare an interconnected porous structure on pre-stretched polydimethylsiloxane in one step. The slippery surface was prepared after being infused with lubricant, which maintained the slippery performance under tensile conditions and after hundreds of stretch cycles. Moreover, it exhibits remarkable self-cleaning and chemical stability. This stretchable slippery surface prepared by femtosecond laser direct writing presents good prospects for flexible electronic devices that require a stable surface in various extreme environmental applications.

Superhydrophobic polytetrafluoroethylene/polyvinylidene fluoride coating for passive daytime radiative refrigeration

Passive daytime radiation refrigeration (PDRR) is a new type of refrigeration that requires no extra energy consumption and also cools objects by reflecting radiant heat from sunlight and mid-infrared wavelengths. However, the properties of ordinary radiative refrigerative (RR) materials are degraded by surface dust accumulation during use. In this work, superhydrophobic radiative refrigerative (SRR) polytetrafluoroethylene/polyvinylidene fluoride (PTFE/PVDF) coating was prepared by one-step spraying method with PTFE as white pigment, PVDF as binder, and N, N-dimethylacetamide (DMAC) as solvent. The PTFE/PVDF coating (containing 20 wt% of PTFE) exhibits synergistic effect with high water contact angle (CA, 153.7°), low water sliding angle (SA, 7.7°), high solar reflectivity (SR, 93.7%), and high infrared emissivity (IE, 93.3%). Under a clear sky and direct sunlight, the coating achieves a RR temperatures of 5.8 °C (shielding convection heat) and 5.3 °C (without shielding convection heat) respectively under two measurement conditions. In addition, the coating exhibits excellent self-cleaning properties that can automatically remove dust accumulated on the surface with the assistance of rainfall, thus maintaining its RR performance for a long time. More importantly, the mechanical robust self-cleaning function also provides excellent corrosion resistance and anti-UV aging ability. The PTFE/PVDF SRR coating developed in this work is simple to fabricate, can be applied over a large area, and has good durability, which is conducive to promoting the practicalization of RR coatings.

Fabrication of durable self-cleaning photocatalytic coating with long-term effective natural light photocatalytic degradation performance

The practical application of photocatalytic coating has been greatly challenged in terms of its long-term effective natural light photocatalytic degradation due to its vulnerability and easy contamination caused by poor self-cleaning properties. In this work, photocatalytic coating with self-cleaning properties was prepared by spraying fluorinated dual-scale TiO2 on the inorganic lithium silicate adhesive, enabling excellent durability and long-term effective photocatalytic degradation performance under natural light. The coating exhibits superhydrophobic properties even after abrasion testing, acid and alkali immersion testing, and UV aging, laying a foundation for the practical use. Moreover, the coating can be applied to various substrates and its excellent self-cleaning properties make it resistant to particulate and liquid contamination that may occur in the environment. Besides, we evaluated the photocatalytic stability of the coating by subjecting it to acidic and alkaline environments and high pollution concentrations. Furthermore, benefiting from the synergistic effect of photocatalytic and self-cleaning properties, the coating achieves long-term effective photocatalytic degradation of dye wastewater under natural light, which still has a high removal rate of 95.8% for methylene blue even after 30 cycles of use. Meanwhile, due to the coating's excellent durability, the long-term quality loss rate of the coating still remained below 0.3%, which avoids the risk of secondary environmental pollution caused by nanoparticle leakage. Therefore, these excellent properties enable the coating to have a broad range of application prospects for the treatment of pollutants in water.

Bionic eco-friendly synergic anti-scaling Cu-Zn-CeO2 coating on steel substrate functionalized by multi-scale structures and heating enhanced adsorption

Scaling is a universal issue encountered in pipeline steel during offshore oil extraction. In this paper, a synergic anti-scaling Cu-Zn-CeO2 coating on the pipeline steel substrate was fabricated by one-step composite electrodeposition and magnetic stirring. It shows the wettability transition from superhydrophilic to superhydrophobic of the multi-scale structured Cu-Zn-CeO2 coating without low-surface-energy modification after heating at 60℃ for 60 min and stored in air for ∼ 35 days. The wettability transition is owing to the hydrocarbons adsorption. The heating treatment and the multi-scale structure improve the hydrocarbons adsorption and reduce the transition time. The inherent hydrophobic CeO2 is beneficial for the superhydrophobic property and reduces the transition time. Compared with the steel substrate and previous superhydrophobic Cu and Cu-Zn coatings, it indicates the superhydrophobic Cu-Zn-CeO2 coating shows the promising synergic anti-scaling property due to its superhydrophobicity and the anti-scaling property of Cu-Zn alloys. This eco-friendly synergic anti-scaling Cu-Zn-CeO2 coating also shows excellent self-cleaning and anti-fouling properties. Moreover, the stability of the superhydrophobic Cu-Zn-CeO2 coating was enhanced compared with our previous superhydrophobic Cu-Zn coating due to CeO2 nanoparticles. This research enriches the theory and the technology of the wetting field, which also provides a technical basis for solving scaling problems of pipelines.

Transparent and superhydrophobic FHA/SiO2 coatings with obvious anti-soiling performance for photovoltaic modules

Dust deposition on photovoltaic (PV) modules obviously affects power generation efficiency. In order to solve this problem, a fluorinated hydroxyacrylate emulsion (FHA)/SiO2 nanoparticles coating with superhydrophobic (SH) surface and visible light transmittance greater than 93 % has been prepared. A silica sol obtained by hydrolysis of tetraethyl orthosilicate (TEOS) is used to cross-link FHA chains, resulting in a significant increase in the SH stability of the SH coating. An FHA hydrophobic coating with smooth surface was also prepared as a control sample. Both anti-soiling and dust removal performances of these two types of coatings were studied. The results show that both the hydrophobic coating and the SH coating have better anti-soiling and dust removal performances compared with bare glass. Among them, the SH coating exhibits better performance. The SH coating loses its SH property after being placed outdoors due to dust deposition. However, washing with water can remove most of the dust and restore its SH property. Moreover, the SH coating shows excellent self-cleaning properties when placed outdoors under low precipitation or light rain. In addition, the SH coating also shows good resistance to the impact of sand and water drops. This simple method of preparing SH coatings is expected to find use in the field of photovoltaic modules.