One-step Spray Research Articles

Robust photothermal anti/de-icing hydrophobic coating based on polydopamine (PDA) composition

The hydrophobic soft coating has low ice adhesion strength and hydrophobic stability in low-temperature and high-humidity environments, which is crucial for preventing ice formation on infrastructure and transportation systems. However, creating mechanically durable hydrophobic soft coatings using simple methods remains challenging. In this study, a high-hardness particle-toughened, self-stratifying organic layer with high photothermal conversion rate was developed to enhance coating durability and ice-repellent performance. By optimizing the ratio of dopamine (DA) and sodium alginate (SA), a hydrophobic photothermal agent (DPSn) with high hardness and a significant light-heat effect was synthesized. A durable, hydrophobic photothermal anti-ice coating (AR/20 %PDMS/x%DPS1) with varying DPS1 amounts was successfully created using a straightforward one-step spray method, utilizing the self-stratification characteristics of acrylic resin (AR) and polydimethylsiloxane (PDMS), along with the toughening effect of DPSn. The fiber cross-linked structure of DPS1 achieved a photothermal conversion rate of 87.5 %. Adding 4 wt% DPS1 increased the surface temperature of the AR/20 %PDMS coating to 96.5 ± 2.4 °C and boosted the coating’s adhesion strength from 6.70 ± 0.3 MPa to 7.23 ± 0.7 MPa. The AR/20 %PDMS/4%DPS1 coating demonstrated excellent anti-/de-icing performance after 60 friction cycles, 60 icing/de-icing cycles, and 132 h of acid-base immersion. Its simple preparation process and durable ice-repellent properties make it highly suitable for practical applications in photothermal hydrophobic soft coatings.

Facile and effective construction of superhydrophobic, multi-functional and durable coatings on steel structure

Nowadays, steel is one of the most significant materials in industry and daily life. Unfortunately, the defects of steel structures such as collapse at high temperature, poor corrosion resistance, and bad surface functionality have severely restricted their further application. Applying functional coatings for steel structures is considered the effective strategy for settling theses disadvantages. Inspired by nature, eco-friendly, superhydrophobic, and multifunctional-integrated coatings were fabricated on steel via one-step spraying strategy in this paper. Along with silicon dioxide (SiO2) nanoparticles and epoxy resin/silicone resin (EP/SR), the coatings are jointly constituted by hydrophobic flame retardants (M-ALHP@ZIF-8) prepared via multi-stage modification. Due to the formation of micro/nano-scaled rough structure with low surface energy, the water contact angle (WCA) and water sliding angle (WSA) of as-prepared coatings can reach 162.4° ± 1.2° and 2.8° ± 0.4°. The water repellency with low water adhesion can endow the surface of steel with excellent self-cleaning, anti-fouling, and long-lasting anti-corrosion ability. Additionally, the superhydrophobic coatings have displayed good mechanical robustness, chemical stability and weather resistance, which can exhibit certain actual values. Accorded with Zn-catalyzed charring effect of flame retardants, as-prepared coatings have possessed outstanding fire protection capacity with the lowest backside temperature of 181 °C after 1 h fire impact tests. Consequently, this work has provided a facile and effective route for synchronously tackling the key challenges of poor fire protection and surface functionality for steel structures, which will be expected to pave the wide pathway for constructing multifunctional coatings in more fields.

A durable superhydrophobic surface with bud-particle structure prepared by one-step spray method

Superhydrophobic surfaces play an essential role in numerous applications such as anti-fouling, waterproofing, and drag reduction due to their water-repellent. However, for most fabrication methods, there are high requirements for the preparation process and conditions. Meanwhile, the superhydrophobic surfaces generally have the problem of insufficient durability. In this study, a one-step method to fabricate a stable superhydrophobic surface by spraying is proposed. A new bud-particle structure is obtained by modifying micron and nano Aluminium hydroxide(Al(OH)3) particles, which helps the coated surface to demonstrate excellent superhydrophobicity with the water contact angle ∼157.0° and rolling angle ∼2.0°, and it shows great repellency to water droplet impact. Due to the compatibility of Al(OH)3with the pretreatment substrate and the reinforcing effect of nanoparticles, the coating maintained the superhydrophobicity well in the sandpaper wear and the ultrasonic damage test, which reflects the outstanding robustness of the coating.Moreover,benefiting from the control of the wetting state by micronand nanoparticles doping,the coating showed an excellent underwater drag reduction effect in the rheometer experiment, with a drag reduction rate of ∼67.7 %. The one-step spraying method proposed is a simple and convenient way to create the surface with excellent superhydrophobicity and durability, which has great potential applications in improving metal surface oxidation resistance and underwater reducing drag.

Facile fabrication of robust, multi-functional and superhydrophobic coatings with corrosion resistance and anti-icing performance

In this paper, a series of superhydrophobic coatings with varying n-SiO2 content were prepared using a simple one-step spray method. The coatings were characterized with SEM, XPS, electrochemical workstation, AFM, etc. The influence of n-SiO2 content on the micro-nanostructure of the coatings was investigated, as well as the elemental composition, the wettability, mechanical stability, chemical stability, and anti-icing performance. The results showed that as the n-SiO2 content increased, the wettability and anti-icing time of the coatings initially increased and then decreased. The optimal performance was achieved at an n-SiO2 content of 4.16 wt%, with a contact angle of 162.62°, a sliding angle of 4.17°, and an anti-icing time of 1095 s. Mechanical stability was improved with increasing n-SiO2 content, and the coatings lasted for 40 sandpaper abrasion cycles, 55 tape peeling cycles, and 31 icing/deicing cycles at 4.88 wt% of n-SiO2. The coatings demonstrated good chemical stability in neutral and acidic environments but failed in strongly alkaline conditions. Electrochemical tests revealed that the superhydrophobic coatings provided excellent protection, with the corrosion inhibition efficiency (η) of Q235 carbon steel reaching 99.99 % after coating compared to uncoated Q235 carbon steel.

Dropwise condensation performance of sprayable polymer/copper oxide composite coating

Even though dropwise condensation (DWC) has received significant attention for its potential to enhance heat transfer performance at a higher order than filmwise condensation (FWC), the scalability of durable DWC-promoting surfaces to sustain prolonged condensation remains challenging. The spray coating presents itself as a potential scalable method to deposit hydrophobic coating onto a metallic substrate. However, the conventional sprayable fluoropolymer exhibits poor adhesion to the substrate and thus requires a base coat before it can be deposited on a metallic substrate. To address this challenge, this study investigated dropwise condensation performance on a polytetrafluoroethylene/imide-based binder/copper oxide composite (PTFE/PI/CuO) coating that is deposited into a copper substrate using simple one-step spray coating and thermal annealing. The PTFE particles provide the necessary hydrophobic characteristics. At the same time, the polymer binder fills the pores between the particles, preventing droplet nucleation within the structure and minimizing the occurrence of flooding that can lead to undesirable droplet pinning. The PTFE/PI/CuO coating successfully promotes pinned-free dropwise condensation, leading to approximately two times higher heat transfer enhancement than filmwise condensation. Moreover, the formation of micro-scale hydrophilic CuO clusters at the top of the coating surface acts as nucleation sites that increase droplet growth rate and departure frequency without altering the droplet departure radius. As a result, PTFE/PI/CuO exhibits 1.4x times higher heat transfer over the PTFE/PI. Furthermore, a durability enhancement was obtained by adding sub-micron copper particles. While PTFE/PI coating failed after exposure to steam, no visible damage was observed from PTFE/PI/CuO, thus indicating enhanced durability. Moreover, the PTFE/PI/CuO composite also exhibited resistance against mechanical damage as its heat transfer performance remained similar even after being subjected to abrasion. Finally, the pull-off adhesion test revealed that PTFE/PI/CuO has higher adhesion strength than PTFE/PI, making it more suitable for dropwise condensation application.

One-Step Spraying Strategy for Fabricating Bioinspired, Graphene-Based, and Multifunctional-Integrated Coatings on Structural Steel with Good Water Repellency, Fireproofing, Anticorrosion, and Durability.

Traditionally, many coatings were merely concentrated on settling the inherent fire protection problem of steel structures, while surface contamination and corrosion susceptibility should also be considered. Concurrently addressing these problems in fireproof efficiency and surface multifunctionality has become an issue of great significance in further expanding the application value in industrial and daily scenarios. Based on this condition, ecofriendly, graphene-based, and superhydrophobic coatings with multifunctional integration were constructed on steel via a one-step spraying method. The as-prepared coatings mainly consist of epoxy resin (EP), silicone resin (SR), a cyclodextrin-based flame retardant (MCDPM), expandable graphite (EG), and multilayered graphene (MG). The results demonstrate that the water contact angle (WCA) and water sliding angle (WSA) of as-prepared coatings can reach 156.8 ± 1.6 and 5.8 ± 0.7°, respectively, revealing good water repellency and self-cleaning properties. The coatings can also exhibit adequate adaptability for various substrates including wood, polyurethane foam, and cotton fabrics. Besides, good durability and robustness of coatings have been also verified via acid/alkali immersion, outdoor exposure, O2/plasma etching, and linear abrasion tests. Simultaneously, the coatings can exhibit excellent anticorrosion capacity for steel materials via a double barrier effect. Most importantly, the coatings have exhibited the lowest backside temperature (234.5 °C) during fire impact tests, suggesting excellent fireproof and heat insulation performance. This fact can be ascribed to the conjunct action between the physical/chemical charring process of flame retardants and the remarkable thermal stability of graphene. Consequently, this article can be expected to further promote the development and application of multifunctional-integrated coatings for steel structures in more fields.

Corrosion-resistant superhydrophobic composite coating with mechanochemical durability

It is important to improve the corrosion resistance of magnesium alloy for expanding its application field. Poor durability seriously restricts the practical application of superhydrophobic anti-corrosion coatings. Here, a durable superhydrophobic anti-corrosion coating was prepared on AZ31 Mg substrate via a facile one-step spraying approach. The microscale glass fibers (GF) and nanoscale hydrophobic SiO2 particles were integrated into the epoxy resin (ER) to construct superhydrophobic composite coating (ER/GF-SiO2). Benefitting from the air cushion and physical barrier effect of superhydrophobic coating, the ER/GF-SiO2 coating exhibits good reinforced protectives properties. Compared with the AZ31, the corrosion current density of superhydrophobic coating decreased by three orders of magnitude and the low-frequency impedance modulus decreased by one order of magnitude. The ER/GF-SiO2 coating still maintained a high protective efficiency (89.44 %) after immersion in 3.5 wt% NaCl solutions for 13 d. The ER/GF-SiO2 coating shown good mechanochemical durability. The superhydrophobicity can be maintained after 40 m of sandpaper abrasion, 30 min of water impact, 20 min of sand impact, and 80 cycles tape-peeling. Furthermore, the high bond strength of the coating-substrate was verified by energetic analysis of molecular dynamics simulation at a microscopic level. The facile and effective preparation process provides an effective strategy for large-scale industrial production of durable superhydrophobic coating.

Study on the construction of durable superhydrophobic coatings using simple spray coating method and their underwater drag reduction performance

Superhydrophobic surfaces have significant applications in industrial and chemical fields. However, their current mechanical stability and underwater durability are insufficient, limiting their widespread application. This study successfully developed a durable superhydrophobic coating suitable for various substrates using a simple one-step spraying technique. By thoroughly investigating the effects of SiO2 concentration and curing temperature on the coating's wettability, underwater durability and mechanical stability, the preparation process was optimized. The prepared superhydrophobic coating achieved a contact angle (CA) of 159.6° and a sliding angle (SA) of less than 1°. In tests of underwater immersion, sandpaper abrasion, repeated water impact, corrosion resistance and ultraviolet (UV) resistance, the coating demonstrated excellent underwater durability, mechanical stability, chemical stability and UV stability. Furthermore, when applied to the steel sphere, the superhydrophobic coating exhibited significant drag reduction effects underwater, reducing the drag coefficient by approximately an order of magnitude and achieving a drag reduction efficiency of 79.1 %. Numerical simulations using STAR-CCM+ showed that the streamlined cavity formed by the superhydrophobic coating effectively suppressed fluid separation, reduced pressure-induced drag, and allowed the superhydrophobic steel sphere to attain a higher terminal velocity. Therefore, the superhydrophobic coating developed in this study has tremendous application potential in underwater drag reduction and is expected to provide effective solutions for energy-saving and drag reduction in fields such as maritime navigation.

Robust superhydrophobic self-cleaning coating prepared by silane modified multi-walled carbon nanotubes: A combined experimental and molecular dynamics study

As a functional material, superhydrophobic coating has been widely studied in the field of self-cleaning. However, obtaining superhydrophobic coatings with robustness through simple preparation processes remains a challenge. In this paper, a robust superhydrophobic coating is prepared based on multi-walled carbon nanotubes modified by octyltrimethoxysilane, and its performance and hydrophobic mechanism are studied by experiments and molecular dynamics simulation. The superhydrophobic coating is prepared by one-step spraying method. The coating is characterized and analyzed by scanning electron microscopy and Fourier transform infrared spectroscopy, and the properties of the coating are tested by experiments. Molecular dynamics simulation is used in the study to construct a molecular model system, and the molecular modification mechanism and coating wettability are simulated under the COMPASSII force field. The results show that octyltrimethoxysilane successfully modified carbon nanotubes, and the hydroxyl groups at the head of the molecular chain are bound to the surface of the carbon nanotubes in the form of hydrogen bonds, while the tail of the molecular chain is far away from the surface. After modification, the surface of carbon nanotubes changed from hydrophilic to hydrophobic. The prepared superhydrophobic coating not only has excellent self-cleaning properties, but also exhibits corrosion resistance to acid and alkali solutions. The coating still has superhydrophobic when the wear length is in the range of 400 cm. It can be seen that a robust superhydrophobic self-cleaning coating is successfully prepared by a simple one-step spraying method. The modification mechanism and the hydrophobic mechanism of the coating were obtained by the combination of experiment and molecular dynamics simulation, which provided theoretical support for the superhydrophobic of the coating at the micro level.

Facile and scalable growth of bimetallic 3D Ag/MIL125-NH2 on cotton fabric for multifaceted anti-wetting and self-healing characteristics

Multifunctional cotton fabric holds great promise across domestic and healthcare sectors. However, the challenge lies in developing a simple, sustainable method to create versatile, multifunctional cotton fabric. Herein, we designed novel 3D bimetallic organic frameworks (Ag/MIL125-NH2) for the first time and fabricated BM125@COT, a superhydrophobic cotton fabric adorned with porous hierarchical grooves. This was achieved by spraying Ag/MIL125-NH2 onto the cotton fabric's surface, followed by post-synthetic treatment with non-fluorinated myristic acid, resulting in superhydrophobic BM125@COT. The coated fabric showed a water contact angle (WCA) of 162.2° and a water sliding angle (WSA) of 4° ± 1. Surface morphology, size, structural and chemical composition, and anti-wetting properties of synthesized MOFs and BM125@COT were evaluated by SEM, EDS, TEM, XRD, XPS, UV/Vis, ATR, DSC, and Optical Tensiometer. Durability tests, including splash tests, abrasion resistance, tape peeling, washing, pH effects, and ultrasonication cycles, underscored the fabric's robust mechanical stability and chemical resistance. Moreover, superhydrophobic BM125@COT demonstrated UV-blocking efficiency, impressive self-cleaning capabilities, and enhanced antibacterial activity. This low-cost, scalable, and sustainable fabric, fabricated through a straightforward one-step spray coating technique, holds immense potential for versatile applications.

Robust superamphiphobic coating for oil repellency and other versatility prepared via one-step spraying

Robust superamphiphobic coating for oil repellency and other versatility prepared via one-step spraying

One-step spraying of protein-anchored chitosan oligosaccharide antimicrobial coating for food preservation

The persistent global issues of unsafe food and food waste continue to exist. Microbial contamination stands out as a major cause of losses in perishable foods like vegetables and fruits. Herein, we report a self-assembling coating based on disulfide bond cleavage-induced bovine serum albumin (BSA), where the antimicrobial activity of chitosan oligosaccharide (COS) is stably anchored in the coating by electrostatic interactions during the unfolding-aggregation phase of BSA. The intrinsic antimicrobial activity of COS, combined with the positively charged and hydrophobic regions enriched on the BSA coating, significantly disrupts the integrity of bacterial structures. Furthermore, the BSA@COS coating can easily adhere in situ to the grooves on the surface of strawberries through a simple one-step spraying process, extending the shelf life of strawberries and bananas by nearly three times. This makes it a potential economic alternative to current commercial antimicrobial coatings, offering a solution to the rampant global issue of food waste.

A waterborne coating system for constructing inorganic-organic composite anti-corrosion and wear-resistant coating

In the fields of engineering and materials science, enhancing the corrosion resistance of engineered metal materials is extremely important. Most common anti-corrosion coatings often lack the capacity to resist external damages, which can lead to a failure in the coating's physical shielding effect. In this study, we have developed an all-water-based, simple one-step spray method for preparing a modified phosphate-based organic-inorganic composite coating, designated as AP-S30@Al2O3@PTFE. The nanofillers of polytetrafluoroethylene (PTFE) and alumina (Al2O3) were dispersed into inorganic binder aluminum phosphate (AP) modified by silica sol (S30). The effects of the incorporation of S30 and Al2O3 as the second hard phase on their wettability, mechanical properties, microscopic morphology, abrasion resistance, and corrosion resistance of the composite coatings were investigated. The results showed that the AP-S30@Al2O3@PTFE coating significantly improved the corrosion resistance of the metal, with the open current density decreasing from 2.285×10−5 to 1.653×10−7 mA·cm−2, and the open potential decreasing from −0.7533 to −0.2577 V. In addition, the composite coating provides a significant improvement in wear resistance. Thus, this cost-effective and eco-friendly method may offer significant contributions to the design and fabrication of strategic composite coatings, advancing their practical deployment in the protection of metal surfaces.

Translucent superhydrophobic coating for murals protection

This study aims to protect murals by a translucent and superhydrophobic coating using a one-step spraying process, which offers simplicity, efficiency, and cost-effectiveness, while preserving the mural's visual appeal and safeguarding against moisture. Despite numerous advancements in cultural relic conservation, the application of super-hydrophobic coatings for mural preservation remains a novel approach. The coating consists of acrylic resin (Paraloid B72), nano-silica, and polydimethylsiloxane (PDMS). The optimal amounts of silica and PDMS were 3 g each in a basal solution containing 12 g of acrylic resin dissolved in 88 mL of xylene. The resulting composite coating displayed exceptional water repellency, as indicated by a contact angle of 165.5° and a rolling angle of approx. 7°. As a result, the moisture absorption of the mural decreased significantly from ∼53% to ∼5% after the application of the superhydrophobic coating. The coating had minimal impact on the water vapor permeability of the mural, with a ca. 13% decline rate. The coating is translucent with a visible transmittance of approximately 60%. Therefore, the coated mural maintains its original appearance with minimal changes. Furthermore, the superhydrophobic properties of the coating remain intact even after undergoing five cycles of high-low temperature fatigue tests, 196 hours of ultraviolet irradiation, or seven cycles of sand impacting.

Insights into the Spray Synthesis of UiO-66 and UiO-66-NH2 Metal–Organic Frameworks: Effect of Zirconium Precursors and Process Parameters

UiO-66, a zirconium-based metal–organic framework, was synthesized using a one-step spray synthesis method to investigate the effects of preheating the precursor solution and Zr sources on crystallinity. Using ZrCl4 with water as a modulator requires preheating at 80 °C for 120 min or 120 °C for 30 min for the spray synthesis of UiO-66 to form secondary building units (SBUs). By contrast, the use of Zr(OnPr)4 with acetic acid (AcOH) as a modulator allowed the spray synthesis of UiO-66 and UiO-66-NH2 without preheating because of the rapid formation of SBUs with AcOH. The spray-synthesized UiO-66 using Zr(OnPr)4 exhibited a BET surface area of 1258 m2/g and a CO2 adsorption capacity of 3.43 mmol/g at 273 K and 1 bar, while UiO-66-NH2 exhibited a BET surface area of 1263 m2/g and a CO2 adsorption capacity of 6.11 mmol/g under the same conditions.

Facile Fabrication of Porous MoSe2/Carbon Microspheres via the Aerosol Process as Anode Materials in Potassium-Ion Batteries

Recently, potassium-ion batteries (KIBs) have attracted significant interest due to a number of factors, including the growing demand for energy and limited lithium resources. However, their practical use is hampered by poor cycling stability due to the large size of K+. Therefore, it is critical to develop a structural design that effectively suppresses large volume changes. This study presents a simple method of using a salt template to fabricate porous microspheres (p-MoSe2@C MS) of MoSe2 and a carbon matrix as anode materials in KIBs. These microspheres have a distinct porous design, with uniformly distributed MoSe2 nanocrystals embedded in the carbon matrix to prevent MoSe2 overgrowth due to material diffusion during heat treatment. The manufacturing process combined one-step spray drying with recyclable NaCl as a hard template. Through a two-step thermal process under an inert atmosphere, the initial dextrin, NaCl, and Mo salt microspheres were converted into a p-MoSe2@N MS composite. The carbon structure derived from the dextrin maintained the shape of the microspheres when NaCl was removed, ensuring no overgrowth of MoSe2. This well-designed porous structure improves the interaction with the electrolyte, facilitating the transport of ions and electrons and reducing the K+ diffusion distances. In addition, the porous carbon structure accommodates large volume changes during cycling and maintains its structural strength. As a result, p-MoSe2@C MS composite exhibits superior electrochemical properties, with remarkable capacity, long-term cycling stability (193 mA h g−1 after 500 cycles at 2.0 A g−1), and rate capability.

Effect of silver/zinc co-dopant on enhancing cytotoxicity and antibacterial property of spray pyrolyzed bioactive glasses

ABSTRACT Owing to the advancement of bioactive materials, bioactive glasses (BGs) are progressively being recognized as promising choices in fields of bone and tissue engineering with their superior properties such as bioactivity and biocompatibility. However, their applications are limited by the fact that the material itself does not possess antibacterial properties. To address this limitation, antibacterial BGs with silver-zinc co-dopant were proposed and successfully synthesized via the one-step spray pyrolysis technique in this work. The phase composition, chemical composition, surface morphology, and nanoscale structures of the obtained BG specimens were characterized using X-ray diffraction, energy dispersive spectroscopy, scanning electron microscopy, and transmission electron microscopy. Moreover, in-vitro bioactivity was assessed through immersion of the SBF solution, while the in-vitro antibacterial property was examined using Escherichia coli bacteria. Meanwhile, the viability of MC3T3-E1 osteoblast cells was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Finally, the results showed positive effects of zinc addition, and the influence of silver and zinc dopants on the in-vitro bioactivity, antibacterial property, and cell viability were discussed.

Coating technology on mortar surface for extending service life of on-site building construction

The superhydrophobic, self-cleaning and anti-corrosion surface was successfully coated on mortar using an effective one-step spray coating technique. A coating solution was prepared by mixing methyltrichlorosilane-modified SiO2/TiO2 nanoparticles at different ratios to enhance the super-hydrophobicity and reduce water absorption of the mortar. The sample prepared using a SiO2/TiO2 with the ratio of 75/25 was found to be optimal, exhibiting a high water contact angle and low sliding angle, which resulted in a reduction of water absorption more than 97.5 % and chloride ion penetration depth. Furthermore, the robustness of the superhydrophobic coating was analyzed against various tests including water drop impact, sand abrasion impact, tape peeling and sandpaper abrasion tests, with each test conducted over 10000 drops, 300 g, 60 cycles, and 5 cycles, respectively. Notably, the coating showed excellent water absorption reduction of 82.6 % after sandpaper abrasion for a length of 200 cm (20 cycles), even though the water contact angle was reduced to 118?. Thus, the fabrication of superhydrophobic mortar surface offers a novel, alternative approach that is simple, efficient, cost-effective and provides multifunction protection surface to increase the service life of on-site building construction with enhanced mechanical durability and anti-corrosion properties.

Facile one-step spraying preparation of fluorine-free transparent superhydrophobic composite coatings with tunable adhesion for self-cleaning and anti-icing applications

Transparent superhydrophobic coatings are of vital importance for various rising applications, such as photovoltaics, touch panels, smart windows, etc. However, their large-scale practical applications are severely restricted by hazardous fluorinated reagents, multistep preparation procedures, thermal treatment requirements, and poor durability. In this study, a facile one-step spraying method was proposed to fabricate transparent superhydrophobic coatings on various substrates, using an integrated fluorine-free suspension composed of siloxane-containing acrylate copolymers and SiO2 nanoparticles. Thanks to the incorporation of siloxane groups in the copolymers, the prepared coatings can be cured at room temperature without any thermal curing procedure. The resultant coatings exhibit excellent superhydrophobicity and high transparency, with a WCA of 162.2 ± 1.8° and ∼90.83 % transmittance at 550 nm, respectively. Besides, superhydrophobic surfaces with tunable water adhesion can be achieved by adjusting spray pressure. After a series of mechanical durability tests and chemical stability tests, the obtained coatings can still maintain their superhydrophobicity and high transparency. Moreover, the water freezing time on the coated glass can be extended and the ice adhesion strength was significantly reduced, exhibiting excellent anti-icing performance. The facile, fluorine-free, and one-step spraying coating method has scalability and universality, demonstrating the promising prospect of large-scale application in industry.

Towards a Higher Energy Density for Lithium-Ion Battery Anodes Via Hierarchically Structured Silicon/Carbon Supraparticles Using Spray Drying

Silicon has a high potential to replace commercial graphite anodes in lithium-ion batteries (LiBs). It can facilitate achieving excellent energy densities because of its high theoretical specific lithiation capacity (Chan et al. 2008). However, major challenges such as rapid capacity fading and low Coulombic efficiency due to the huge volume change (∼300 %) during cycling have seriously hindered its commercialization (Wu et al. 2013). Although nanostructuring has been successful in minimizing volume expansion issues, the electrochemical performance of nano-sized silicon is still limited due to unstable solid-electrolyte interphase, low coating density and overall poor electrical properties due to the higher interparticle resistance (Liu et al. 2014). To tackle those challenges, here we introduce a new concept of post-synthesis spray drying to produce hierarchically structured micro-agglomerates from silicon/carbon (Si/C) composite nanoaggregates synthesized in the gas phase (Amin et al. 2023; Adil Amin et al.).The resulting agglomerates were characterized i) on the powder level by scanning electron microscopy (Fig. 1a) and N2 sorption, ii) on the dispersion level by rheometry and analytical centrifugation, iii) on the electrode level by atomic force microscopy for structure and iv) via electrochemical testing on half-cells for electrochemical performance (Fig. 1b). These results show that electrodes from Si/C supraparticles with the highest concentration of stabilizer exhibit better redispersion stability and excellent first cycle specific discharge capacity as well as better cycling stability as compared to the Si/C composite nanoaggregates (4 wt.% carbon content). Furthermore, compared to the reference electrodes made of nanoaggregates, the more stable supraparticles (3 wt.% stabilizer) showed the highest first Coulombic efficiency. This is due to the reduction of their surface to volume ratio which helps in forming less volume of solid electrolyte interface.To conclude, our investigation suggests how an established industrial process (gas phase synthesis of nanoparticle in a hot-wall reactor) can be combined with scalable one-step spray drying to get dense active materials for LiBs. This enables to fully utilize the new materials’ potential by the right packaging into optimum electrode structures with high performance and longevity. Furthermore, we are of the opinion that this pioneering method can be utilized as a broadly relevant design principle to enhance other (anode) materials that encounter analogous problems of volume expansion. Publication bibliography Amin, Adil; Özcan, Fatih; Loewenich, Moritz; Kilian, Stefan O.; Wiggers, Hartmut; Segets, Doris; Wassmer, Theresa; Bade, Stefan; Lyubina, Julia: Hierarchically Structured Si/C Agglomerates by Spray-Drying. Patent no. PCT / EP 2022/ 052453.Amin, Adil; Loewenich, Moritz; Kilian, Stefan O.; Wassmer, Theresa; Bade, Stefan; Lyubina, Julia et al. (2023): One-Step Non-Reactive Spray Drying Approach to Produce Silicon/Carbon Composite-Based Hierarchically Structured Supraparticles for Lithium-Ion Battery Anodes. In J. Electrochem. Soc. 170 (2), p. 20523. DOI: 10.1149/1945-7111/acb66b.Chan, Candace K.; Peng, Hailin; Liu, Gao; McIlwrath, Kevin; Zhang, Xiao Feng; Huggins, Robert A.; Cui, Yi (2008): High-performance lithium battery anodes using silicon nanowires. In Nature nanotechnology 3 (1), pp. 31–35. DOI: 10.1038/nnano.2007.411.Liu, Nian; Lu, Zhenda; Zhao, Jie; McDowell, Matthew T.; Lee, Hyun-Wook; Zhao, Wenting; Cui, Yi (2014): A pomegranate-inspired nanoscale design for large-volume-change lithium battery anodes. In Nature nanotechnology 9 (3), pp. 187–192. DOI: 10.1038/nnano.2014.6.Wu, Hui; Yu, Guihua; Pan, Lijia; Liu, Nian; McDowell, Matthew T.; Bao, Zhenan; Cui, Yi (2013): Stable Li-ion battery anodes by in-situ polymerization of conducting hydrogel to conformally coat silicon nanoparticles. In Nature communications 4, p. 1943. DOI: 10.1038/ncomms2941. Figure 1