Superhydrophilic Surface Research Articles

Heterogeneous layered multiple transition metal composite electrocatalysts with controlled composition for hydrogen production

The exploration of highly efficient and low-cost bifunctional electrocatalyst is essential for overall water splitting, especially for industrial application under alkaline conditions. Herein, we propose a controllable structural engineering strategy of constructing heterogeneous layered electrocatalyst with wetting surface for hydrogen evolution reaction and oxygen evolution reaction. Heterogeneous layered NiFe LDH (layered double hydroxide)/CoFeP/NF (Ni foam) with superhydrophilic surfaces is successfully fabricated by successive electrodeposition, phosphorization and solvothermal method. The NiFe LDH/CoFeP/NF for hydrogen evolution achieves a low overpotential of 198 mV at 50 mA cm−2 in 1.0 M KOH. An overpotential of 269 mV is required at 50 mA cm−2 for oxygen evolution. Meanwhile, the practical utilization of NiFe LDH/CoFeP/NF as bifunctional electrocatalysts for overall water splitting yields 1.73 V at 50 mA cm−2 in the two-electrode cell. Moreover, NiFe LDH/CoFeP/NF can retain over 50 h without an obvious degradation at 10 mA cm−2. The satisfactory operating stability and high activity of NiFe LDH/CoFeP/NF in alkaline solution can be attributed to the heterogeneous layered structure and excellent hydrophilic surface. The study provides a strategy to engineering heterogeneous layered structures with wetting surface for excellent electrocatalytic activities toward overall water splitting.

Crystalline Ni-Fe phosphide/amorphous P doped Fe-(oxy)hydroxide heterostructure as a multifunctional electrocatalyst for solar cell-driven hydrogen production

Hydrogen production by electrocatalytic water splitting is considered to be an effective and environmental method, and the design of an electrocatalyst with high efficiency, low cost, and multifunction is of great importance. Herein, we developed a crystalline NiFe phosphide (NiFeP)/amorphous P-doped FeOOH (P-FeOOH) heterostructure (defined as P-NiFeOxHy) as a high-efficiency multifunctional electrocatalyst for water electrolysis. The NiFeP nanocrystals provide remarkable electronic conductivity and plenty of active sites, the amorphous P-FeOOH improves the adsorption energy of oxygen-containing species, and the crystalline/amorphous heterostructure with superhydrophilic and superaerophobic surface generates synergistic effects, providing plentiful active sites and efficient charge/mass transfer. Benefiting from this, the designed P-NiFeOxHy displays ultralow overpotentials of 159.2 and 20.8 mV to achieve 10 mA cm−2 for oxygen evolution reaction and hydrogen evolution reaction, and also shows the superior performance of urea oxidation reaction with a low voltage of 1.37 V at 10 mA cm−2 in 1 M KOH with 0.33 M urea. In-situ Raman spectra and ex-situ XPS analysis were also used to investigate the catalytic process and reveal the surface structure evolution of P-NiFeOxHy under electrochemical oxidation. Accordingly, the designed P-NiFeOxHy is employed as both cathode and anode to assemble into the urea-assisted water electrolysis device, which can reach 10 mA cm−2 with a low 1.36 V and could be further driven by a solar cell. The work reveals a design of superior activity, cost-effective and multifunctional electrocatalysts for water splitting.

In Vitro and In Vivo Studies of Hydrogenated Titanium Dioxide Nanotubes with Superhydrophilic Surfaces during Early Osseointegration.

Titanium-based implants are often utilized in oral implantology and craniofacial reconstructions. However, the biological inertness of machined titanium commonly results in unsatisfactory osseointegration. To improve the osseointegration properties, we modified the titanium implants with nanotubular/superhydrophilic surfaces through anodic oxidation and thermal hydrogenation and evaluated the effects of the machined surfaces (M), nanotubular surfaces (Nano), and hydrogenated nanotubes (H-Nano) on osteogenesis and osseointegration in vitro and in vivo. After incubation of mouse bone marrow mesenchymal stem cells on the samples, we observed improved cell adhesion, alkaline phosphatase activity, osteogenesis-related gene expression, and extracellular matrix mineralization in the H-Nano group compared to the other groups. Subsequent in vivo studies indicated that H-Nano implants promoted rapid new bone regeneration and osseointegration at 4 weeks, which may be attributed to the active osteoblasts adhering to the nanotubular/superhydrophilic surfaces. Additionally, the Nano group displayed enhanced osteogenesis in vitro and in vivo at later stages, especially at 8 weeks. Therefore, we report that hydrogenated superhydrophilic nanotubes can significantly accelerate osteogenesis and osseointegration at an early stage, revealing the considerable potential of this implant modification for clinical applications.

Freezing behaviors of impacting water droplets on cold inclined surfaces

Freezing of impacting water droplets on cold inclined surfaces is ubiquitous in nature and many engineering applications. Most of previous studies are limited to the regime where the interaction between the solidification and drop-scale fluid dynamics are weak. In this work, we explore the freezing behaviors of water droplets upon impacting an inclined super-hydrophilic surface at a sufficiently low temperature, so as to improve the coupling effect between the solidification and drop-scale fluid dynamics. Different from an almost identical ice shape when the surface inclination angle α = 30°, the ice at its leading edge becomes steeper with the subcooling degree ΔT when α = 45°. Intriguingly, when α = 60°, the interactions between rivulet dynamics and solidification result in the non-monotonic variations of the rivulet length with impact velocity. Besides, the increasing ΔT has negative (positive) effects on the rivulet length at the low (high) impact velocity regime. Furthermore, the slenderness of rivulet increases with ΔT, indicating the coupling degree between the solidification and rivulet dynamics.

Carbonized ZIF-8/chitosan biomass imprinted hybrid carbon aerogel for phenol selective removal from wastewater

In this work, carbonized ZIF-8/chitosan imprinted hybrid carbon aerogel (MIP@CZIF-8/CS) is constructed. The introduction of CZIF-8 effectively optimizes the specific surface area (664 m2 g−1) of imprinted matrix and further enhances the nitrogen atom doping, leading the increased adsorption sites and the formation of superhydrophilic surface. MIP@CZIF-8/CS exhibits a remarkable phenol adsorption capacity (246.6 mg g−1) at pH of 7 and shows excellent selective adsorption towards phenol against its structural analogues. The adsorption kinetics and isotherms of MIP@CZIF-8/CS follow pseudo-second-order and Langmuir–Freundlich models, respectively. Besides, MIP@CZIF-8/CS with monolithic structure can support about 4167 times its own weight. Thanks to its monolithic structure and excellent mechanical stability, MIP@CZIF-8/CS maintains 94 % adsorption capacity after 10 cycle tests and does not contaminate application system. In addition, MIP@CZIF-8/CS can realize the dynamic filtration of phenol in fixed bed column system. The effluent phenol concentration conforms to GB8978-1996, proving its practical application potential.

Frosting and defrosting characteristics of multi-layer coated aluminum surfaces

Delaying frost formation and shortening defrosting time were both of importance to enhance anti-frosting characteristics. To achieve those, functional multi-layers with a total thickness of <20 μm were successfully integrated over aluminum substrates by sequentially depositing a bottom electrical insulating layer, a middle heating layer, and a top superhydrophilic-superhydrophobic patterned layer. Frosting and defrosting characteristics of functional multi-layers were experimentally investigated. Coating functional multi-layers over aluminum substrates considerably enhanced anti-frosting characteristics. Specifically, the functional multi-layers effectively retarded frost formation on the surfaces, compared to superhydrophilic surfaces, while showing slightly higher frost formation than superhydrophobic surfaces. During defrosting, melting was completed in a fast manner due to the combined effects of the ultrafast temperature increase by the functional multi-layers and the excellent water drainage characteristics by the top superhydrophilic-superhydrophobic patterned layer.

Wetting Ridge-Guided Directional Water Self-Transport.

Directional water self-transport plays a crucial role in diverse applications such as biosensing and water harvesting. Despite extensive progress, current strategies for directional water self-transport are restricted to a short self-driving distance, single function, and complicated fabrication methods. Here, a lubricant-infused heterogeneous superwettability surface (LIHSS) for directional water self-transport is proposed on polyimide (PI) film through femtosecond laser direct writing and lubricant infusion. By tuning the parameters of the femtosecond laser, the wettability of PI film can be transformed into superhydrophobic or superhydrophilic. After trapping water droplets on the superhydrophilic surface and depositing excess lubricant, the asymmetrical wetting ridge drives water droplets by an attractive capillary force on the LIHSS. Notably, the maximum droplet self-driving distance can approach ≈3mm, which is nearly twice as long as the previously reported strategies for direction water self-transport. Significantly, it is demonstrated that this strategy makes it possible to achieve water self-transport, anti-gravity pumping, and chemical microreaction on a tilted LIHSS. This work provides an efficient method to fabricate a promising platform for realizing directional water self-transport.

Experimental and theoretical investigation of bubble dynamics on vertical surfaces with different wettability for pool boiling

Surface wettability is generally employed to manipulate the bubble dynamics to enhance the performance of boiling heat transfer. This work conducted an experimental and theoretical investigation of bubble dynamics on vertical surfaces with different wettability for pool boiling. The side-by-side comparison for bubble growth, bubble detachment diameter and frequency on superhydrophilic, superhydrophobic, and neutral surfaces were visualized, the bubbles detachment diameter and growth time in a negative exponential dependence with the subcooling degree, even a tiny difference in subcooling, such as 1–2K, contributes significantly to the shrinking of bubble volume. When the fluid was in a saturated state or the subcooling of the fluid can be neglected, the bubble was tightly adhered to the wall and cannot detach from the superhydrophobic surface, the bubbles would gather to a certain volume and then slide upward, and the first time of bubble detachment was observed when the coolant subcooling reached 2K. An energy balance model was developed to evaluate the bubble diameter in the bubble growth period, with 94% reproduction of the consolidated database within the error band of ± 40%. In addition, a new correlation is proposed for bubble detachment diameter, the new correlation performed significantly better in a broad range of contact angle, with 82% confidence interval of the consolidated datasets was ± 30%.

Bioactive composite Janus nanofibrous membranes loading Ciprofloxacin and Astaxanthin for enhanced healing of full-thickness skin defect wounds

In this paper, skin-inspired multilayer Janus composite nanofibrous membranes with superhydrophilicity and superhydrophobicity as a wound dressing were designed and prepared to manage and utilize the exudates. Wettability, morphology, in-vitro release, cytotoxicity, antimicrobial activity and healing effect were investigated. Animal experiment and histological analysis confirmed the composite membranes were more effective in improving the healing of full-thickness defect wound, the growth of collagen fibers and collagen deposition. The four-layer composite membranes include the drug-loading layer containing Ciprofloxacin (CIP) and Astaxanthin (ATX) with superhydrophilic surface for self-pumping and drugs backflow, the hydrophobic polyvinylidene fluoride layer for delaying the exudates loss, and the superhydrophobic coating with self-cleaning properties for avoiding adhesion of foreign microorganisms. The exudates were absorbed into the composite membrane and locked in the nanofiber network to avoid dehydration of the wound, meanwhile, CIP and ATX were delivered to the wound bed to effectively inhibit bacterial growth and stimulate tissue regeneration. These results demonstrate that skin-inspired Janus composite nanofibrous membrane is a promising wound dressing for promoting full-thickness skin defect wound healing, displaying its great potential applications in skin tissue engineering.

Fast UV-Curable Zwitter-Wettable Coatings with Reliable Antifogging/Frost-Resisting Performances.

Antifogging surfaces with unique properties to migrate severe fog formation have gained extensive interest, which is of particular interest for transparent substrates to obtain high visibility and transparency. To date, a large number of strategies including superhydrophilic or superhydrophobic surfaces and titanium dioxide (TiO2)-based composite coatings have been developed based on different mechanisms. Although these surfaces exhibit effective antifogging properties, the rigid nanostructures, cumbersome preparation, and the need for UV light excitation largely limit their widespread applications. Herein, we report a zwitter-wettable antifogging and frost-resisting coating through a fast UV-curable cross-linking of copolymer with benzophenone groups. A series of random copolymers consisting of hydrophilic hydroxyethyl methacrylate (HEA), hydrophobic methyl methacrylate (MMA), and benzophenone-based acrylate units are developed by thermally triggered free-radical polymerization. Upon UV light irradiation, a highly efficient antifogging/frost-resisting coating is covalently bonded on a polycarbonate plate surface, maintaining a light transmission higher than 85%, which was confirmed in both high and low temperature anti-fog tests. Moreover, the wetting behaviors reveal that the antifogging performance exhibited by the zwitter-wettable surface mainly relies on its surface water-adsorbing capability to imbibe condensed water vapor on the surface outmost layer. Notably, the antifogging/frost-resisting behaviors can be well regulated by adjusting the hydrophilic/hydrophobic units, due to the proper balance between the water-adsorption and coating stability. Owing to its simplicity, low-cost preparation and high efficiency, this UV-curable acrylate antifogging coating may find a wide range of applications in various display devices in analytical and detection instruments.

Machine learning based prediction and optimization of thin film nanocomposite membranes for organic solvent nanofiltration

In this study, machine learning was used to form prediction models for thin film nanocomposite (TFN) organic solvent nanofiltration (OSN) membrane performance evaluation in terms of relative permeability (RP) and relative selectivity (RS). Twenty references including 9252 data points were collected to form four different models: linear, support vector machine (SVM), boosted tree (BT), and artificial neural network (ANN). Among the four models, BT exhibited optimal prediction accuracy in terms of root mean square error (RMSE) and coefficient of determination (R2) values for membrane RP (RMSE: 0.295, R2: 0.918) and RS (RMSE: 0.053, R2: 0.849) performance prediction. Parameter contribution analysis indicated that nanoparticle loading, amine concentration, chloride concentration, water contact angle, solvent viscosity, and molar volume are the main parameters influencing RP performance. For RS performance, nanoparticle loading, amine concentration, chloride concentration, and solute molecular weight play important roles. Partial dependence analysis indicated that the optimal conditions for TFN-OSN membrane fabrication are nanoparticle loading less than 5 wt%, the amine concentration around 2 wt%, and the chloride concentration around 0.15 wt%. In addition, membrane with super-hydrophilic or super-hydrophobic surface property exhibited higher RP performance based on different feed solvent types. Overall, this work introduces new ways both for TFN-OSN membrane performance prediction and for higher performance membrane design and development.

Maximizing the ion accessibility and high mechanical strength in nanoscale ion channel MXene electrodes for high-capacity zinc-ion energy storage

Two-dimensional transition-metal carbides (MXenes) have superhydrophilic surfaces and superior metal conductivity, making them competitive in the field of electrochemical energy storage. However, MXenes with layered structures are easily stackable, which reduces the ion accessibility and transport paths, thus limiting their electrochemical performance. To fully exploit the advantages of MXenes in electrochemical energy storage, this study reports the etching of large-sized MXene into nanosheets with nanoscale ion channels via a chemical oxidation method. While the resulting ion-channel MXene electrodes retain the excellent mechanical strength and electrical conductivity of large-sized MXene nanosheets, they can effectively shorten the ion transport distance and improve the overall electrochemical activity. The fabricated self-healing MXene-based zinc-ion microcapacitor exhibits a high areal specific capacitance (532.8 mF cm−2) at the current density of 2 mA cm−2, a low self-discharge rate (4.4 mV h−1), and high energy density of 145.1 μWh cm−2 at the power density of 2800 μW cm−2. The proposed nanoscale ion channel structure provides an alternative strategy for constructing high-performance electrochemical energy storage electrodes, and has great application prospects in the fields of electrochemical energy storage and flexible electronics.

Electrostimulation of fibroblast proliferation by an electrospun poly (lactide-co-glycolide)/polydopamine/chitosan membrane in a humid environment

Exogenous electrical stimulation (ES) facilitates skin wound healing and accelerates cell proliferation. Scaffolds fabricated with electrically-conductive materials combined with ES further promote cellular activity. Here, an electrospun membrane made of poly (lactide-co-glycolide) (PLGA) coated with chitosan (CS) via polydopamine (PDA) serving as a linker was developed and evaluated in vitro for the proliferation and migration of fibroblast cells involved in skin wound repair. PLGA/PDA/CS exhibited multiple optimal characteristics for cell proliferation and dressing materials including good mechanical properties, low cytotoxicity, a super-hydrophilic surface, and an excellent swelling ratio suitable for the absorption of wound exudates. Because of ionic charges, wet PLGA/PDA/CS had an electrical conductivity of 2.85 × 10-3 S/cm, which was comparable to the highest electrical conductivities observed with natural skin. Upon intermittent ES of 100 mV, PLGA/PDA/CS increased fibroblast proliferation 2 and 1.3 times compared to PLGA and PLGA/PDA, respectively. These results demonstrate the potential of PLGA/PDA/CS as a biodegradable polymeric surface for the ES of cells involved in skin wound healing. It also shows that polymers with low electrical conductivity in dry conditions can become suitable for the ES of humid wounds where ionic conductivity is occurring.

Mass production of superhydrophilic micropatterned copper surfaces using powder injection molding process

Hydrophilic micropatterned copper surfaces are manufactured using a powder injection molding (PIM) process. Copper powder and a wax-polymer-based binder system are utilized to prepare a feedstock. The rheological properties of the feedstock are evaluated to design the PIM process. Polymethylmethacrylate (PMMA) sacrificial mold inserts fabricated by photolithography are used to shape the micropatterns. Both PIM and photolithography processes are suitable for high-volume products; therefore, the micropatterned surfaces can be mass-produced. The wettability of the manufactured surfaces is investigated by measuring the apparent contact angle. The apparent contact angle tends to decrease as the absolute value of the difference in effective surface free energy between the wet and dry states increases. When the absolute value of the difference is equal to or exceeds 150 mJ/m 2 , the surface is fully wetted immediately and exhibits superhydrophilicity. Both high aspect ratio and small gap size are key to achieving superhydrophilicity of the micropatterned surface. • Superhydrophilic micropatterned copper surface is manufactured without any defects. • Rheological analysis of the copper feedstock indicates that it is suitable for PIM. • PMMA sacrificial mold inserts fabricated using photolithography shape micropatterns. • The combined process is suitable for mass production of superhydrophilic surfaces. • Wettability of the micropatterned surface is linked to the dimensions of the pattern.

A S-scheme heterojunction of Co9S8 decorated TiO2 for enhanced photocatalytic H2 evolution

Construction of heterojunction photocatalyst is an effective strategy for optimizing the light absorption, charge carrier separation and surface reaction efficiency during the photocatalytic processes. Herein, an S-scheme Co9S8/TiO2 heterojunction was fabricated by an in-situ deposition hydrothermal method. The experimental results indicate that Co9S8 can broaden the light absorption range of TiO2 from 400 to 800 nm, accelerate charge carrier separation using Co-O-Ti chemical bonds as the transfer bridge. The enhanced H2 evolution reaction (HER) performance over 20 wt% Co9S8/TiO2 is 12.6 and 283.0 times than that of pure TiO2 and Co9S8 after electrochemical active surface area (ECSA) normalization, the HER over 20 wt% Co9S8/TiO2 can reach up to 3982 μmol·g–1·h–1 in absence of cocatalysts, which is 13.2 and 73.7 times than that of pristine TiO2 and Co9S8, respectively. Further investigation shows that the water contact angle (WAC) of TiO2 is obviously reduced from 23.3° to 5.4° after introducing Co9S8, this super-hydrophilic surface benefits the adsorption of water molecules on the catalyst surface. This composite also exhibits an excellent stability during three cycles of H2 production tests. Based on band structure analysis and ·OH/·O2- radical trapping experiments, the charge carrier separation process is in accord with the S-scheme route. The useless e– on the CB of Co9S8 are driven to combine with h+ on the VB of TiO2. Simultaneously, the e– with strong reduction ability are preserved in the CB of TiO2 to participate in HER, while the h+ on the VB of Co9S8 are consumed for the oxidation of the sacrificial agent. This work demonstrates Co9S8 is a potential material for fabricating heterojunction with desired activity, although the activity of Co9S8 is unsatisfactory alone.

Activated carbon-cement composite coated polyurethane foam as a cost-efficient solar steam generator

Solar thermal evaporation (STE) is a promising advanced technique to purify contaminated water under the influence of solar light. Naturally, cement has served as a binder in masonry-related applications and possesses light-absorbing properties. Herein, we fabricated a cost-effective high-durable cement/carbon/polyurethane foam (CCPF) composite material as a solar-driven evaporator. It provided an excellent evaporation rate of ∼2.4 kg m−2 h−1 under one sun (1 kW/m2) illumination. The CCPF exhibits a high solar light absorbance due to the presence of carbon. Also, the high-interconnected porous foam provides the self-floating ability to maximize heat localization. Simultaneously, the interconnected crisscross porous foam and the porous activated carbon coat on the air-water interface behave like a highly concentrated dye water filter, salt-water filter, and high density muddy water filter. Moreover, the super hydrophilic surface of CCPF and the addition of polyurethane (PU) foam ensure adequate water supply. Complete wastewater filtering ability was confirmed by UV–Vis spectral analysis. As-fabricated composite can attain the maximum surface temperature of 62 °C under one sun illumination for 1 h. The stability and adhesive strength of the coating were confirmed from successive 60 days of water treatment. No carbon was excreted from the device even after 60 days of the experiment. The small size solar still setup was fabricated with an area of 30 × 30 cm2 to show the performance of the device under ambient conditions. Collection of 140–180 ml ultrapure water from the device under ∼0.6 kW/m2 (variable solar intensity) at environment temperature 30–32 °C in 4–5 h. Therefore, this easily fabricated, cost-effective, highly stable CCPF solar-driven evaporator can be used as a strategy for high water production on a potential scale for the long term.

Long-Time Persisting Superhydrophilicity on Sapphire Surface via Femtosecond Laser Processing with the Varnish of TiO2.

The acquiring of superhydrophilic surfaces attracts the strong interest in self-cleaning, anti-fogging and anti-icing fields based on the unique features. However, the persistent time of superhydrophilic surfaces is still facing a big challenge because of easily adsorbing hydrophobic groups. Here, we propose a strategy to achieve a superhydrophilicity persisting for an unprecedently long time on sapphire surfaces, by compounding the femtosecond laser-induced hierarchical structures and the subsequent varnish of TiO2. The superhydrophilic effect (with a contact angle of CA = 0°) created by our method can be well prolonged to at least 180 days, even for its storage in air without additional illumination of UV lights. Based on comprehensive investigations, we attribute the underlying mechanisms to the coordination of laser-induced metal ions on the material surface via TiO2 doping, which not only prevents the adsorption of the nonpolar hydrocarbon groups, but also modulates the photo-response properties of TiO2. In addition, further experiments demonstrate the excellent anti-fogging properties of our prepared samples. This investigation provides a new perspective for further enhancing the durability of superhydrophilicity surfaces.

Visible-Light-Driven Photocatalysts for Self-Cleaning Transparent Surfaces.

Highly transparent photocatalytic self-cleaning surfaces capable of harvesting near-visible (365-430 nm) photons were synthesized and characterized. This helps to address a current research gap in self-cleaning surfaces, in which photocatalytic coatings that exhibit activity at wavelengths longer than ultraviolet (UV) generally have poor optical transparency, because of broadband scattering and the attenuation of visible light. In this work, the wavelength-dependent photocatalytic activity of Pt-modified TiO2 (Pt-TiO2) particles was characterized, which exhibited activity for wavelengths up to 430 nm. Pt-TiO2 nanoparticles were embedded in a mesoporous SiO2 sol-gel matrix, forming a superhydrophilic surface that allowed for water adsorption and formation of reactive oxide species upon illumination, resulting in the removal of organic surface contaminants. These self-cleaning surfaces only interact strongly with near-visible light (∼365-430 nm), as characterized by photocatalytic self-cleaning tests. Broadband visible transparency was preserved by generating a morphology composed of small clusters of Pt-TiO2 surrounded by a matrix of SiO2, which limited diffuse visible light scattering and attenuation. The wavelength-dependent self-cleaning rate by the films was quantified using stearic acid degradation under both monochromatic and AM1.5G spectral illumination. By varying the film morphology, the average transmittance relative to bare glass can be tuned from ∼93%-99%, and the self-cleaning rate can be adjusted by more than an order of magnitude. Overall, the ability to utilize photocatalysts with tunable visible light activity, while maintaining broadband transparency, can enable the use of photocatalytic self-cleaning surfaces for applications where UV illumination is limited, such as touchscreen displays.

A Review on Research Progress in Plasma-Controlled Superwetting Surface Structure and Properties.

Superwetting surface can be divided into (super) hydrophilic surface and (super) hydrophobic surface. There are many methods to control superwetting surface, among which plasma technology is a safe and convenient one. This paper first summarizes the plasma technologies that control the surface superwettability, then analyzes the influencing factors from the micro point of view. After that, it focuses on the plasma modification methods that change the superwetting structure on the surface of different materials, and finally, it states the specific applications of the superwetting materials. In a word, the use of plasma technology to obtain a superwetting surface has a wide application prospect.

A Superhydrophilic, Light/Microwave-Absorbing Coating with Remarkable Antibacterial Efficacy.

Driven by the overuse of antibiotics, pathogenic infections, dominated by the rapid emergence of antibiotic resistant bacteria, have become one of the greatest current global health challenges. Thus, there is an urgent need to explore novel strategies that integrate multiple antibacterial modes to deal with bacterial infections. In this work, a Co(Ni,Ag)/Fe(Al,Cr)2O4 composite duplex coating was fabricated using template-free sputtering deposition technology. The phase constitution of the coating was estimated to be 79 wt % Fe(Al,Cr)2O4 phase and 21 wt % of an Ag-containing metallic phase. The composite coating consisted of a ∼10 μm-thick porous outer-layer and a ∼6 μm-thick compact inner-layer, in which the outer-layer is composed of a densely stacked array of microscale cones. After exposure to ambient air for 14 days, the composite coating showed a wettability transition from a superhydrophilic nature to exhibit adhesive superhydrophobic behavior with a water contact angle of 142° ± 2.8°, but it reverted to its initial superhydrophilic state after annealing in air at 200 °C for 5 h. The absorption rate of the as-received composite coating exceeds 99% in a broad band spanning both the visible and NIR regions and showed a high photothermal efficiency to convert photon energy into heat. Similarly, the composite coating showed microwave absorption behavior with a minimum reflection loss value of 38 dB at 4.4 GHz. In vitro antibacterial tests were used to determine the antibacterial behavior of the composite coating against Escherichia coli and Staphylococcus aureus after 60 min of visible light irradiation. After this exposure, the as-prepared composite coating exhibited nearly 100% bactericidal efficiency against these bacteria. The antibacterial behavior of the coating was attributed to the synergistic effects of the superhydrophilic surface, the release of Ag+ ions, and the photothermal effect. Therefore, this composite coating may be a promising candidate to efficiently combat medical device-associated infections.