Phospholipid Bilayer Inspired Sandwich Structural Nanofibrous Membrane for Atmospheric Water Harvesting and Selective Release.

Atmospheric water harvesting (AWH) has been broadly exploited to meet the challenge of water shortage. Despite the significant achievements of AWH, the leakage of hydroscopic salt during the AWH process hinders its practical applications. Herein, inspired by the unique selective permeability of the phospholipid bilayer, a sandwich structural (hydrophobic-hydrophilic-hydrophobic) polyacrylonitrile nanofibrous membrane (San-PAN) was fabricated for AWH. The hydrophilic inner layer loaded with LiCl could capture water from the air. The hydrophobic microchannels in the outer layer could selectively allow the free transmission of gaseous water molecules but confine the hydroscopic salt solution in the hydrophilic layer, achieving continuous and recyclable water sorption/desorption. As demonstrated, the as-prepared AWH devices presented high-efficient adsorption kinetics from 1.66 to 4.08 g g-1 at 30% to 90% relative humidity. Thus, this work strengthens the understanding of the water transmission process along microchannels and provides insight into the practical applications of AWH.

Fluorine-Free Amphiphobic SBS/PAN Micro/Nanofiber Membrane by Integrating Click Reaction with Electrospinning for Efficient and Recyclable Air Filtration.

The membrane fouling derived from the accumulated dust pollutants and highly viscous oily particles causes irreversible damage to the filtration performance of air filters and results in a significant reduction in their service life. However, it is still challenging to construct high-efficiency and antifouling air filtration membranes with recyclable regeneration. Herein, the fluorine-free amphiphobic micro/nanofiber composite membrane was controllably constructed by integrating click chemistry reaction and electrospinning technique. Low-surface-energy fibers were constructed by a thiol-ene click chemical reaction between mercaptosilane and vinyl groups of polystyrene-butadiene-styrene (SBS), combined with hydroxyl-terminated poly(dimethylsiloxane) during the electrospinning process. The functional air filter is then prepared by the two-layer composite strategy. Because of the advantages of liquid-like fibrous surface and micro/nanofibrous porous structure, SBS/PAN composite membrane simultaneously shows superior antifouling performances of pollutants and filtration efficiency of over 97% PM0.3 removal. More importantly, the antifouling fibrous membrane still presents a stable and efficient filtration efficiency after multiple washes. Its service life in dust filtration environments is approximately 1.7 times longer than that of the substrate membrane. This work may provide a significant reference for the design of antifouling fiber membranes and high-efficiency air filters with long life spans and reusability.

Recent advances in conductive hydrogels: classifications, properties, and applications.

Hydrogel-based conductive materials for smart wearable devices have attracted increasing attention due to their excellent flexibility, versatility, and outstanding biocompatibility. This review presents the recent advances in multifunctional conductive hydrogels for electronic devices. First, conductive hydrogels with different components are discussed, including pure single network hydrogels based on conductive polymers, single network hydrogels with additional conductive additives (i.e., nanoparticles, nanowires, and nanosheets), double network hydrogels based on conductive polymers, and double network hydrogels with additional conductive additives. Second, conductive hydrogels with a variety of functionalities, including self-healing, super toughness, self-growing, adhesive, anti-swelling, antibacterial, structural color, hydrophobic, anti-freezing, shape memory and external stimulus responsiveness are introduced in detail. Third, the applications of hydrogels in flexible devices are illustrated (i.e., strain sensors, supercapacitors, touch panels, triboelectric nanogenerator, bioelectronic devices, and robot). Next, the current challenges facing hydrogels are summarized. Finally, an imaginative but reasonable outlook is given, which aims to drive further development in the future.

In Operando Neutron Scattering Multiple-Scale Studies of Lithium-Ion Batteries.

Real-time observation of the electrochemical mechanistic behavior at various scales offers new insightful information to improve the performance of lithium-ion batteries (LIBs). As complementary to the X-ray-based techniques and electron microscopy-based methodologies, neutron scattering provides additional and unique advantages in materials research, owing to the different interactions with atomic nuclei. The non-Z-dependent elemental contrast, in addition to the high penetration ability and weak interaction with matters, makes neutron scattering an advanced probing tool for the in operando mechanistic studies of LIBs. The neutron-based techniques, such as neutron powder diffraction, small-angle neutron scattering, neutron reflectometry, and neutron imaging, have their distinct functionalities and characteristics regimes. These result in their scopes of application distributed in different battery components and covering the full spectrum of all aspects of LIBs. The review surveys the state-of-the-art developments of real-time investigation of the dynamic evolutions of electrochemically active compounds at various scales using neutron techniques. The atomic-scale, the mesoscopic-scale, and at the macroscopic-scale within LIBs during electrochemical functioning provide insightful information to battery researchers. The authors envision that this review will popularize the applications of neutron-based techniques in LIB studies and furnish important inspirations to battery researchers for the rational design of the new generation of LIBs.

Bimetallic-MOF-Derived ZnxCo3-xO4/Carbon Nanofiber Composited Sorbents for High-Temperature Coal Gas Desulfurization.

Desulfurization sorbent with a high active component utilization is of importance for the removal of H2S from coal gas at high temperatures. Thus, the hypothesis for producing ZnxCo3-xO4/carbon nanofiber sorbents via the combinations of electrospinning, in situ hydrothermal growth, and carbonization technique has been rationally constructed in this study. ZnxCo3-xO4 nanoparticles derived from metal-organic frameworks are uniformly loaded on the electrospun carbon nanofibers (CNFs) with high dispersion. ZnxCo3-xO4/CNFs sorbents possess the highest breakthrough sulfur adsorption capacity (12.4 g S/100 g sorbent) and an excellent utilization rate of the active component (83.2%). The excellent performance of ZnxCo3-xO4/CNFs can be attributed to the synergetic effect of the hierarchical structure and widely distributed ZnxCo3-xO4 on the CNFs supporter. The decomposition of Zn/Co-ZIFs not only generates the nucleus of oxides but also realizes their physical isolation through the formation of carbon grids on the surface of CNFs, avoiding the aggregation of oxides. Furthermore, ZnxCo3-xO4/CNFs sorbents show an overwhelming superiority over the ZnO/CNFs sorbent, which is attributed to the introduction of Co and then the promotion of the stability of Zn at high temperatures. The presence of Co also accelerates the adsorption of H2S on the active site of the oxide surface. The presented method is beneficial for promoting desulfurization performances and producing sorbents with high utilization of active components.

Reducing Oxygen Evolution Reaction Overpotential in Cobalt-Based Electrocatalysts via Optimizing the "Microparticles-in-Spider Web" Electrode Configurations.

Sluggish kinetics of the multielectron transfer process is still a bottleneck for efficient oxygen evolution reaction (OER) activity, and the reduction of reaction overpotential is crucial to boost reaction kinetics. Herein, a correlation between the OER overpotential and the cobalt-based electrode composition in a "Microparticles-in-Spider Web" (MSW) superstructure electrode is revealed. The overpotential is dramatically decreased first and then slightly increased with the continuous increase ratio of Co/Co3 O4 in the cobalt-based composite electrode, corresponding to the dynamic change of electrochemically active surface area and charge-transfer resistance with the electrode composition. As a proof-of-concept, the optimized electrode displays a low overpotential of 260 mV at 10.0 mA cm-2 in alkaline conditions with a long-time stability. This electrochemical performance is comparable and even superior to the most currently reported Co-based OER electrocatalysts. The remarkable electrocatalytic activity is attributed to the optimization of the electrochemically active sites and electron transfer in the MSW superstructure. Theoretical calculations identify that the metallic Co and Co3 O4 surface catalytic sites play a vital role in improving electron transport and reaction Gibbs free energies for reducing overpotential, respectively. A general way of boosting OER kinetics via optimizing the electrode configurations to mitigate reaction overpotential is offered in this study.

Mechanically Reinforced Localized Structure Design to Stabilize Solid-Electrolyte Interface of the Composited Electrode of Si Nanoparticles and TiO2 Nanotubes.

Silicon anode with extremely high theoretical specific capacity (≈4200 mAh g-1 ), experiences huge volume changes during Li-ion insertion and extraction, causing mechanical fracture of Si particles and the growth of a solid-electrolyte interface (SEI), which results in a rapid capacity fading of Si electrodes. Herein, a mechanically reinforced localized structure is designed for carbon-coated Si nanoparticles (C@Si) via elongated TiO2 nanotubes networks toward stabilizing Si electrode via alleviating mechanical strain and stabilizing the SEI layer. Benefited from the rational localized structure design, the carbon-coated Si nanoparticles/TiO2 nanotubes composited electrode (C@Si/TiNT) exhibits an ideal electrode thickness swelling, which is lower than 1% after the first cycle and increases to about 6.6% even after 1600 cycles. While for traditional C@Si/carbon nanotube composited electrode, the initial swelling ratio is about 16.7% and reaches ≈190% after 1600 cycles. As a result, the C@Si/TiNT electrode exhibits an outstanding capacity of 1510 mAh g-1 at 0.1 A g-1 with high rate capability and long-time cycling performance with 95% capacity retention after 1600 cycles. The rational design on mechanically reinforced localized structure for silicon electrode will provide a versatile platform to solve the current bottlenecks for other alloyed-type electrode materials with large volume expansion toward practical applications.

Bioinspired Special Wettability Surfaces: From Fundamental Research to Water Harvesting Applications.

Nowadays, the pollution of water has become worse in many parts of the world, which causes a severe shortage of clean water and attracts widespread attention worldwide. Bioinspired from nature, i.e. spider silk, cactus, Namib desert beetle, Nepenthes alata, special wettability surfaces have attracted great interest from fundamental research to water-harvesting applications. Here, recently published literature about creatures possessing water-harvesting ability are reviewed, with a focus on the corresponding water-harvesting mechanisms of creatures in dry or arid regions, consisting of the theory of wetting and transporting. Then a detailed account of the innovative fabrication technologies and bionic water-harvesting materials with special wetting are summarized, i.e. bio-inspired artificial spider silk, bio-inspired artificial cactus-like structures, and bio-inspired artificial Namib desert beetle-like surfaces. Special attentions are paid to the discussion of the advantages and disadvantages of the technologies, as well as factors that affect the amount of water-harvesting. Finally, conclusions, future outlooks and the current challenges for future development of the water-harvesting technology are presented and discussed.

Bioinspired Surfaces with Superwettability for Anti-Icing and Ice-Phobic Application: Concept, Mechanism, and Design.

Ice accumulation poses a series of severe issues in daily life. Inspired by the nature, superwettability surfaces have attracted great interests from fundamental research to anti-icing and ice-phobic applications. Here, recently published literature about the mechanism of ice prevention is reviewed, with a focus on the anti-icing and ice-phobic mechanisms, encompassing the behavior of condensate microdrops on the surface, wetting, ice nucleation, and freezing. Then, a detailed account of the innovative fabrication and fundamental research of anti-icing materials with special wettability is summarized with a focus on recent progresses including low-surface energy coatings and liquid-infused layered coatings. Finally, special attention is paid to a discussion about advantages and disadvantages of the technologies, as well as factors that affect the anti-icing and ice-phobic efficiency. Outlooks and the challenges for future development of the anti-icing and ice-phobic technology are presented and discussed.

Understanding the Role of Dynamic Wettability for Condensate Microdrop Self-Propelling Based on Designed Superhydrophobic TiO2 Nanostructures.

The ability to release the adhered drops on superhydrophobic surfaces is very important for self-cleaning, antifrosting/icing, microfluidic device, and heat transfer applications. In this paper, three types of in situ electrochemical anodizing TiO2 nanostructure films are rationally designed and fabricated on titanium substrates with special superwettability, viz., TiO2 nanotube arrays, irregular TiO2 nanotube arrays, and hierarchical TiO2 particle arrays (HTPA), and their corresponding behavior in condensate microdrop self-propelling (CMDSP) is investigated. Compared to the flat titanium counterpart, all three types of rough TiO2 samples demonstrate a uniform distribution of smaller microscale droplets. Among the treated surfaces, the HTPA possesses the highest condensate density, and more than 80% of the droplets possess a diameter below 10 µm. Theoretical analysis indicates that the feature is mainly due to the morphology and structure induced extremely low droplet adhesion on super-antiwetting TiO2 hierarchical surfaces, where the excess surface energy released from the migration leads to the self-propelling of merged microdrop. This work offers a way to rationally construct CMDSP surfaces with excellent self-cleaning, antifrosting/icing ability, and enhanced condensation heat transfer efficiency.

Immobilization of Pt Nanoparticles via Rapid and Reusable Electropolymerization of Dopamine on TiO2 Nanotube Arrays for Reversible SERS Substrates and Nonenzymatic Glucose Sensors.

Inspired by mussel-adhesion phenomena in nature, polydopamine (PDA) coatings are a promising route to multifunctional platforms for decorating various materials. The typical self-polymerization process of dopamine is time-consuming and the coatings of PDA are not reusable. Herein, a reusable and time-saving strategy for the electrochemical polymerization of dopamine (EPD) is reported. The PDA layer is deposited on vertically aligned TiO2 nanotube arrays (NTAs). Owing to the abundant catechol and amine groups in the PDA layer, uniform Pt nanoparticles (NPs) are deposited onto the TiO2 NTAs and can effectively prevent the recombination of electron-hole pairs generated from photo-electrocatalysis and transfer the captured electrons to participate in the photo-electrocatalytic reaction process. Compared with pristine TiO2 NTAs, the as-prepared Pt@TiO2 NTA composites exhibit surface-enhanced Raman scattering sensitivity for detecting rhodamine 6G and display excellent UV-assisted self-cleaning ability, and also show promise as a nonenzymatic glucose biosensor. Furthermore, the mussel-inspired electropolymerization strategy and the fast EPD-reduced nanoparticle decorating process presented herein can be readily extended to various functional substrates, such as conductive glass, metallic oxides, and semiconductors. It is the adaptation of the established PDA system for a selective, robust, and generalizable sensing system that is the emphasis of this work.

Recent Advances in TiO2 -Based Nanostructured Surfaces with Controllable Wettability and Adhesion.

Bioinspired surfaces with special wettability and adhesion have attracted great interest in both fundamental research and industry applications. Various kinds of special wetting surfaces have been constructed by adjusting the topographical structure and chemical composition. Here, recent progress of the artificial superhydrophobic surfaces with high contrast in solid/liquid adhesion has been reviewed, with a focus on the bioinspired construction and applications of one-dimensional (1D) TiO2-based surfaces. In addition, the significant applications related to artificial super-wetting/antiwetting TiO2-based structure surfaces with controllable adhesion are summarized, e.g., self-cleaning, friction reduction, anti-fogging/icing, microfluidic manipulation, fog/water collection, oil/water separation, anti-bioadhesion, and micro-templates for patterning. Finally, the current challenges and future prospects of this renascent and rapidly developing field, especially with regard to 1D TiO2-based surfaces with special wettability and adhesion, are proposed and discussed.

Multifunctional superamphiphobic TiO2 nanostructure surfaces with facile wettability and adhesion engineering.

Compared to conventional top-down photo-cleavage method, a facile bottom-up ink-combination method to in situ and rapidly achieve water wettability and adhesion transition, with a great contrast on the superamphiphobic TiO2 nanostructured film, is described. Moreover, such combination method is suitable for various kinds of superamphiphobic substrate. Oil-based ink covering or removing changes not only the topographical morphology but also surface chemical composition, and these resultant topographical morphology and composition engineering realize the site-selectively switchable wettability varying from superamphiphobicity to amphiphilicity, and water adhesion between sliding superamphiphobicity and sticky superamphiphobicity in micro-scale. Additionally, positive and negative micro-pattern can be achieved by taking advantage of the inherent photocatalytic property of TiO2 with the assistance of anti-UV light ink mask. Finally, the potential applications of the site-selectively sticky superamphiphobic surface were demonstrated. In a proof-of-concept study, the microdroplet manipulation (storage, moving, mixing, and transfer), specific gas sensing, wettability template for positive and negative ZnO patterning, and site-selective cell immobilization have been demonstrated. This study will give an important input to the field of advanced functional material surfaces with special wettability.

Metal organic framework-assisted copper-modified titania (Cu/TiO2) with abundant exposed active sites and highly accessible pore channels for an enhanced photo-generation of hydrogen.

Metal-doping is a common strategy for establishing active sites on photocatalyst, but appropriately exposing them for maximized atomic utilization remains a great challenge in photocatalytic research. Herein, we propose a metal organic framework (MOF)-assisted approach to synthesis copper-modified titania (Cu-TiO2/Cu) photocatalyst with homogenously distributed and highly accessible active sites in its matrix. Significantly, an MOF precursor, namely NH2-MIL-125, with co-chelation of titania (Ti) and copper (Cu) was subjected to mild calcination, subsequently results in Cu-modified TiO2 with highly accessible channels to its inner surface. These channels provide not only a large reactive surface (>400 m2 g-1); they also enable facile modifying route for the pre-deposited Cu in prior to photoreaction. Specifically, NH3 treatment was applied to partially reduce deposited Cu ions (Cu+ and Cu2+) into Cu nanoparticles, where their interplays realize improved optical properties and charge separation during photoreactions. Furthermore, the NH3-induced Cu nanoparticles could also serve as the adsorptive site for H+, thereby enabling 5629 µmol h-1 g-1 H2 generation over the optimum photocatalyst of Cu20/TiO2/Cu500. Such performance is associated to 35.44 and 1.71-fold improvements compared to pure TiO2 (Cu0/TiO2) and untreated Cu-ion modified TiO2 (Cu20/TiO2), respectively. This work offers a new synthetic strategy for obtaining photocatalyst with evenly distributed and highly accessible active sites, thus improving the commensurability of photocatalytic H2 generation from the industrial perspective.

Fast Energy Storage of SnS2 Anode Nanoconfined in Hollow Porous Carbon Nanofibers for Lithium-Ion Batteries.

The development of conversion-typed anodes with ultrafast charging and large energy storage is quite challenging due to the sluggish ions/electrons transfer kinetics in bulk materials and fracture of the active materials. Herein, the design of porous carbon nanofibers/SnS2 composite (SnS2 @N-HPCNFs) for high-rate energy storage, where the ultrathin SnS2 nanosheets are nanoconfined in N-doped carbon nanofibers with tunable void spaces, is reported. The highly interconnected carbon nanofibers in three-dimensional (3D) architecture provide a fast electron transfer pathway and alleviate the volume expansion of SnS2 , while their hierarchical porous structure facilitates rapid ion diffusion. Specifically, the anode delivers a remarkable specific capacity of 1935.50 mAh g-1 at 0.1 C and excellent rate capability up to 30 C with a specific capacity of 289.60 mAh g-1 . Meanwhile, at a high rate of 20 C, the electrode displays a high capacity retention of 84% after 3000 cycles and a long cycle life of 10 000 cycles. This work provides a deep insight into the construction of electrodes with high ionic/electronic conductivity for fast-charging energy storage devices.

Ultrathin, ultralight dual-scale fibrous networks with high-infrared transmittance for high-performance, comfortable and sustainable PM0.3 filter.

Highly permeable particulate matter (PM) can carry various bacteria, viruses and toxics and pose a serious threat to public health. Nevertheless, current respirators typically sacrifice their thickness and base weight for high-performance filtration, which inevitably causes wearing discomfort and significant consumption of raw materials. Here, we show a facile yet massive splitting eletrospinning strategy to prepare an ultrathin, ultralight and radiative cooling dual-scale fiber membrane with about 80% infrared transmittance for high-protective, comfortable and sustainable air filter. By tailoring antibacterial surfactant-triggered splitting of charged jets, the dual-scale fibrous filter consisting of continuous nanofibers (44 ± 12 nm) and submicron-fibers (159 ± 32 nm) is formed. It presents ultralow thickness (1.49 µm) and base weight (0.57 g m-2) but superior protective performances (about 99.95% PM0.3 removal, durable antibacterial ability) and wearing comfort of low air resistance, high heat dissipation and moisture permeability. Moreover, the ultralight filter can save over 97% polymers than commercial N95 respirator, enabling itself to be sustainable and economical. This work paves the way for designing advanced and sustainable protective materials.

A Robust Biomimetic Superhydrophobic Coating with Superior Mechanical Durability and Chemical Stability for Inner Pipeline Protection.

Durable superhydrophobic anti-erosion/anticorrosion coatings are highly demanded across various applications. However, achieving coatings with exceptional superhydrophobicity, mechanical strength, and corrosion resistance remains a grand challenge. Herein, a robust microstructure coating, inspired by the cylindrical structures situated on the surface of conch shell, for mitigating erosion and corrosion damages in gas transportation pipelines is reported. Specifically, citric acid monohydrate as a pore-forming agent is leveraged to create a porous structure between layers, effectively buffering the impact on the surface. As a result, the coating demonstrates remarkable wear resistance and water repellency. Importantly, even after abrasion by sandpaper and an erosion loop test, the resulting superhydrophobic surfaces retain the water repellency. The design strategy offers a promising route to manufacturing multifunctional materials with desired features and structural complexities, thereby enabling effective self-cleaning and antifouling abilities in harsh operating environments for an array of applications, including self-cleaning windows, antifouling coatings for medical devices, and anti-erosion/anticorrosion protection, among other areas.

Bioinspired patterning with extreme wettability contrast on TiO2 nanotube array surface: a versatile platform for biomedical applications.

Binary wettability patterned surfaces with extremely high wetting contrasts can be found in nature on living creatures. They offer a versatile platform for microfluidic management. In this work, a facile approach to fabricating erasable and rewritable surface patterns with extreme wettability contrasts (superhydrophilic/superhydrophobic) on a TiO2 nanotube array (TNA) surface through self-assembly and photocatalytic lithography is reported. The multifunctional micropatterned superhydrophobic TNA surface can act as a 2D scaffold for site-selective cell immobilization and reversible protein absorption. Most importantly, such a high-contrast wettability template can be used to construct various well-defined 3D functional patterns, such as calcium phosphate, silver nanoparticles, drugs, and biomolecules in a highly selective manner. The 3D functional patterns would be a versatile platform in a wide range of applications, especially for biomedical devices (e.g., high-throughput molecular sensing, targeted antibacterials, and drug delivery). In a proof-of-concept study, the surface-enhanced Raman scattering and antibacterial performance of the fabricated 3D AgNP@TNA pattern, and the targeted drug delivery for site-specific and high-sensitivity cancer cell assays was investigated.

Iron-optimized oxygen vacancy concentration to strengthen the electrocatalytic ability of the urea oxidation reaction.

Iron-modified Ni(OH)2/NiSe2 enhances oxygen vacancies, expanding the electrochemically active surface area, which exhibiting superior selectivity and stability in urea oxidation reaction, outperforming pristine Ni(OH)2@NiSe2. It also demonstrates superior catalytic performance in the oxidation reactions of other small molecules.

Development of an asymmetric composite PPS-based bag-filter material through membrane laminating and superfine fiber blending: Lab test, field application and development of numerical models.

Dedusting is crucial for air pollution control, and nonwoven needle felt (NWNF) bag-filters are widely applied for this purpose. Surface treatment of the filter materials can enhance NWNF's performance, but the large discrepancy in pore size between the surface and NWNF layers causes interface effects, impairing reverse cleaning and shortening service life. In this study, a novel PTFE membrane-laminated asymmetrical composite bag-filter was developed, by blending superfine polyphenylene sulfide fiber (PPS) in the original NWNF structure. Image analysis shows a gradual increase in pore size from the surface to the downstream layer. In standard lab-scale tests, the novel M-PPSF-S filter showed moderately higher resistance, significantly longer service life, higher dedusting efficiencies and better cleaning performance, compared to filters without surface laminating and/or superfine fiber blending. Numerical modelling was performed, and the flow fields and pressure distribution in these filter materials were visualized, confirming that M-PPSF-S' unique structure facilitated the alleviation of interface effect and non-steady flow. M-PPSF-S was further scaled up to treat real flue gas from a coal-fired power plant, where constant good performance was observed over 5 months. This study offers a novel and practical way to develop low-cost, high-performance filter materials for high temperature flue gas treatment.