Ginkgo seed shell provides a unique model for bioinspired design.

Natural structural materials typically feature complex hierarchical anisotropic architectures, resulting in excellent damage tolerance. Such highly anisotropic structures, however, also provide an easy path for crack propagation, often leading to catastrophic fracture as evidenced, for example, by wood splitting. Here, we describe the weakly anisotropic structure of Ginkgo biloba (ginkgo) seed shell, which has excellent crack resistance in different directions. Ginkgo seed shell is composed of tightly packed polygonal sclereids with cell walls in which the cellulose microfibrils are oriented in a helicoidal pattern. We found that the sclereids contain distinct pits, special fine tubes like a "screw fastener," that interlock the helicoidal cell walls together. As a result, ginkgo seed shell demonstrates crack resistance in all directions, exhibiting specific fracture toughness that can rival other highly anisotropic natural materials, such as wood, bone, insect cuticle, and nacre. In situ characterization reveals ginkgo's unique toughening mechanism: pit-guided crack propagation. This mechanism forces the crack to depart from the weak compound middle lamella and enter into the sclereid, where the helicoidal cell wall significantly inhibits crack growth by the cleavage and breakage of the fibril-based cell walls. Ginkgo's toughening mechanism could provide guidelines for a new bioinspired strategy for the design of high-performance bulk materials.

Flexible and Highly Conductive Textiles Induced by Click Chemistry for Sensitive Motion and Humidity Monitoring.

To date, multifunctional sensors have aroused widespread concerns owing to their vital roles in the healthcare area. However, there are still significant challenges in the fabrication of functionalized integrated devices. In this work, hydrophobic-hydrophilic patterns are constructed on polyester-spandex-blended knitted fabric surface by the chemical click method, enabling accurate deposition of functionalized materials for sensitive and stable motion and humidity sensing. Representatively, a conductive silver nanowire (Ag NW) network was deliberately deposited on only the designated hydrophilic fabric surface to realize accurate, repeatable, and stable motion sensing. Such a Ag NWs sensor recorded a low electrical resistance (below 60 Ω), stable resistance cycling response (over 2000 cycles), and fast response time to humidity (0.46 s) during the sensing evaluation. In addition to experimental sensing, real human motions, such as mouth-opening and joint-flexing (wrist and neck), could also be detected using the same sensor. Similar promising outputs were also obtained over the humidity sensor fabricated over the same chemical click method, except the sensing material was replaced with polydopamine-modified carboxylated carbon nanotubes. The resultant sensor exhibits excellent sensitivity to not only experimentally adjusted environment humidity but also to the moisture content of breath and skin during daily activities. On top of all these, both sensors were fabricated over highly flexible fabric that offers high wearability, promising great application potential in the field of healthcare monitoring.

Smart surfaces with reversibly switchable wettability: Concepts, synthesis and applications.

As a growing hot research topic, manufacturing smart switchable surfaces has attracted much attention in the past a few years. The state-of-the-art study on reversibly switchable wettability of smart surfaces has been presented in this systematic review. External stimuli are brought about to render the alteration in chemical conformation and surface morphology to drive the wettability switch. Here, starting from the fundamental theories related to the surfaces wetting principles, highlights on different triggers for switchable wettability, such as pH, light, ions, temperature, electric field, gas, mechanical force, and multi-stimuli are discussed. Different applications that have various wettability requirement are targeted, including oil-water separation, droplets manipulation, patterning, liquid transport, and so on. This review aims to provide a deep insight into responsive interfacial science and offer guidance for smart surface engineering. It ends with a summary of current challenges, future opportunities, and potential solutions on smart switch of wettability on superwetting surfaces.

Commercialization-Driven Electrodes Design for Lithium Batteries: Basic Guidance, Opportunities, and Perspectives.

Current lithium-ion battery technology is approaching the theoretical energy density limitation, which is challenged by the increasing requirements of ever-growing energy storage market of electric vehicles, hybrid electric vehicles, and portable electronic devices. Although great progresses are made on tailoring the electrode materials from methodology to mechanism to meet the practical demands, sluggish mass transport, and charge transfer dynamics are the main bottlenecks when increasing the areal/volumetric loading multiple times to commercial level. Thus, this review presents the state-of-the-art developments on rational design of the commercialization-driven electrodes for lithium batteries. First, the basic guidance and challenges (such as electrode mechanical instability, sluggish charge diffusion, deteriorated performance, and safety concerns) on constructing the industry-required high mass loading electrodes toward commercialization are discussed. Second, the corresponding design strategies on cathode/anode electrode materials with high mass loading are proposed to overcome these challenges without compromising energy density and cycling durability, including electrode architecture, integrated configuration, interface engineering, mechanical compression, and Li metal protection. Finally, the future trends and perspectives on commercialization-driven electrodes are offered. These design principles and potential strategies are also promising to be applied in other energy storage and conversion systems, such as supercapacitors, and other metal-ion batteries.

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.

Transparent Antibacterial Nanofiber Air Filters with Highly Efficient Moisture Resistance for Sustainable Particulate Matter Capture.

Particulate matter (PM) pollution has posed great threat to human health. This calls for versatile protection or treatment devices that are both efficient and easy to use. Herein, we have rationally designed a novel reusable bilayer fibrous filter consisting of electrospun superhydrophobic poly(methylmethacrylate)/polydimethylsiloxane fibers as the barrier for moisture ingression and superhydrophilic chitosan fibers for a PM capture efficiency of over 96% at optical transmittance of 86%. Furthermore, it could realize a high-level PM2.5 capture efficiency (>98.23%) even after 100-h test during extremely hazardous air environment (PM2.5 > 3,000 µg m-3) and retain a high PM removal efficiency (PM2.5 > 98.39%) after five washing cycles. Besides, such membranes possessed high antibacterial activity at 96.5% for E. coli and 95.2% for Staphylococcus aureus. As a proof-of-concept study, continuous particle removing has been successfully demonstrated on a window screen to prevent particle pollution.

Particulate Matter Capturing via Naturally Dried ZIF-8/Graphene Aerogels under Harsh Conditions.

Particulate matter (PM) pollution poses a serious threat to the environment and public health. Capture of PM is best performed at the emission source, such as car exhaust exit points, although it is a challenge for filters to work under harsh conditions of high temperatures and flow rate. Here we designed a thermally stable PM filter by in situ anchoring of zeolite imidazole framework-8 (ZIF-8) on a three-dimensional (3D) network of reduced graphene oxide aerogel (rGA) through natural drying. Owing to high specific surface area, well-connected porous network of graphene aerogel, and large number of metal sites from ZIF-8/rGA, the capture efficiencies for PM2.5 and PM10 are over 99.3% and 99.6%, respectively, at ambient conditions, and the efficiencies remain high in harsh conditions (PM2.5 and PM10: >98.8% and >99.1%, respectively, at 200°C at a flow velocity of 30 L/min). The filter can be regenerated by a simple washing process.

Rapid and Controllable Design of Robust Superwettable Microchips by a Click Reaction for Efficient o-Phthalaldehyde and Glucose Detection.

Superwettable patterns with superhydrophobic and superhydrophilic units have the capacity of enriching and absorbing microdroplets for multifunctional biosensing. Combining the advantages of superwettable micropatterns and a rapid click reaction, we first prepared a film using propargyl methacrylate-ethylene dimethacrylate and then created a superhydrophobic-superhydrophilic micropattern by a rapid thiol-yne click reaction. Due to the high wettability contrast, water droplets tend to be anchored in the superhydrophilic region. Molecules dissolved in a water droplet are therefore uniformly enriched in the superhydrophilic region after evaporation because of the Malangoni effect. This provides a rational strategy to develop novel patterned microchips for sensing applications. Combining with fluorescence imaging technology, the Ti superwettable microchip can be used to detect o-phthalaldehyde in water, with a detection limit as low as 10-7 mol L-1. In addition, taking advantage of the oxidative color rendering ability of glucose, the microchip, when fabricated on a glass substrate, can realize reuseable glucose detection with a detection limit of 2 mM within 15 min.

In vivo and in vitro efficient textile wastewater remediation by Aspergillus niger biosorbent.

In this work, the treatment of textile wastewater by a facile and high-efficiency technology using eco-friendly Aspergillus niger as a biosorbent was investigated. We measured physical changes (weight, size) during the formation and growth of fungus pellets and the pH values that influence the adsorption performance and biosorption mechanism. Three acid anionic dyes containing Acid Orange 56, Acid Blue 40 and Methyl Blue were chosen as model dyes to investigate batch adsorption efficiency. Two adsorption models (in vivo and in vitro) were adopted to decolorize the acid dyes. The results show that fungus pellets have excellent decoloration abilities with a high adsorption efficiency of 98% for 200 mg L-1 of acid dye. The pH value of the dye solution varied with the adsorption time and the dye removal efficiency greatly depended on the pH. The bioadsorption mechanism of nano-scale hyphae was revealed to be mainly due to electrostatic interactions caused by the pH change. Furthermore, the surface morphologies of the fungus after adsorption indicated that the dyes had been adsorbed on the surface of the fungus mycelia. Moreover, prepared 3D fungus/GO aerogels demonstrated superior dye removal abilities compared with fungus aerogels.

Recent Progress in Fabrication and Applications of Superhydrophobic Coating on Cellulose-Based Substrates.

Multifuntional fabrics with special wettability have attracted a lot of interest in both fundamental research and industry applications over the last two decades. In this review, recent progress of various kinds of approaches and strategies to construct super-antiwetting coating on cellulose-based substrates (fabrics and paper) has been discussed in detail. We focus on the significant applications related to artificial superhydrophobic fabrics with special wettability and controllable adhesion, e.g., oil-water separation, self-cleaning, asymmetric/anisotropic wetting for microfluidic manipulation, air/liquid directional gating, and micro-template for patterning. In addition to the anti-wetting properties and promising applications, particular attention is paid to coating durability and other incorporated functionalities, e.g., air permeability, UV-shielding, photocatalytic self-cleaning, self-healing and patterned antiwetting properties. Finally, the existing difficulties and future prospects of this traditional and developing field are briefly proposed and discussed.