Bioinspired 2D Nanomaterials for Sustainable Applications

Zn-ion ultrafluidity via bioinspired ion channel for ultralong lifespan Zn-ion battery

Rechargeable aqueous Zn-ion batteries have been deemed a promising energy storage device. However, the dendrite growth and side reactions have hindered their practical application. Herein, inspired by the ultrafluidic and K+ ion-sieving flux through enzyme-gated potassium channels (KcsA) in biological plasma membranes, a metal-organic-framework (MOF-5) grafted with -ClO4 groups (MOF-ClO4) as functional enzymes is fabricated to mimic the ultrafluidic lipid-bilayer structure for gating Zn2+ 'on' and anions 'off' states. The MOF-ClO4 achieved perfect Zn2+/SO4 2- selectivity (∼10), enhanced Zn2+ transfer number ([Formula: see text]) and the ultrafluidic Zn2+ flux (1.9 × 10-3 vs. 1.67 mmol m-2 s-1 for KcsA). The symmetric cells based on MOF-ClO4 achieve a lifespan of over 5400 h at 10 mA cm-2/20 mAh cm-2. Specifically, the performance of the PMCl-Zn//V2O5 pouch cell keeps 81% capacity after 2000 cycles at 1 A g-1. The regulated ion transport, by learning from a biological plasma membrane, opens a new avenue towards ultralong lifespan aqueous batteries.

Advancements in Functional Nanomaterials Inspired by Viral Particles

Virus-like particles (VLPs) are nanostructures composed of one or more structural proteins, exhibiting stable and symmetrical structures. Their precise compositions and dimensions provide versatile opportunities for modifications, enhancing their functionality. Consequently, VLP-based nanomaterials have gained widespread adoption across diverse domains. This review focuses on three key aspects: the mechanisms of viral capsid protein self-assembly into VLPs, design methods for constructing multifunctional VLPs, and strategies for synthesizing multidimensional nanomaterials using VLPs. It provides a comprehensive overview of the advancements in virus-inspired functional nanomaterials, encompassing VLP assembly, functionalization, and the synthesis of multidimensional nanomaterials. Additionally, this review explores future directions, opportunities, and challenges in the field of VLP-based nanomaterials, aiming to shed light on potential advancements and prospects in this exciting area of research.

BioinspiredLLM: Conversational Large Language Model for the Mechanics of Biological and Bio-Inspired Materials

The study of biological materials and bio-inspired materials science is well established; however, surprisingly little knowledge is systematically translated to engineering solutions. To accelerate discovery and guide insights, an open-source autoregressive transformer large language model (LLM), BioinspiredLLM, is reported. The model is finetuned with a corpus of over a thousand peer-reviewed articles in the field of structural biological and bio-inspired materials and can be prompted to recall information, assist with research tasks, and function as an engine for creativity. The model has proven that it is able to accurately recall information about biological materials and is further strengthened with enhanced reasoning ability, as well as with Retrieval-Augmented Generation (RAG) to incorporate new data during generation that can also help to traceback sources, update the knowledge base, and connect knowledge domains. BioinspiredLLM also has shown to develop sound hypotheses regarding biological materials design and remarkably so for materials that have never been explicitly studied before. Lastly, the model shows impressive promise in collaborating with other generative artificial intelligence models in a workflow that can reshape the traditional materials design process. This collaborative generative artificial intelligence method can stimulate and enhance bio-inspired materials design workflows. Biological materials are at a critical intersection of multiple scientific fields and models like BioinspiredLLM help to connect knowledge domains.

Atomically Substitutional Engineering of Transition Metal Dichalcogenide Layers for Enhancing Tailored Properties and Superior Applications

Transition metal dichalcogenides (TMDs) are a promising class of layered materials in the post-graphene era, with extensive research attention due to their diverse alternative elements and fascinating semiconductor behavior. Binary MX2 layers with different metal and/or chalcogen elements have similar structural parameters but varied optoelectronic properties, providing opportunities for atomically substitutional engineering via partial alteration of metal or/and chalcogenide atoms to produce ternary or quaternary TMDs. The resulting multinary TMD layers still maintain structural integrity and homogeneity while achieving tunable (opto)electronic properties across a full range of composition with arbitrary ratios of introduced metal or chalcogen to original counterparts (0-100%). Atomic substitution in TMD layers offers new adjustable degrees of freedom for tailoring crystal phase, band alignment/structure, carrier density, and surface reactive activity, enabling novel and promising applications. This review comprehensively elaborates on atomically substitutional engineering in TMD layers, including theoretical foundations, synthetic strategies, tailored properties, and superior applications. The emerging type of ternary TMDs, Janus TMDs, is presented specifically to highlight their typical compounds, fabrication methods, and potential applications. Finally, opportunities and challenges for further development of multinary TMDs are envisioned to expedite the evolution of this pivotal field.

Precise Control of Two-Dimensional Hexagonal Platelets via Scalable, One-Pot Assembly Pathways Using Block Copolymers with Crystalline Side Chains

Crystallization-driven self-assembly (CDSA) of block copolymers (BCPs) in selective solvents provides a promising route for direct access to two-dimensional (2D) platelet micelles with excellent uniformity, although significant limitations also exist for this robust approach, such as tedious, multistep procedures, and low yield of assembled materials. Herein, we report a facile strategy for massively preparing 2D, highly symmetric hexagonal platelets with precise control over their dimensions based on BCPs with crystalline side chains. Mechanistic studies unveiled that the formation of hexagonal platelets was subjected to a hierarchical self-assembly process, involving an initial stage of formation of kinetically trapped spheres upon cooling driven by solvophobic interactions, and a second stage of fusion of such spheres to the 2D nuclei to initiate the lateral growth of hexagonal platelets via sequential particle attachments driven by thermodynamically ordered reorganization of the BCP upon aging. Moreover, the size of the developed 2D hexagonal platelets could be finely regulated by altering the copolymer concentration over a broad concentration range, enabling scale-up to a total solids concentration of at least 6% w/w. Our work reveals a new mechanism to create uniform 2D core-shell nanoparticles dictated by crystallization and particle fusion, while it also provides an alternative facile strategy for the design of soft materials with precise control of their dimensions, as well as for the scalability of the derived nanostructures.

Bio-Inspired Nanomaterials for Micro/Nanodevices: A New Era in Biomedical Applications

Exploring bio-inspired nanomaterials (BINMs) and incorporating them into micro/nanodevices represent a significant development in biomedical applications. Nanomaterials, engineered to imitate biological structures and processes, exhibit distinctive attributes such as exceptional biocompatibility, multifunctionality, and unparalleled versatility. The utilization of BINMs demonstrates significant potential in diverse domains of biomedical micro/nanodevices, encompassing biosensors, targeted drug delivery systems, and advanced tissue engineering constructs. This article thoroughly examines the development and distinctive attributes of various BINMs, including those originating from proteins, DNA, and biomimetic polymers. Significant attention is directed toward incorporating these entities into micro/nanodevices and the subsequent biomedical ramifications that arise. This review explores biomimicry's structure-function correlations. Synthesis mosaics include bioprocesses, biomolecules, and natural structures. These nanomaterials' interfaces use biomimetic functionalization and geometric adaptations, transforming drug delivery, nanobiosensing, bio-inspired organ-on-chip systems, cancer-on-chip models, wound healing dressing mats, and antimicrobial surfaces. It provides an in-depth analysis of the existing challenges and proposes prospective strategies to improve the efficiency, performance, and reliability of these devices. Furthermore, this study offers a forward-thinking viewpoint highlighting potential avenues for future exploration and advancement. The objective is to effectively utilize and maximize the application of BINMs in the progression of biomedical micro/nanodevices, thereby propelling this rapidly developing field toward its promising future.

Core-Shell Structured Fluorescent Protein Nanoparticles: New Paradigm Toward Zero-Thermal-Quenching in High-Power Biohybrid Light-Emitting Diodes

Stable and efficient high-power biohybrid light-emitting diodes (Bio-HLEDs) using fluorescent proteins (FPs) in photon downconverting filters have not been achieved yet, reaching best efficiencies of 130 lm W^-1 stable for >5 h. This is related to the rise of the device temperature (70-80 °C) caused by FP-motion and quick heat-transmission in water-based filters, they lead to a strong thermal emission quenching followed by the quick chromophore deactivation via photoinduced H-transfer. To tackle both issues at once, this work shows an elegant concept of a new FP-based nanoparticle, in which the FP core is shielded by a SiO₂ -shell (FP@SiO₂ ) with no loss of the photoluminescence figures-of-merit over years in foreign environments: dry powder at 25 °C (ambient) or constant 50 °C, as well as suspensions in organic solvents. This enables the preparation of water-free photon downconverting coatings with FP@SiO₂ , realizing on-chip high-power Bio-HLEDs with 100 lm W^-1 stable for >120 h. Both thermal emission quenching and H-transfer deactivation are suppressed, since the device temperature holds <40 °C and remote high-power Bio-HLEDs exhibit final stabilities of 130 days compared to reference devices with water-based FP@SiO₂ (83 days) and FP-polymer coatings (>100 h). Hence, FP@SiO₂ is a new paradigm toward water-free zero-thermal-quenching biophosphors for first-class high-power Bio-HLEDs.

Synthesis and Application of Liquid Metal Based-2D Nanomaterials: A Perspective View for Sustainable Energy

With the continuous exploration of low-dimensional nanomaterials, two dimensional metal oxides (2DMOs) has been received great interest. However, their further development is limited by the high cost in the preparation process and the unstable states caused by the polarization of surface chemical bonds. Recently, obtaining mental oxides via liquid metals have been considered a surprising method for obtaining 2DMOs. Therefore, how to scientifically choose different preparation methods to obtain 2DMOs applying in different application scenarios is an ongoing process worth discussing. This review will provide some new opportunities for the rational design of 2DMOs based on liquid metals. Firstly, the surface oxidation process and in situ electrical replacement reaction process of liquid metals are introduced in detail, which provides theoretical basis for realizing functional 2DMOs. Secondly, by simple sticking method, gas injection method and ultrasonic method, 2DMOs can be obtained from liquid metal, the characteristics of each method are introduced in detail. Then, this review provides some prospective new ideas for 2DMOs in other energy-related applications such as photodegradation, CO₂ reduction and battery applications. Finally, the present challenges and future development prospects of 2DMOs applied in liquid metals are presented.

Heterostructure Engineering of 2D Superlattice Materials for Electrocatalysis

Exploring low-cost and high-efficient electrocatalyst is an exigent task in developing novel sustainable energy conversion systems, such as fuel cells and electrocatalytic fuel generations. 2D materials, specifically 2D superlattice materials focused here, featured highly accessible active areas, high density of active sites, and high compatibility with property-complementary materials to form heterostructures with desired synergetic effects, have demonstrated to be promising electrocatalysts for boosting the performance of sustainable energy conversion and storage devices. Nevertheless, the reaction kinetics, and in particular, the functional mechanisms of the 2D superlattice-based catalysts yet remain ambiguous. In this review, based on the recent progress of 2D superlattice materials in electrocatalysis applications, the rational design and fabrication of 2D superlattices are first summarized and the application of 2D superlattices in electrocatalysis is then specifically discussed. Finally, perspectives on the current challenges and the strategies for the future design of 2D superlattice materials are outlined. This review attempts to establish an intrinsic correlation between the 2D superlattice heterostructures and the catalytic properties, so as to provide some insights into developing high-performance electrocatalysts for next-generation sustainable energy conversion and storage.

Nanostructures for the Prevention, Diagnosis, and Treatment of SARS-CoV-2: A Review

Scientists, doctors, engineers, and even entire societies have become aware of the seriousness of the COVID-19 infection and are taking action quickly, using all the tools from protection to treatment against coronavirus SARS-CoV-2. Especially in this sense, scientific approaches and materials using nanotechnology are frequently preferred. In this review, we focus on how nanoscience and nanotechnology approaches can be used for protective equipment, diagnostic and treatment methods, medicine, and vaccine applications to stop the coronavirus SARS-CoV-2 and prevent its spread. SARS-CoV-2, which itself can be considered as a core-shell nanoparticle, can interact with various materials around it and remain bound for variable periods of time while maintaining its bioactivity. These applications are especially critical for the controlled use of disinfection systems. One of the most important processes in the fight against coronavirus is the rapid diagnosis of the virus in humans and the initiation of isolation and treatment processes. The development of nanotechnology-based test and diagnostic kits is another important research thrust. Nanotechnological therapeutics based on antiviral drug design and nanoarchitecture vaccines have been vital. Nanotechnology plays critical roles in the production of protective film surfaces for self-cleaning and antiviral masks, gloves, and laboratory clothes. An overview of literature studies highlighting nanotechnology and nanomaterial-based approaches to combat SARS-CoV-2 is presented.

Cobalt silicate: critical synthetic conditions affect its electrochemical properties for energy storage and conversion

Cobalt silicate (CoSi) is a promising electrode material for supercapacitors (SCs) and an electrocatalytic material for the oxygen evolution reaction (OER). How to synthesize cobalt silicate with excellent energy storage and OER properties has not been reported and it is a great challenge for researchers to accomplish it. In this work, we find that the electrochemical properties of CoSi are particularly affected by critical factors during the synthesis process. Three types of CoSi compounds are synthesized using Stöber SiO₂ as the self-sacrificing template via a hydrothermal reaction. The CoSi compounds generated from different reaction systems have obvious differences in the macrostate, microscopic morphology, composition and valence, leading to different electrochemical performances for energy storage and OER properties. The findings reveal that the differences (especially valence) among CoSi are determined by the formation of the metal source in the reaction system. The specific capacitance of CoSi-3 obtained from the system with basic salts as the metal source is eight times higher than that of CoSi-1 obtained from the system with coordination compounds as the metal source, whereas CoSi-1 has a greater advantage in electrocatalytic activity. This work provides insight for the synthesis of cobalt silicates applied to energy storage and conversion.

Bioinspired Materials for Energy Storage

Nature offers a variety of interesting structures and intriguing functions for researchers to be learnt for advanced materials innovations. Recently, bioinspired materials have received intensive attention in energy storage applications. Inspired by various natural species, many new configurations and components of energy storage devices, such as rechargeable batteries and supercapacitors, have been designed and innovated. The bioinspired designs on energy devices, such as electrodes and electrolytes, have brought about excellent physical, chemical, and mechanical properties compared to the counterparts at their conventional forms. In this review, the design principles for bioinspired materials ranging from structures, synthesis, and functionalization to multi-scale ordering and device integration are first discussed, and then a brief summary is given on the recent progress on bioinspired materials for energy storage systems, particularly the widely studied rechargeable batteries and supercapacitors. Finally, a critical review on the current challenges and brief perspective on the future research focuses are proposed. It is expected that this review can offer some insights into the smart energy storage system design by learning from nature.

Ferrocene-Functionalized Crystalline Biomimetic Catalysts for Efficient CO2 Photoreduction

Photoreducing carbon dioxide (CO2) into highly valued chemicals or energy products has been recognized as one of the most promising proposals to degrade atmospheric CO2 concentration and achieve carbon neutrality. Adenine with a photosensitive amino group and aromatic nitrogen atom can strongly interact with CO2 and has been authenticated for its catalytic activity for the CO2 photoreduction reaction (CO2RR). Herein, two adenine-constructed crystalline biomimetic photocatalysts (Co2-AW and Co2-AF) were designed and synthesized to achieve CO2RR. Between them, Co2-AF displayed higher photocatalytic activity (225.8 μmol g-1 h-1) for CO2-to-HCOOH conversion than that of Co2-AW. It was found that the superior charge transfer capacity of the functional ferrocene group in Co2-AF is the primary reason to facilitate the photocatalytic performance efficiently. Additionally, this work also demonstrated the great potential of the ferrocene group as an electron donor and mediator in improving the photocatalytic activity of crystalline coordination catalysts.

Solid-State Preparation of Metal and Metal Oxides Nanostructures and Their Application in Environmental Remediation

Nanomaterials have attracted much attention over the last decades due to their very different properties compared to those of bulk equivalents, such as a large surface-to-volume ratio, the size-dependent optical, physical, and magnetic properties. A number of solution fabrication methods have been developed for the synthesis of metal and metal oxides nanoparticles, but few solid-state methods have been reported. The application of nanostructured materials to electronic solid-state devices or to high-temperature technology requires, however, adequate solid-state methods for obtaining nanostructured materials. In this review, we discuss some of the main current methods of obtaining nanomaterials in solid state, and also we summarize the obtaining of nanomaterials using a new general method in solid state. This new solid-state method to prepare metals and metallic oxides nanostructures start with the preparation of the macromolecular complexes chitosan·Xn and PS-co-4-PVP·MXn as precursors (X = anion accompanying the cationic metal, n = is the subscript, which indicates the number of anions in the formula of the metal salt and PS-co-4-PVP = poly(styrene-co-4-vinylpyridine)). Then, the solid-state pyrolysis under air and at 800 °C affords nanoparticles of M°, M_xO_y depending on the nature of the metal. Metallic nanoparticles are obtained for noble metals such as Au, while the respective metal oxide is obtained for transition, representative, and lanthanide metals. Size and morphology depend on the nature of the polymer as well as on the spacing of the metals within the polymeric chain. Noticeably in the case of TiO₂, anatase or rutile phases can be tuned by the nature of the Ti salts coordinated in the macromolecular polymer. A mechanism for the formation of nanoparticles is outlined on the basis of TG/DSC data. Some applications such as photocatalytic degradation of methylene by different metal oxides obtained by the presented solid-state method are also described. A brief review of the main solid-state methods to prepare nanoparticles is also outlined in the introduction. Some challenges to further development of these materials and methods are finally discussed.

Soft Bioelectronics Based on Nanomaterials

Recent advances in nanostructured materials and unconventional device designs have transformed the bioelectronics from a rigid and bulky form into a soft and ultrathin form and brought enormous advantages to the bioelectronics. For example, mechanical deformability of the soft bioelectronics and thus its conformal contact onto soft curved organs such as brain, heart, and skin have allowed researchers to measure high-quality biosignals, deliver real-time feedback treatments, and lower long-term side-effects in vivo. Here, we review various materials, fabrication methods, and device strategies for flexible and stretchable electronics, especially focusing on soft biointegrated electronics using nanomaterials and their composites. First, we summarize top-down material processing and bottom-up synthesis methods of various nanomaterials. Next, we discuss state-of-the-art technologies for intrinsically stretchable nanocomposites composed of nanostructured materials incorporated in elastomers or hydrogels. We also briefly discuss unconventional device design strategies for soft bioelectronics. Then individual device components for soft bioelectronics, such as biosensing, data storage, display, therapeutic stimulation, and power supply devices, are introduced. Afterward, representative application examples of the soft bioelectronics are described. A brief summary with a discussion on remaining challenges concludes the review.

Crystal Channel Engineering for Rapid Ion Transport: From Nature to Batteries

Ion transport behaviours through cell membranes are commonly identified in biological systems, which are crucial for sustaining life for organisms. Similarly, ion transport is significant for electrochemical ion storage in rechargeable batteries, which has attracted much attention in recent years. Rapid ion transport can be well achieved by crystal channels engineering, such as creating pores or tailoring interlayer spacing down to the nanometre or even sub-nanometre scale. Furthermore, some functional channels, such as ion selective channels and stimulus-responsive channels, are developed for smart ion storage applications. In this review, the typical ion transport phenomena in the biological systems, including ion channels and pumps, are first introduced, and then ion transport mechanisms in solid and liquid crystals are comprehensively reviewed, particularly for the widely studied porous inorganic/organic hybrid crystals and ultrathin inorganic materials. Subsequently, recent progress on the ion transport properties in electrodes and electrolytes is reviewed for rechargeable batteries. Finally, current challenges in the ion transport behaviours in rechargeable batteries are analysed and some potential research approaches, such as bioinspired ultrafast ion transport structures and membranes, are proposed for future studies. It is expected that this review can give a comprehensive understanding on the ion transport mechanisms within crystals and provide some novel design concepts on promoting electrochemical ion storage capability in rechargeable batteries.

Biodegradable and Excretable 2D W1.33 C i-MXene with Vacancy Ordering for Theory-Oriented Cancer Nanotheranostics in Near-Infrared Biowindow

MXenes, a new class of two-dimensional (2D) nanomaterials, have shown enormous potential for biological applications. Notably, the development of 2D MXenes in nanomedicine is still in its infancy. Herein, a distinct W1.33 C i-MXene with multiple theranostic functionalities, fast biodegradation, and satisfactory biocompatibility is explored. By designing a parent bulk laminate in-plane ordered (W2/3 Y1/3 )2 AlC ceramic and optionally etching aluminum (Al) and yttrium (Y) elements, 2D W1.33 C i-MXene nanosheets with ordered divacancies are efficiently fabricated. Especially, theoretical simulations reveal that W1.33 C i-MXene possesses a strong predominance of near-infrared (NIR) absorbance. The constructed ultrathin W1.33 C nanosheets feature excellent photothermal-conversion effectiveness (32.5% at NIR I and 49.3% at NIR II) with desirable biocompatibility and fast degradation in normal tissue rather than in tumor tissue. Importantly, the multimodal-imaging properties and photothermal-ablation performance of W1.33 C-BSA nanosheets are systematically revealed and demonstrated both in vitro and in vivo. The underlying mechanism and regulation factors for the W1.33 C-BSA nanosheets-induced hyperthermia ablation are also revealed by transcriptome and proteome sequencing. This work offers a paradigm that i-MXenes achieve the tailoring biomedical applications through composition and structure design on the atomic scale.

Liquid-Based Adaptive Structural Materials

Structural materials are used to provide stable mechanical architectures and transmit or support forces, and they play an important role in materials science and technology. During the long process of the exploitation of structural materials, the functionality of structural materials has gained prominence. Adaptive structures responding to external stimuli have come to the fore with significant advantages in structural materials. However, many solid adaptive structural materials still suffer from their single function and the lack of dynamic performance, such as issue around fouling and energy consumption, defects present everywhere in materials at the microscale, etc. To meet the increasing demands, more and more researchers have started turning their attention to liquid-based materials owing to their intrinsic spontaneous, dynamic, and functional properties. Liquid-based adaptive structural materials (LASMs) have been proposed and developed. Building upon both dynamic liquids and fixed solids, LASMs have been demonstrated to possess both dynamic adaptivity (from the active liquid part) and stable mechanical structure (from the fixed solid part), which are desired in many applications such as 3D printing, droplet manipulation, omniphobic surfaces, microfluidics, mass separation, etc. A unifying view of the recent progress of LASMs is presented, including liquid with particles, liquid with surfaces, as well as liquid with membranes. In addition, the discussion of the prospects and challenges are provided for promoting the development of LASMs.

Fabrication of Smart Tantalum Carbide MXene Quantum Dots with Intrinsic Immunomodulatory Properties for Treatment of Allograft Vasculopathy

MXene nanomaterials have sparked significant interest among interdisciplinary researchers to tackle today's medical challenges. In particular, colloidal MXene quantum dots (MQDs) offer the high specific surface area and compositional flexibility of MXene while providing improvements to aqueous stability and material-cell interactions. The current study for the first time reports the development and application of immunoengineered tantalum-carbide (Ta4C3T x ) MQDs for in vivo treatment of transplant vasculopathy. This report comes at a critical juncture in the field as poor long-term safety of other MXene compositions challenge the eventual clinical translatability of these materials. Using rational design and synthesis strategies, the Ta4C3T x MQDs leverage the intrinsic anti-inflammatory and antiapoptotic properties of tantalum to provide a novel nanoplatform for biomedical engineering. In particular, these MQDs are synthesized with high efficiency and purity using a facile hydrofluoric acid-free protocol and are enriched with different bioactive functional groups and stable surface TaO2 and Ta2O5. Furthermore, MQDs are spontaneously uptaken into antigen-presenting endothelial cells and alter surface receptor expression to reduce their activation of allogeneic T-lymphocytes. Finally, when applied in vivo, Ta4C3T x MQDs ameliorate the cellular and structural changes of early allograft vasculopathy. These findings highlight the robust potential of tailored Ta4C3T x MQDs for future applications in medicine.

Synergetic Advantages of Atomically Coupled 2D Inorganic and Graphene Nanosheets as Versatile Building Blocks for Diverse Functional Nanohybrids

2D nanostructured materials, including inorganic and graphene nanosheets, have evoked plenty of scientific research activity due to their intriguing properties and excellent functionalities. The complementary advantages and common 2D crystal shapes of inorganic and graphene nanosheets render their homogenous mixtures powerful building blocks for novel high-performance functional hybrid materials. The nanometer-level thickness of 2D inorganic/graphene nanosheets allows the achievement of unusually strong electronic couplings between sheets, leading to a remarkable improvement in preexisting functionalities and the creation of unexpected properties. The synergetic merits of atomically coupled 2D inorganic-graphene nanosheets are presented here in the exploration of novel heterogeneous functional materials, with an emphasis on their critical roles as hybridization building blocks, interstratified sheets, additives, substrates, and deposited monolayers. The great flexibility and controllability of the elemental compositions, defect structures, and surface natures of inorganic-graphene nanosheets provide valuable opportunities for exploring high-performance nanohybrids applicable as electrodes for supercapacitors and rechargeable batteries, electrocatalysts, photocatalysts, and water purification agents, to give some examples. An outlook on future research perspectives for the exploitation of emerging 2D nanosheet-based hybrid materials is also presented along with novel synthetic strategies to maximize the synergetic advantage of atomically mixed 2D inorganic-graphene nanosheets.

Functionalized Masks: Powerful Materials against COVID-19 and Future Pandemics

The outbreak of COVID-19 revealed the vulnerability of commercially available face masks. Without having antibacterial/antiviral activities, the current masks act only as filtering materials of the aerosols containing microorganisms. Meanwhile, in surgical masks, the viral and bacterial filtration highly depends on the electrostatic charges of masks. These electrostatic charges disappear after 8 h, which leads to a significant decline in filtration efficiency. Therefore, to enhance the masks' protection performance, fabrication of innovative masks with more advanced functions is in urgent demand. This review summarizes the various functionalizing agents which can endow four important functions in the masks including i) boosting the antimicrobial and self-disinfectant characteristics via incorporating metal nanoparticles or photosensitizers, ii) increasing the self-cleaning by inserting superhydrophobic materials such as graphenes and alkyl silanes, iii) creating photo/electrothermal properties by forming graphene and metal thin films within the masks, and iv) incorporating triboelectric nanogenerators among the friction layers of masks to stabilize the electrostatic charges and facilitating the recharging of masks. The strategies for creating these properties toward the functionalized masks are discussed in detail. The effectiveness and limitation of each method in generating the desired properties are well-explained along with addressing the prospects for the future development of masks.

Controlling the Orientation and Viscoelasticity of Materials-Binding Peptides on Hexagonal Boron Nitride Using Fatty Acids

The adsorption of materials-binding peptides to technologically relevant 2D nanosheets of h-BN could be transformative for both property modulation and materials applications. To enhance binding, integration of non-natural functionalities into the biomolecule could prove to be important. However, very little is understood regarding the impact of these biomolecular structural alterations on the binding, which could influence the affinity and surface-adsorbed structures. Here, the effect of fatty acid incorporation site and carbon chain length is investigated using the BP7 peptide, previously identified with affinity for h-BN. The peptide was modified at either the N- or C-terminus with a fatty acid chain length of 6-12 carbons long. The binding affinity and bio-overlayer viscoelasticity are quantified using quartz crystal microbalance analysis. While fatty acid conjugation did not substantially affect the affinity of the resultant biomolecules, it did alter the viscoelasticity of the biomolecular overlayer on the h-BN surface based upon the carbon chain length and incorporation site. Molecular dynamics simulations demonstrate interplay between enthalpic and entropic effects in modifying the overlayer viscoelasticity. The simulations predict that C-terminal conjugation promotes the enhancement of upright adsorbed states, compared with the N-terminal case, with this effect most pronounced for the 10-carbon chain.

Miniaturized Salinity Gradient Energy Harvesting Devices

Harvesting salinity gradient energy, also known as "osmotic energy" or "blue energy", generated from the free energy mixing of seawater and fresh river water provides a renewable and sustainable alternative for circumventing the recent upsurge in global energy consumption. The osmotic pressure resulting from mixing water streams with different salinities can be converted into electrical energy driven by a potential difference or ionic gradients. Reversed-electrodialysis (RED) has become more prominent among the conventional membrane-based separation methodologies due to its higher energy efficiency and lesser susceptibility to membrane fouling than pressure-retarded osmosis (PRO). However, the ion-exchange membranes used for RED systems often encounter limitations while adapting to a real-world system due to their limited pore sizes and internal resistance. The worldwide demand for clean energy production has reinvigorated the interest in salinity gradient energy conversion. In addition to the large energy conversion devices, the miniaturized devices used for powering a portable or wearable micro-device have attracted much attention. This review provides insights into developing miniaturized salinity gradient energy harvesting devices and recent advances in the membranes designed for optimized osmotic power extraction. Furthermore, we present various applications utilizing the salinity gradient energy conversion.

Self-Standing Film Assembled using SnS-Sn/Multiwalled Carbon Nanotubes Encapsulated Carbon Fibers: A Potential Large-Scale Production Material for Ultra-stable Sodium-Ion Battery Anodes

High-energy sodium-ion batteries have a significant prospective application as a next-generation energy storage technology. However, this technology is severely hindered by the lack of large-scale production of battery materials. Herein, a self-standing film, assembled with SnS-Sn/multiwalled carbon nanotubes encapsulated in carbon fibers (SnS-Sn/MCNTs@CFs), is prepared using ball milling and electrospinning techniques and used as sodium-ion battery anodes. To compensate the poor internal conductivity of SnS-Sn nanoparticles, MCNTs are used to interweave SnS-Sn nanoparticles to improve the conductivity. Moreover, the designed three-dimensional carbon fiber conductive network can effectively shorten the diffusion path of electron/Na⁺, accelerate the reaction kinetics, and provide abundant active sites for sodium absorption. Benefiting from these unique features, the self-standing film offers a high reversible capacity of 568 mA h g^-1 at 0.1 A g^-1 and excellent cycling stability at 1 A g^-1 with a reversible capacity of 359.3 mA h g^-1 after 1000 cycles. In the sodium-ion full cell device, the capacity is stable at 283.7 mA h g^-1 after 100 cycles at a current of 100 mA g^-1. This work provides a new strategy for electrode design and facilitates the large-scale application of the sodium-ion battery.

Facile Approach to Fabricate a High-Performance Superhydrophobic Mesh

When superhydrophobic meshes are used for oil/water separation, high flux and high intrusion pressure are usually compromised. Herein, a high-performance superhydrophobic stainless steel mesh membrane with a hairy-like poly(divinylbenzene) (PDVB) coating is fabricated by precipitated cationic polymerization. The synthesis is facile, which is completed in one step at ambient temperature within a short time, i.e., less than 90 s. The unique hair-like microstructure of PDVB is responsible for the superhydrophobic performance with less blockage for the pores. A higher flux for oil is achieved while keeping a high intrusion pressure. Especially, the ellipsoidal pore texture with two sharp tips can give additional high intrusion pressure. In the case of 2800 mesh, the superhydrophobic mesh displays an unprecedentedly high value of up to 22 kPa while maintaining a high flux of 2.0 × 10⁴ L·m^-2·h^-1. The high intrusion pressure enables further increment of flux to 4.2 × 10⁴ L·m^-2·h^-1 under a reduced pressure at a higher loading. The current high-performance superhydrophobic mesh realizes higher efficiency in separating oil/water mixtures, which is promising for practical applications, for example, in industrial extraction.

Heteroatom-Doping of Non-Noble Metal-Based Catalysts for Electrocatalytic Hydrogen Evolution: An Electronic Structure Tuning Strategy

Electrocatalytic water splitting for hydrogen production is an appealing way to reduce carbon emissions and generate renewable fuels. This promising process, however, is limited by its sluggish reaction kinetics and high-cost catalysts. Construction of low-cost and high-performance non-noble metal-based catalysts have been one of the most effective approaches to address these grand challenges. Notably, the electronic structure tuning strategy, which could subtly tailor the electronic states, band structures, and adsorption ability of the catalysts, has become a pivotal way to further enhance the electrochemical water splitting reactions based on non-noble metal-based catalysts. Particularly, heteroatom-doping plays an effective role in regulating the electronic structure and optimizing the intrinsic activity of the catalysts. Nevertheless, the reaction kinetics, and in particular, the functional mechanisms of the hetero-dopants in catalysts yet remains ambiguous. Herein, the recent progress is comprehensively reviewed in heteroatom doped non-noble metal-based electrocatalysts for hydrogen evolution reaction, particularly focus on the electronic tuning effect of hetero-dopants in the catalysts and the corresponding synthetic pathway, catalytic performance, and activity origin. This review also attempts to establish an intrinsic correlation between the localized electronic structures and the catalytic properties, so as to provide a good reference for developing advanced low-cost catalysts.

Lightweight, Flexible Cellulose-Derived Carbon Aerogel@Reduced Graphene Oxide/PDMS Composites with Outstanding EMI Shielding Performances and Excellent Thermal Conductivities

In order to ensure the operational reliability and information security of sophisticated electronic components and to protect human health, efficient electromagnetic interference (EMI) shielding materials are required to attenuate electromagnetic wave energy. In this work, the cellulose solution is obtained by dissolving cotton through hydrogen bond driving self-assembly using sodium hydroxide (NaOH)/urea solution, and cellulose aerogels (CA) are prepared by gelation and freeze-drying. Then, the cellulose carbon aerogel@reduced graphene oxide aerogels (CCA@rGO) are prepared by vacuum impregnation, freeze-drying followed by thermal annealing, and finally, the CCA@rGO/polydimethylsiloxane (PDMS) EMI shielding composites are prepared by backfilling with PDMS. Owing to skin-core structure of CCA@rGO, the complete three-dimensional (3D) double-layer conductive network can be successfully constructed. When the loading of CCA@rGO is 3.05 wt%, CCA@rGO/PDMS EMI shielding composites have an excellent EMI shielding effectiveness (EMI SE) of 51 dB, which is 3.9 times higher than that of the co-blended CCA/rGO/PDMS EMI shielding composites (13 dB) with the same loading of fillers. At this time, the CCA@rGO/PDMS EMI shielding composites have excellent thermal stability (T_HRI of 178.3 °C) and good thermal conductivity coefficient (λ of 0.65 W m^-1 K^-1). Excellent comprehensive performance makes CCA@rGO/PDMS EMI shielding composites great prospect for applications in lightweight, flexible EMI shielding composites.

2D Nanomaterials for Effective Energy Scavenging

The development of a nation is deeply related to its energy consumption. 2D nanomaterials have become a spotlight for energy harvesting applications from the small-scale of low-power electronics to a large-scale for industry-level applications, such as self-powered sensor devices, environmental monitoring, and large-scale power generation. Scientists from around the world are working to utilize their engrossing properties to overcome the challenges in material selection and fabrication technologies for compact energy scavenging devices to replace batteries and traditional power sources. In this review, the variety of techniques for scavenging energies from sustainable sources such as solar, air, waste heat, and surrounding mechanical forces are discussed that exploit the fascinating properties of 2D nanomaterials. In addition, practical applications of these fabricated power generating devices and their performance as an alternative to conventional power supplies are discussed with the future pertinence to solve the energy problems in various fields and applications.

Electronic Structure Tuning of 2D Metal (Hydr)oxides Nanosheets for Electrocatalysis

2D metal (hydr)oxide nanosheets have captured increasing interest in electrocatalytic applications aroused by their high specific surface areas, enriched chemically active sites, tunable physiochemical properties, etc. In particular, the electrocatalytic reactivities of materials greatly rely on their surface electronic structures. Generally speaking, the electronic structures of catalysts can be well adjusted via controlling their morphologies, defects, and heterostructures. In this Review, the latest advances in 2D metal (hydr)oxide nanosheets are first reviewed, including the applications in electrocatalysis for the hydrogen evolution reaction, oxygen reduction reaction, and oxygen evolution reaction. Then, the electronic structure-property relationships of 2D metal (hydr)oxide nanosheets are discussed to draw a picture of enhancing the electrocatalysis performances through a series of electronic structure tuning strategies. Finally, perspectives on the current challenges and the trends for the future design of 2D metal (hydr)oxide electrocatalysts with prominent catalytic activity are outlined. It is expected that this Review can shed some light on the design of next generation electrocatalysts.

Bioinspired Hybrid Micro/Nanostructure Composited Membrane with Intensified Mass Transfer and Antifouling for High Saline Water Membrane Distillation

Membrane distillation (MD) holds great promise for high-saline solution treatment, but it is typically impeded by the trade-off between the high mass transfer and antifouling properties of the membrane. Herein, a new MD utilized membrane with bioinspired micro/nanostructure (lotus leaf and fish gill) was constructed on commercial PP membrane, which can simultaneously enhance the permeation flux and antifouling in the hypersaline MD operation. On the basis of the classic nucleation theory and hydrodynamics simulation, the nanoscale structure can intensify the interfacial nanoscale turbulent flow and hinder the crystal deposition, which works like the fish gill. In addition, the optimized nanoscale feature size renders the membrane with the heterogeneous nucleation barrier very similar to the homogeneous system, which works like the lotus leaf and hinders the induced nucleation effectively. The microscale structure as the supporting platform of nanostructure can additionally enlarge the effective evaporative surface with superior hydrophobicity and then promote the permeation transfer through the membrane. The hybrid micro/nanostructures render the fabricated membrane with excellent high-permeation flux and significantly prolonged fouling induction time, which sheds light on a new approach for the development of ideal MD utilized membrane.

Distributed Electric Field Induces Orientations of Nanosheets to Prepare Hydrogels with Elaborate Ordered Structures and Programmed Deformations

Living organisms use musculatures with spatially distributed anisotropic structures to actuate deformations and locomotion with fascinating functions. Replicating such structural features in artificial materials is of great significance yet remains a big challenge. Here, a facile strategy is reported to fabricate hydrogels with elaborate ordered structures of nanosheets (NSs) oriented under a distributed electric field. Multiple electrodes are distributed with various arrangements in the precursor solution containing NSs and gold nanoparticles. A complex electric field induces sophisticated orientations of the NSs that are permanently inscribed by subsequent photo-polymerization. The resultant anisotropic nanocomposite poly(N-isopropylacrylamide) hydrogels exhibit rapid deformation upon heating or photoirradiation, owing to the fast switching of permittivity of the media and electric repulsion between the NSs. The complex alignments of NSs and anisotropic shape change of discrete regions result in programmed deformation of the hydrogels into various configurations. Furthermore, locomotion is realized by a spatiotemporal light stimulation that locally triggers time-variant shape change of the composite hydrogel with complex anisotropic structures. Such a strategy on the basis of the distributed electric-field-generated ordered structures should be applicable to gels, elastomers, and thermosets loaded with other anisotropic particles or liquid crystals, for the design of biomimetic/bioinspired materials with specific functionalities.

Future antiviral surfaces: Lessons from COVID-19 pandemic

It is an urgent priority for advanced materials researchers to help find solutions to eliminate the COVID-19 pandemic. The transmission of the SARS-CoV-2 coronavirus is majorly through touching the contaminated surfaces and then the vulnerable mouth and eyes besides the direct contact with the infected person. This lesson inspired us to propose a strategy from the view of materials scientists on designing effective antiviral surfaces to prevent the transmission of infectious coronaviruses by disrupting their survival on various surfaces. In this perspective, based on current progress in antiviral and antibacterial coatings, we put forward some general principles for designing effective antiviral surfaces by applying natural viral inhibitors, physical/chemical modifications, and bioinspired patterns, with the mechanisms of direct disinfection, indirect disinfection, and receptor inactivation. This work maps possible solutions to inactivate the receptors of the coronavirus spikes and resist the transmission of the COVID-19 and other infectious diseases, and contribute to the prevention of future outbreaks and control of epidemics.

Bio-Inspired High Sensitivity of Moisture-Mechanical GO Films with Period-Gradient Structures

Moisture actuators can accomplish humidity-triggered energy-conversion process, through material screening and structural design. Inspired by natural caterpillars and the hydrophilic properties of graphene oxide (GO), this work proposes a geometrical design of period-gradient structures in GO films for fabricating moisture actuators. These novel period-gradient-structured GO films exhibit excellent dynamic performance that they could deform at 1000° with a small radius in several seconds at a high relative humidity (RH ≈ 80%). The properties of fast actuating speed and high response to deformation are achieved through the structural designing of the sole GO film by a one-step formation process. A mechanics-based theoretical model combined with the finite element simulation is presented to demonstrate the actuating mechanism in geometry, moisture, and mechanics, which lays the foundation for potential applications of GO films in remote control, environmental monitoring, and man-machine interactions.

Transition Metal Dichalcogenide-Silk Nanofibril Membrane for One-Step Water Purification and Precious Metal Recovery

With the rapid worldwide industrial development, large amounts of pollutants such as heavy metals are discharged into the water sources, causing a huge threat to living beings. To mitigate this issue, there is an urgent need for new water treatment strategies. Inspired by a natural shell nacre structure and a multidimensional hybrid concept, we demonstrate multilayered inorganic-organic hybrid membranes using metallic molybdenum disulfide (MoS₂) as two-dimensional transition metal dichalcogenide nanosheets and one-dimensional silk nanofibrils for water purification. Because of its possessing negatively charged layers and interaction sites, the hybrid film could adsorb metal ions and dyes from water. The separation performance can be tuned by changing the component ratios of these two nanomaterials. During filtration, due to the reducing effect of the MoS₂ nanosheets, precious metal ions are reduced to their nanoparticle form without any further thermal or chemical treatments. In addition to the one-step removal and recovery of metal ions, the hybrid membranes exhibit excellent potential for the determination and removal of different dyes from water. The results of this research can open up an effective and green avenue for water purification and recovery of metal ions dissolved in water.

Engineering Two-dimensional Nanomaterials to Enable Structure-Activity Relationship Studies in Nanosafety Research

Emerging, two-dimensional engineered nanomaterials (2DNMs) possess unique and diverse physical and chemical properties, such as extreme aspect ratios, adjustable electronic properties as well as functional lattice defects and surface chemistry which underpin their interactions with biological systems. This perspective highlights the need for structure activity relationship (SAR) studies for key properties of emerging grapheme-related and inorganic 2DNMs upon prioritization based on their potential impact and trajectory for large-scale production and applications. Further, it is discussed how a synthesis platform of microbiologically sterile, size-sorted, "model" 2DNMs with precise structure would enable SAR toxicological studies and allow for the sustainable and safe translation of 2D nanotechnology to real-world applications.

Recent Advances of Two-Dimensional Nanomaterials for Electrochemical Capacitors

Two-dimensional (2D) nanomaterials have drawn a wide range of research interests because of their unique ultrathin layered structures and attractive properties. In particular, the electrochemical properties and great variety of 2D nanomaterials make them highly attractive candidates for electrochemical capacitors, such as supercapacitors, lithium-ion capacitors, and sodium-ion capacitors. Herein, a comprehensive review of recent progress towards the application of 2D nanomaterials for electrochemical capacitors is provided. Several typical types of 2D nanomaterials are first briefly introduced, followed by detailed descriptions of their electrochemical capacitor applications. Finally, research perspectives and future research directions of these interesting areas are also provided.

Rotational Periodicity Display of the Tunable Wettability Pattern in a Photoswitch Based on a Response Bilayer Photonic Crystal

Although the forward diffraction of the three-dimensional (3D) photonic crystal is easily applied to a photoswitch, backward diffraction rainbows are rarely reported. The first rotational photoswitch based on a bilayer 3D photonic crystal with backward diffractions similar to those of two-dimensional photonic crystals was fabricated by vertically combining different thicknesses of nanoparticle templates. When rotating the bilayer photonic crystal, the opening or closing of the rotational photoswitch shows periodic reproducibility values of 30 and 60°. Different periods are regulated by the thickness and scattering effect of the top layer. Moreover, invisible patterns can be encoded and erased by changing the wettability via pH. Because of the decreasing of the refractive index differentials, it will be revealed rapidly when immersed in water. The revealed pattern can be periodically turned on and off by rotating the bilayer photonic crystal. It has great application prospects in optical prism, warning board, anti-counterfeiting, steganography, watermarking, and complex information coding.