Boosting electrochemical ammonia synthesis via dynamic nitrogen carriers coupled with electron-rich Lewis acidic sites on TiO nanofiber.

In light of the high energy consumption and substantial carbon emissions associated with traditional NH production based on the Haber-Bosch process, the aqueous electrochemical nitrogen reduction reaction (NRR) offers a clean and sustainable alternative production route. Nevertheless, activating the NN bonds at room temperature is challenging due to the high bond energy, severely hindering the development and commercialization of the electrochemical NRR. Herein, we report a synergistic strategy for achieving efficient N activation at ambient conditions that combines electrolyte engineering with catalytic site-modulated TiO nanofiber electrocatalysts.

Confined Gelation Synthesis of Flexible Barium Aluminate Nanofibers as a High-Performance Refractory Material.

Barium aluminate (BAO) ceramics are highly sought after as a kind of high-temperature refractory material due to their exceptional thermal stability in both vacuum and oxygen atmospheres, but their inherent brittleness results in rapid hardening, imposing a negative impact on the overall construction performance. Here, we report a strategy to synthesize flexible BAO nanofibers with a needle-like structure through confined-gelation electrospinning followed by in situ mineralization. The confined gelation among the colloidal particles promotes the formation of precursor nanofibers with high continuity and a large aspect ratio.

Ceramic Meta-Aerogel with Thermal Superinsulation up to 1700 °C Constructed by Self-Crosslinked Nanofibrous Network via Reaction Electrospinning.

Thermal insulation under extreme conditions requires the materials to be capable of withstanding complex thermo-mechanical stress, significant gradient temperature transition, and high-frequency thermal shock. The excellent structural and functional properties of ceramic aerogels make them attractive for thermal insulation. However, in extremely high-temperature environments (above 1500 °C), they typically exhibit limited insulation capacity and thermo-mechanical stability, which may lead to catastrophic accidents, and this problem is never effectively addressed.

Building-Envelope-Inspired, Thermomechanically Robust All-Fiber Ceramic Meta-Aerogel for Temperature-Controlled Dominant Infrared Camouflage.

The unsatisfactory properties of ceramic aerogels when subjected to thermal shock, such as strength degradation and structural collapse, render them unsuitable for use at large thermal gradients or prolonged exposure to extreme temperatures. Here, a building-envelope-inspired design for fabricating a thermomechanically robust all-fiber ceramic meta-aerogel with interlocked fibrous interfaces and an interwoven cellular structure in the orthogonal directions is presented, which is achieved through a two-stage physical and chemical process. Inspired by the reinforced concrete building envelope, a solid foundation composed of fibrous frames is constructed and enhanced through supramolecular in situ self-assembly to achieve high compressibility, retaining over 90% of maximum stress under a considerable compressive strain of 50% for 10 000 cycles, and showing temperature-invariance when compressed at 60% strain within the range of -100 to 500 °C.

Enhanced N Adsorption and Activation by Combining Re Clusters and In Vacancies as Dual Sites for Efficient and Selective Electrochemical NH Synthesis.

The electrochemical N reduction reaction (NRR) is a green and energy-saving sustainable technology for NH production. However, high activity and high selectivity can hardly be achieved in the same catalyst, which severely restricts the development of the electrochemical NRR. InSe with partially occupied p-orbitals can suppress the H evolution reaction (HER), which shows excellent selectivity in the electrochemical NRR.

Way to a Library of Ti-Series Oxide Nanofiber Sponges that are Highly Stretchable, Compressible, and Bendable.

Ti-series oxide ceramics in the form of aerogels, such as TiO, SrTiO, BaTiO, and CaCuTiO, hold tremendous potential as functional materials owing to their excellent optical, dielectric, and catalytic properties. Unfortunately, these inorganic aerogels are usually brittle and prone to pulverization owing to weak inter-particulate interactions, resulting in restricted application performance and serious health risks. Herein, a novel strategy is reported to synthesize an elastic form of an aerogel-like, highly porous structure, in which activity-switchable Ti-series oxide sols transform from the metastable state to the active state during electrospinning, resulting in condensation and solidification at the whipping stage to obtain curled nanofibers.

Multiscale Synergetic Bandgap/Structure Engineering in Semiconductor Nanofibrous Aerogels for Enhanced Solar Evaporation.

Solar-driven interface evaporation has been identified as a sustainable seawater desalination and water purification technology. Nonetheless, the evaporation performance is still restricted by salt deposition and heat loss owing to weak solar spectrum absorption, tortuous channels, and limited plane area of conventional photothermal material. Herein, the semiconductor nanofibrous aerogels with a narrow bandgap, vertically aligned channels, and a conical architecture are constructed by the multiscale synergetic engineering strategy, encompassing bandgap engineering at the atomic scale and structure engineering at the nano-micro scale.

Multiscale Interpenetrated/Interconnected Network Design Confers All-Carbon Aerogels with Unprecedented Thermomechanical Properties for Thermal Insulation under Extreme Environments.

With ultralight weight, low thermal conductivity, and extraordinary high-temperature resistance, carbon aerogels hold tremendous potential against severe thermal threats encountered by hypersonic vehicles during the in-orbit operation and re-entry process. However, current 3D aerogels are plagued by irreconcilable contradictions between adiabatic and mechanical performance due to monotonicity of the building blocks or uncontrollable assembly behavior. Herein, a spatially confined assembly strategy of multiscale low-dimensional nanocarbons is reported to decouple the stress and heat transfer.

Scalable Synthesis of Flexible Single-Atom Monolithic Catalysts for High-Efficiency, Durable CO Oxidation at Low Temperature.

The creation of single-atom catalysts in a large-size, high-yield, and stable form represents an important direction for high-efficiency industrial catalysis in the future. Herein, we report a strategy to synthesize flexible single-atom monolithic catalysts (SAMCs) based on the hierarchical 3D assembly of single-atom-loaded oxide ceramic nanofibers. The nanofibers, which can be produced in a continuous and scalable manner, serve as an ideal support for single atoms spontaneously and almost completely exposed at the surface through the Kirkendall effect-enabled ion migration during the spinning process, resulting in both high yield and large loading quantity.

Inhibited Grain Growth Through Phase Transition Modulation Enables Excellent Mechanical Properties in Oxide Ceramic Nanofibers up to 1700 °C.

Oxide ceramics are widely used as thermal protection materials due to their excellent structural properties and earth abundance. However, in extremely high-temperature environments (above 1500 °C), the explosive growth of grain size causes irreversible damage to the microstructure of oxide ceramics, thus exhibiting poor thermomechanical stability. This problem, which may lead to catastrophic accidents, remains a great challenge for oxide ceramic materials.

High Toughness Combined with High Strength in Oxide Ceramic Nanofibers.

Traditional oxide ceramics are inherently brittle and highly sensitive to defects, making them vulnerable to failure under external stress. As such, endowing these materials with high strength and high toughness simultaneously is crucial to improve their performance in most safety-critical applications. Fibrillation of the ceramic materials and further refinement of the fiber diameter, as realized by electrospinning, are expected to achieve the transformation from brittleness to flexibility owing to the structural uniqueness.

Fibrous MXene Aerogels with Tunable Pore Structures for High-Efficiency Desalination of Contaminated Seawater.

The seawater desalination based on solar-driven interfacial evaporation has emerged as a promising technique to alleviate the global crisis on freshwater shortage. However, achieving high desalination performance on actual, oil-contaminated seawater remains a critical challenge, because the transport channels and evaporation interfaces of the current solar evaporators are easily blocked by the oil slicks, resulting in undermined evaporation rate and conversion efficiency. Herein, we propose a facile strategy for fabricating a modularized solar evaporator based on flexible MXene aerogels with arbitrarily tunable, highly ordered cellular/lamellar pore structures for high-efficiency oil interception and desalination.

Complementary Design in Multicomponent Electrocatalysts for Electrochemical Nitrogen Reduction: Beyond the Leverage in Activity and Selectivity.

Electrochemical nitrogen reduction reaction (eNRR) is promising in place of the Haber-Bosch process for artificial N fixation. However, the high activity and selectivity of eNRR are challenging to achieve simultaneously due to the scaling relations. Such "leverage" between activity and selectivity has severely restricted eNRR.

From 1D Nanofibers to 3D Nanofibrous Aerogels: A Marvellous Evolution of Electrospun SiO Nanofibers for Emerging Applications.

One-dimensional (1D) SiO nanofibers (SNFs), one of the most popular inorganic nanomaterials, have aroused widespread attention because of their excellent chemical stability, as well as unique optical and thermal characteristics. Electrospinning is a straightforward and versatile method to prepare 1D SNFs with programmable structures, manageable dimensions, and modifiable properties, which hold great potential in many cutting-edge applications including aerospace, nanodevice, and energy. In this review, substantial advances in the structural design, controllable synthesis, and multifunctional applications of electrospun SNFs are highlighted.

Direct synthesis of highly stretchable ceramic nanofibrous aerogels via 3D reaction electrospinning.

Ceramic aerogels are attractive for many applications due to their ultralow density, high porosity, and multifunctionality but are limited by the typical trade-off relationship between mechanical properties and thermal stability when used in extreme environments. In this work, we design and synthesize ceramic nanofibrous aerogels with three-dimensional (3D) interwoven crimped-nanofibre structures that endow the aerogels with superior mechanical performances and high thermal stability. These ceramic aerogels are synthesized by a direct and facile route, 3D reaction electrospinning.

Highly Active and Selective Electroreduction of N by the Catalysis of Ga Single Atoms Stabilized on Amorphous TiO Nanofibers.

The electroreduction of N under ambient conditions has emerged as one of the most promising technologies in chemistry, since it is a greener way to make NH than the traditional Haber-Bosch process. However, it is greatly challenged with a low NH yield and faradaic efficiency (FE) because of the lack of highly active and selective catalysts. Inherently, transition (d-block) metals suffer from inferior selectivity due to fierce competition from H evolution, while post-transition (p-block) metals exhibit poor activity due to insufficient "π back-donation" behavior.

P-doped WO flowers fixed on a TiO nanofibrous membrane for enhanced electroreduction of N.

Herein, nanoneedle-constructed WO3 flowers are prepared by hydrothermal synthesis, which are characterized by a large surface area leading to abundant active sites. Additionally, P doping is employed as an effective way to generate charge imbalance and induce more empty d-orbitals around W6+, thus facilitating the adsorption of N2 molecules. Moreover, a flexible TiO2 nanofibrous membrane is used as an electrocatalytically active matrix to fix the P-doped, nanoneedle-constructed WO3 flowers.

Conductive and Elastic TiO Nanofibrous Aerogels: A New Concept toward Self-Supported Electrocatalysts with Superior Activity and Durability.

Recently, various titanium dioxide (TiO ) nanostructures have received increasing attention in the fields of energy conversion and storage owing to their electrochemical properties. However, these particulate nanomaterials exclusively exist in the powder form, which may cause health risks and environmental hazards. Herein we report a novel, highly elastic bulk form of TiO for safe use and easy recycling.

Promoted Electrocatalytic Nitrogen Fixation in Fe-Ni Layered Double Hydroxide Arrays Coupled to Carbon Nanofibers: The Role of Phosphorus Doping.

The key to bringing the electrocatalytic nitrogen fixation from conception to application lies in the development of high-efficiency, cost-effective electrocatalysts. Layered double hydroxides (LDHs), also known as hydrotalcites, are promising electrocatalysts for water splitting due to multiple metal centers and large surface areas. However, their activities in the electrocatalytic nitrogen fixation are unsatisfactory.

SbS nanoparticles anchored on SnO nanofibers: a high-performance hybrid electrocatalyst toward ammonia synthesis under ambient conditions.

Herein, we report a novel transition-metal-based electrocatalyst, Sb2S3 nanoparticles, which exhibits electrocatalytic activity toward ammonia synthesis under ambient conditions. These Sb2S3 nanoparticles are further anchored on SnO2 nanofibers, which act as an active substrate to prevent them from aggregation while enhancing the electrocatalytic activity. The obtained Sb2S3@SnO2 nanofibers deliver excellent ammonia yield (22.

Carbon-Nanoplated CoS@TiO Nanofibrous Membrane: An Interface-Engineered Heterojunction for High-Efficiency Electrocatalytic Nitrogen Reduction.

Developing noble-metal-free electrocatalysts is important to industrially viable ammonia synthesis through the nitrogen reduction reaction (NRR). However, the present transition-metal electrocatalysts still suffer from low activity and Faradaic efficiency due to poor interfacial reaction kinetics. Herein, an interface-engineered heterojunction, composed of CoS nanosheets anchored on a TiO nanofibrous membrane, is developed.

Stable Confinement of Black Phosphorus Quantum Dots on Black Tin Oxide Nanotubes: A Robust, Double-Active Electrocatalyst toward Efficient Nitrogen Fixation.

A conceptually new, metal-free electrocatalyst, black phosphorus (BP) is presented, which is further downsized to quantum dots (QDs) for larger surface areas, and thus, more active sites than the bulk form. However, BP QDs are prone to agglomeration, which inevitably results in the loss of active sites. Besides, their poor conductivity is not favorable for charge transport during electrolysis.