Tailoring Nanoporous-Engineered Sponge Fiber Molecular Sieves with Ternary-Nested Architecture for Precise Molecular Separation

High mechanical property and hydrophilic electrospun poly amidoxime/poly acrylonitrile composite nanofibrous mats for extraction uranium from seawater

Seawater reserves about 4.5 billion tons of uranium, if properly extracted, could be a sustainable green energy resource for hundreds of years, alternating its limited terrestrial ore and reducing the CO2 emitted from fossil fuels. The current seawater uranium adsorbents suffer neither economically viable nor adsorption efficiency, requiring more development to harvest satisfactorily uranium from seawater. Amidoxime-based fibrous adsorbents are the most promising adsorbents of seawater uranium due to abundant chelating sites. However, they suffer from severe shrinkage and stiffness once they dry, losing porous architecture and mechanical properties. Herein, an economical and scalable two-nozzle electrospinning technology was applied to produce poly amidoxime nanofibers (PAO NFs) supported by Poly acrylonitrile nanofibers (PAN NFs) as composite PAO/PAN nanofibrous mats with high structure stability. These PAO/PAN mats, with rapid wettability and excellent mechanical strength, show promising uranium adsorption capacities of 369.8 mg/g at seawater pH level, much higher than PAO and PAN NFs. The uranium adsorption capacity of the PAO/PAN mat reached 5.16 mg/g after 7 days of circulating (10 ppm uranium) spiked natural seawater. Importantly, the composite mat maintained its fibrous structure after five adsorption-desorption cycles with more than 80 % of its adsorption capacity, confirming its recyclability and stability. Therefore, the composite PAO/PAN mat fulfills the basic requirements for effectively and economically trapping uranium from seawater, which could be a matrix for further development.

Biporous silica nanostructure-induced nanovortex in microfluidics for nucleic acid enrichment, isolation, and PCR-free detection

Efficient pathogen enrichment and nucleic acid isolation are critical for accurate and sensitive diagnosis of infectious diseases, especially those with low pathogen levels. Our study introduces a biporous silica nanofilms-embedded sample preparation chip for pathogen and nucleic acid enrichment/isolation. This chip features unique biporous nanostructures comprising large and small pore layers. Computational simulations confirm that these nanostructures enhance the surface area and promote the formation of nanovortex, resulting in improved capture efficiency. Notably, the chip demonstrates a 100-fold lower limit of detection compared to conventional methods used for nucleic acid detection. Clinical validations using patient samples corroborate the superior sensitivity of the chip when combined with the luminescence resonance energy transfer assay. The enhanced sample preparation efficiency of the chip, along with the facile and straightforward synthesis of the biporous nanostructures, offers a promising solution for polymer chain reaction-free detection of nucleic acids.

Bi2O3/Gd2O3 Meta-Aerogel with Leaf-Inspired Nanotrap Array Enables Efficient X-Ray Absorption

The increasing utilization of X-rays has generated a growing need for efficient shielding materials. However, the existing Pb-based materials suffer from a narrow X-ray absorbing range, high weight, and rigidity. Inspired by the natural leaf, which can efficiently absorb light through chlorophyll and carotenoids in confined cells, we engineer ultralight and superelastic nanofibrous Bi2O3/Gd2O3 meta-aerogels (BGAs) with X-ray nanotrap arrays by manipulating the 3D confined assembly of 1D Bi2O3 and Gd2O3 nanofibers. The BGAs can synergistically absorb X-ray photons from complementary energy ranges into the nanotraps and induce cyclic collisions with Bi2O3 and Gd2O3 nanofibers, maximizing the effective X-ray attenuation. The meta-aerogel exhibits the integrated performance of efficient X-ray shielding efficiency (60-83%, 16-90 keV), ultralow density (10 mg cm-3), and superelasticity. The production of these meta-aerogels presents an avenue for the development of next-generation X-ray protective materials and the resolution of X-ray imaging systems.

Janus Dual Self-Strengthening Structure of Bi2 O3 /Gd2 O3 Nanofibrous Membranes for Superior X-Ray Shielding

Bi2 O3 /rare earth oxide biphasic absorbers are attractive for high-efficiency X-ray shielding due to the complementary X-ray absorption effects. However, its application is severely hindered by poor interphasic contact. Here, a new Janus interface engineering strategy is reported for the construction of continuous and flexible Bi2 O3 /Gd2 O3 crystal nanofibrous membranes (FJNMs) with micro/nano dual self-strengthening interphasic adhesion. This strategy facilitates online micro-interlocking between Bi2 O3 /Gd2 O3 nanofibers and in situ nano-grain fusion between Bi2 O3 /Gd2 O3 crystals, significantly enhancing the adhesive strength at the Bi2 O3 /Gd2 O3 interface. Additionally, the synergistic shielding effect from Bi2 O3 /Gd2 O3 absorption and multiple reflections in Bi2 O3 and Gd2 O3 crystal lattices make the nanofibrous membranes a superior X-ray radiation barrier. The FJNMs demonstrate integrated features of exceptional X-ray shielding efficiency (91%-100%), robust interfacial adhesion (lap-shear strength >3.8 MPa), prominent flexibility, lightweight, and outstanding breathability. The design concepts of fibrosing biphasic absorber assemblies pave the way for asymmetrically assembling biphasic materials, setting the stage for a fundamental shift in next-generation radiation shielding materials.

Meta-Aerogel Ion Motor for Nanofluid Osmotic Energy Harvesting

Osmotic power, also known as "blue energy", is a vast, sustainable, and clean energy source that can be directly converted into electricity by nanofluidic membranes. However, the key technological bottleneck for large-scale osmotic electricity is that macroscopic-scale bulky membrane cannot synergistically satisfy the demands of high power density and low resistance without sacrificing scalability and mechanical robustness. Here, inspired by the anatomy and working principle of electric eels, which harness osmotic energy through embedded neuron-mediated fibril nanochannels with nanoconfined transport dynamics. Fibrous nanofluidic meta-aerogel ion motors, 3D-assembled from nanofluidic cable fibers with actuatable stimulation/transport "ion highways" are engineered. The meta-aerogel exhibits the integrated coupling effect of boosted ion propulsion and surface-charge-dominated selective ion transport. Driven by osmosis, the meta-aerogel ion motor can produce an unprecedented output power density of up to 30.7 W m-2 under a 50-fold salinity gradient. Advancing ultra-selective ion transport in nanofluidic meta-aerogels may provide a promising roadmap for blue energy harvesting.

Regulating Alkyl Chain Length on Quaternization TiO2 for Boosting Photocatalytic Performance: Synergism of Promoting Photogenerated Charge Separation and Improving Reactant Adsorption

To explore the effect of surface charge properties of a photocatalyst on photocatalytic activity, quaternization TiO₂ particles with different alkyl chain lengths (CT-X/P25) are first synthesized to boost the photocatalytic activity. The effect of a quaternary ammonium group with different alkyl chain lengths on the photocatalytic activity of CT-X/P25 is investigated. Interestingly, the introduction of a quaternary ammonium group on CT-X/P25 not only contributes to improving the photodegradation efficiency of anionic dyes due to enhancing of adsorption capacity through electrostatic attraction, but also it can improve the photodegradation efficiency of cationic dyes. Therefore, there seems to be another factor affecting the photocatalytic activity. The results of photoelectric characterization show that the photogenerated charge separation of CT-X/P25 is greatly enhanced, which is beneficial to improve the photocatalytic activity. Simultaneously, the results show that the difference in the photocatalytic activity of CT-X/P25 is mainly related to the charge intensity of -N⁺(CH₃)₂- in the quaternary amine salt. According to X-ray photoelectron spectroscopy, the charge intensity of -N⁺(CH₃)₂- in CT-X/P25 gradually increases with the increase in alkyl chain lengths, which is conducive to promoting photogenerated charge separation and improving the adsorption for anionic dyes. The photocatalytic activity has been further enhanced due to the enhancement of this synergy. In summary, the quaternary ammonium salt-modified CT-X/P25 shows an excellent synergistic effect on the process of photodegradation of anionic dyes: promoting photogenerated charge separation and adsorption.

Ultralight and Superelastic Gd2O3/Bi2O3 Nanofibrous Aerogels with Nacre-Mimetic Brick-Mortar Structure for Superior X-ray Shielding

The widespread use of X-rays has prompted a surge in demand for effective and wearable shielding materials. However, the Pb-containing materials currently used to shield X-rays are commonly bulky, hard, and biotoxic, severely limiting their applications in wearable scenarios. Inspired by the nacre, we report on ultralight, superelastic, and nontoxic X-ray shielding nanofibrous aerogels with microarch-engineered brick/mortar structure by combining polyurethane/Bi₂O₃ nanofibers (brick) and Gd₂O₃ nanosheets (mortar). The synergistic attenuation effect toward X-rays from the reflection of microarches and absorption of Bi/Gd elements significantly enhances the shielding efficiency of aerogels, and microarches/robust nanofibrous networks endow the materials with superelasticity. The resultant materials exhibit integrated properties of superior X-ray shielding efficiency (91-100%), ultralow density (52 mg cm^-3), large stretchability of 800% reversible elongation, and high water vapor permeability (8.8 kg m^-2 day^-1). The fabrication of such novel aerogels paves the way for developing next-generation effective and wearable X-ray shielding materials.

Biodegradable, biomimetic, and nanonet-engineered membranes enable high-flux and highly-efficient oil/water separation

Porous membranes with fascinating super-wettable surface and tunable porous architecture for oil-water separation have been developed rapidly, however, the serious secondary marine pollution caused by the non-degradable defectiveness of membranes themselves is still a thorny problem. Herein, we create an eco-friendly membrane with biomimetic cobweb-like nanostructure via assembling two-dimensional bacterial cellulose nanonets on the starch nanofibrous membrane on a large scale. The obtained novel composite membranes exhibit integrated properties of sub-micron pore size, ultrahigh porosity, superhydrophilicity, and underwater superoleophobicity, stemming from the synergistic effect of the hydrated nanonet-skin-layer and porous starch matrix. By virtue of the narrow-distributed sub-micron pores, ultrahigh porosity, and ultrathin thickness, the resulting membrane shows outstanding performance of excellent separation efficiency (up to 99.996%), high percolation flux (maximum of 15968 L m^-2 h^-1), well surpassing the conventional microfiltration membranes. More significantly, with the advantage of biodegradability and anti-oil-fouling property, the membrane could serve as the robust platform for long-term wastewater remediation.

Green Preparation of a Carboxymethyl Cellulose-Coated Membrane for Highly Efficient Separation of Crude Oil-In-Water Emulsions

Developing high-performance membranes is an extremely significant strategy to combat increasing severe oil pollution. However, most of the previously reported superwettable membranes have been inevitably involved with the use of toxic solvents and complicated preparation processes. In addition, most of them lacked the capacity of separating crude oil-in-water emulsions. Herein, a facile and green strategy is employed to fabricate a polytetrafluoroethylene (PTFE) membrane with a mixed suspension of PDA@ZIF-8 and carboxymethyl cellulose (CMC) using water as a solvent via the vacuum filtration method. Combining hydrophilic property with micro-nano-roughness, the CMC-PDA@ZIF-8-coated PTFE membrane (CPZP membrane) exhibits excellent underwater superoleophobicity. More importantly, the separation efficiency of various surfactant-stabilized oil-in-water emulsions including crude oil/water emulsion is higher than 99.2% with a flux up to 1306.5 L m^-2 h^-1, and the separation performance remains nearly the same after 10 cycles. Moreover, outstanding underwater superoleophobic and self-cleaning properties are maintained after long-distance sandpaper abrasion and multiple bending tests. Meanwhile, its exceptional separation performance is still maintained in harsh environments (3.5 wt % NaCl, 1 M HCl, 60 °C hot water) even after immersing it for 24 h. Therefore, this green-prepared and high-performance membrane has tremendous application prospects in treating oily wastewater.

Sub-Nanoporous Engineered Fibrous Aerogel Molecular Sieves with Nanogating Channels for Reversible Molecular Separation

Gating molecular separation using artificial sub-nanoporous molecular sieves is highly desirable in large-scale chemical and energy processing, such as gas separation, hydrogen recovery, carbon dioxide capture, seawater desalination, etc. However, it has remained an insurmountable challenge to create such materials. Herein, a binary meso-reconstruction strategy to develop biomimetic sub-nanoporous engineered aerogel molecular sieves (NAMSs) with reversible nanogating channels is demonstrated, in which sub-1 nm pores (≈7 Å) provide coupling size-thermodynamic gated functions that enable molecule discrimination and trapping in a reversible manner. The NAMSs show polarity-reversible adsorption in which adsorbate molecules are discriminated by each gate-admission sponge-fiber molecular sieve, facilitating size/interface synergistically induced selective separation of 1,3,5-trimethyl benzene/ethylene glycol with high separation factor and fast adsorption rate. The nanogating aerogel molecular sieves with molecularly defined sub-1 nm nanoporous architecture (≈7 Å), Murray's law hierarchical channels, ultrahigh surface area (686 m² g^-1 ), and robust self-supporting characteristics define a new benchmark for both aerogels and molecular sieves, exhibiting great potential in diversified on-demand molecular separations that are prevalent in chemical, energy, and environmental processes.