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1.
Intelligent membranes with adaptive gating channels play a crucial role in cellular functions and separation processes. This study introduces a novel approach to controlling channel expansion using biomimetic adaptive aggregates, fundamentally overcoming the drawbacks of existing methods relying on intertwined polyelectrolyte chains for channel blockage. Specifically, a pH-responsive 2D material membrane is constructed through the self-assembling of protein-mimetic zwitterionic polydopamine (ZPDA) soft molecular aggregates within graphene oxide (GO) interlayers. Similar to the conformational switch of inserted proteins in cellular membranes, the embedded ZPDA in GO nanofluidic channels undergoes an adaptive conformational transformation in response to pH changes. This dynamic adjustment of ZPDA physicochemical properties allows for reversible regulation of GO nanofluidic channel size and charge by external pH modulation. The resulting GO/ZPDA membrane exhibits programmable separation performance for dye molecules (i.e., water permeance of 18.8–35.4 L m−2 h−1 bar−1 and molecular selectivity of 73.7–32.9) and salt ions (i.e., ionic permeance of 0.69–1.25 mol m−2 h−1 and ionic selectivity of 20.8–21.9). This work sheds new light on the engineering of intelligent stimuli-responsive 2D nanofluidic channels with adaptive gating properties, holding promise across a wide range of applications including separation, drug delivery, sensing, and catalysis.  相似文献   

2.
The intrinsic porosity in the periodic structures of metal–organic frameworks (MOFs) endows them with a great potential for membrane separation. However, facile fabrication of crystalline MOF membranes has been challenging and limited to few materials for economic and environmental considerations. Herein, a continuous Zr-MOF thin film with a thickness of ≈180 nm has been fabricated via in situ recrystallization of MOF nanoparticles on the porous support under formic acid vapor. Owing to the inherent microporosity and the well-established hydrophilicity during membrane fabrication, the MOF thin films exhibit excellent pervaporation performance with separation factors of 2630, 501 and fluxes of 1.45, 1.41 kg m−2 h−1) for n-butanol dehydration and methanol/methyl tert-butyl ether (MeOH/MTBE) separation, respectively. The structural stability of the film has been further confirmed by its steady performance in the 10-day pervaporation test. This in situ recrystallization method induced by a trace amount of acid vapor with no extra ingredients opens a new avenue for the facile membrane fabrication of various MOF materials to feasibly realize their versatile potential as membrane materials.  相似文献   

3.
Lithium extraction from salt lake brines is highly demanded to circumvent the lithium supply shortage. However, polymer nanofiltration membranes suffer from low lithium permeability while nanofluidic devices are hindered by complicated preparation and miniaturized scales despite high permeability. Here, the authors report a facile strategy to prepare positively charged nanofiltration membranes for ultrapermeable and selective separation of lithium ions from concentrated magnesium/lithium mixtures. A new electrolyte monomer (diaminoethimidazole bromide, DAIB) containing bidentate amine groups is designed to modify pristine polyamide composite membranes. Structure characterizations and simulations show that the DAIB modification brings about nano-heterogeneity that not only improves surface hydrophilicity, but also reduces water transport resistance through the ≈100 nm thick separation layer. Water permeance of the modified membrane improves fivefold and is coupled with good stability in 200-h continuous nanofiltration. It exhibits high lithium flux (0.7 mol m−2 h−1) for brines (Mg2+/Li+ ratio 20) at 6 bar operation pressure.  相似文献   

4.
Membranes with ultrahigh ion selectivity and high liquid permeance are needed to produce high-quality product water with increased recovery and process efficiency in water desalination. The narrow pore size distribution and controlled surface charge in the separation layer of nanofiltration membranes significantly improve the ion selectivity through molecular sieving and Donnan exclusion of co-ions. Here, the ultraselective and yet highly water permeable polyamide nanofilm composite nanofiltration membranes developed by precisely controlling the kinetics of the interfacial polymerization reaction by maintaining the stoichiometric equilibrium at the interface is reported. The kinetically favorable stoichiometric equilibrium condition prohibits the formation of aggregate pores in the nanofilm and leads to the formation of narrow network pores with a high surface negative charge. Nanofilms are designed with a controlled degree of crosslinking and made as thin as ≈7 nm to achieve increased water permeance. The ultraselective membranes exhibit up to 99.99% rejection of divalent salt (Na2SO4) and demonstrate monovalent to divalent ion selectivity of >4000. The selectivity of these nanofilm composite membranes is beyond the permeance–selectivity upper-bound line of the state-of-the-art nanofiltration membranes and one to two orders of magnitude higher than the commercially available membranes with pure water permeances of up to 23 L m−2 h−1 bar−1. The fabrication process is scalable for membrane manufacturing.  相似文献   

5.
Transient optical spectroscopy is used to quantify the temperature-dependence of charge separation and recombination dynamics in P3TEA:SF-PDI2 and PM6:Y6, two non-fullerene organic photovoltaic (OPV) systems with a negligible driving force and high photocurrent quantum yields. By tracking the intensity of the transient electroabsorption response that arises upon interfacial charge separation in P3TEA:SF-PDI2, a free charge generation rate constant of ≈2.4 × 1010 s−1 is observed at room temperature, with an average energy of ≈230 meV stored between the interfacial charge pairs. Thermally activated charge separation is also observed in PM6:Y6, and a faster charge separation rate of ≈5.5 × 1010 s−1 is estimated at room temperature, which is consistent with the higher device efficiency. When both blends are cooled down to cryogenic temperature, the reduced charge separation rate leads to increasing charge recombination either directly at the donor-acceptor interface or via the emissive singlet exciton state. A kinetic model is used to rationalize the results, showing that although photogenerated charges have to overcome a significant Coulomb potential to generate free carriers, OPV blends can achieve high photocurrent generation yields given that the thermal dissociation rate of charges outcompetes the recombination rate.  相似文献   

6.
Nanoporous graphene membranes are attractive for molecular separations, but it remains challenging to maintain sufficient mechanical strength during scalable fabrication and module development. Inspired by the composite structure of cell membranes and cell walls, a large-area atomically thin nanoporous graphene membrane supported by a fiber-reinforced structure with strong interlamellar adhesion is designed. Compared with other graphene-based membranes of large scale, the fracture stress, fracture strength, and tensile stiffness of the composite membranes can be enhanced by a factor of 17, 67, and 94, respectively. This fiber-reinforced structure also confers stability of the composite membrane to different curvature states and repeated bending processes after 10 000 times, which provides an opportunity for modularization. The breathable function of such membrane with an ultrahigh gas permeance (≈8.6–23 L m−2 d−1 Pa−1) and an ultralow water vapor transportation rate (WVTR) (≈23–129 g L m−2 d−1) is observed, superior to most commercial materials. This work provides a facile method to fabricate large-area graphene membranes and paves the road to practical application in the membrane separation field for other 2D films.  相似文献   

7.
Oil–water separation membranes easily fail to oil foulants with low surface energy and high viscosity, which severely limits these membranes’ applications in treating oily wastewater. Herein, an oil–water separation membrane by bioinspired bubble-mediated antifouling strategy is fabricated via growing hierarchical cobalt phosphide arrays on stainless steel mesh. The as-prepared membrane is superhydrophilic/superaerophobic and electrocatalytic for hydrogen evolution under water, which helps to rapidly generate and release abundant microbubbles surrounding the oil-fouled region on the membrane. These microbubbles can spontaneously coalesce with the oil foulants to increase their buoyancy and warp their interface tension by morphing the oil shape. And this spontaneous coalescence also increases the kinetic energy of oil foulants resulting from the decreased bubbles’ interface energy and potential energy. The synergy of the warped interface tension, increased buoyancy, and kinetic energy drives the efficiently dynamic antifouling of this membrane. This dynamic antifouling even can remove some solid sediment such as oily sand particles that causes more serious fouling of the membrane. Thus, this membrane maintains high flux (>11920 L m−2 h−1 bar−1) in the long-term separation of oil–water and oil–sand–water emulsions by dynamically recovering the decayed flux on demand, which exhibits great potential in treating industrial oily wastewater.  相似文献   

8.
High-frequency actuators are reported based on non-flammable lithium-ion conducting phosphate liquid crystal–polymer composite electrolytes, which exhibit a bending response at frequencies up to 80 Hz under an AC voltage of 2 V, owing to its high ionic conductivity reaching 10−4 S cm−1 at room temperature. An equimolar complex of a phosphate-containing mesogenic molecule and lithium bis(trifluoromethylsulfonyl)imide through the ion-dipole interactions induced a room-temperature smectic A liquid-crystalline (LC) phase forming 2D ion-transport pathways comprising the 2D array of the phosphate moieties. A blend of 80 wt% LC electrolyte and 20 wt% polymers (poly(vinyl chloride) and poly(vinylidene fluoride-co-hexafluoropropylene)) formed a flexible, mechanically robust LC–polymer composite film. Scanning electron microscopy and white light interference microscopy revealed a microphase-segregated structure consisting of a continuous LC phase and a porous polymer matrix. In addition, the continuity of porous structure across the film is confirmed by permeation experiments of solvents thorough the membrane with a homemade filter in a dead-end filtration mode. The LC–polymer composite film sandwiched between two poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) electrodes is found to simultaneously exhibit high bending strain (0.63%) and high output force (0.35 mN), owing to the high ion migration into the composite electrolyte and electrode.  相似文献   

9.
The performance of alkaline fuel cells is severely limited by substandard anion exchange membranes (AEMs) due to the lower ionic conductivity compared to the proton exchange membranes. The ionic conductivity of AEMs can be effectively improved by regulating the microphase structure, but it still cannot meet the practical use requirements. Here, enhanced microphase-separated structures are constructed by the cooperativity of highly hydrophilic dual cations and highly hydrophobic fluorinated side chains. Meanwhile, the introduction of  O enhances the flexibility of side chains and facilitates the formation of ion transport channels. The dual piperidinium cation functionalized membrane (PB2Pip-5C8F) which is grafted with the ultra-hydrophobic fluorocarbon chain exhibits a high conductivity of 74.4 mS cm−1 at 30 °C and 168.46 mS cm−1 at 80 °C. Furthermore, the PB2Pip-5C8F membrane achieves the highest peak power density of 718 mW cm−2 at 80 °C under a current density of 1197 mA cm−2 without back pressure. A long-term life cell test of this AEM shows a low voltage decay rate of 1.68 mV h−1 over 70 h of operation at 80 °C.  相似文献   

10.
To overcome the critical safety and performance issues of lithium metal batteries, it is urgent to develop advanced electrolytes with multi-defensive properties against fire, mechanical puncture, and dendrite growth simultaneously, in addition to high ion-conductivity. However, realizing these essential properties by one electrolyte has proved to be extremely challenging due to the inherent conflicts among them. Herein, to circumvent this challenge, a neuron-like gel polymer electrolyte (simply referred as Neu-PE) to simultaneously achieve supertoughness, nonflammability, dendrite-suppression capability and self-driven property is reported. This Neu-PE takes advantage of nano-phase separation regulated by highly ion-conductive deep-eutectic solvent. As a result, the Neu-PE holds high ambient ionic conductivity (1.27±0.09 mS cm−1), super-toughness and strength (22.52 MJ m−3 and 13.5±0.6 MPa), fire resistance and importantly, lithium-metal anode protection capability. Lithium metal batteries assembled with this multi-defensive Neu-PE can work normally even under metal-probe puncture or serious damage by cutting.  相似文献   

11.
Architected hydrogels are widely used in biomedicine, soft robots, and flexible electronics while still possess big challenges in strong toughness, and shape modeling. Here, inspired with the universal hydrogen bonding interactions in biological systems, a strain-induced microphase separation path toward achieving the printable, tough supramolecular polymer hydrogels by hydrogen bond engineering is developed. Specifically, it subtly designs and fabricates the poly (N-acryloylsemicarbazide-co-acrylic acid) hydrogels with high hydrogen bond energy by phase conversion induced hydrogen bond reconstruction. The resultant hydrogels exhibited the unique strain-induced microphase separation behavior, resulting in the excellent strong toughness with, for example, an ultimate stress of 9.1 ± 0.3 MPa, strain levels of 1020 ± 126%, toughness of 33.7 ± 6.6 MJ m−3, and fracture energy of 171.1 ± 34.3 kJ m−2. More importantly, the hydrogen bond engineered supramolecular hydrogels possess dynamic shape memory character, i.e shape fixing at low temperature while recovery after heating. As the proof of concept, the tailored hydrogel stents are readily manufactured by 3D printing, which showed good biocompatibility, load-bearing and drug elution, being beneficial for the biomedical applications. It is believed that the present 3D printing of the architected dynamic hydrogels with ultrahigh toughness can broaden their applications.  相似文献   

12.
Nanofluidic membranes consisting of 2D materials and polymers are considered promising candidates for harvesting osmotic energy from river estuaries owing to their unique ion channels. However, micron-scale polymer chains agglomerate in the nanochannels, resulting in steric hindrance and affection ion transport. Herein, a nanofluidic membrane is designed from MXene and xylan nanoparticles that are derived from paper-mill waste. The demonstrated membrane reinforced by paper-mill waste has the characteristics of green, low-cost, and outstanding performance in mechanical properties and surface-charge-governed ionic transport. The MXene/carboxmethyl xylan (CMX) membrane demonstrates a high surface charge (ζ-potential of −44.3 mV) and 12 times higher strength (284.96 MPa) than the pristine MXene membrane. The resulting membrane shows intriguing features of high surface charge, high ion selectivity, and reduced steric hindrance, enabling it high osmotic energy generation performance. A potential of the nanofluidic membrane is ≈109 mV, the corresponding current of up to 2.73 µA, and the output power density of 14.52 mW m−2 are obtained under a 1000-fold salt concentration gradient. As the electrolyte pH increases, the power density reaches 56.54 mW m−2. This works demonstrate that CMX nanoparticles can effectively enhance the properties of the nanofluidic membrane and provide a promising strategy to design high-performance nanofluidic devices.  相似文献   

13.
Hydrogen energy is a truly renewable and clean energy source. Alkaline water electrolysis (AWE) is the most promising technology for green hydrogen production currently. In the AWE process, the critical part of an alkaline electrolyzer is the membrane, which acts to conduct hydroxide ions and block gases. However, developing low area resistance, high bubble point pressure and highly stable membrane for high-performance AWE is still a challenge. Herein, porous skeleton-supported composite membranes via the blade-coating method for advanced AWE are prepared. The porous composite membranes, besides having hydrophilic surface, also show ultra-low area resistance (≈0.15 Ω cm2), ultra-high bubble point pressure (≈27 bar) and excellent mechanical properties (tensile stress, ≈14 MPa). By using commercial catalysts, the composite membranes exhibit a current density of up to 1.9 A cm−2 at the voltage of 2 V in 30 wt% KOH solution at 80 °C and achieve ultra-high H2 purity (up to 99.996%) when applied in AWE. Notably, the composite membrane can operate for more than 1600 h without performance attenuation, demonstrating excellent stability. This study opens up the feasibility of preparing high-performance AWE membranes for large-scale hydrogen production.  相似文献   

14.
High-temperature proton-exchange membrane fuel cells (HT-PEMFCs) fabricated with phosphoric acid (PA)-doped polybenzimidazole (PBI) show apparent technical advantages. In practical automotive applications, achieving cold start-up capability is crucial. In this work, a kind of branched block proton exchange membrane (PEM) based on PBI with a low content of porphyrin ring (<1 mol.%) is reported as a branched monomer. Self-assembly into high-density helical nanochannels under the synergistic effect of phase separation and porphyrin π−π stacking, thus the PEM can maintain a high level of PA doping. Specifically, the PA/1.8TCPP-BrPy-OPBI membrane shows a proton conductivity of 0.169 and 0.071 S cm−1, as well as an H2-O2 fuel cell peak power density of 1077 and 357 mW cm−2 at 180 and 80 °C without humidification and backpressure, respectively. The membrane electrode assembly (MEA) can exhibit good fuel cell stability, with a voltage decay rate of only 7.0 µV h−1 at 80 °C. Furthermore, it maintains a peak power density of 93% even after 150 start-up/shut-down cycles at 25 °C. This work expands the operating temperature range of conventional PBI membranes between 25 and 200 °C and thus provides a novel strategy for high-performance PBI-based HT-PEMFCs.  相似文献   

15.
Lead halide perovskites have made great advance in direct X-ray detection, however the presence of toxic lead and the requirement of high working voltages severely limit their applicability and operational stability. Thus, exploring “green” lead-free hybrid perovskites capable of detecting X-rays at zero bias is crucial but remains toughly challenging. Here, utilizing chiral R/S-1-phenylpropylamine (R/S-PPA) cations, a pair of 0D chiral-polar perovskites, (R/S-PPA)2BiI5 ( 1 R / 1 S ) are constructed. Their intrinsic spontaneous electric polarization induces a large bulk photovoltage of 0.63 V, which acts as a driving force to separate and transport photogenerated carriers, thus endowing them with the capability of self-driven detection. Consequently, self-driven X-ray detectors with a low detection limit of 270 nGy s−1 are successfully constructed based on high-quality, inch-sized single crystals of 1 R . Notably, they show suppressed baseline drift under the self-driven mode, exhibiting superior operational stability. This study realizes self-driven X-ray detection in a single-phase lead-free hybrid perovskite by exploiting the intrinsic bulk photovoltaic effect, which sheds light on future explorations of lead-free hybrid perovskites toward “green” self-driven radiation detectors with high performance.  相似文献   

16.
Multifunctional separation membrane is usually realized by multi-component collaborative construction, which makes the membrane preparation method complicated and uncontrollable. Herein, a novel multifunctional photocatalytic separation membrane is prepared by vacuum self-assembly of single seaweed-like g-C3N4 photocatalyst. The seaweed-like g-C3N4 gives membrane certain roughness, large specific surface area, excellent hydrophilicity and abundant transport channels. Through a systematic study, the membrane exhibits excellent separation of five oil-in-water emulsions with a maximum flux of 3114.0 ± 113.0 L m−2 h−1 bar−1 for 1, 2-dichloroethane-in-water (Dc/W) emulsion and a maximum efficiency of 97.4 ± 0.1% for chloroform-in-water (C/W) emulsion. In addition, the seaweed-like g-C3N4 with large specific surface area and narrow bandgap render excellent visible light absorption characteristics and accelerate e-h+ pairs transport rate, giving the membrane excellent photocatalytic degradation and antibacterial properties. The membrane shows good degradation for eight different pollutants, among which the degradation effect for rhodamine B (RhB), methylene blue (MB), and crystal violet (CV) were ≈100%. The antibacterial efficiency against E. coli and S. aureus is also close to 100%. After 35 consecutive separations of C/W emulsion and 10 consecutive degradations of RhB, the membrane still maintains excellent separation performance. This long-lasting multifunctional separation membrane exhibits broad application prospects in complex wastewater purification.  相似文献   

17.
Constructing crystalline covalent organic frameworks (COF) robust 3D reusable macroscopic objects exposing more adsorption sites with high water flux for use as a filter is an unresolved challenge. A simple scalable procedure is shown for making a robust, highly compressible 3D crystalline COF nanowire interconnected porous open-cell sponge. The compressive strength and Young's modulus (80% strain) of the sponge are 175 and 238 kPa, respectively. The sponge can withstand multiple compression-release cycles and a load of 2800 times its weight without collapsing. As an exemplary application, the use of a COF sponge in the selective removal and separation of cationic model dye from a mixture of dyes in water by adsorption and filtration with >99% efficiency is shown. Depending on the dye concentration, the dye removal time can be as short as 2 min, and dye adsorption efficiency can be as high as 653 mg g−1 (COF in the sponge). During filtration, the sponges as filters show a high water flux of 2355 L h−1 m−2 under ambient conditions and maintain their performance for many cycles. The lightweight, reusability, and efficiency make present sponges sustainable materials as adsorbents and filters.  相似文献   

18.
Cross-linking is widely accepted as an effective method to improve the mechanical strength and durability of phosphoric acid (PA) doped polybenzimidazole (PBI) membranes. However, the cross-linked membranes generally exhibit compromised overall performance since their compact network structures decrease the free volumes of membranes, leading to poor proton conductivity. In this study, a locally high-density cross-linked polybenzimidazole network based on pillar[5]arene bearing multiple alkyl bromide is constructed for the first time to achieve high proton conductivity, desired mechanical properties, and excellent fuel cell performance. The pillar[5]arene-cross-linked network considerably enhances the mechanical strength of membrane (14.6 MPa), particularly with high PA uptake, and provides loose PBI chain segment packing to retain PA (315.9%). Surprisingly, the pillar[5]arene-cross-linked PBI membrane displays a high-power density of 1,084.1 mW cm−2 at 180 °C and 0.6 mg cm−2 Pt loading without backpressure and humidification, that is the highest value reported in cross-linked membranes for high-temperature proton exchange membrane fuel cells.  相似文献   

19.
Developing ion-selective membranes with anti-biofouling property and biocompatibility is highly crucial in harvesting osmotic energy in natural environments and for future biomimetic applications. However, the exploration of membranes with these properties in osmotic energy conversion remain largely unaddressed. Herein, a tough zwitterionic gradient double-network hydrogel membrane (ZGDHM) with excellent biofouling resistance and cytocompatibility for sustainable osmotic energy harvesting is demonstrated. The ZGDHM, composed of negatively charged 2-acrylamido-2-methylpropanesulfonic acid (AMPS) as the first scaffold network and zwitterionic sulfobetaine acrylamide (SBAA) as the second network, is prepared by a two-step photopolymerization, thus creating continuous gradient double-network nanoarchitecture and then remarkably enhanced mechanical properties. As verified by the experiments and simulations, the gradient nanoarchitecture endows the hydrogel membrane with apparent ionic diode effect and space-charge-governed transport property, thus facilitating directional ion transport. Consequently, the ZGDHM can achieve a power density of 5.44 W m−2 by mixing artificial seawater and river water, surpassing the commercial benchmark. Most importantly, the output power can be promoted to an unprecedented value of 49.6 W m−2 at the mixing of salt-lake water and river water, nearly doubling up most of the existing nanofluidic membranes. This study paves a new avenue toward developing ultrahigh-performance osmotic energy harvesters for biomimetic applications.  相似文献   

20.
Piezocatalysis, governed by piezo-potential within piezoelectrics, has gained prominence for reactive oxygen species (ROS) generation, which is significant to environmental and biological applications. However, designing piezocatalysts with excellent piezocatalytic performance in a wide temperature and efficient charge carrier separation ability is still challenging. Herein, eco-friendly BaTiO3 (BT)-based perovskite ferroelectrics with tailored multiphase coexistence in a wide temperature range are constructed to boost higher piezoelectricity and large piezo-potential, which is attributed to decreased polarization anisotropy by flat Gibbs energy profile. Elevated piezo-potential in designed BT-based piezocatalyst guarantees high-efficient generation rate of •OH (200 µmol g−1 h−1) and •O2 (40 µmol g−1 h−1) by ultrasound stimulation, which is 3.5 times more than that of pure BT. Besides, piezocatalytic capacity to degrade dye wastewater shows a rate constant of 0.0182 min−1 and gives an antibacterial rate of 95% within 30 min for eliminating E. coli. Theoretical simulations validate that the local distortion of TiO6 octahedra also contributes to piezocatalytic performance by inducing electron–hole pairs separation in real space, and better response to slight structural deformation. This work is important to design high-performance piezocatalysts with high-efficiency ROS generation for sewage treatment and sonodynamic therapy.  相似文献   

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