Nanowire Membrane Research Articles

Three-dimensionally assembled polyelectrolyte multilayers-functionalized silica nanowire membrane for highly-efficient adsorptive separation of copper ions from water

High-performance materials for heavy metal ion removal are highly demanded in environmental treatment. Membrane adsorption has the advantages of being easy to operate and avoiding secondary pollution. It remains challenging to prepare adsorption membranes with both high removal rate and high permeability. Here, we present a novel strategy for preparing poly(acrylic acid) (PAA) and polyethyleneimine (PEI) multilayer-assembled silica nanowires (SiO2 NWs) membrane with abundant, multiple functional groups on a highly porous network for Cu(II) capture. The SiO2 NWs in the hybrid membranes serve as a rigid 3D framework to improve membrane porosity and water flux, while the polyelectrolyte multilayers assembled on the SiO2 NWs provide abundant, highly accessible adsorption sites for Cu(II) uptake. The adsorption capacity of the membranes can be tuned by changing the dosage of the assembled SiO2 NWs and the PAA/PEI pair layers. The maximum adsorption capacity of the active polyelectrolyte layer for SiO2 NWs@(PAA/PEI)4 composite membrane was 272.5 mg/g toward Cu(II), outperforming the counterpart (PAA/PEI)4 membrane (97.5 mg/g) after removal of the SiO2 NWs framework. The hybrid membrane shows excellent adsorption performance for the removal of low concentrations of Cu(II) in a dynamic adsorption mode, and the removal rate is maintained at above 90% after eight recycles.

Soft Thermoplastic Polyurethane/Silver Nanowire Membranes with Low Hysteresis for Large Strain Sensing and Joule Heating

Soft Thermoplastic Polyurethane/Silver Nanowire Membranes with Low Hysteresis for Large Strain Sensing and Joule Heating

Surface-Enhanced Raman Spectroscopy Sensor Integrated with Ag@ZIF-8@Au Core-Shell-Shell Nanowire Membrane for Enrichment, Ultrasensitive Detection, and Inactivation of Bacteria in the Environment.

A core-shell-shell sandwich material is developed with silver nanowires as the core, ZIF-8 as an inner shell, and gold nanoparticles as the outer shell, namely, Ag@ZIF-8@Au nanowires (AZA-NW). Then, the synthesized AZA-NW is transformed into a surface-enhanced Raman spectroscopy (SERS) sensor (named M-AZA) by the vacuum filtration method and used to enrich, detect, and inactivate traces of bacteria in the environment. The M-AZA sensor has three main functions: (1) trace bacteria are effectively enriched, with an enrichment efficiency of 91.4%; (2) ultrasensitive detection of trace bacteria is realized, with a minimum detectable concentration of 1 × 101 CFU/mL; (3) bacteria are effectively killed up to 92.4%. The shell thickness of ZIF-8 (5-75 nm) is controlled by adjusting the synthesis conditions. At an optimum shell thickness of 15 nm, the effect of gold nanoparticles and ZIF-8 shell on the sensor's stability, SERS activity, and antibacterial performance is investigated. The simulation of the SERS sensor using the finite difference time domain (FDTD) method is consistent with the experimental results, theoretically demonstrating the role of the gold nanoparticles and the ZIF-8 shell. The sensor also shows excellent stability, safety, and generalizability. The campus water sample is then tested on-site by the M-AZA SERS sensor, indicating its potential for practical applications.

Surface decoration of flexible Si3N4 nanowire membrane by hydroxyapatite micron-flake with excellent thermal insulation at 1300 °C

Flexible and excellent thermal insulation membranes are required as the thermal protection system materials of aerospace vehicles for next-generation space missions. Using ceramic membranes with ultralow thermal conductivity has been proved to be an effective way to protect the electronic components inside the fuselage. Herein, we decorate hydroxyapatite (HA) micron-flake onto Si3N4 nanowire membrane (SR), and investigate the thermal stability, fire-resistance and thermal insulating properties of the obtained SR decorated by HA micron-flake (SRHM). Surface decoration of HA micron-flake onto the SR results in the formation of well-interconnected junctions and the increase of interfacial thermal resistance. Due to the increased interfacial thermal resistance, the as-prepared SRHM exhibits good thermal insulation and outstanding fire-retardant performance. SRHM shows robust mechanical property with tensile strength value of 4.10 MPa, increased by 247.5% compared to the SR without the surface decoration by HA micron-flake. The thermal conductivity of SRHM is as low as 0.037 W m−1 K−1, reduced by 33.9% compared to the SR without the surface decoration by HA micron-flake. After SRHM is heated by a butane blow torch at 1300 °C for 30 min, no obvious change is observed in the macroscopic morphology. And the temperature of the backside for SRHM maintains at a stable temperature of ∼260 °C for 300 s, which is 1040 °C lower than that of the front side. Additionally, SRHM can protect the electronic components form being burnt under the heating of an alcohol lamp for 30 min. The successful preparation of such thermal insulating and fire-retardant SRHM will open up a new world for the widespread applications of ceramic membranes in the fields of aerospace vehicles.

A Simple and Colorful Experiment to Show Nanowire Membrane Construction for Molecule Separation

A Simple and Colorful Experiment to Show Nanowire Membrane Construction for Molecule Separation

A composite gel polymer electrolyte for sodium metal battery at a wide temperature range

AbstractSodium‐metal batteries (SMBs) are considered a promising alternative to lithium‐metal batteries due to their high‐energy density, low cost, and good low‐temperature performance. However, the serious side reactions and dendrites growth during the process of sodium ions deposition/stripping are the bottleneck that inhibits the further capitalization of SMBs, especially at low temperatures. Herein, a porous framework of 50 μm thickness composite gel‐polymer‐electrolyte (GPE) supported by polyvinylidene difluoride nanowires membrane and Na3Zr2Si2PO12 ceramic particles is proposed to tackle the issues. This GPE not only has high ionic conductivity but also can promote the uniform transportation of sodium ions to form a stable and dense metal‐GPE interfacial layer, which can effectively inhibit the side reactions and dendrites growth in a wide temperature range. The assembled Na//GPE//Na3V2(PO4)3 full battery provides a specific capacity of 100 mAh g−1 at 10 C for more than 3000 cycles calendar life at room temperature. Moreover, the full battery based on this GPE has an extraordinary performance at low temperatures, reaching a specific capacity of 93 and 61 mAh g−1 at 0.5 and 1 C at −20°C, respectively. This work provides a reliable solution for low‐temperature applications of high‐energy density and long‐cycle life SMBs.

Enhanced separation properties of polyvinylidene membranes with MnO2 nanowire addition

In this study, novel MnO2-PVDF ultrafiltration membranes were prepared by incorporating MnO2 nanowires through the immersion-precipitation phase inversion process. Scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FT-IR) and X-ray powder diffraction (XRD) were employed to investigate the microstructure of the prepared membranes. The characterization results indicated that the hydrophilicity and smoothness of the membranes increased with increasing MnO2 nanowire content. When the MnO2 nanowires is 1.5 wt%, the MnO2-PVDF nanowire membrane has the best performance, the water flux of the membrane increased from 491.98 L·(m2h)−1 to 657.75 L·(m2h)−1 compared with the pure PVDF membrane. At the same time, the BSA rejection of the membrane reached to 100% and the FRR% increased to 85.37%. Furthermore, the PVDF membrane with 1.5 wt% MnO2 nanowire content exhibited outstanding BSA and oil rejection. This method has potential for the preparation of high flux and good antifouling ultrafiltration membranes.

Multifunctional Ti3C2Tx MXene/Silver Nanowire Membranes with Excellent Catalytic, Antifouling, and Antibacterial Properties for Nitrophenol-Containing Water Purification.

The uncontrolled release of nitrophenol and dye pollutants into water systems is an increasingly serious worldwide concern, and thus efficient wastewater treatment technologies are urgently needed. Herein we report a novel two-dimensional (2D) transition metal carbides and/or nitrides (Ti3C2Tx MXene) membrane modified with silver nanowires (AgNWs) by vacuum assisted filtration technology for the ultrafast nitrophenol catalysis and water purification applications. Regular and controllable membrane transport channels were constructed by stacking Ti3C2Tx MXene nanosheets. Furthermore, the intercalation of AgNWs into the Ti3C2Tx MXene interlayer greatly enlarged the interlayer spacing, resulting in more gaps for fast and selective molecular transport. The optimized Ti3C2Tx MXene@AgNWs (M@A) membrane exhibited a water flux up to ∼191.9 L/(m2 h) while maintaining a high bovine serum albumin (BSA) rejection of ∼95.4%. We emphatically used M@A membranes as efficient catalysts for the reduction of 4-nitrophenol (4-NP), and the results indicated that M@A-12% membrane exhibited the greatest catalytic reduction ability, and recycling utilization. M@A-12% membrane also had an antibacterial rate of more than 99% against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). This work provides a possibility to expand the application of 2D multifunctional M@A membranes in wastewater treatment and pollutant catalytic degradation.

Thermal insulating and fire-retardant Si3N4 nanowire membranes resistant to high temperatures up to 1300 °C

Superior thermal insulating and fire-retardant ceramic membranes are urgently demanded in the aerospace, construction, and chemical engineering industries. However, the generic characteristics of ceramic membranes, such as brittleness, structural collapse, and crystallization-induced pulverization behavior, present a great plague to their practical applications. Herein, we report a highly flexible, mechanically stable, fire-retardant, and high-temperature-resistant ceramic membrane based on the interlocked Si3N4 nanowires formed by the precursor pyrolysis method. The Si3N4 nanowire membrane (SNM) has excellent high-temperature resistance under alcohol lamps and butane spray lance. The thermal insulation with a thermal conductivity as low as 0.056 W m–1 K–1 can be attributed to the high porosity of SNM, which makes it a desirable candidate for heat insulators under harsh conditions. More importantly, SNM exhibits thermal stability and robust mechanical properties in the range of 25 to 1300 °C. The high-temperature resistance of SNM up to 1300 °C is achieved by the four stages: Si3N4 nanowires, Si3N4@SiO2 nanowires, SiO2 nanowires, and bead-like SiO2 nanowires. After heat-treated at 1300 °C, the macroscopic size of SNM does not change significantly, and the interlocked structure is still maintained. Furthermore, SNM still maintains excellent mechanical properties, with tensile strength as high as 0.26 MPa. This work provides a facile method for fabricating excellent thermal insulating and fire-retardant ceramic membranes, showing prospective application prospects in the era of thermal insulating materials.

Graphene oxide enabled self-assembly of silver trimolybdate nanowires into robust membranes for nanosolid capture and molecular separation.

A graphene oxide (GO) assisted self-assembly strategy for growing a silver trimolybdate nanowire membrane with capabilities of nanosolid capture and small molecule separation is reported. Thanks to the GO bridges and the accurate self-assembly process, the resulting membrane exhibits outstanding mechanical properties (can withstand 4300 times its weight) and impressively high porosity (97%). On the basis of the robustness and high porosity of the membrane, column-shaped filter apparatus has been fabricated, in which the membrane served as a self-standing permeation barrier to assess its permeability and practical application as a nanosolid filter and molecule filter. The permeability test of the membrane with pure water uncovers that the membrane exhibits fast permeability while driven by hydrostatic pressure only because of its significantly high porosity. The separation test of the membrane with P25 TiO2 solution, 13 nm Au solution, and yellow-emitting CdTe QDs reveals that all the tiny nanosolids are completely removed from the solution, which suggests that the membrane is an efficient nanosolid filter. Its efficiency is increased by the induction of surface collision from numerous nanowire barriers and the deposition of nanosolids on the nanowire surface. The separation test of the membrane with a mixed-dye solution reveals that sulfur containing methylene blue (MB) molecules are highly efficiently extracted under various chemical conditions, evidencing that the membrane is an ideal molecule filter too. Its high selectivity and high efficiency originated from the Ag-S bonding between the interlayered silver ions of the silver trimolybdate nanowire and the sulfur atom of MB molecules. Based on the above results, the silver trimolybdate nanowire membrane has been applied to purify drugs, which successfully removed sulbactam sodium impurity F from sulbactam sodium, demonstrating a purity increment from 98.92% to 99.93%. The present work should provide a significant step forward to bringing macroscopic 1D nanomaterial architectures much closer to real-world applications involving isolation and enrichment of catalyst reclamation, high-value chemical recovery, drug purification, and environmental remediation.

Balanced Mechanical and Biotribological Properties of Polymer Composites Reinforced by a 3D Interlocked Si3N4 Nanowire Membrane.

Polymer composites have great potential applications in the hip joint replacement, where the combinations of high mechanical strength and excellent biotribological properties are required. In this work, a well-dispersed three-dimensional (3D) silicon nitride nanowire membrane (SNm) designed as a reinforcement and brushite (Bs) served as bioactive filler are constructed into the polymer matrix, forming SNm-reinforced Bs/polymer composites (SNm-Bs/Pm). Especially, SNm could form a 3D interlocked structure, where the ultralong silicon nitride nanowires are entangled with each other. SNm could effectively facilitate the penetration of the polymer matrix and improve the cohesion strength of the polymer, thereby promoting mechanical and biotribological properties for SNm-Bs/Pm. The performances for polymer composites are optimized by increasing the layer number of preform. By comparing SNm-Bs/Pm with one-layer preform, the tensile strength of SNm-Bs/Pm with six-layer preforms reaches 83.3 MPa with an increase of 767.7%. In addition, the friction coefficient and wear rate of SNm-Bs/Pm with six-layer preforms in fetal bovine serum medium achieve 0.06 and 0.21 × 10-14 m3(N·m)-1 and decrease by 82.4 and 72.4%, respectively. The present work provides a promising methodology of preparing interlocked SNm-reinforced polymer composites with enhanced mechanical and biotribological properties that are potential for hip joint replacement applications.

Silicon carbide catalytic ceramic membranes with nano-wire structure for enhanced anti-fouling performance

Membrane fouling is a critical challenge for current ceramic membranes, which suffer from low flux and insufficient removal. Development of self-cleaning catalytic ceramic membranes is promising to address this challenge. Herein, we design heterogeneous silicon carbide ceramic membranes featuring a novel structure of g-C3N4-decorated β-SiC nano-wire catalytic functional layer, which enables enhanced anti-fouling self-cleaning performance. At chemical harsh (alkaline or especially acidic) conditions, the nano-wire membrane exhibits catalysis-enhanced removal performance for organic contaminants. Unlike conventional particle-packing membrane structure, such a nano-wire network membrane structure has not only high porosity (56.1%), but exceptional water permeance (110 L·m−2·h−1·bar−1) and removal (100%) of organic substance under simulated sunlight, outperforming state-of-the-art organic membranes and ceramic membranes. Superoxide radical (∙O2−) was experimentally confirmed to be major reactive species responsible for self-cleaning function. We also propose a catalytic mechanism model with radical formation pathway, enabled by the as-formed g-C3N4@β-SiC heterojunction structure with reduced electron-hole recombination. This work would provide new insights into not only rational design of next-generation ceramic membranes with self-cleaning function but also more applications of efficient treatment of refractory wastewaters containing degradable organic substances by using such membranes.

Identification of Trace Polystyrene Nanoplastics Down to 50 nm by the Hyphenated Method of Filtration and Surface-Enhanced Raman Spectroscopy Based on Silver Nanowire Membranes.

Nanoplastics are emerging pollutants that pose potential threats to the environment and organisms. However, in-depth research on nanoplastics has been hindered by the absence of feasible and reliable analytical methods, particularly for trace nanoplastics. Herein, we propose a hyphenated method involving membrane filtration and surface-enhanced Raman spectroscopy (SERS) to analyze trace nanoplastics in water. In this method, a bifunctional Ag nanowire membrane was employed to enrich nanoplastics and enhance their Raman spectra in situ, which omitted sample transfer and avoided losing smaller nanoplastics. Good retention rates (86.7% for 50 nm and approximately 95.0% for 100-1000 nm) and high sensitivity (down to 10-7 g/L for 50-1000 nm and up to 105 SERS enhancement factor) of standard polystyrene (PS) nanoplastics were achieved using the proposed method. PS nanoplastics with concentrations from 10-1 to 10-7 g/L and sizes ranging from 50 to 1000 nm were successfully detected by Raman mapping. Moreover, PS micro- and nanoplastics in environmental water samples collected from the seafood market were also detected at the μg/L level. Consequently, the proposed method provides more possibilities for analyzing low-concentration nanoplastics in aquatic environments with high enrichment efficiency, minimal sample loss, and high sensitivity.

Facile preparation of α-MnO2 nanowires for assembling free-standing membrane with efficient Fenton-like catalytic activity

Assembling MnO2 nanowires into macroscopic membrane is a promising engineered technology for catalyst separation and enhancement of Fenton-like reaction activity, yet its development is limited by the deficiencies in preparation and property modulation of the MnO2 nanowires. In this work, we developed a facile method using C2H5OH and CH3COOK as reductive and vital control reagents to react with KMnO4 by hydrothermal reaction at 140 °C for 12 h, to prepare the ultralong α-MnO2 nanowires up to tens of micrometers with high purity and aspect ratio. Such strategy not only had the advantages of being mild, easily controlled and environmental pollution-free, but also endowed α-MnO2 nanowires with excellent ability as a Fenton catalyst when assembled into free-standing membrane for degrading phenolic compounds (kobs = 0.0738 ∼ 0.1695 min−1) in a continuous flow reaction. The reactive oxygen species (i.e., •OH) from Fenton-like reaction were enriched within this α-MnO2 nanowire membrane via nanoconfinement effect, which further enhanced the mass transportation of •OH available for phenolic contaminants. MnO2 nanowire membrane using our method possessed the high practical potential for water purify due to its easy-preparation and enhanced catalytic performances.

Direct separation of phosphate under highly acidic conditions using MnO2@CeO2 nanowires membrane

Selective separation of phosphate from highly acidic media is both a critical requirement prior to their downstream processing and an important pursuit for separation science. Herein a CeO2-wrapped MnO2 nanowires membrane was applied for phosphate separation from highly acidic solution. Combing the extremely low solubleness with structure stability, such membrane exhibits a superior strong acid-resistant. Under acidic conditions (pH = 2.2), the protonizated hydroxyl bonds on CeO2 surface achieved selective removal of phosphate with a high phosphorus rejection (> 97.5%) at 0.02 MPa. More practically, the membrane maintains 93.6% of phosphorus rejection after 5 times reusage. Overall, the as-prepared MnO2@CeO2 membrane is highly efficient for separation of phosphate under highly acidic media and very promising for treatment of industrial acidic wastewater in nuclear power industry, chemical manufacturing and other facilities.

Screening of silver nanoparticles in antibacterial products by leveraging a silver nanowire membrane as a filter and amplifier

A filtration-based SERS platform was proposed to separate and analyse AgNPs in antibacterial products.

Enhancement of super-hydrophilic/underwater super-oleophobic performance of ceramic membrane with TiO2 nanowire array prepared via low temperature oxidation

A gradient porous ceramic membrane with surface super-hydrophilic and underwater super-oleophobic performance was prepared by combining hydrogel directional freezing method and low temperature oxidation process. The effects of solid contents and sintering temperature on the ceramic membrane matrix were examined. The reaction time and synthesis temperature on the TiO2 nanowire array were also evaluated. In addition, the related effects on pore size distribution, permeation flux, contact angle, and oil-in-water emulsion separation were systematically investigated. The ceramic membrane matrix pore size changed from 0.5 μm to 25 μm gradually, indicating the gradient structure controlled by the growth of ice. The super-hydrophilic and underwater super-oleophobic performance of ceramic membrane surface was obtained with surface modification by TiO2 nanowire array, and the surface water contact angle and underwater oil contact angle were less than 5° and over 158°, respectively. The bonding strength between TiO2 nanowire and ceramic membrane matrix was high enough to withstand ultrasonic waves. The ceramic membrane modified with TiO2 nanowire array was used for 1000 ppm diesel oil-in-water emulsion separation, and the stable separation efficiency and flux were about 97% and 100–200 L/(m2 h bar) even after 10 filtration cycles.

Chitosan modified inorganic nanowires membranes for ultra-fast and efficient removal of Congo red

Chitosan modified hydrogen titanate nanowires membrane is prepared through a simple immersion-filtration method, which can be used to adsorb anionic dyes. The adsorption kinetics data shows that the adsorption process follows the pseudo-second-order model. Thermodynamics analysis reveals the adsorption is a spontaneous process. During the dynamic adsorption process, chitosan modified hydrogen titanate nanowires membrane shows excellent removal rate of 99.5% and adsorption capacity of 374.4 mg g−1 for Congo red. The membrane exhibits excellent cyclic adsorption performance and satisfactory removal rate in the pH range of 2.5–12.5. After 15 adsorption–desorption cycles, the removal rate and permeability of Congo red remain above 98.7% and 1120.0 L m-2h−1 bar−1, respectively.

(Invited) Programmable Gold Nanowire Tattoo for Multimodal Wearable Sensors

Sensitive, specific yet multifunctional tattoo-like electronics are ideal wearable systems for health monitoring anytime anywhere because they are virtually becoming parts of Human skins offering burdenless “unfeelable” wearing experience. Here, I will present a new skin-like, multifunctional electronic tattoo entirely from gold using standing enokitake mushroom-like vertically aligned nanowire membrane in conjunction with programmable local cracking technology. Only a single material type is needed for our integrated gold circuits involved in interconnects and multiplexed specific sensors, thereby avoiding complex multi-materials interface. We can fine-tune the properties of elastic gold conductors from strain-insensitive to highly strain-sensitive simply by programming localized crack size, shape and orientations. Furthermore, we demonstrate in-plane integration of strain/pressure sensor, anisotropic orientation-specific sensors, strain-insensitive stretchable interconnects, temperature sensors, glucose sensors, and lactate sensors without the need of soldering or gluing.

Robust silver nanowire membrane with high porosity to construct stable Li metal anodes

Silver is a promising candidate component in the fabrication of Li metal anodes. While most efforts are focused on performance improvement via regulating the lithiophilicity of Ag-based electrodes, the detailed lithiation behavior of Ag nanoparticles is another key research topic for the rational design of Li–Ag anodes. In this work, we report the fabrication of Ag nanowire (AgNW) membranes to examine their electrochemical alloying process in Li cells. The robust and compact membranes show high porosity up to 90% with tunable thickness of 1–10 μm, thus facilitating lithiation reactions as well as accommodating the subsequently deposited Li. Electrochemical tests reveal compositions and phases of lithiated AgNWs can be varied depending on external current, and the electrochemically formed Li–Ag interfaces effectively guide uniform Li deposition from both experimental and theoretical analyses. Full cells composed with thin Li-AgNW composite anodes (10 mAh/cm2) and high-loading LiFePO4 cathodes (12 mg/cm2) also demonstrate stable life over 150 cycles. These findings provide insight into fundamental Ag electrochemistry in Li cells and meanwhile highlight the great potentials of Ag-based Li anodes for practical applications.