Inherent Porosity Research Articles

Synergistic effect of Al2O3 and MoS2 on the corrosion behaviour of plasma sprayed aluminium matrix composite coating

In this study, the incorporation of alumina (Al2O3) and molybdenum disulfide (MoS2) in Aluminium (Al) was successfully fabricated through shroud plasma spray. This strategic incorporation of MoS2 and Al2O3 effectively fills voids, leading to a remarkable reduction in inherent porosity within the aluminium coating, achieving an impressive ∼76.54 % reduction. These composite coatings exhibited outstanding hydrophobicity (contact angle ∼119°), signifying remarkable water repellency and anti-corrosion properties compared to bare aluminium (contact angle ∼81.7°). During the electrochemical corrosion test, the corrosion rates (CR) of Al coating (CR = 9.14 mpy) was notably around 23 times higher compared to MoS2 and Al2O3 reinforced aluminium composite coating (CR = 0.372 mpy) in a 3.5 wt % NaCl electrolyte. The subsequent post-corrosion analysis further confirmed the composite coating's efficiency in mitigating the impact of corrosive salts, underlining the effectiveness of the hybrid coating in combating corrosion attacks. A corrosion behaviour prediction model was established based on computational and experimental data.

Influence of Build Height on Quality of Additively Manufactured Thermoplastic Polyurethane Parts

Due to geometrical degrees of freedom, low cost, and ease of realizing complex structures, polymer additive manufacturing (AM) has emerged exceptionally well. Even with rapid evolutionary growth, AM lacks sound quality mainly including inherent porosity and surface roughness compared to their counterparts (conventional manufacturing processes) due to the involvement of several printing parameters in AM processes. This quality‐based comparative assessment presents the influence of build/layer height on the porosity (using micro‐X‐ray computed tomography) and surface roughness (in build direction) of additively manufactured thermoplastic polyurethane (due to its versatile properties in applications like wearable electronics and biomedical) using three different polymer AM processes namely selective laser sintering, fused deposition modeling, and stereolithography. Along with porosity, an in‐depth pore characterization is also performed to understand the geometrical feature and severity of pores present in each sample of the AM process. Results are compared finally to make concluding remarks.

Resistive Memristors Using Robust Electropolymerized Porous Organic Polymer Films as Switchable Materials.

Porous organic polymers (POPs) with inherent porosity, tunable pore environment, and semiconductive property are ideally suitable for application in various advanced semiconductor-related devices. However, owing to the lack of processability, POPs are usually prepared in powder forms, which limits their application in advanced devices. Herein, we demonstrate an example of information storage application of POPs with film form prepared by an electrochemical method. The growth process of the electropolymerized films in accordance with the Volmer-Weber model was proposed by observation of atomic force microscopy. Given the mechanism of the electron transfer system, we verified and mainly emphasized the importance of porosity and interfacial properties of porous polymer films for memristor. As expected, the as-fabricated memristors exhibit good performance on low turn-on voltage (0.65 ± 0.10 V), reliable data storage, and high on/off current ratio (104). This work offers inspiration for applying POPs in the form of electropolymerized films in various advanced semiconductor-related devices.

Activated carbon and their nanocomposites derived from vegetable and fruit residues for water treatment

Water pollution remains a pressing environmental issue, with diverse pollutants such as heavy metals, pharmaceuticals, dyes, and aromatic hydrocarbon compounds posing a significant threat to clean water access. Historically, biomass-derived activated carbons (ACs) have served as effective adsorbents for water treatment, owing to their inherent porosity and expansive surface area. Nanocomposites have emerged as a means to enhance the absorption properties of ACs, surpassing conventional AC performance. Biomass-based activated carbon nanocomposites (ACNCs) hold promise due to their high surface area and cost-effectiveness. This review explores recent advancements in biomass-based ACNCs, emphasizing their remarkable adsorption efficiencies and paving the way for future research in developing efficient and affordable ACNCs. Leveraging real-time communication for ACNC applications presents a viable approach to addressing cost concerns.

Influence of the colloidal nano silica on the bonding of new-to-old concrete interface

The quality of the interface between new and existing concrete is a crucial factor that significantly affects the effectiveness of concrete patching and rehabilitation. This transitional zone between concrete layers exhibits inherent porosity and diminished structural integrity, which can potentially serve as the origin of cracks and fractures. The presented study was conducted to evaluate the quality of the new-to-old concrete interface when colloidal nano silica (CNS) is used. Apart from directly blending CNS with concrete materials, this study uniquely employed CNS as a surface agent to enhance the quality of the interface. The microstructure, mechanical bonding performance and chloride resistance property were evaluated on samples with new-to-old interface. By microstructural analysis, it was found that the porosity at the interface region was reduced from 24% to less than 16% when CNS was directly added into the concrete. Due to the improved hydration and the formation of a denser and uniform interface, a higher bonding strength was therefore achieved. Improvement in bonding strength was also found when CNS was used as an agent on the surface of the old layer, due to the precipitation and pozzolanic reaction of the nano silica particles. There were no apparent signs of increased porosity at the interface region as the precipitation of nano silica particles densified the cement matrix. Additionally, the solid precipitates generated frictional force, increasing the bonding strength under shearing loading. However, due to the lack of cohesion, the nano silica precipitates couldn’t sustain the tension under flexural test. Durability evaluation showed that the chloride resistance of the double-layer sample was effectively enhanced as the quality of the interface was improved with the use of CNS, especially when the surface method was used. The outcome of this study provides insight into the use of low CNS dosage to improve the new-to-old concrete interface and sheds light on the use of CNS as an interface agent.

Valorization of Crab Shells as Potential Sorbent Materials for CO2 Capture.

This study delves into the potential advantage of utilizing crab shells as sustainable solid adsorbents for CO2 capture, offering an environmentally friendly alternative to conventional porous adsorbents, such as zeolites, silicas, metal-organic frameworks (MOFs), and porous carbons. The investigation focuses on crab shell waste, which exhibits inherent natural porosity and N-bearing groups, making them promising candidates for CO2 physisorption and chemisorption applications. Selective deproteinization and demineralization treatments were used to enhance textural properties while preserving the natural porous structure of the crab shells. The impact of deproteinization and demineralization treatments on CO2 adsorption and speciation at the atomic scale, via solid-state NMR, and correlated findings with textural properties and biomass composition were investigated. The best-performing sample exhibits a surface area of 36 m2/g and a CO2 adsorption capacity of 0.31 mmol/g at 1 bar and 298 K, representing gains of ∼3.5 and 2, respectively, compared to the pristine crab shell. These results underline the potential of fishing industry wastes as a cost-effective, renewable, and eco-friendly source to produce functional porous adsorbents.

Halfa grass assembled double-layered hydrogel evaporator for sunlight-driven steam generation and selective uranium extraction

Fresh drinking water and energy are crucial for the human society to live in a sustainable way, and both of these could be attained from the seawater. Herein, we designed a double-layered hydrogel evaporator (PCG@FCG) by using calcined carbon fiber derived from halfa grass (Desmostachya bipinnata) as a light absorbing photothermal material. The bottom hydrophilic layer composed of chitosan (CS), carboxy methyl cellulose (CMC), and amidoxime-modified chitosan (AOC), which helps in water transport to the upper surface of evaporator. The amidoxime modified chitosan helps in selective binding and recovery of uranium from the seawater. Such a judiciously designed PCG@FCG evaporator shows light absorbance of 96 %, stable evaporation rate of 2.0 kg m−2 h−1, having an outstanding selective uranium recovery of 325 mg g−1 under one sun irradiation. These outcomes result from the inherent structural porosity, enhanced evaporation rate, and selectively designed uranium binding sites. In addition, excellent salt-mitigating ability to promote uninterrupted evaporation, ability to purify the organic-contaminated wastewater/seawater endow the PCG@FCG evaporator with efficient seawater desalination ability and selective adsorption of uranium from the seawater. Overall, this innovatively-designed floating evaporator offers a sustainable approach to utilize the lavish resources in the seawater.

A machine-learning based approach to estimate acoustic macroscopic parameters of porous concrete

Porous concrete with expanded clay inherent porosity makes it an interesting and effective acoustic material, applied in numerous scenarios such as highways, airports and architectural structures, due to its capacity to mitigate noise pollution, by absorbing and damping sound waves. It is usually accepted that macroscopic properties such as open porosity, tortuosity or airflow resistivity of such materials play a fundamental role in the definition of the internal absorption process. This study explores the application of tailored artificial neural networks (ANNs) for predicting first the macroscopic properties (open porosity, tortuosity and airflow resistivity) and then the sound absorption coefficient (α) of these porous concrete mixtures, using only two input parameters (size class of the expanded clay and density of the test specimens). The results demonstrate the efficacy of the proposed ANN approach in accurately predicting macroscopic properties and the sound absorption coefficient of these mixtures, making it possible to obtain such important parameters in an effective and much simpler way.

A Novel Method to Enhance the Mechanical Properties of Polyacrylonitrile Nanofiber Mats: An Experimental and Numerical Investigation.

This study addresses the challenge of enhancing the transverse mechanical properties of oriented polyacrylonitrile (PAN) nanofibers, which are known for their excellent longitudinal tensile strength, without significantly compromising their inherent porosity, which is essential for effective filtration. This study explores the effects of doping PAN nanofiber composites with varying concentrations of polyvinyl alcohol (PVA) (0.5%, 1%, and 2%), introduced into the PAN matrix via a dip-coating method. This approach ensured a random distribution of PVA within the nanofiber mat, aiming to leverage the synergistic interactions between PAN fibers and PVA to improve the composite's overall performance. This synergy is primarily manifested in the structural and functional augmentation of the PAN nanofiber mats through localized PVA agglomerations, thin films between fibers, and coatings on the fibers themselves. Comprehensive evaluation techniques were employed, including scanning electron microscopy (SEM) for morphological insights; transverse and longitudinal mechanical testing; a thermogravimetric analysis (TGA) for thermal stability; and differential scanning calorimetry (DSC) for thermal behavior analyses. Additionally, a finite element method (FEM) analysis was conducted on a numerical simulation of the composite. Using our novel method, the results demonstrated that a minimal concentration of the PVA solution effectively preserved the porosity of the PAN matrix while significantly enhancing its mechanical strength. Moreover, the numerical simulations showed strong agreement with the experimental results, validating the effectiveness of PVA doping in enhancing the mechanical properties of PAN nanofiber mats without sacrificing their functional porosity.

2-Pyran-4-Ylidene Malononitrile Based Conjugated Microporous Polymers as Metal-Free Heterogeneous Photocatalysts for Organic Synthesis.

Photoactive conjugated microporous polymers (CMPs) as heterogeneous photocatalysts provide a sustainable alternative to classical metal-based semiconductor photosensitizers. However, previously reported CMPs are typically synthesized through metal catalyzed coupling reactions, which bears product separation, but also increases the price of materials. Herein, a new type of sp2 carbon linked DCM-CMPs are successfully designed and synthesized by organic base catalyzed Knoevenagel reaction using 2,6-Dimethyl-4H-pyran-4-ylidene-malononitrile and aromatic polyaldehydes as monomers. The new polymers feature inherent porosity, excellent stability, and fully π-conjugated skeleton with broad visible-light absorption. They effectively induce the synthesis of benzimidazole compounds under light irradiation, and exhibit wide substrate adaptability with outstanding recyclability.

Multilayered Fe3O4@(ZIF-8)3 combined with a computer-vision-enhanced immunosensor for chloramphenicol enrichment and detection

The misuse and overuse of chloramphenicol poses severe threats to food safety and human health. In this work, we developed a magnetic solid-phase extraction (MSPE) pretreatment material coated with a multilayered metal–organic framework (MOF), Fe3O4 @ (ZIF-8)3, for the separation and enrichment of chloramphenicol from fish. Furthermore, we designed an artificial-intelligence-enhanced single microsphere immunosensor. The inherent ultra-high porosity of the MOF and the multilayer assembly strategy allowed for efficient chloramphenicol enrichment (4.51 mg/g within 20 min). Notably, Fe3O4 @ (ZIF-8)3 exhibits a 39.20% increase in adsorption capacity compared to Fe3O4 @ZIF-8. Leveraging the remarkable decoding abilities of artificial intelligence, we achieved the highly sensitive detection of chloramphenicol using a straightforward procedure without the need for specialized equipment, obtaining a notably low detection limit of 46.42 pM. Furthermore, the assay was successfully employed to detect chloramphenicol in fish samples with high accuracy. The developed immunosensor offers a robust point-of-care testing tool for safeguarding food safety and public health.

Granular Hydrogels Improve Myogenic Invasion and Repair after Volumetric Muscle Loss.

Skeletal muscle injuries including volumetric muscle loss (VML) lead to excessive tissue scarring and permanent functional disability. Despite its high prevalence, there is currently no effective treatment for VML. Bioengineering interventions such as biomaterials that fill the VML defect to support cell and tissue growth are a promising therapeutic strategy. However, traditional biomaterials developed for this purpose lack the pore features needed to support cell infiltration. The present study investigates for the first time, the impact of granular hydrogels on muscle repair - hypothesizing that their flowability will permit conformable filling of the defect site and their inherent porosity will support the invasion of native myogenic cells, leading to effective muscle repair. Small and large microparticle fragments are prepared from photocurable hyaluronic acid polymer via extrusion fragmentation and facile size sorting. In assembled granular hydrogels, particle size and degree of packing significantly influence pore features, rheological behavior, and injectability. Using a mouse model of VML, it is demonstrated that, in contrast to bulk hydrogels, granular hydrogels support early-stage (satellite cell invasion) and late-stage (myofiber regeneration) muscle repair processes. Together, these results highlight the promising potential of injectable and porous granular hydrogels in supporting endogenous repair after severe muscle injury.

Designing a Se-intercalated MOF/MXene-derived nanoarchitecture for advancing the performance and durability of lithium-selenium batteries

Lithium-selenium batteries have emerged as a promising alternative to lithium-sulfur batteries due to their high electrical conductivity and comparable volume capacity. However, challenges such as the shuttle effect of polyselenides and high-volume fluctuations hinder their practical implementation. To address these issues, we propose synthesizing Fe-CNT/TiO2 catalyst through high-temperature sintering of an amalgamated nanoarchitecture of carbon nanotubes decorated metal–organic framework (MOF) and MXene, optimized for efficient selenium hosting, leveraging the distinctive physicochemical properties. The catalytic features inherent in the porous Se@Fe-CNT/TiO2 nanoarchitecture were instrumental in promoting efficient ion and electron transport, and lithium-polyselenide kinetics, while its inherent porosity could play a crucial role in inhibiting electrode stress during cycling. This nanoarchitecture exhibits remarkable battery performance, retaining 99.7% of theoretical capacity after 425 cycles at 0.5 C rate and demonstrating 95.8% capacity retention after 2000 cycles at 1 C rate, with ∼100% Coulombic efficiency. Additionally, the Se@Fe-CNT/TiO2 electrode exhibited an impressive recovery of 297.5 mAh/g (97.9%) capacity after undergoing 450 cycles at a charging rate of 10 C and a discharging rate of 1 C. This synergistic integration of MOF- and MXene-derived materials unveils new possibilities for high-performance and durable LSeBs, thus advancing electrochemical energy storage systems.

Metal-free thiophene-based covalent organic frameworks achieve efficient photocatalytic hydrogen evolution by accelerating interfacial charge transfer

Photocatalysis is widely recognized as an efficient and environmentally friendly pathway for the conversion of solar energy into chemical energy. In recent years, designing efficient hydrogen evolution to obtain green clean energy has been one of the major challenges faced by researchers. Covalent organic frameworks (COFs) are considered as new and effective photocatalyst due to the inherent porosity, high crystallinity and structural adjustability. In this study, two metal-free thiophene-based covalent organic frameworks (JLNU-308 and JLNU-309) were constructed by solvothermal method through effective modulation sites. Because JLNU-COFs has a narrow band gap and good absorption capacity in the spectral range, the interfacial charge transfer speed is accelerated to solve the problem of low charge separation efficiency. Remarkably, JLNU-309 displays an impressive hydrogen evolution rate of 2868.57 μmol g−1 h−1 under visible light irradiation (λ > 420 nm). The superior hydrogen evolution reaction (HER) activity is due to the triazine units, which have high visible light absorption capacity, one-dimensional nanochannels of two-dimensional COFs and synergy with charge mobility. The photoelectrochemical measurements and calculation of density functional theory (DFT) supports the accuracy of the experiment. This work opens an avenue for constructing functional covalent organic frameworks for environmentally relevant critical applications. In addition, the simple synthesis process, excellent activity and high chemical stability indicate that JLNU-COFs are promising photocatalytic hydrogen production materials.

A Highly‐Flexible and Breathable Photo‐Thermo‐Electric Membrane for Energy Harvesting

AbstractPhoto‐thermo‐electric (PTE) technology is a simple but sustainable method that directly converts solar energy into electricity. However, the manufacturing of flexible and breathable PTE generators for practical applications, such as intelligent wearable and self‐powered sensors, poses significant challenges due to the rigid thermoelectric materials and unbreathable substrates. Here, a highly‐flexible and breathable photo‐thermal‐electric membrane (FB‐PTEM) is developed by magnetron sputtering (MS) on a photo‐thermal nanofiber membrane. A single unit of FB‐PTEM produced an open‐circuit voltage of 0.52 V under 1 sun (100 mW cm−2) and 0.2 V under LED illumination, making it suitable for all‐weather use. The photo‐thermal nanofiber membrane exhibited high photo‐thermal conversion capacity of reaching 70 °C within 50 s under 1 sun irradiation. The FB‐PTEM with a thickness of 0.35 mm achieved a self‐temperature difference of 20.6 °C under 1 sun with the low thermal conductivity of the nanofiber membrane. Furthermore, it has a vapor permeability of 14.6 kg m−2 d−1 due to the inherent high porosity of the nanofiber membranes. The FB‐PTEM demonstrates great potential for the development of highly flexible thermoelectric materials, as it encompasses various advantageous features such as self‐temperature difference, lightweight design, high breathability, and all‐weather suitability.

Effect of Tautomerization on Water Desalination by Covalent Organic Frameworks

Covalent organic frameworks (COFs) have gained increasing interest as promising building blocks for desalination membranes due to their inherent porosity. Efforts have been made to prepare COF membranes and explore their transport mechanisms, however the effect of tautomerization has not been reported. Using non-equilibrium molecular dynamics, we discover here that a mere 0.5-Å atomic displacement between two tautomers of an imine-based COF (TpHZ) can surprisingly lead to dramatic changes in the desalination behavior of their multilayers. The tautomeric transformation (from TpHZ-NH to TpHZ-OH) improves the water permeability by about 1.6–3 times. The interior resistance rather than the entrance resistance is found to dominate the water transport. The weaker adhesion and the smoother channel path of TpHZ-OH result in a much lower interior resistance. Furthermore, NaCl rejection increases from ∼ 89 % to 100 % due to the stronger sieving effect resulting from the reduced compensatory effect of TpHZ-OH for ion hydrations.

Cellulose acetate-based electrospun nanofiber aerogel with excellent resilience and hydrophobicity for efficient removal of drug residues and oil contaminations from wastewater

Cellulose acetate (CA)-based electrospun nanofiber aerogel (ENA) has drawn extensive attention for wastewater remediation due to its unique separation, inherent porosity and biodegradability. However, the low mechanical strength, poor durability, and limited adsorption ability hinder its further applications. We herein propose using silane-modified ENA, namely T-CA@Si@ZIF-67 (T-ENA), with enhanced resilience, hydrophobicity, durability and hetero-catalysis to remediate a complex wastewater containing oil and drug residues. The robust T-ENA was fabricated by pre-doping tetraethyl orthosilicate (TEOS) and ligand in its spinning precursors, followed by in-situ anchoring of porous ZIF-67 on the electrospun nanofibers (ENFs) via seeding method before freeze-drying and thermal curing (T). Results show that the T-ENA displays enhanced mechanical stability/resilience and hydrophobicity without compromise of its high porosity (>98 %) and low density (10 mg/cm3) due to the silane cross-linking. As a result, the hydrophobic T-ENA shows over 99 % separation efficiency towards different oil-water solutions. Meanwhile, thanks to the enhanced adsorption-catalytic ability and the activation of peroxymonosulfate (PMS) from the porous ZIF-67, fast degradation of carbamazepine (CBZ) residue in the wastewater can be achieved within 20 min. This work might provide a novel strategy for developing CA aerogels to remove organic pollutants.

Promoting CO2 electroreduction activity of porphyrinic conjugated microporous polyanilines via accelerating proton transfer dynamics

Conjugated microporous polymers (CMPs) with π-conjugated framework, inherent porosity and tunable structure have been considered as the promising platforms as electrocatalysts for carbon dioxide reduction reaction (CO2RR). Promoting the proton...

Analyzing the charge contributions of metal-organic framework derived nanosized cobalt nitride/carbon composites in asymmetrical supercapacitors.

Metal-organic framework derived nanostructures have recently received research attention owing to their inherent porosity, stability, and structural tailorability. This work involves the conversion of zeolitic imidazolate frameworks (ZIFs) into cobalt nitride nanoparticles embedded within a porous carbon matrix (Co4N/C). The as-prepared composite shows great synergy by providing a high surface area and efficient charge transfer, showcasing outstanding electrochemical performance by providing a specific capacitance of 313 F g-1. Moreover, we meticulously conducted calculations to derive the most precise values for the surface contribution, a crucial aspect often overlooked in existing literature, thereby ensuring the reliability of our calculated measurements. Correct calculations of surface and diffusion charge contributions are necessary for evaluating the overall electrochemical performance of supercapacitors. For practical utility, we successfully assembled an asymmetrical supercapacitor employing the Co4N/carbon composite as the negative electrode that achieved an impressive energy density of 26.6 W h kg-1 at a power density of 0.36 kW kg-1. This study opens up new avenues for investigating the use of other metal nitride nanoparticles embedded in carbon structures for various energy storage applications.

Activated carbon fibers functionalized with superhydrophilic coated pDA/TiO2/SiO2 with photoluminescent self-cleaning properties for efficient oil-water separation

The adhesion of high-viscosity oil contamination poses limitations on three-dimensional (3D) materials' practical use in treating oilfield-produced water (OPW). In this study, we developed a hybrid pDA/TiO2/SiO2 coating (PTS) on the surface of hydrophilic activated carbon (ACF1) through a combination of dopamine (DA) polymerization, ethyl orthosilicate (TEOS) hydrolysis, and the condensation of TiO2 nanoparticles (NPs) with SiO2 NPs. This coating was designed for gravity-based oil-water separation. The inherent porosity and generous pore size of ACF1-PTS conferred it an ultra-high permeation flux (pure water flux of 3.72 × 105 L∙m−2∙h−1), allowing it to effectively separate simulated oil-water mixtures and oil-water emulsions while maintaining exceptional permeation flux and oil rejection efficiency. When compared to cleaning methods involving ethanol aqueous solutions and NaClO, ultraviolet (UV) illumination cleaning proved superior, enabling oil-contaminated ACF1-PTS to exhibit remarkable flux recovery efficiency and oil-removal capabilities during cyclic separation of actual OPW. Furthermore, the ACF1-PTS material demonstrated impressive stability and durability when exposed to acidic environments (acid, alkali, and salt), robust hydraulic washout conditions, and 25-cycle tests. This study offers valuable insights and research avenues for the development of highly efficient and environmentally friendly 3D oil-water separation materials for the actual treatment of OPW.