Porous Assemblies Research Articles

Making 2D Materials Sparkle in Energy Storage via Assembly.

ConspectusTwo-dimensional (2D) materials such as graphene and MXenes offer appealing opportunities in electrochemical energy storage due to their large surface area, tunable surface chemistry, and unique electronic properties. One of the primary challenges in utilizing these materials for practical electrodes, especially those with industrial-level thickness, is developing a highly interconnected and porous conductive network. This network is crucial for supporting continuous electron transport, rapid ion diffusion, and effective participation of all active materials in electrochemical reactions. Moreover, the demand for efficient energy storage in advanced electronic devices and electric vehicles has led to the need for not only thicker but also denser electrodes to achieve compact energy storage. Traditional densification methods often compromise between volumetric capacitance and ion-accessible surface area, which can diminish rate performance. As versatile building blocks, 2D materials can overcome these limitations through the assembly into complex superstructures such as 1D fibers, 2D thin films, and 3D porous networks, a capability less attainable by other nanomaterials.This Account explores the pathways from exfoliated 2D nanosheets to densely packed, yet porous assemblies tailored for compact energy storage. Focusing on graphene and MXenes, we delve into the intricate relationships between surface structure, assembly behaviors, and electrochemical performance. We emphasize the crucial role of surface chemistry and interfacial interactions in forming stable colloidal dispersions and subsequent macroscopic structures. Furthermore, we highlight how solvents, acting as spacers, are instrumental in microstructure formation and how capillary force-driven densification is essential for creating compact assemblies. With precise control over shrinkage, the customized dense assemblies can strike a balance between high packing density and sufficient porosity, ensuring efficient ion transport, mechanical stability, and high volumetric performance across various electrochemical energy storage technologies.Furthermore, we highlight the importance of understanding and manipulating the surface chemistry of 2D materials at the atomic level to optimize their assembly and enhance electrochemical behaviors. Advanced in situ characterizations with high temporal and spatial resolution are necessary to gain deeper insights into the complex assembly process. Moreover, the integration of machine learning and computational chemistry emerges as a promising method to predict and design new materials and assembly strategies, potentially accelerating the development of next-generation energy storage systems. Our insights into the assembly and densification of 2D materials provide a comprehensive foundation for future research and practical applications in compact, high-performance energy storage devices. This exploration sets the stage for a transformative approach to overcoming the challenges of current energy storage technologies, promising significant advancements in 2D materials in the field.

Design and application of hierarchical α-Fe2O3/In2O3 heterojunction photoanode for enhanced photoelectrochemical water oxidation

α-Fe2O3 attracted great attention as a promising photoanode candidate for photoelectrochemical (PEC) H2O spitting. In this paper, one dimensional (1D) α-Fe2O3 nanorods coupled 2D porous In2O3 nanosheet assemblies were designed to construct a S-scheme α-Fe2O3/In2O3 heterojunction photoanode. The unique porous In2O3 nanosheet assemblies are conductive to improve light-harvesting efficiency and provide more active sites. An internal electric field induced at the α-Fe2O3/In2O3 heterojunction interface could promote interfacial charge separation and transfer, enhancing redox kinetics. The as-obtained 2D/1D In2O3/α-Fe2O3 photoanode achieved a stable photocurrent density of 2.2 mA cm−2 at 1.23 V (vs. RHE). It is 6.3 times higher than that of the α-Fe2O3 component, and got a max applied bias photo-to-current efficiency (ABPE) of 0.28%, which is about 5.8 times that of bare α-Fe2O3 at 1.01 V. The work provides a promising strategy to construct high-performance S-scheme heterostructure photoanodes, featuring the role of surface and interface science in sustainable energy.

(Digital Presentation) Multiscale Modeling of Two-Phase Transport in the Membrane Electrode Assembly of Polymer Electrolyte Membrane Fuel Cells: Effect of Relative Humidity and Temperature

Water management plays an important role in the performance and durability of polymer electrolyte membrane fuel cells (PEMFCs). Achieving enhanced water removal at high current density without membrane dehydration requires an optimal design of the membrane electrode assembly (MEA) and MEA-channel interaction depending on operating conditions. The analysis of two-phase transport is challenged by the wide range of pore sizes found in porous layer assemblies, varying from 1-100 nm in the catalyst layer (CL), 50-1000 nm in the microporous layer (MPL) and 10 µm in the gas diffusion layer (GDL), up to the millimeter-sized channel. In this work, a hybrid multiscale model is presented to describe two-phase transport and performance of a representative unit cell as a function of relative humidity (RH) and temperature [1-3]. A control volume (CV) decomposition is used to represent the multiscale pore space of the GDL, MPL and CL in terms of local effective transport properties (porosity, effective diffusivity, permeability, thermal/electrical conductivity and entry capillary pressure) [4]. The model incorporates a macroscopic continuum formulation for gas flow and species, energy, liquid-phase pressure, water dissolved in ionomer, and electronic and ionic potentials [5]. Liquid water transport is modeled by means of a multi-cluster invasion-percolation algorithm, which is coupled to the macroscopic continuum formulation by the phase-change source term of water (evaporation/condensation). Water clusters with a net condensation rate grow by invading the adjacent dry CV with the lowest entry capillary pressure, while clusters with a net evaporation rate shrink by drying the wet CV of the cluster with the lowest entry capillary pressure. An all-or-nothing invasion law is adopted for saturation in the GDL (one pore per CV), while a macroscopic description in terms of capillary pressure curve at the representative elementary volume scale (REV) is used for the MPL and the GDL (thousands to millions of pores per CV). An example of the saturation distribution in the cathode MEA is shown in Figure 1. Local saturation remains between 0.1-0.4 in REVs of the CL and the MPL, increasing up to 1 in macropores of the GDL. Water condenses preferentially under the ribs and transport by capillary action to the GDL/channel interface, where the water flow is released to the channel. The channel saturation remains low, around 0.1, due to the large gas flow velocity used in the differential cell.[1] P.A. García-Salaberri, Modeling diffusion and convection in thin porous transport layers using a composite continuum-network model: Application to gas diffusion layers in polymer electrolyte fuel cells, 167 (2021) 120824.[2] D. Zapardiel, P.A. García-Salaberri, Modeling the interplay between water capillary transport and species diffusion in gas diffusion layers of proton exchange fuel cells using a hybrid computational fluid dynamics formulation, J. Power Sources 520 (2022) 230735.[3] P.A. García-Salaberri, Effect of thickness and outlet area fraction of macroporous gas diffusion layers on oxygen transport resistance in water injection simulations, Transp. Porous Media 145 (2022) 413-440.[4] P.A. García-Salaberri, I.V. Zenyuk, A General-Purpose Tool for Modeling Multifunctional Thin Porous Media (POREnet): From Pore Network To Effective Property Tensors, Heliyon (2023), submitted.[5] P.A. García-Salaberri, A. Sánchez-Ramos, A numerical analysis of the effect of layer-scale and microscopic parameters of membrane electrode assembly in proton exchange fuel cells under two-phase conditions, J. Power Sources (2023), accepted. Figure 1. Saturation distribution in the cathode MEA of a PEMFC operated at 70 oC and RH=0.95 at high stoichiometric conditions. The current density is I=0.5 A cm-2.- Figure 1

Ultrasensitive and highly selective NO2 gas sensing of porous MXene nanoribbon assemblies

Nitrogen dioxide (NO2), a potential source for acid rain and photochemical smog, is known to harm human health, plant growth and crop yield, and the environment. Therefore, designing a room temperature operable NO2 gas sensor with exceptional sensitivity and selectivity is extremely important. Herein, we report that Ti3C2Tx MXene (Tx = –OH, –O, –F, etc.) nanoribbons containing inbuilt anatase TiO2 on their surfaces achieve highly sensitive detection of NO2 gas at room temperature with negligible cross-responses to other gas analytes. The MXene nanoribbons' ability to form porous gas sensor film facilitates the efficient diffusion of gas molecules and the sufficient utilization of surface-active sites, leading to a high response of −87.5 % to 50 ppm NO2 gas exposure with a response time of 9.2 s at room temperature. Signifying the low concentration NO2 detection abilities, MXene nanoribbons displayed a response of −4.4 % towards 500 ppb NO2 exposure. MXene nanoribbons' NO2 gas sensing ability is carrier gas dependent and declines monotonically as operating temperature increases. In addition, the performance comparison experiments conducted at 50 ppm NO2 gas exposure suggest that the MXene nanoribbons' response is 14.3, 1.6, and 45.3 times higher than the responses of multilayer MXene, MXene-TiO2 nanoplate, and MXene-TiO2 nanoparticle structures, respectively. The explicit selectivity and high sensitivity of MXene nanoribbons toward NO2 gas are expected to provide exciting opportunities for personal safety and environmental monitoring.

Porous interlocking assembly: performance-based dry masonry construction with digital stereotomy

Architected porosity in masonry structures can be created by transforming stock materials into a lattice of interlocking units through an automated batch process. Porous masonry forms numerous enclosed cavities for thermal performance and reduces material usage while maintaining structural integrity. This work investigates the potential and limits of digital tectonics of porous masonry through a complete process of design, manufacturing, and construction. The confluence of digital fabrication with tectonic exploration opens new dimensions unattainable by traditional stereotomy. Interlocking materials inspired by Abeille vault and digital stereotomy have made rapid progress. Following the theory of poetic construction, this work proposes that masonry construction should evoke visual or haptic enhancement through the fulfillment of pragmatic functions. We formulated a design challenge for a confined dry masonry wall for the envelope of the 2226 building. It assumes batch-cutting bespoke units out of large blocks of high-strength foam. Through a process of cutting and reassembling, the stock material is topologically expanded into a porous structure. A series of prototypes were developed to explore novel articulation, structural and thermal performance, and economical manufacturing. One can perceive the logic of porous construction through visual and haptic empathy. The materialization process interacts with the design masonry units and the interlocking mechanism. For future practice in masonry, the porosity should be planned at multiple scales (molecular scale, aggerate scale, construction scale) across the life cycle of the material.

Morphology engineering and electronic structure remodeling of manganese-incorporated VN for boosting urea-assisted energy-saving hydrogen production

Urea-assisted water electrolysis offers a promising route to reduce energy consumption for hydrogen production and meanwhile treat urea-rich wastewater. Herein, we devised a shear force-involved polyoxometalate-organic supramolecular self-assembly strategy to fabricate 3D hierarchical porous nanoribbon assembly Mn-VN cardoons. A bimetallic polyoxovanadate (POV) with the inherent structural feature of Mn surrounded by [VO6] octahedrons was introduced to trigger precise Mn incorporation in VN lattice, thereby achieving simultaneous morphology engineering and electronic structure modulation. The lattice contraction of VN caused by Mn incorporation drives electron redistribution. The unique hierarchical architecture with modulated electronic structure that provides more exposed active sites, facilitates mass and charge transfer, and optimizes the associated adsorption behavior. Mn-VN exhibits excellent activity with low overpotentials of 86 mV and 1.346 V at 10 mA/cm2 for hydrogen evolution reaction (HER) and urea oxidation reaction (UOR), respectively. Accordingly, in the two-electrode urea-assisted water electrolyzer utilizing Mn-VN as a bifunctional catalyst, hydrogen production can occur at low voltage (1.456 V@10 mA/cm2), which has the advantages of energy saving and competitive durability over traditional water electrolysis. This work provides a simple and mild route to construct nanostructures and modulate electronic structure for designing high-efficiency electrocatalysts.

Investigating the protective performance of turnout gears for firefighters under diverse exposure conditions: Effect of age and body segments

Present work investigates the impact of different exposures (flame, 50/50 convection and radiation, and radiation alone) on thermal performance of firefighters' clothing. The protective performance is evaluated across various body segments for firefighters of different ages. Transient heat transport equations are numerically discretized using finite difference approach. The computational domain comprises of a three-layer fabric assembly, a single-layer skin, and a microclimate between the fabric and skin. Heat transfer in the porous fabric assembly results from the interaction of both conduction and incident radiation penetrating through confined hot air within the fabric. The energy equation of fabric employs a two-flux model, encompassing self-emission originating from absorbed incident radiation in the encapsulated hot air. A nonlinear bioheat transfer model, accounting for age and body segment, incorporates temperature-dependent thermal conductivity, blood perfusion rate, skin thickness, and heat generation from metabolism, shivering, and external work. Results found that first and second-degree burn durations decrease by 30.85 % and 37.92 %, 26.73 % and 29.76 %, and 24.23 % and 26.63 % for flame, 50/50 convection-radiation and pure radiation heat exposure respectively as firefighter’s age from 25 to 65 years. The protective attire excels the best for the torso against direct flame but is the least effective for shielding arms from radiant heat. Moreover, the transition time from first to second-degree burn injury decreases by 64.77 %, 65.73 %, and 66.03 % for arms, and by 70.93 %, 66.29 %, and 67.22 % for legs in flame, 50/50 convective-radiative, and purely radiant heat exposures, respectively, with a 100 % reduction in skin conductivity coefficient.

Regulating the Flexibility to Assemble Porous Single-Atom Fe-Coordinated Metallopolymers for Efficient Heterogeneous Catalytic Oxidations.

Metallopolymers as organic-inorganic hybrid materials formulated by metal embedding organic polymers show great potential for novel heterogeneous catalysis, in terms of the facile structural design and tunability. Herein, the disadvantage of nonporous stacking of one-dimensional (1D) structures has been suppressed by chain modulation of the 1D metallopolymers, allowing for the convenient construction of porous assemblies with single-atom dispersion and accessible active sites. By postmodification, the Fe/CM-1 catalyst readily synthesized by coordinating the Fe(II) to the twisted chain of 1D Schiff-base polymer possesses expedient flexibility, showing the highest porosity, remarkable heterogeneous recyclability, and thus prominent catalytic activity for the selective oxidation of benzylamine and alcohols. Moreover, control experiments supported by computational studies demonstrated that the unique pincer structure of Fe/CM-1 effectively maintains the valence state of the anchored single-atom iron, facilitating single-electron transfer and promoting efficient iron redox cycling during the catalytic process. Notably, these 1D metallopolymers have the advantage of cost-effectiveness, easy preparation in gram-scale, and utilization in continuous reaction, providing inspirations for facile synthesis of efficient heterogeneous catalysts from the well-developed 1D metallopolymers.

Designing External Pores of Aluminum Oxo Polyhedrons for Efficient Iodine Capture.

Although metal-organic polyhedra (MOPs) expansion has been studied to date, it is still a rare occurrence for their porous intermolecular assembly for iodine capture. The major limitation is the lack of programmable and controllable methods for effectively constructing and utilizing the exterior cavities. Herein, the goal of programmable porous intermolecular assembly is realized in the first family of aluminum oxo polyhedrons (AlOPs) using ligands with directional H-bonding donor/acceptor pairs and auxiliary alcohols as structural regulation sites. The approach has the advantage of avoiding the use of expensive edge-directed ditopic and face-directed tritopic ligands in the general synthesis strategy of MOPs. Combining theoretical calculations and experiments, the intrinsic relationship is revealed between alcohol ligands and the growth mechanism of AlOPs. The maximum I2 uptake based on the mass gain during sorption corresponds to 2.35gg-1, representing the highest reported I2 sorption by an MOP. In addition, it can be easily regenerated and maintained the iodine sorption capacity, revealing its further potential application. This method of constructing stable and programmable porous materials will provide a new way to solve problems such as radionuclide capture.

Designing Configurable Soft Microgelsomes as a Smart Biomimetic Protocell.

Self-assembly is an intriguing aspect of primitive cells. The construction of a semipermeable compartment with a robust framework of soft material capable of housing an array of functional components for chemical changes is essential for the fabrication of synthetic protocells. Microgels, loosely cross-linked polymer networks, are suitable building blocks for protocell capsule generation due to their porous structure, tunable properties, and assembly at the emulsion interface. Here, we present an interfacial assembly of microgel-based microcompartments (microgelsomes, MGC) that are defined by a semipermeable, temperature-responsive elastic membrane formed by densely packed microgels in a monolayer. The water-dispersible microgelsomes can thermally shuttle between 10 and 95 °C while retaining their structural integrity. Importantly, the microgelsomes exhibited distinct properties of protocells, such as cargo encapsulation, semipermeable membrane, DNA amplification, and membrane-gated compartmentalized enzymatic cascade reaction. This versatile approach for the construction of biomimetic microcompartments augments the protocell library and paves the way for programmable synthetic cells.

Revealing the impact of different precursors and solvents for supramolecular complex formation and in-situ C-doping in g-C3N4 with enhanced photocatalytic H2O2 production

The reinforced light-harvesting capability suppresses photocarrier recombination and increases the specific surface area, representing the possibility of excellent photocatalytic performance for graphitic carbon nitride (CN) photocatalysts. Herein, the remarkable photocatalytic properties of porous carbon-doped g-C3N4 (CCN) were enhanced through the incorporation of a supramolecular complex, M-CA-U (melamine-cyanuric acid-urea), in DMSO as the carbon dopant source. Through the diverse characterization methods, the successful formation of the supramolecular g-C3N4 using varying polarity of solvent was verified, achieved through a simple hydrothermal/solvothermal process. The CCN-MCAU-DMSO photocatalyst achieved the maximum photocatalytic H2O2 production rate, 1.3-fold higher than other prepared samples. The outstanding performances of CCN-MCAU-DMSO were probably attributed to the extended specific surface area, robust visible light response, adjusted electronic band structure, accelerated charge separation, and limited charge recombination. The photocurrent response and photoluminescence spectroscopy analysis confirmed excellent charge carriers and separation. Overall, this work provided a new idea to design and construct high-efficiency porous supramolecular assembly of CCN photocatalysts for photocatalytic studies.

Two-Phase Flow Through the PTL of PEM Water Electrolyzer: MRI Experiments and Numerical Modeling Using Phase-Field Theory

In 2021, estimation shows that the worldwide annual hydrogen production is around 94 Mt. Exploitation of native hydrogen being not mature, it is obtained by its separation from other elements by different methods such as steam methane reforming, and electrolysis of water. The latter supplied by a renewable power source will take part in the development of a green hydrogen economy [1]. In this context, Proton Exchange Membrane (PEM) Electrolyzer is a promising technology due to its flexibility and very quick adaptation to load variations. However, its current development still confronts some limitations at a large industrial scale. For instance, efficiency and durability are directly impacted by the mass transport and electrical transfer within the porous materials at the anode side. Limitation of the water supply to the catalyst layer happens once there is a poor oxygen evacuation which decreases the performance of the device by inducing high overpotential. Furthermore, the PTL has an important role as an electrical conductor for charge transfer from the catalyst layer [1]. The efficiency of all the transport phenomena through the PTL and porous electrode assembly depends on their transport properties which are related to their microstructure and operating conditions. For instance, PTL with a large pore size allows good water and gas transport, while produced electrons choose a long-distance path generating an electrical resistance higher than that in the case of PTL with a small pore size [1]. So, controlled and optimum porosity and pore size could contribute to efficient water, gas, and electron transport. To define the best porous layers morphologies, a deep and accurate understanding of the phenomena is developed in this work by combining modeling and experiments.The magnetic resonance imaging (MRI) technique was used to quantify the water content within the porous layer during the two-phase flow. Instead of the real PTL made of titanium which is paramagnetic and cannot be used in the MRI, borosilicate filters with thickness, porosity, and pore size similar to the PTL were used. After positioning the sample in the 600 MHz vertical imager (Figure 1-A), a constant water flow rate is introduced while the gas flow rate is varied. The saturation profiles measured through the porous material depend on the gas flow rate and a semi-dryness of the sample occurs (Figure 1-B) with a residual quantity trapped between pores (minimum stable water content). The water flow rate variation in the channel does not affect saturation, but a higher gas flow rate is needed to reach a minimum stable water content for higher water flow rate.The gas pressure drop through the porous medium was measured and bubble formation in the channel was also analyzed. The results show that the pressure drops and types of flow (slug, annular, and bubble flow) depend on orientation of the water channel (horizontally and vertically) and flow direction (up or downward), and on the water and gas flow rates.To reach a better understanding of the dynamic characteristics of water and oxygen transport over the PTL, the phase-field model based on the Cahn-Hilliard theory was used to simulate the two-phase flow through a porous medium [2]. In this model, the modified Navier-Stokes equations for two phases are coupled with a phase-field equation for describing the diffuse interface. Numerical simulations performed in the COMSOL® multiphysics software were carried on 2D geometries composed of spherical solid grains of different sizes, having properties similar to the PTL used in the MRI experiments. Gas is injected on one side of the sample and flows through the porous medium initially saturated and evacuated on another side in contact with the water channel (Figure 1-C). Gas flow in the porous medium and bubble formation in the water channel are studied while varying the gas and water flow rates. The simulation results give information about the gas pathways within the porous medium and the saturation profiles over time, depending on the gas/water flow rates, which will be compared with experimental results.[1] J. Parra-Restrepo, “Caractérisation des hétérogénéités de fonctionnement et de dégradation au sein d’un électrolyseur à membrane échangeuse de protons (PEM),” Université de Lorraine, 2020.[2] J. W. Cahn and J. E. Hilliard, “Free Energy of a Nonuniform System. I. Interfacial Free Energy,” The Journal of Chemical Physics, vol. 28, no. 2, pp. 258–267, Feb. 1958. Figure 1

Multiscale Modeling of the Membrane Electrode Assembly in Polymer Electrolyte Fuel Cells: Interaction of Pore Size and Wettability of Porous Layers

Design of the membrane electrode assembly (MEA) plays a crucial role in polymer electrolyte membrane fuel cells (PEMFCs). However, predictive modeling of mass, charge and heat transport considering primary microstructural information rather than previously measured effective transport properties is challenged by the multiscale pore structure found in an MEA, which spans around 4-5 orders of magnitude (from tens of nanometers in the catalyst layer to tens of micrometers in the gas diffusion layer). It is not clear how to incorporate microstructural information to guide design, while preserving moderate computational cost (see log-scale pore size distribution in an MEA in Figure a). In this work, a 3D two-phase, non-isothermal model is presented, which combines continuum and pore network (PN) formulations in a single CFD framework. Transport at fine pore scales of the catalyst layer and the microporous layer (below 1 um) is modeled by means of a continuum bundle-of-capillary-tubes (BCT) submodel, and transport at coarse pore scales of the gas diffusion layer and manufacturing defects above 1 um (cracks, gaps, etc.) by means of a continuum-based PN submodel. The BCT submodel accounts for microscopic (<20 nm), mesoscopic (20-300 nm) and macroscopic (300 nm-1 um) pore scales considering a subdivision of pore size distributions in the integral volume-averaged formulation. The interplay between pore size distribution and wettability of the various porous layers is analyzed, with a focus on the role of microporous layer wettability and defects, depending on operating relative humidity and temperature (see water distribution in Figure b from an invasion-percolation simulation). Best design practices of porous assemblies are extracted for maximum performance from a large computational campaign, including stochastic effects from different sample realizations. Analysis of degradation phenomena will be the focus of subsequent work to determine optimal microstructures arising from a trade-off between performance and durability. Figure 1

Crystal structures and syntheses of four novel Cu(I)-MOFs with in-situ reduced of Cu(II) and highly efficient fluorescent sensor for trace nitroaromatics

Four novel Cu(I)-based metal-organic frameworks, [Cu3(p-IPIB)(CN)Cl2]n (Cu(I)-MOF-7), [Cu3(p-IPIB)(CN)Cl2]n (Cu(I)-MOF-8), [Cu3(p-IPIB)Cl3]n (Cu(I)-MOF-9) and [Cu2(p-IPIB-Cl)1/2Cl2(H2O)]n (Cu(I)-MOF-10) where ligand p-IPIB is 1,4-bis[(2-(4-(1H-imidazol -1-yl)-phenyl)-1H-imidazole-1-yl)-methyl]-benzene, have been successfully synthesized by in-situ reduction of Cu(II) under solvothermal reaction condition. Single X-ray diffraction analysis shown that Cu(I)-MOF-7 and 8 are not only structural supramolecular isomerism containing cyano-bridge which was in situ obtained from the cleavage of the CCN bond of acetonitrile solvent, but also a 3D twofold interpenetration metallo-supramolecular assembly for Cu(I)-MOF-7 and a 3D porous supramolecular assembly containing the macrometallacyclic box structure for Cu(I)-MOF-8, respectively. Cu(I)-MOF-9 is a 1D channel polymeric chain motif with macrometallacyclic structure containing [Cu3Cl3] cluster of μ3- and μ2-chloride bridge. And Cu(I)-MOF-10 is also a 3D twofold interpenetration metallo-supramolecular assembly with [Cu4Cl3(H2O)2] cluster of μ4-chloride bridge. They are thermally stable and exhibit apparent porous properties with adsorption of N2 and CO2 gas. The fluorescence sensing experiment indicated that Cu(I)-MOF 7–10 can be used for detecting nitroaromatic explosives through fluorescence quenching in the solution and they have the best sensing effects on the detection of 2,4,6-Trinitrophenol (TNP). Especially, Cu(I)-MOF-9 has the best sensing property towards TNP with a higher quenching constant of 4.53 × 104 L/mol and a lower detection limit of 1.21 ppm.

Gravity wave interaction with a composite pile-rock breakwater

Abstract Surface gravity wave interaction with a novel composite pile-rock breakwater having a stack of porous plates fixed on its top is investigated in the present study. A novel numerical code based on dual-boundary-element-method is developed to understand the wave scattering and force coefficients within framework of linearized potential flow theory. Out of the four different proposed configurations (pile-rock alone, vertical, horizontal, and H-shaped porous plate assembly with pile-rock), it is found that a novel H-shaped porous plates with submerged pile-rock are very effective in attenuating the wave energy. The parametric study for the H-shaped configuration with several key aspects like porosity of the permeable plates, submergence depth of the horizontal plate, pile-rock relative height and width of the pile-rock barriers are investigated. Increasing relative rock barrier width from 0.25-0.75 offers only a marginal reduction in wave transmission but increases the vertical wave force on the H-plate barrier almost twice. By changing relative submergence of the horizontal porous plate from, it is possible to reduce wave transmission by about 10% but at the expense of increasing vertical wave force almost 50%-75%. Increasing the pile-rock height helps to reduce the wave transmission but significantly increases horizontal wave force and moment on perforated H-shaped barrier. The results of the parametric study can be used for optimizing the dimensions of pile-rock cum porous plate wave barrier for a wide range of field conditions.

Spatial self-confinement of heterogeneous metallic CoX (X = Cu, Ni, Fe) within laminated porous carbon assemblies to efficiently activate peroxymonosulfate for tetracycline destruction

Sustainable and universal fabrication of carbon-loaded non-precious bimetallic nanocatalysts with tuned catalytic surface sites is crucially important but challengeable toward peroxymonosulfate(PMS)-motivated antibiotic degradation. We propose herein a universal, easily removable and sustainable salt template-mediated spatial self-confinement strategy to fabricate bimetallic nanoparticles deposited onto lamellar porous carbon assemblies for PMS-assisted tetracycline hydrochloride (TCH) destruction. Among CoX@C-600 (X = Cu, Ni, Fe) samples, CoCu@C-600 has the highest catalytic performance with a degradation efficiency of 98.6% and a rate constant of 0.3174 min−1 for TCH degradation via PMS motivation. The synergy between the heterogeneous metallic Co and Cu nanoparticles, unique tertiary pore structure and copious surface-exposed active sites are responsible for the high performance of CoCu@C-600. The magnetically recoverable CoCu@C-600 shows a good separation property and can be reused for five consecutive runs. Experimental and characterization results affirm the radical/non-radical (major active species of SO4•− and 1O2) and direct electron transfer mechanism. The degradation pathways and toxicity evaluation with the CoCu@C-600/PMS system are unveiled. The rational architecture design and catalytic site regulation are inspirable for universal syntheses of efficient catalysts for antibiotic degradation.

MOF-derived Porous Carbon Nanofiber Assembly as High Efficiency ORR Electrocatalysts for Zinc-air Batteries

MOF-derived Porous Carbon Nanofiber Assembly as High Efficiency ORR Electrocatalysts for Zinc-air Batteries

Novel Sol-Gel Synthesis of TiO2 Spherical Porous Nanoparticles Assemblies with Photocatalytic Activity.

For this study, the synthesis of TiO2 nanomaterials was performed via a novel sol-gel method employing titanium butoxide as a metal precursor, Pluronic F127 as a templating agent, toluene as a swelling agent, and acidic water or ethanol as the reaction solvents. The method was designed by tailoring certain reaction parameters, such as the sequence of toluene addition, magnetic stirring, the type of reaction solvent, and the calcination conditions. Analysis of the specific surface area and porosity was carried out via N2 physisorption, whereas the morphological features of the solids were investigated via transmission electron microscopy. The crystalline structure of both the dried powders and the calcined materials was evaluated using X-ray diffraction analysis. It transpired that the different phase compositions of the solids are related to the specific synthesis medium employed. Under the adopted reaction conditions, ethanol, which was used as a reaction solvent, promoted the local arrangement of dispersed anatase particles, the specific arrangement of which does not lead to rutile transformation. Conversely, the use of water alone supported high-particle packing, evolving into a rutile phase. The photodegradation of Rhodamine B was used as a target reaction for testing the photocatalytic activity of the selected samples.

Construction of 2D metal-organic precursor networks with tunable porosity: A Monte Carlo simulation approach

Two-dimensional network structures comprising functional organic building blocks have been recently recognized as promising platforms for various physio-chemical processes running in confined spaces. In this study, we present theoretical results of the self-assembly of metal-organic precursor networks on a crystalline surface and provide quantitative characteristics of these planar architectures. To that end, a coarse-grained model of the adsorbed overlayer comprising halogenated polyaromatic aromatic hydrocarbon (PAH) molecules and bivalent metal atoms was used in combination with the equilibrium Monte Carlo (MC) simulation method. Our calculations focused on the effect of molecular features, such as size, shape and distribution of halogen substituents in the PAH monomer, on the quality and morphology of the networks formed on a model (111) crystalline surface. For the simulated porous assemblies, representing the precursor stage of the surface-assisted Ullmann coupling reaction, such descriptors as the unit cell parameters, radial distribution functions, pore size distributions and structure factors were determined. The obtained results demonstrated that fine-tuning of the monomeric PAH units enables the creation of periodic and aperiodic networks having diverse porous properties, ranging from monoporous to heteroporous with bi- and multimodal pore-size distributions. The findings of our theoretical investigations, apart from the potential application in the optimization of 2D polymeric networks, can also be helpful in designing real confined nanoenvironments for selective capture and immobilization/transformation of guest species.

Precisely Designed Difunctionalized Cyclodextrin Produces a Solid-State Organic Porous Hierarchical Supramolecular Assembly.

Regioselective di-functionalization of a cyclodextrin allows hydrophobic domains to be directed in a geometrically controlled manner. This controlled orientation ultimately gives access to an original hierarchical assembly in the solid state. This assembly spans over three levels of hierarchy which are governed by synergistic host-guest inclusions, directed hydrophobic effect and hydrogen bonding. This combination of interactions precisely positioned in space through regioselective functionalization of a cyclodextrin creates a porous organic architecture.