Tailorable Porosity Research Articles

Rationally tailored configuration of multifunctional scavengers by encapsulating nanoscale Fe0 and FeS into zeolite imidazole framework–8 with reinforced perrhenate/pertechnetate confinement

In order to probe into the potential application prospects of multifunctional scavengers in remediating nuclear wastewater, we combined versatile functionality of nanoscale Fe0 and FeS with tailorable porosity of zeolitic imidazole frameworks–8 (ZIF–8) to manufacture two multifunctional scavengers for ReO4– confinement i.e., NZVI@ZIF–8 by reduction approach and FeS@ZIF–8 by coprecipitation approach. Batch approaches unveiled that as–manufactured scavengers illustrated an reinforced performance towards ReO4– confinement. The pseudo-second-order model was well simulated with the kinetic of ReO4– confinement. Thermodynamic analysis unraveled that ReO4– confinement was endothermic and spontaneous. The mechanism was explored via characterization alters of structure and composition of NZVI@ZIF–8 and FeS@ZIF–8 before and after ReO4– confinement. Specifically, fourier transform infrared spectrometer (FTIR) and X-ray diffraction (XRD) indicated that NZVI and FeS were successfully encapsulated into ZIF–8, and NZVI@ZIF–8 and FeS@ZIF–8 remained stable after ReO4– confinement. X–ray absorption fine structure (XAFS) unveiled that various Fe mineral phases were formed on the scavenger surfaces under various reaction conditions. X-ray photoelectron spectroscopy (XPS) unraveled existence of Re(VI)/Re(IV) on scavengers surfaces, unveiling ReO4– was initially enriched NZVI@ZIF–8 and FeS@ZIF–8 surfaces with subsequent reduction into Re(VI)/Re(IV). This work proposed an innovative perspective to tailored multifunctional scavengers in nuclear waste management.

Leveraging porosity and morphology in hierarchically porous carbon microtubes for CO2 capture and separation from humid flue gases

Leveraging porosity, surface chemistry and morphology of porous carbons play a critical role in CO2 capture performance. However, the effective and sustainable synthesis of porous carbons with well-interconnected hierarchical pore structure, high-proportioned micropores and high yield remains a huge challenging by a mild one-step chemical activation without damaging the natural unique nanostructure. Here, we proposed a green and sustainable strategy to fabricate porous carbons with tailorable porosity and unique tubular structure by an inorganic dynamic porogen of CuCl2. The dynamic activation mechanism of CuCl2 was explored in detail. In particular, the hierarchical porosity with a high-proportioned narrow micropores can be finely tuned without sacrificing the natural tubular morphology. Importantly, the resultant porous carbon adsorbents have an excellent resistance to water vapor, which can capture CO2 from humid flue gases with satisfactory adsorption capacity and selectivity. The HPCM-3 can achieve the best CO2 uptakes of 4.05 and 2.05 mmol/g under 100 kPa at 25 and 50 °C, respectively. Such superior CO2 adsorption behaviors can be well maintained even at high humidity of 70 %, and hardly decay with the enhancement of humidity. This route provides a promising avenue for developing the practical trace CO2 carbon-based adsorbents on a large scale to sieve CO2 from humid flue gases.

Interconnected Nanoporous Polysulfone by the Self-Assembly of Randomly Linked Copolymer Networks and Linear Multiblocks.

Porous materials have attracted considerable attention due to their versatile applications, especially in water purification. Interconnected nanoporous structures are distinguished by their high degree of porosity and resistance to clogging, as well as their insensitivity to nanostructural orientation. Previous works on randomly linked copolymer systems have shown that they can effectively produce disordered cocontinuous nanostructures, which upon removal of one component yield interconnected nanoporous materials. However, the cocontinuous nanomaterials previously developed using polystyrene (PS) and poly(d,l-lactic acid) (PLA) strands, and the resulting interconnected nanoporous PS monoliths, were far too brittle to enable practical use as membranes. Here, we study the self-assembly of randomly linked copolymer networks prepared using blocks of the engineering polymer polysulfone (PSU). A wide cocontinuous regime (spanning 40 wt %) was found for randomly end-linked copolymer networks (RECNs) constructed from PSU and PLA strands, via a combination of mechanical testing, gravimetry, small-angle X-ray scattering, and scanning electron microscopy. The PSU/PLA cocontinuous nanomaterial with symmetric composition showed 2.4 times higher Young's modulus and ∼100 times greater toughness than the corresponding PS/PLA sample. The interconnected nanoporous PSU fabricated after etching of PLA even exhibited 1.6 times greater toughness than PS/PLA prior to PLA removal. To facilitate the production of thin films of cocontinuous nanomaterials, we applied solution-processable randomly linked linear PSU/PLA multiblock polymers onto ultrafiltration membranes. The interconnected nanoporous PSU thin film generated by etching PLA was found to effectively reject 50 nm diameter particles without significantly compromising permeability. This discovery presents a valuable addition to the existing techniques used to fabricate PSU membranes. In contrast to traditional methods, which are sensitive to processing conditions, produce a wide range of pore sizes, and offer limited adjustability of pore size, the current technique is anticipated to enable interconnected PSU membranes with more uniform and tailorable porosity.

Porous Titanium for Medical Implants

Porous titanium and its alloys have shown immense promise as orthopedic and dental implant materials owing to their outstanding properties, namely tailorable porosity, the ability of blood vessels and bone ingrowth, the transport of nutrients and/or biofluids, and vascularization. The previously mentioned properties facilitate osseointegration, a crucial device integration and stability factor. The presented review investigates the influence of pore characteristics of porous titanium and its alloys (e.g., size, shape, interconnectivity, and gradients) on biological response, mechanical properties, and key considerations in scaffold design. Recent literature showed that the progress of porous titanium and its alloys is summarized in biomaterials, specifically the processing techniques utilized in fabricating porous. Accordingly, recent advances in the previously stated processing techniques are powder metallurgy, additive manufacturing, plasma spraying, etc., which are applied in constructing optimized porous architectures. Overall, porous titanium structures with controlled porosity and tailored pore networks can promote bone ingrowth and long-term stability, thereby overcoming the limitations of traditional dense titanium (Ti) implants.

Isoreticular Expansion and Linker-Enabled Control of Interpenetration in Titanium-Organic Frameworks.

Titanium-organic frameworks offer distinctive opportunities in the realm of metal-organic frameworks (MOFs) due to the integration of intrinsic photoactivity or redox versatility in porous architectures with ultrahigh stability. Unfortunately, the high polarizing power of Ti4+ cations makes them prone to hydrolysis, thus preventing the systematic design of these types of frameworks. We illustrate the use of heterobimetallic cluster Ti2Ca2 as a persistent building unit compatible with the isoreticular design of titanium frameworks. The MUV-12(X) and MUV-12(Y) series can be all synthesized as single crystals by using linkers of varying functionalization and size for the formation of the nets with tailorable porosity and degree of interpenetration. Following the generalization of this approach, we also gain rational control over interpenetration in these nets by designing linkers with varying degrees of steric hindrance to eliminate stacking interactions and access the highest gravimetric surface area reported for titanium(IV) MOFs (3000 m2 g-1).

Stimuli-Responsive Design of Metal-Organic Frameworks for Cancer Theranostics: Current Challenges and Future Perspective.

Scientific fraternity revealed the potential of stimuli-responsive nanotherapeutics for cancer treatment that aids in tackling the major restrictions of traditionally reported drug delivery systems. Among stimuli-responsive inorganic nanomaterials, metal-organic frameworks (MOFs) have transpired as unique porous materials displaying resilient structures and diverse applications in cancer theranostics. Mainly, it demonstrates tailorable porosity, versatile chemical configuration, tunable size and shape, and feasible surface functionalization, etc. The present review provides insights into the design of stimuli-responsive multifunctional MOFs for targeted drug delivery and bioimaging for effective cancer therapy. Initially, the concept of cancer, traditional cancer treatment, background of MOFs, and approaches for MOFs synthesis have been discussed. After this, applications of stimuli-responsive multifunctional MOFs-assisted nanostructures that include pH, light, ions, temperature, magnetic, redox, ATP, and others for targeted drug delivery and bioimaging in cancer have been thoroughly discussed. As an outcome, the designed multifunctional MOFs showed an alteration in properties due to the exogenous and endogenous stimuli that are beneficial for drug release and bioimaging. The several reported types of stimuli-responsive surface-modified MOFs revealed good biocompatibility to normal cells, promising drug loading capability, target-specific delivery of anticancer drugs into cancerous cells, etc. Despite substantial progress in this field, certain crucial issues need to be addressed to reap the clinical benefits of multifunctional MOFs. Specifically, the toxicological compatibility and biodegradability of the building blocks of MOFs demand a thorough evaluation. Moreover, the investigation of sustainable and greener synthesis methods is of the utmost importance. Also, the low flexibility, off-target accumulation, and compromised pharmacokinetic profile of stimuli-responsive MOFs have attracted keen attention. In conclusion, the surface-modified nanosized design of inorganic diverse stimuli-sensitive MOFs demonstrated great potential for targeted drug delivery and bioimaging in different kinds of cancers. In the future, the preference for stimuli-triggered MOFs will open a new frontier for cancer theranostic applications.

Hierarchically Nanoporous Carbon for CO2 Capture and Separation: Roles of Morphology, Porosity, and Surface Chemistry

Nanoporous carbons, as promising adsorbents for CO2 capture and separation from flue gas, span the major challenge of optimizing the physicochemical property to meet the need of CO2 capture and separation. Herein, we rationally engineered sustainable nanoporous carbons with tailorable porosity and rich surface chemistry using an activating agent of small-molecule organic acids. The porosity could be easily tailored by varying the activation temperature and activator dosage. The surface chemistry and morphology could be tuned by changing the dopant concentration. In detail, porosity played a determinant role in CO2 adsorption capacity, especially ultramicroporosity. Narrow micropores brought major contributions to CO2 uptake at low pressure, while mesopores played a great role at high adsorption pressure. Surface chemistry played a critical role in CO2 capture, especially adsorption selectivity and the isosteric heat of adsorption when the ultramicroporosity was optimal. We revealed that the C–OH group (one type of oxygen-containing species) made a relatively high contribution for improving CO2 capture by hydrogen bonding. For nitrogen-containing groups, the pyridinic-N, pyrrolic-N, and amine groups provoked more improvements in CO2 capture by offering more basic CO2-philic sites, while the oxidized-N group made a weak influence. Sheet-like structures exhibited more accessible affine sites for fast CO2 capture and separation. We proposed a valuable reference for rationally engineering nanoporous carbons with the optimal texture to meet the different requirements of CO2 capture. More importantly, the conversion of biowaste into high-added-value adsorbents for effective CO2 capture and separation opened up an elegant route of killing two birds with one stone.

Rational design of β-cyclodextrins-derived hierarchically porous carbons for CO2 capture: The roles of surface chemistry and porosity on CO2 capture

CO2 capture, storage and utilization (CCSU) is the most promising strategy for ameliorating the ever-increasing atmospheric CO2 concentrations problem. The development of advanced porous solid adsorbents for efficient CCSU is a burgeoning interest in materials science. Currently, porous carbon-based adsorbents face the major challenge of balancing the structural features of porosity and surface chemistry for CCSU in a durable and scalable material. To this end, we designed hierarchically porous carbons with tailorable porosity and adjustable surface chemistry, and clarify the influence of porosity and surface chemistry on CO2 capture. Meanwhile, the systematic study revealed the synergetic effect of microporosity of less than 10 Å and surface chemistry on CO2 capture, and the synergistic effect mechanism of various surface groups on CO2 capture property was also ascertained in detail. Porosity was found to be the determinant role on CO2 capture, in particular the microporosity of < 10 Å and ultramicroporosity of < 7.0 Å. While, surface chemistry played a significant role on the improvement of CO2 capture, especially the CO2/N2 selectivity at higher temperature. Importantly, this work provided an instructive guideline for rational design of high-efficient porous carbon CO2 adsorbents with a balanced porosity and surface chemistry property.

One-pot synthesized, Fe-incorporated self-standing carbons with a hierarchical porosity remove carbamazepine and sulfamethoxazole through heterogeneous electro-Fenton

Hierarchically porous carbons (HPC) are promising electrode materials for heterogeneous electro-Fenton (HEF), where in-situ produced hydrogen peroxide (H2O2) on the carbon surface reacts with the adjacently-immobilized catalyst to form unselective radicals. However, the synthesis of HPC usually comprises several steps, particularly catalyst-containing HPC. Moreover, HPCs (with or without catalysts) have been mostly produced or ultimately used as powders, requiring additional efforts (e.g., adding polymeric binders) to make a functional electrode. Besides blocking some catalytically active carbon sites and the immobilized catalysts, polymeric binders pose risks of secondary pollution due to their undesired release since they are polyfluorinated compounds. This study introduces a one-pot method to synthesize Fe-incorporated self-standing HPCs using bio-based precursors to serve as binder-free electrodes, with potential scalability by numbering up. Monolithic HPCs with tailorable porosity (e.g., micro-, meso-, and macroporosity) offer a high specific surface area (up to 607m2g−1) despite adding no activating agent or receiving any additional thermal activation. At an applied cathodic potential of -0.17V vs. SHE, monolithic HPCs electrodes showed a maximum H2O2 production rate of 0.3mgcm−2h−1, and Fe-embedded HPCs electrodes proved to remove carbamazepine and sulfamethoxazole, as two frequently detected micropollutants in water bodies, with a maximum rate constant of 0.045min−1 and 0.076min−1, respectively. Moreover, the reusability of Fe-embedded HPC electrodes was demonstrated via consecutive runs at pH 3 and 7 with negligible catalyst leaching while elaborating different diffusion-controlled degradation mechanisms. These results unveil the potential of as-synthesized freestanding Fe-embedded HPC to remove recalcitrant pollutants via HEF.

Wet‐Chemistry: A Useful Tool for Deriving Metal–Organic Frameworks toward Supercapacitors and Secondary Batteries

AbstractMetal–organic frameworks (MOFs) possess the advantages of tailorable porosity, adjustable composition, and tunable topologies and are considered promising precursors and self‐templates for the synthesis of complex nanostructures as advanced electrode materials for energy storage. Among various strategies, wet‐chemical method endows better control over topological evolution and compositional transformation of MOF crystals. Herein, the authors comprehensively review the recent achievements on wet‐chemical derivation of MOF via etching, ion‐exchange, hydrolysis, and chemical transformation, underscore the corresponding mechanisms, and highlight their important applications in supercapacitors and secondary batteries.

Recent progress on MOF-based optical sensors for VOC sensing.

The raising apprehension of volatile organic compound (VOC) exposures urges the exploration of advanced monitoring platforms. Metal-organic frameworks (MOFs) provide many attractive features including tailorable porosity, high surface areas, good chemical/thermal stability, and various host-guest interactions, making them appealing candidates for VOC capture and sensing. To comprehensively exploit the potential of MOFs as sensing materials, great efforts have been dedicated to the shaping and patterning of MOFs for next-level device integration. Among different types of sensors (chemiresistive sensors, gravimetric sensors, optical sensors, etc.), MOFs coupled with optical sensors feature distinctive strength. This review summarized the latest advancements in MOF-based optical sensors with a particular focus on VOC sensing. The subject is discussed by different mechanisms: colorimetry, luminescence, and sensors based on optical index modulations. Critical analysis for each system highlighting practical aspects was also deliberated.

Advanced Carbon Materials Derived from Polybenzoxazines: A Review.

This comprehensive review article summarizes the key properties and applications of advanced carbonaceous materials obtained from polybenzoxazines. Identification of several thermal degradation products that arose during carbonization allowed for several different mechanisms (both competitive ones and independent ones) of carbonization, while also confirming the thermal stability of benzoxazines. Electrochemical properties of polybenzoxazine-derived carbon materials were also examined, noting particularly high pseudocapacitance and charge stability that would make benzoxazines suitable as electrodes. Carbon materials from benzoxazines are also highly versatile and can be synthesized and prepared in a number of ways including as films, foams, nanofibers, nanospheres, and aerogels/xerogels, some of which provide unique properties. One example of the special properties is that materials can be porous not only as aerogels and xerogels, but as nanofibers with highly tailorable porosity, controlled through various preparation techniques including, but not limited to, the use of surfactants and silica nanoparticles. In addition to the high and tailorable porosity, benzoxazines have several properties that make them good for numerous applications of the carbonized forms, including electrodes, batteries, gas adsorbents, catalysts, shielding materials, and intumescent coatings, among others. Extreme thermal and electrical stability also allows benzoxazines to be used in harsher conditions, such as in aerospace applications.

Microporous Graphite Composites of Tailorable Porosity, Surface Wettability, and Water Permeability for Fuel Cell Bipolar Plates

To address the water management problem in proton-exchange membrane fuel cells, porous graphite composites were prepared by incorporating sacrificial pore-forming agents in the blend of graphite and a phenolic resin formed into a flat plate using compression molding. Sucrose was found to be an effective porogen in the porous plate production process. The effects of relative amounts of graphite, polymer, and porogen in the composite were studied. Bipolar plate properties such as the water uptake by wicking and vacuum infusion, gas-breakthrough pressure across the water-infused pores, electrical conductivity, and flexural strength of the plates were measured and correlated with the plate composition. The plate porosity was evaluated by determining the masses of dry and water-infused plates in air and under water. The porosity, ε, showed a linear increase with an increase in the porogen concentration in the range of 0–10%. The permeabilities, K, of water through the graphite plates with different porosity values were calculated by measuring the water flux over a range of pressures. The water permeability increased with oxidation and hydrophilization of the pore surface. Dynamic water contact angle measurements were used to characterize the effect of chemical and thermal treatments on the water wettability of the plates. The gas-breakthrough pressure of the water-infused plates was found to be linearly correlated with the parameter, γcos⁡θ/K/ε, proportional to the capillary pressure of the gas–water interface of surface tension, γ, and contact angle, θ. Porous plates capable of a total water uptake greater than 25 wt %, with the gas-breakthrough pressure higher than 10 psi, through-plane electrical conductivity exceeding 100 S cm–1, and flexural strength exceeding 25 MPa were obtained.

Expanding the ZIFs Repertoire for Biological Applications with the Targeted Synthesis of ZIF-20 Nanoparticles.

Owing to their facile synthesis, tailorable porosity, diverse compositions, and low toxicity, zeolitic imidazolate framework (ZIF) nanoparticles (NPs) have emerged as attractive platforms for a variety of biologically relevant applications. To date, a small subset of ZIFs representing only two topologies and very few linker chemistries have been studied in this realm. We seek to expand the bio-design space for ZIF NPs through the targeted synthesis of a hierarchically complex ZIF based on two types of cages, ZIF-20, with lta topology. This study demonstrates the rapid synthesis and size tunability of ZIF-20 particles across the micro and nanoregimes via microwave heating and the use of a modulating agent. To evaluate the utility of ZIF particles for biological applications, we examine their stability in biologically relevant media and demonstrate biocompatibility with A549 human epithelial cells. Further, the ability to encapsulate and release methylene blue, a therapeutic and bioimaging agent, is validated. Importantly, ZIF-20 NPs display a unique behavior relative to previously studied ZIFs based on their specific structural and chemical features. This finding highlights the need to expand the design space across the broader ZIFs family, to exploit a wider range of relevant properties for biological applications and beyond.

Considerations Using Additive Manufacture of Emulsion Inks to Produce Respiratory Protective Filters Against Viral Respiratory Tract Infections Such as the COVID-19 Virus

This review paper explores the potential of combining emulsion-based inks with additive manufacturing (AM) to produce filters for respiratory protective equipment (RPE) in the fight against viral and bacterial infections of the respiratory tract. The value of these filters has been highlighted by the current severe acute respiratory syndrome coronavirus-2 crisis where the importance of protective equipment for health care workers cannot be overstated. Three-dimensional (3D) printing of emulsions is an emerging technology built on a well-established field of emulsion templating to produce porous materials such as polymerized high internal phase emulsions (polyHIPEs). PolyHIPE-based porous polymers have tailorable porosity from the submicron to 100 s of µm. Advances in 3D printing technology enables the control of the bulk shape while a micron porosity is controlled independently by the emulsion-based ink. Herein, we present an overview of the current polyHIPE-based filter applications. Then, we discuss the current use of emulsion templating combined with stereolithography and extrusion-based AM technologies. The benefits and limitation of various AM techniques are discussed, as well as considerations for a scalable manufacture of a polyHIPE-based RPE.

Electrochemical characterization of RuO2 and activated carbon (AC) electrodes using multivalent Ni(NO3)2 electrolyte for charge storage applications

Among various transition metal oxides, Ruthenium oxide (RuO2) has been widely studied for its high ionic conductivity, excellent electrochemical reversibility and superior pseudocapacitive properties. However, it is significantly expensive from the practical applications point of view. On the other hand, activated carbon (AC) has been an attractive choice for electrochemical double layer supercapacitors due to its tailorable porosity and surface area, high electronic conductivity and low cost. In the current study, we examined the electrochemical behavior of nanocrystalline RuO2 against AC in an asymmetric configuration using a multivalent aqueous Ni(NO3)2 electrolyte with a purpose to understand the applicability of a multivalent and inexpensive Ni based electrolyte for charge storage in RuO2 electrodes. The electrochemical characterization of asymmetric RuO2/AC cells in 1M aqueous Ni(NO3)2 electrolyte revealed a maximum specific capacitance of 248 Fg−1 for RuO2 electrodes with a retention of 93.9% of its initial capacitance over one thousand cycles. These results demonstrated the viability of charge storage in RuO2 and AC electrodes using multivalent Ni2+ ion/electrolyte while shedding the light on possible changes in the crystallinity and surface chemistry of RuO2 electrode.

Tailored Porous Organic Polymers for Task-Specific Water Purification.

The Industrial Revolution has resulted in social and economic improvements, but unfortunately, with the development of manufacturing and mining, water sources have been pervaded with contaminants, putting Earth's freshwater supply in peril. Therefore, the segregation of pollutants-such as radionuclides, heavy metals, and oil spills-from water streams, has become a pertinent problem. Attempts have been made to extract these pollutants through chemical precipitation, sorbents, and membranes. The limitations of the current remediation methods, including the generation of a considerable volume of chemical sludge as well as low uptake capacity and/or selectivity, actuate the need for materials innovation. These insufficiencies have provoked our interest in the exploration of porous organic polymers (POPs) for water treatment. This category of porous material has been at the forefront of materials research due to its modular nature, i.e., its tunable functionality and tailorable porosity. Compared to other materials, the practicality of POPs comes from their purely organic composition, which lends to their stability and ease of synthesis. The potential of using POPs as a design platform for solid extractors is closely associated with the ease with which their pore space can be functionalized with high densities of strong adsorption sites, resulting in a material that retains its robustness while providing specified interactions depending on the contaminant of choice.POPs raise opportunities to improve current or enable new technologies to achieve safer water. In this Account, we describe some of our efforts toward the exploitation of the unique properties of POPs for improving water purification by answering key questions and proposing research opportunities. The design strategies and principles involved for functionalizing POPs include the following: increasing the density and flexibility of the chelator to enhance their cooperation, introducing the secondary sphere modifiers to reinforce the primary binding, and enforcing the orientation of the ligands in the pore channel to increase the accessibility and cooperation of the functionalities. For each strategy, we first describe its chemical basis, followed by presenting examples that convey the underlying concepts, giving rise to functional materials that are beyond the traditional ones, as demonstrated by radionuclide sequestration, heavy metal decontamination, and oil-spill cleanup. Our endeavors to explore the applicability of POPs to deal with these high-priority contaminants are expected to impact personal consumer water purifiers, industrial wastewater management systems, and nuclear waste management. In our view, more exciting will be new applications and new examples of the functionalization strategies made by creatively merging the strategies mentioned above, enabling increasingly selective binding and efficiency and ultimately promoting POPs for practical applications to enhance water security.

Rational Synthesis of a Hierarchical Supramolecular Porous Material Created via Self-Assembly of Metal-Organic Framework Nanosheets.

Hierarchically porous materials with high stability and tailorable pore characters have potential for mass transfer applications, including bulky molecule capture and separation, heterogeneous catalysis, and drug delivery. The scope of functionalities can be notably broadened by employing metal-organic framework (MOF) sheets with tunable thickness as giant molecular building blocks for self-assembly into hierarchical supramolecular porous coordination materials. However, synthesizing MOF sheets with controllable bulkiness has proved challenging for scientists. We present a rational yet unprecedented bottom-up strategy to prepare a novel two-dimensional MOF sheet [Zn(BPDI)(Py)2] (BPDI = N,N'-bis(glycinyl)pyromellitic diimide; Py = pyridine) with unusual and highly desired tunable thickness. These sheets self-organize into a unique three-dimensional supramolecular coordination material (NEU-1) with tailorable porosity. To assess its technological relevance, NEU-1c is tested as a support of amine sorbent for CO2 capture. Multichannel porous NEU-1c solves the conventional trade-off suffered by supported amine carbon dioxide adsorbents between increasing amine content and decreasing access to amine sites. Our synthesis process opens the door to novel MOF nanosheets and unique hierarchical supramolecular porous materials with tailorable porosity.

A new nFe@ZIF-8 for the removal of Pb(II) from wastewater by selective adsorption and reduction

A nFe@ZIF-8 composite, which combined the tailorable porosity of ZIF-8 with the versatile functionality of Fe nanoparticles (nFe), was synthesized for Pb(II) removal. Batch adsorption experiments showed that more than 95.3% of Pb(II) was removed from aqueous solution at an initial concentration of 50 mg L−1 when using nFe@ZIF-8 within 60 min at pH value of 5. The mechanism of Pb(II) removal was studied via characterization of changes the morphology, size and composition of in nFe@ZIF-8 before and after exposure the solutions containing Pb(II). Specifically, Fourier transform infrared (FTIR) and X-ray powder diffraction (XRD) indicated that nFe@ZIF-8 was successfully synthesized and also remained stable after Pb(II) removal. Transmission Electron Microscope (TEM) and Scanning electron microscopy-X-ray energy dispersive spectrometer (SEM-EDS) both confirmed that Pb(II) was partially adhered onto the surface of nFe@ZIF-8, where X-ray photoelectron spectroscopy (XPS) specifically revealed the existence of Pb(0) on the surface. This indicated that Pb(II) was initially adsorbed onto the surface of nFe@ZIF-8 and subsequently reduced to Pb(0). Moreover, Pb(II) removal fit well to kinetics of absorption and reduction. Finally, in practice, nFe@ZIF-8 could remove 96.3% of Pb(II) from an electroplating wastewater.

Nanorattle Au@PtAg encapsulated in ZIF-8 for enhancing CO2 photoreduction to CO

Imidazolate-based ZIF-8 catalysts M@ZIF-8 (M = Au NR, Au@Ag NR, or Au@PtAg NRT; NR = nanorod, NRT = nanorattle), were assembled. Au NRs acted as the core for the epitaxial growth of the Ag shell, and oxidative etching of Au@Ag NRs led to Au@PtAg NRTs with K2PtCl4 aqueous solution. All metal nanorods (MNRs) and metal nanorattles (MNRTs) were well dispersed and fully encapsulated in ZIF-8. Au@PtAg NRTs encapsulated in ZIF-8 could lead to enhanced stability and selectivity for catalytic applications, combining the advantages of ZIF-8 (tailorable porosity) with the high surface area and improved optical sensitivity of rod-shaped NRTs. The catalyst Au@PtAg@ZIF-8 exhibited efficient catalytic activity and CO selectivity for the gas-phase photoreduction of CO2 with H2O.