Metal-organic Aerogels Research Articles

A phytic acid-based CoMn bimetallic metal-organic aerogel (PA-CoMn-1 : x : 2 - x) as a modifier for electrochemical detection of non-steroidal anti-inflammatory drug 4-acetaminophenol.

Metal phosphides and phosphate-based materials have received significant attention due to their high electrocatalytic activity, adjustable structure composition and stability. Herein, we introduce a phytic acid-based CoMn bimetallic metal-organic (PA-CoMn) aerogel as an electrode modifier, derived from PA and mixed transition metal ions (Co2+, Mn2+). We explored its performance in the sensitive sensing of non-steroidal anti-inflammatory drug 4-acetaminophenol (4-AP) for the first time. We investigated the electrochemical behavior of the modified screen-printed carbon electrode (SPCE) by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The PA-CoMn-1 : 1.5 : 0.5 aerogel/Nafion/SPCE proved to be highly sensitive and selective towards the detection of 4-AP. A double linear response was recorded for 4-AP over the range of 1 μM to 0.1 mM and lower detection limits (LOD) of 0.2133 μM. The applicability of the PA-CoMn-1 : 1.5 : 0.5 aerogel/Nafion/SPCE in the detection of 4-AP in commercial drug samples with good recoveries was investigated, confirming the great potential of PA-CoMn-1 : 1.5 : 0.5 aerogel/SPCE in clinical applications.

Copper(II)-porphyrin functionalized titanium(IV) metal-organic aerogels for the visible-light driven conversion of CO2 to alcohols

This manuscript covers the synthesis and characterization of a series of titanium based metal-organic aerogels (MOAs) functionalized with copper(II)-metalated porphyrins for their application in visible-light-driven carbon dioxide (CO2) conversion to alcohols. A thorough characterization is performed using a set of spectroscopic and microstructural analysis techniques to reveal the structural and microstructural features that can aid in establishing structure-activity relationships. The parent MOAs consist of metal-organic nanoparticles (5–10 nm) crosslinked into a highly porous microstructure (surface area: 600–800 m2·g−1). The post-synthetic reaction with copper(II) enables the metalation of the tetrapyrrole ring of porphyrin, which is confirmed by analyzing the absorption and luminescence spectra. High-angle annular dark-field electron microscopy imaging demonstrates a uniform distribution of the metalation throughout the nanoparticles that compose the material. The CO2 photoreduction experiments performed in an optofluidic microreactor show that the metalation markedly invigorates the total alcohol (methanol and ethanol) production rates and apparent quantum yields (AQY), from 21 to 367 μmol·g−1·h−1 (AQY: 0.4–7%) prior to metalation to values of 356–642 μmol·g−1·h−1 (AQY: 11–20%). Additionally, the metalation inverts the selectivity towards ethanol, increasing from 0–12% in the parent MOA to 67–76% after incorporating Cu(II).

Microwave-assisted synthesis of l-aspartic acid-based metal organic aerogel (MOA) for efficient removal of oxytetracycline from aqueous solution

Developing advanced adsorption materials is of great significance for removing antibiotics from wastewater owing to the increasingly severe issue of antibiotic contamination. Herein, a novel bio-based metal organic aerogel (FLAM) adsorbent with macroscopic shapeability, formed through the coordination of l-aspartic acid (L-AA) and Fe salt, was fabricated for the first time via the microwave-assisted synthesis method. Subsequently, the FLAM was used to remove oxytetracycline (OTC) from aqueous solution, and the result indicated FLAM exhibited ultrahigh adsorption capacity for OTC with a record-high value of 1566 mg·g−1, which greatly outperformed the reported adsorbents. The adsorption equilibrium curve and adsorption thermodynamics followed the pseudo-second-order kinetics model and the Freundlich model respectively, which indicated multilayer adsorption and chemisorption dominated the adsorption process. Significantly, the adsorbent also enabled efficient decontamination of tetracycline (TC) and chlortetracycline hydrochloride (CTC). Such an excellent adsorption capability of FLAM can be attributed to multiple factors, i.e., electrostatic interaction, surface complexation and hydrogen bonding. Coexisting experiments demonstrated that the FLAM possessed excellent application ability in treating practical antibiotic wastewater. Ultrahigh adsorption capacity and fast-synthesis method prefigured its broad prospect for OTC-related wastewater remediation.

Metal-organic aerogels based on titanium(IV) for visible-light conducted CO2 photoreduction to alcohols

Metal-organic frameworks (MOFs) imply an appealing source of photocatalysts as they combine porosity with tailorable electronic properties and surface chemistry. Herein, we report a series of unprecedented metal-organic aerogels (MOAs) comprised by Ti(IV) oxo-clusters and aromatic dicarboxylic linkers as an alternative to microporous MIL-125 and MIL-125-NH2 MOFs. Discrete titanium oxo-clusters polymerized upon the addition of the dicarboxylic linkers to give rise to a metal-organic gel. Their supercritical drying led to aerogels comprised by nanoscopic particles (ca. 5–10 nm) cross-linked into a meso/macroporous microstructure with surface area ranging from 453 to 617 m2·g−1, which are comparatively lower than the surface area of the microporous counterparts (1336 and 1145 m2·g−1, respectively). However, the meso/macroporous microstructure of MOAs can provide a more fluent diffusion of reagents and products than the intrinsic porosity of MOFs, whose narrower channels are expected to imply a more sluggish mass transport. In fact, the assessment of the continuous visible-light-driven photocatalytic CO2 reduction into methanol shows that MOAs (221–786 μmol·g−1·h−1) far exceed not only the performance of their microporous counterparts (49–65 μmol·g−1·h−1) but also surpass the production rates provided by up-to-date reported photocatalysts.

Hierarchical Metal-Organic Aerogel as a Highly Selective and Sustainable CO2 Adsorbent.

Typical amorphous aerogels pose great potential for CO2 adsorbents with high surface areas and facile diffusion, but they lack well-defined porosity and specific selectivity, inhibiting utilization of their full functionality. To assign well-defined porous structures to aerogels, a hierarchical metal-organic aerogel (HMOA) is designed, which consists of well-defined micropores (d ∼ 1 nm) by coordinative integration with chromium(III) and organic ligands. Due to its hierarchical structure with intrinsically flexible coordination, the HMOA has excellent porous features of a high surface area and a reusable surface with appropriate binding energy for CO2 adsorption. The HMOA features high CO2 adsorption capacity, high CO2/N2 IAST selectivity, and vacuum-induced surface regenerability (100% through 20 cycles). Further, the HMOA could be prepared via simple ambient drying methods while retaining the microporous network. This unique surface-tension-resistant micropore formation and flexible coordination systems of HMOA make it a potential candidate for a CO2 adsorbent with industrial scalability and reproducibility.

Porous Fe-N-C Aerogels Derived from Metal-Organic Aerogels as Electrocatalysts for the Oxygen Reduction Reaction.

Synthesis of Fe-N-C electrocatalysts by pyrolysis of porous materials has been shown to be a promising pathway for the oxygen reduction reaction (ORR). Metal-organic aerogels (MOAs) with unique micropores and mesopores should provide an excellent precursor for Fe-N-C electrocatalysts. This work reports a Fe-N-C aerogel synthesized by pyrolysis of MOA. The Fe-N-C aerogel shows excellent ORR performance in alkaline condition with an onset potential of 0.96 V (vs. RHE) and a limiting current density of 5.02 mA cm-2 . The markedly enhanced ORR performance for Fe-N-C aerogel can be assigned to the synergistic catalytic effect between Fe-N catalytic sites and graphitized carbon and excellent mass transport due to the unique hierarchically porous architecture. In addition, satisfactory durability and methanol tolerance were obtained, demonstrating a promising material for ORR.

CsPbBr3/aluminum (III)-1,3,5-benzenetricarboxylate composites for white light-emitting diode applications

BackgroundCsPbX3 (X = Cl, Br, and I) perovskite quantum dots (PQDs) have attracted increasing attention in recent years, primarily because of their outstanding electrical and optical properties. PQDs have strong photoluminescence properties, cramped lines, and tunable wavelengths. However, the inadequate stability of CsPbX3 PQDs impedes their use in practical applications. MethodsIn this study, all-inorganic PQD/metal-organic aerogel composites were synthesized by following a two-step hot-inject and package process. The concept involved encapsulating CsPbBr3 PQDs into surface-modified aluminum (III)-1,3,5-benzenetricarboxylate (AlBTC)—a hydrophobic metal-organic aerogel—to produce CsPbBr3/AlBTC composites. Significant findingsThe prepared composites were subjected to various characterization processes, including luminescence property examinations, crystal structure identification, and stability tests. The results revealed that the air storage stability of the CsPbBr3 PQDs coated with hydrophobic AlBTC aerogel was superior to that of the uncoated counterparts. Finally, we used a red-emitting CaAlSiN3:Eu2+ phosphor, a green-emitting CsPbBr3/AlBTC composite, and a blue-emitting InGaN-based chip to fabricate a white light-emitting diode with CIE1931 chromaticity coordinates of (0.3971,0.3244) and a color temperature of 3032K.

Introduction of Cascade Biocatalysis Systems into Metal–Organic Aerogel Nanostructures for Colorimetric Sensing of Glucose

Introduction of Cascade Biocatalysis Systems into Metal–Organic Aerogel Nanostructures for Colorimetric Sensing of Glucose

Metal-organic aerogel derived hierarchical porous metal-carbon nanocomposites as efficient bifunctional electrocatalysts for overall water splitting

An efficient strategy to construct non-noble metal-base electrocatalysts for water splitting is the direct carbonization of metal–organic aerogel composites. Herein for the first time, a novel tube-like metal–carbon nanocomposite with encapsulated small-size individual Fe, Cr and Ni nanoparticles, is prepared by the carbonization of a FeCr-doped Ni-benzenetricarboxylate aerogel. The slender skeleton of the aerogel, supercritical drying and Cr doping alleviates metal aggregation and facilitates the in-situ growth of carbon tubes. This nanocomposite exhibits remarkably low overpotential of the hydrogen evolution reaction (137 mV) and oxygen evolution reaction (220 mV). Further, the cell voltage could be as low as 1.54 V with the current density of 10 mA cm−2 and illustrates excellent stability under a continuous operation for 50 h. This non-noble metal-base electrocatalyst is comparable to noble metal-based electrocatalysts and the impressive performance is ascribed to the abundant active catalytic sites and short reactant diffusion pathways. This work demonstrates great capability of aerogel derivation in the highly active electrocatalyst design for promising electrochemical applications.

Metal-Organic Aerogels Based on Titanium(Iv) for Visible-Light Conducted Co2 Photoreduction to Alcohols

Metal-Organic Aerogels Based on Titanium(Iv) for Visible-Light Conducted Co2 Photoreduction to Alcohols

Novel Porous Rhodium Metal-Organic Aerogel for Efficient Removal of Organic Dyes and Catalysis of Si-H Insertion Reactions.

Metal–organic gels (MOGs) are attracting increasing attention for removal of organic dyes from aqueous solution and for catalysis of Si–H insertion reactions. Herein, we report that a reaction of porphyrin derivative 1 with Rh2(OAc)4 generates stable metal–organic gels and subsequent subcritical carbon dioxide drying affords metal–organic aerogels. Owing to their micro- and mesoporosity, the aerogels adsorbed dyes. Moreover, aerogel I catalyzed Si–H insertion reactions to give organosilicon compounds in high yields.

Advances and Novel Perspectives on Colloids, Hydrogels, and Aerogels Based on Coordination Bonds with Biological Interest Ligands.

This perspective article shows new advances in the synthesis of colloids, gels, and aerogels generated by combining metal ions and ligands of biological interest, such as nucleobases, nucleotides, peptides, or amino acids, among other derivatives. The characteristic dynamism of coordination bonds between metal center and biocompatible-type ligands, together with molecular recognition capability of these ligands, are crucial to form colloids and gels. These supramolecular structures are generated by forming weak van der Waals bonds such as hydrogen bonds or π–π stacking between the aromatic rings. Most gels are made up of nano-sized fibrillar networks, although their morphologies can be tuned depending on the synthetic conditions. These new materials respond to different stimuli such as pH, stirring, pressure, temperature, the presence of solvents, among others. For these reasons, they can trap and release molecules or metal ions in a controlled way allowing their application in drug delivery as antimicrobial and self-healable materials or sensors. In addition, the correct selection of the metal ion enables to build catalytic or luminescent metal–organic gels. Even recently, the use of these colloids as 3D-dimensional printable inks has been published. The elimination of the solvent trapped in the gels allows the transformation of these into metal–organic aerogels (MOAs) and metal–organic xerogels (MOXs), increasing the number of possible applications by generating new porous materials and composites useful in adsorption, conversion, and energy storage. The examples shown in this work allow us to visualize the current interest in this new type of material and their perspectives in the short-medium term. Furthermore, these investigations show that there is still a lot of work to be done, opening the door to new and interesting applications.

Metal–Organic Aerogel Assisted Reduced Graphene Oxide Coated Sulfur as a Cathode Material for Lithium Sulfur Batteries

As a sort of cathode material with appreciable theoretical capacity, sulfur has received a lot of attention for lithium–sulfur batteries. There is extensive research focused on cathode materials. H...

A bio-based metal–organic aerogel (MOA) adsorbent for capturing tetracycline from aqueous solution

In this work, we synthesized a novel bio-based Fe-centered metal–organic aerogel and provided valuable guidance for solving practical TC-related pollution issues.

Self-sorting multimetal–organic gel electrocatalysts for a highly efficient oxygen evolution reaction

Multimetallic metal–organic aerogels with self-sorting phases are developedviaa facile one-pot method for high electrochemical performance.

Metal-Organic Gels Based on a Bisamide Tetracarboxyl Ligand for Carbon Dioxide, Sulfur Dioxide, and Selective Dye Uptake.

A metal-organic gel (metallogel) based on the new tetracarboxyl ligand N1, N4-(diterephthalic acid)terephthalamide in combination with chromium(III) has been converted into its xero- and aerogel and demonstrated to have excellent specific sorption properties for dyes in its metallogel state, where fuchsine is adsorbed faster than the two other dyes, calcein and disulfine blue, and for water, sulfur dioxide and carbon dioxide in its xero- and aerogel state. The metallogel showed very good shape retention and could be extruded from molds in designed shapes. In a rheology experiment, the storage modulus was determined to be 1440 Pa, and the metallogel is elastic up to 3 Hz, breaking at strains higher than 0.3%. Additional metallogels utilizing the same ligand with a wide range of metal ions (Al(III), Fe(III), Co(III), In(III), and Hg(II)) have also been synthesized, and the aluminum and mixed aluminum-chromium derivative were also converted into its aerogel. The highly porous Cr, Al, and AlCr metal-organic aerogels proved stable against water vapor in a physisorption experiment and were used to model breakthrough curves for SO2/CO2 gas mixtures with the idealized adsorbed solution theory from their physisorption isotherms. The breakthrough simulation utilized SO2/CO2 equivalencies from a real world application and showed effective retention of SO2 from the gas mixture. Furthermore, the materials in this work exhibit the highest SO2 uptake values for metal-organic aerogels so far (up to 116.8 cm3 g-1, or 23.4 wt %).

Preparation, Characterization and Gas Adsorption Properties of Metal-Organic Aerogels†

Preparation, Characterization and Gas Adsorption Properties of Metal-Organic Aerogels†

A porous metal–organic aerogel based on dirhodium paddle-wheels as an efficient and stable heterogeneous catalyst towards the reduction reaction of aldehydes and ketones

A new mesoporous metal–organic aerogel based on dirhodium paddle-wheels has been successfully synthesized and applied in the hydrosilylation reaction of aldehydes and ketones.

Nitrogen-doped hierarchical porous carbon derived from metal–organic aerogel for high performance lithium–sulfur batteries

Nitrogen-doped three-dimensional (3D) porous carbon materials have numerous applications due to their highly porous structures, abundant structural nitrogen heteroatom decoration and low densities. Herein, nitrogen doped hierarchical 3D porous carbons (NHPC) were prepared via a novel metal–organic aerogel (MOA), using hexamethylenetetramine (HMT), 1,3,5-benzenetricarboxylic acid and copper (II) as starting materials. The morphology, porous structure of the building blocks in the NHPC can be tuned readily using different amount of HMT, which makes elongation of the pristine octahedron of HKUST-1 to give rise to different aspect ratio rod-like structures. The as-prepared NHPC with rod-like carbons exhibit high performance in lithium sulfur battery due to the rational ion transfer pathways, high N-doped doping and hierarchical porous structures. As a result, the initial specific capacity of 1341 mA h/g at rate of 0.5 C (1 C = 1675 mA h/g) and high-rate capability of 354 mA h/g at 5 C was achieved. The decay over 500 cycles is 0.08% per cycle at 1 C, highlighting the long-cycle Li–S batteries.

Metal-organic aerogel as a coating for solid-phase microextraction

An iron-based metal-organic aerogel was synthesized using metal-organic framework nanoparticles and applied as a fiber coating for solid-phase microextraction (SPME). Chemical, thermal and morphological characteristics of the material were investigated. Headspace SPME followed by gas chromatography-electron capture detection was used for the determination of chlorobenzenes in the environmental samples. The key experimental factors affecting the extraction efficiency of the analytes, such as ionic strength, extraction and desorption temperature, and extraction time were investigated and optimized. The applicability of the coating for the extraction of chlorobenzenes from the environmental samples including river and tap water, sludge, and coastal soil was evaluated. The detection limits were in the range of 0.1–60 ng L−1. The relative standard deviations were between 2.0 and 5.0%. The extraction recovery of the analytes was in the range of 88–100%. Compared to the commercial PDMS fiber, the present fiber showed better extraction efficiency.