Macroporous Structure Research Articles

Unravelling co-catalyst integration methods in Ti-based metal-organic gels for photocatalytic H2 production.

The synthesis, characterization and photocatalytic hydrogen evolution reaction (HER) performance of a series of metal-organic gels (MOGs) constructed from titanium(IV)-oxo clusters and dicarboxylato linkers (benzene-1,4-dicarboxylato and 2-aminobenzene-1,4-dicarboxylato) are described. All the MOGs exhibit a microstructure comprised of metal-organic nanoparticles intertwined into a highly meso-/macroporous structure, as demonstrated by cryogenic transmission electron microscopy and gas adsorption isotherms. Comprehensive chemical characterization enabled the estimation of the complex formula for these defective materials, which exhibit low crystallinity and linker vacancies. To gain deeper insights into the local structure, X-ray absorption fine structure (XAFS) spectroscopy experiments were performed and compared to that of the analogous crystalline metal-organic framework. Additionally, the ultraviolet-visible absorption properties and optical band gaps were determined from diffuse reflectance spectroscopy data. The MOGs were studied as light absorbers for the sacrificial photocatalytic HER under simulated solar light irradiation using a platinum co-catalyst by either (1) in situ photodeposition or (2) ex situ doping process, through a post-synthetic metalation of the MOG structure. The chemical analysis of the metalation, along with high-angle annular dark-field scanning transmission electron microscopy, revealed that although the in situ addition of the co-catalyst led to greater HER rates (227 vs. 110 μmolH2 gMOG-1 h-1 for in situ and ex situ, respectively), the ex situ modification provided a finer distribution of platinum nanoparticles along the porous microstructure and, as a result, it led to a more efficient utilization of the co-catalyst (45 vs. 110 mmolH2 gPt-1 h-1).

Bio-based sunflower carbon/polyethylene glycol shape-stabilized phase change materials for thermal energy storage.

The exploitation of shape-stabilized phase change materials with high thermal conductivity and energy storage capacity is an effective strategy for improving energy efficiency. In this work, sunflower stem carbon/polyethylene glycol (SS-PEG) and sunflower receptacle carbon/polyethylene glycol (SR-PEG) shape-stabilized phase change materials, utilizing sunflower stem and receptacle biomass carbon with high specific surface area and pore volume obtained by carbonization as frameworks and polyethylene glycol as an energy storage material, were prepared by the vacuum impregnation method. The ability to load polyethylene glycol into the pore structure of carbon materials in different sunflower parts was mainly investigated, and the micro-morphology, compositional structure and thermal properties were characterized and analyzed using SEM, IR spectroscopy, XRD, DSC and TG techniques. The results showed that the carbonized sunflower stems maintained the sieve pore structure, and the carbonized sunflower receptacle was a macroporous structure containing a large number of three-dimensional interconnections. At the same time, the interaction between polyethylene glycol and each carbon material occurred through physisorption. The melting enthalpies of SS-PEG and SR-PEG shape-stabilized phase change materials were 153.4 J g-1 and 171.5 J g-1, respectively, and the loading rates reached 81.9% and 91.5%, with initial thermal decomposition temperatures (T 5%) of 344 °C and 368 °C.

3D printing of reactive macroporous polymers via thiol-ene chemistry and polymerization-induced phase separation.

Using thiol-ene chemistry, polymerization-induced phase separation, and DLP 3D printing, we present a method for manufacturing reactive macroporous 3D structures. This approach enables the fabrication of structures with tunable physicochemical properties and compressibility. Moreover, it facilitates post-functionalization through thiol-Michael addition reactions, thereby expanding performance and application potential.

Ring-opening polymerization of emulsion-templated deep eutectic system monomer for macroporous polyesters with controlled degradability.

Biodegradable polyesters with interconnected macroporosity, such as poly(l-lactide) (PLLA) and poly(ε-caprolactone) (PCL), have gained significant importance in the fields of tissue engineering and separation. This study introduces functional macroinitiators, specifically polycaprolactone triol (PCLT) and polyethylene glycol (PEG), both OH-terminated, in the solventless ring-opening polymerization (ROP) of a liquid deep eutectic system monomer (DESm) composed of LLA and CL at a 30 : 70 molar ratio, respectively. The macroinitiators selectively initiate the organocatalyzed ROP of LLA in the DESm during the first polymerization stage, thereby modifying the PLLA architecture. This results in the formation of either branched or linear PLLA copolymers depending on the macroinitiator, PCLT and PEG, respectively. In the second stage, the ROP of the CL, which is a counterpart of the DESm, produces PCL that blends with the previously formed PLLA. The insights gained into the PLLA architectures during the first stage of the DESm ROP, along with the overall molecular weight and hydrophobicity of the resulting PLLA/PCL blend in bulk, were advantageously used to design polymerizable high internal phase emulsions (HIPEs) oil-in-DESm. By incorporating a liquid mixture of DESm and macroinitiators (PCLT or PEG), stable HIPE formulations were achieved. These emulsions sustained the efficient organocatalyzed ROP of the continuous phase at 37 °C with high conversions. The resulting polymer replicas of the HIPEs, characterized by macroporous and interconnected structures, were subjected to a degradation assay in PBS at pH 7.4 and 37 °C and remained mechanically stable for at least 30 days. Notably, they exhibited the capability to sorb crude oil in a proof-of-concept test, with a rate of 2 g g-1. The macroporous and interconnected features of the polyHIPEs, combined with their inherent degradation properties, position them as promising degradable polymeric sorbents for efficient separation of hydrophobic fluids from water.

Solvent-induced structural transformation in a one-dimensional coordination polymer.

We have rationally designed a one-dimensional coordination polymer (1D CP), termed 1D-DGIST-18, that exhibits intrinsic structural flexibility. This 1D CP enables its expansion into a three-dimensional network through supramolecular interactions involving coordinated solvents and/or ligands. The strategic selection of solvents for solvent exchange, prior to drying, significantly influences the structures of 1D-DGIST-18 by removing certain coordinating solvents and modulating π-π stacking. Consequently, a hierarchical porosity emerges, ranging from micro- to meso- to macroporous structures, which is attributed to its inherent structural dynamics. Additionally, the formation of excimers endows 1D-DGIST-18, when immersed in acetone, with 'turn-on' fluorescence, as evidenced by fluorescence decay profiles. These structural transitions within 1D-DGIST-18 are further elucidated using single-crystal X-ray diffractometry. The insights from this study provide a foundation for the design of materials with structural dynamics and tunable properties.

Optimal MEA structure and operating conditions for fuel cell reactors with hydrogen peroxide and power cogeneration

The cogeneration of hydrogen peroxide (H2O2) and power in proton exchange membrane fuel cell (PEMFC) reactors via two-electron oxygen reduction reaction on the cathode is an economical, low-carbon, and green route for the on-site production of H2O2. However, in practice, the H2O2 that cannot be collected timely will accumulate and self-decompose in the catalyst layer (CL), reducing the H2O2 generation efficiency. Thus, accelerating the mass transport of H2O2 within the cathode CL is critical to efficient H2O2 generation in PEMFC. Herein, we investigated the effects of the membrane electrode assembly (MEA) fabrication process, cathode CL thickness, and cathode carrier water flow rate on H2O2 generation and cell performance in a PEMFC reactor. The results show that the catalyst-coated membrane-type MEA exhibits high power output due to its lower proton transport resistance. However, the formed CL with a dense structure significantly limits H2O2 collection efficiency. The catalyst-coated gas diffusion electrode (GDE)-type MEA formed macroporous structures in the cathode CL, facilitating carrier water entry and H2O2 drainage. In particular, carbon cloth GDE with thin CL could construct rich macroscopic liquid channels, thus maximizing the generation of H2O2, but will impede fuel cell performance. These results suggest that the construction of a well-connected interface between CL and proton exchange membrane (PEM) in MEA and the establishment of a macroscopic pore structure of the CL are the keys to improve the cell performance and H2O2 collection efficiency.

Investigation of Textural And Surface Chemical Properties of Some Animal Bones

The aim of the study is to examine the textural structure and organic functional groups of horse-donkey, cow, dog, and sheep bones by nitrogen gas adsorption-desorption and Fourier Transform Infrared (FT-IR) spectroscopic methods, respectively. For this purpose, textural properties such as BET (Brunauer-Emmett-Teller) surface area, total pore volume, average pore diameter, and surface organic functional groups were determined by nitrogen gas adsorption/desorption at -196 oC and FT-IR spectral analysis methods, respectively. It was observed that the nitrogen gas adsorption isotherms obtained from the BET analysis results were similar to Type-V, which indicates that they have a mesoporous and/or macroporous textural structure, in the IUPAC nitrogen gas isotherm classification. In addition, it was determined from the FT-IR analysis results that they mainly contain organic functional groups such as amine, alcohol, carboxylic acid, ester, ether.

Heterostructures of NiFe-MOF/PBAs with high-performance supercapacitors obtained by compounding Prussian blue analogues on bimetallic organic frames

Metal organic framework (MOF) is considered as an excellent electrode material for supercapacitors due to its low cost and homogeneous nanostructure, but the drawbacks of single MOF, such as low specific capacity and stability, limit its development, so the design of bimetallic MOF structural composites is a challenging but favourable strategy for the development of supercapacitors. In this paper, NiFe-MOF/PBAs heterostructure, a bimetallic MOF material with a granular rod-like structure, is successfully prepared by using bimetallic MOF as a precursor and introducing [Co(CN)6]3− ions to further convert it into PBAs (Prussian blue analogs). Due to the special macroporous structure of PBAs, the composite combines the advantages of the two MOF materials, and the specific capacity is as high as 4270.19 C g−1 at 1 A g−1. The composite still has excellent electrochemical properties when assembled into devices. The specific capacity is 1996.01 C g−1 at 1 A g−1, the energy density reached 749.99 W h kg−1 at a power density of 415.85 W kg−1, and the decay rate is only 1.14 % after 20,000 cycles at 10 A g−1. These results indicate that the designed dual MOFs composite electrodes have good application prospects in the field of electrochemical energy storage.

Hierarchical porous SAPO-34 decorated with Mo and W oxides for concurrent transesterification-esterifications for efficient biodiesel production from acidic soybean oil

Hierarchical porous materials have gained much attention as promising heterogeneous catalyst supports due to their high efficiency of mass transfer and high exposure of active centers. In this research, the hierarchical porous SAPO-34 support with microporous, mesoporous, and macroporous hierarchical structure was initially prepared by in-situ alkali etching. Then, Mo and W oxides were incorporated into this hierarchical porous support by using the impregnation method to prepare Mo15W15/HSAPO-34/70 catalyst. This developed catalyst was applied to concurrently catalyze the oil transesterification and free fatty acid (FFA) esterification to biodiesel as the low-value oils severed as feedstocks. The textural and physicochemical properties of the nanocatalysts were evaluated by XRD, XPS, SEM, EDS, TEM, UV–vis, NH3-TPD, Py-FTIR, and nitrogen porosimetry measurement. This catalyst had hierarchical porous structure to ameliorate the large oil molecular transfer, and featured dual Brønsted-Lewis acid sites to synergistically boost the catalytic efficiency for the biodiesel production. Over this catalyst, the oil conversion of 90.1 % and full FFA conversion were achieved under optimized operation conditions, therefore imparting to one-pot conversion to biodiesel with low-value oils as feedstocks. In addition, this catalyst not only exhibited superior tolerance to moisture and FFAs, but also retained high activities after five reuse cycles, thus revealing its tremendous potential of being used in durable and efficient biodiesel production. The present work opens a new avenue for synthesizing a robust solid acid catalyst to achieve a one-pot biodiesel production from low-value oils.

A novel scalable polycationic melamine sponge-based filtration matrix for continuous ultrafast adsorption of anionic pollutants

Effective capturing of anionic pollutants from wastewater under industrial operating conditions, which requires high processing flux and fast adsorption rate remains a challenge. Here, a commercially available melamine sponge (MS) with reticulated 3D macroporous structures was covalently modified with positively charged moieties using a single step functionalization under mild conditions. The developed novel polycationic melamine sponge (MS+) was formed by a nucleophilic addition reaction between glycidyltrimethylammonium chloride (GMTA) and MS, followed by a self-propagation of GMTA. The produced MS+ possessed strong electrostatic interactions with different anions such as Rose Bengal (RB) and phosphates (P) under a wide pH range (3–11). The MS+ exhibited promoted static adsorption efficiencies of 400 mg g−1 (P) and 600 mg g−1 (RB), within 5 min and 60 s, respectively. Furthermore, the MS+ showed high stability and recyclability for up to 15 cycles of uses, and the recycling process was environmentally friendly by using 1 M NaCl as a releasing solution. Benefiting from fast flow through the macroporous MS+ and highly positive charged skeleton, the MS+ was applied for rapid dynamic enrichment process of P from real manure wastewater with an enrichment factor of 4.4. Utilization of the MS+ as the substrate brings additional advantages such as low cost, availability, and flexibility to fit into existing filtration devices. The developed MS+ could be expanded for enrichments of other anionic species from various polluted water sources.

Three-dimensionally ordered macroporous ZSM-5 zeolite supported high-dispersed Ni2P: Highly active catalyst for quinoline hydrodenitrogenation

Zeolite catalysts have shown significant advantages in hydrogenation reactions due to their ordered pore structure and abundant acid sites. Common zeolites exhibit pore accessibility limited to microporous states, which restricts their application in diffusion-limited processes. In this study, a steam-seeding-assisted colloidal crystal template (SSAC) method was used to prepare ZSM-5 zeolite with a three-dimensionally ordered macroporous (3DOM) structure, which was then loaded with nickel phosphide for hydrodenitrogenation reactions. SEM and TEM characterization demonstrated that the prepared zeolite material possessed a highly ordered 3DOM structure with interconnected macropores. XRD, FT-IR, and BET analysis indicated that the macroporous zeolite material exhibited a typical MFI structure, mesoporous channels, and a higher specific surface area. The high external surface area facilitated the formation of uniformly sized Ni2P nanoparticles on the zeolite surface. The introduction of macroporous structures also leads to suitable Brönsted acid and Lewis acid sites in zeolite materials. The resultant Ni2P/3DOMZSM-5 catalyst exhibited higher reaction rate constants and TOF (10.87×10−2 μmolg−1s−1 and 1.5×10−3s−1, respectively) compared to other zeolite catalysts and commercial catalysts.

Insight into Structural and Physicochemical Properties of ZrO2-SiO2 Monolithic Catalysts with Hierarchical Pore Structure: Effect of Zirconium Precursor

Zirconia–silica monolithic catalysts with hierarchical micro/macroporous structure were obtained in a sol-gel process combined with phase separation using inorganic salts, i.e., oxychloride, oxynitrate and sulphate, as a zirconium source. It was found that the use of zirconium oxychloride and prehydrolysis of tetraethoxysilane (TEOS) resulted in materials characterized by a well-developed continuous structure of macropores with a diameter of ca. 10 μm. For zirconium oxynitrate and sulfate modified materials, the prehydrolysis hardly affected the macropore size. The micropores with a diameter of 1.5 nm in the skeleton of all materials provided a large surface area of 550–590 m2/g. A high dispersion of zirconia in the silica skeleton in all studied materials was shown. However, the largest surface concentration of Lewis and Brönsted acid sites was found in the monolith synthesized with zirconium oxychloride. The monoliths were used as a core for continuous-flow microreactors and high catalytic activity was confirmed in the deacetalization of benzylaldehyde dimethyl acetal. The process was characterized by a high efficiency at low temperature, i.e., 35 °C.

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Three‐dimensionally ordered macro/mesoporous carbon material is a new material with interconnected macroporous structure and rich meso/micropores. The interconnected macroporous structure can effectively reduce mass transfer resistance and improve the contact efficiency between reactants and active sites during the catalytic process. More details are discussed in the article by Sun et al. on page 164—170. image

Study on material structure design, selective adsorption mechanism, and application for adsorption recovery of oil substances in coal chemical wastewater

In response to the problem of high emulsified and dissolved oils being difficult to recovery from coal chemical wastewater (CCW), this study specifically constructed a non-polar, macropore, and hydrophobic adsorption material (pSt-X) based on the main components of these two oils (aromatics and phenols) for selective recovery. The results revealed that pSt-X had an adsorption capacity of 215.52 mg/g, which had remained stable for multiple recycling sessions, with an adsorption capacity constantly above 95 %. The pSt-X has significantly larger particle size (0.7 mm–1.2 mm), which simplifies the process of adsorption regeneration and effectively prevents the loss of the adsorbent powder problem. The pSt-X adsorbent demonstrated remarkable selectivity towards dissolved and emulsified oils, exhibiting removal rates of 90.2 % and 81.7 %, respectively. Moreover, pSt-X proved remarkable selectivity in removing aromatic hydrocarbons (AHs) and phenols, with impressive removal rates of 77.8 % and 85.9 %, respectively. The selective separation mechanism of pSt-X for oil substances was further analyzed, indicating that its selective adsorption of oils was primarily driven by hydrophobic, π-π, and hydrogen bonding interactions owing to its non-polar and macropore structure and hydrophobic properties. The results of this study provide solid theoretical support for green and low-carbon recovery of oil substances in CCW and are of positive practical importance for clean production in the coal chemical industry.

Atomically Dispersed ZnN4 Sites Anchored on P-Functionalized Carbon with Hierarchically Ordered Porous Structures for Boosted Electroreduction of CO2.

Tuning the coordination structures of metal sites is intensively studied to improve the performances of single-atom site catalysts (SASC). However, the pore structure of SASC, which is highly related to the accessibility of active sites, has received little attention. In this work, single-atom ZnN4 sites embedded in P-functionalized carbon with hollow-wall and 3D ordered macroporous structure (denoted as H-3DOM-ZnN4 /P-C) are constructed. The creation of hollow walls in ordered macroporous structures can largely increase the external surface area to expose more active sites. The introduction of adjacent P atoms can optimize the electronic structure of ZnN4 sites through long-rang regulation to enhance the intrinsic activity and selectivity. In the electrochemical CO2 reduction reaction, H-3DOM-ZnN4 /P-C exhibits high CO Faradaic efficiency over 90% in a wide potential window (500mV) and a large turnover frequency up to 7.8×104 h-1 at -1.0V versus reversible hydrogen electrode, much higher than its counterparts without the hierarchically ordered structure or P-functionalization.

Pore Structure and Fractal Characteristics of Coal Measure Shale in the Wuxiang Block in the Qinshui Basin

To study the fractal characteristics of the pore structure and the main controlling factors of coal measure shale in the Wuxiang block in Qinshui Basin, gas adsorption (CO2 and N2), mercury intrusion porosimetry (MIP), total organic carbon (TOC) content, and X-ray diffraction (XRD) experiments were carried out. The fractal dimensions of the micropores, mesopores, and macropores were computed by combining the V-S, FHH, and MENGER models. The results show that the fractal dimension increases with the increase in pore size; so, the macropore structure is the most complex. The effects of the TOC content, mineral fractions, and pore structure on the fractal dimensions were analyzed. The results showed that the TOC content certainly correlated with the mesopore fractal dimension, and the R2 is 0.9926. The pore volume and specific surface area show an obvious positive correlation with the macroporous fractal dimension, and their R2 values are 0.6953 and 0.6482, indicating that the macroporous pore structure of coal shale in the study area is more complex. There is a significant positive correlation between kaolinite and the macropore fractal dimension, and the R2 is 0.7295. Therefore, the organic carbon and kaolinite contents and the pore structure parameters are the most important factors affecting the fractal dimension characteristics.

Hierarchical macroporous polymer structures fabricated by coassembly of polymersomes and polymer brushes

Synthesis of hierarchical macroporous structures has aroused great interest due to the potential applications and unique properties of the materials. In this research, polymersomes and polymer brush-grafted silica particles are used as building blocks for the fabrication of hierarchical macroporous polymer particles. In order to investigate the mechanism of the self-assembly and synthesize hierarchical materials, two-component self-assembly of poly(2-(dimethylamino)ethyl methacrylate)-block-polystyrene (PDMAEMA55-b-PS316) and PS343, and three-component self-assembly of PDMAEMA55-b-PS316, PS343 and PS brushes on silica particles (SiO2-PS343) in THF/methanol mixtures were performed. In the coassembly of PDMAEMA55-b-PS316 and PS343, with an increase in PS343 content the morphology of the self-assembled structures changes from spherical micelles, to polymersomes, and to aggregated polymersomes. In the coassembly of PDMAEMA55-b-PS316, PS343 and SiO2-PS343, aggregated polymersomes and silica particles are formed. After etching silica particles with HF acid, macroporous polymer structures are produced. After quaternization of PDMAEMA blocks with methyl iodide, hierarchical macroporous structures with hydrophilic quaternized PDMAEMA blocks at the coronae and hydrophobic PS domains inside the structures are produced in aqueous solution. Toluene, used as a model compound, is able to diffuse into the hydrophobic domains of the structures, and at high toluene content a transition from the hierarchical macroporous structures to hollow structures is observed.

γ-irradiation induced ultrafine Ni nanoparticles supported on biomass-derived macroporous carbon for enhanced microwave absorption in the X-band

A series of ultrafine Ni nanoparticles (NPs) supported on biomass-derived macroporous carbon composites are conducted by γ-irradiation induced reduction method. The scanning electron microscopy (SEM) and transmission electron microscope (TEM) characterization show that the obtained materials have abundant macroporous structure and the Ni NPs are evenly decorated on the surface of macroporous carbon. Both high irradiation doses and increasing Ni2+ contents favor the production of smaller dots. When the irradiation dose is 220 kGy and the C/Ni2+ mole ratio is 1:6, the average diameter of Ni NPs can reach 7.7 nm. Electromagnetic analyses indicate that the ultrafine Ni NPs have a positive effect on the magnetic loss ability, due to their strong natural ferromagnetic resonances. The obtained sample (CSC–Ni-3) exhibits the best microwave absorption performances among these composites, with the strongest reflection loss (RL) value of −70.2 dB at 10.8 GHz for the thickness of 2.3 mm, and the effective absorption band (EAB) in the X-band (8.2–12.4 GHz) is up to 3.2 GHz. The advantages of CSC-Ni-3 can be clearly established in both matched impedance and high magnetic loss ability. The γ-irradiation strategy presents a promising way for the design of ultrafine Ni NPs for high-performance microwave absorption.

The Effect of TiO2 and GeO2 Composite Mixing on the Behavior of Macroporous Li-Ion Battery Anode Materials

Highly ordered, macroporous inverse opal structures can be made as TiO2/GeO2 nanocomposites with various GeO2 content and provide Coulombic and voltage stable response where the Ge content and its distribution influence the overall capacity at both slow and fast rates. These interconnected binder-free anodes were characterized using X-ray diffraction, high resolution transmission electron microscopy, selected area electron diffraction, energy dispersive X-ray spectroscopy and electron energy loss spectroscopy. The electrochemical response in half cells over 2000 cycles and various rates showed how the mixture affected key metrics for the material in battery cells. The data shows that a composite of intercalation and alloying compounds can provide good capacity (between theoretical maxima for either material alone) and excellent coulombic efficiency (>99%), even with low quantities of the higher capacity alloying compound. Compositional gradients or spatial heterogeneities in the distribution of one material in the composite are shown to affect capacity during cycling life, where a coulombically efficient increasing capacity is found as the higher capacity material becomes electrochemically active within the composite matrix as the material is modified during cycling.

Novel three-dimensional electrode structures with urchin-like pore canal for high-performance microbial fuel cells

In this work, a kind of urchin-like porous structural gel beads as three-dimensional (3D) packed anode materials were prepared to utilize the chemical coprecipitation method, forming the reduced graphene/chitosan/Fe3O4 (rGO/CHI/Fe3O4) gel beads (GFe100). The average diameter of Fe3O4 nanoparticles in the gel beads was about 13 nm, distributing uniformly in GFe100 gel beads in situ. Fe3O4 nanoparticles formed in the material-preparation process had a significant pore-creating function to form urchin-like pore canals with the help of the micro-reactor. The average size of these canals was 13.55 μm, which could enhance more functional microbes in the gel beads to strengthen the biocompatibility and extracellular electron transfer (EET) of anode electrodes. The maximum output voltage and power density of GFe100 was 759 mV and 17.823 W·m-3, which was 2.3 times (327 mV) and 23.21 times (0.768 W m-3) higher than that of GFe0 prepared without any addition of Fe2+, respectively. The significant electricity generation performance of GFe100 was mainly attributed to the urchin-like canal structure. Exoelectrogens possessed the macropore structure for the controlled diffusion process and extracellular metabolic products occupied the micropore and mesopore structure donating for the surface reactant process. This work suggested that three-dimensional gel beads filled into the anode chamber might be the potential for long-term MFC practice application with a high electricity generation performance.