Nanoengineering Multilength-Scale Porous Hierarchy in Mesoporous Metal-Organic Framework Single Crystals.

Developing a reliable method for constructing mesoporous metal-organic frameworks (MOFs) with single-crystalline forms remains a challenging task despite numerous efforts. This study presents a solvent-mediated assembly method for fabricating zeolitic imidazolate framework (ZIF) single-crystal nanoparticles with a well-defined micro-mesoporous structure using polystyrene-block-poly(ethylene oxide) diblock copolymer micelles as a soft-template. The precise control of particle sizes, ranging from 85 to 1200 nm, is achieved by regulating nucleation and crystal growth rates while maintaining consistent pore diameters in mesoporous nanoparticles and a rhombohedral dodecahedron morphology. Furthermore, this study presents a robust platform for nanoarchitecturing to prepare hierarchically porous materials (e.g., core-shell and hollow structures), including microporous ZIF@mesoporous ZIF, hollow mesoporous ZIF, and mesoporous ZIF@mesoporous ZIF. Such a multimodal pore design, ranging from microporous to microporous/mesoporous and further micro-/meso-/macroporous, provides significant evidence for the future possibility of the structural design of MOFs.

Coembedding Fe Single Atom-Coupled MoC Nanoparticles in N-Doped Hierarchically Porous Carbon Cubes for Oxygen Electroreduction.

Promotion of oxygen reduction reaction (ORR) kinetics, to a large extent, depends on the rational modulation of the electronic structure and mass diffusion of electrocatalysts. Herein, a ferrocene (Fc)-assisted strategy is developed to prepare Fc-trapped ZnMo-hybrid zeolitic imidazolate framework (Fc@ZnMo-HZIF-50) and the derived Fe single atom coupling with MoC nanoparticles, coembedded in hierarchically porous N-doped carbon cubes (MoC@FeNC-50). The introduced Fc is utilized not only as an iron source for single atoms but also as a morphology regulator for generating a hierarchically porous structure. The redistribution of electrons between Fe single atoms and MoC nanoparticles effectively promotes the adsorption of O2 and the formation of *OOH intermediates during the ORR process. Along with a 3D hierarchically porous architecture for enhanced mass transport, the as-fabricated MoC@FeNC-50 presents excellent activity (E1/2 = 0.83 V) and durability (only 9.5% decay in current after 40000 s). This work could inspire valuable insights into the construction of efficient electrocatalysts through electron configuration and kinetics engineering.

ExpoNano: A Strategy Based on Hyper-Cross-Linked Polymers Achieves Urinary Exposome Assessment for Biomonitoring.

Urinary analysis of exogenous and endogenous molecules constitutes an efficient, noninvasive approach to evaluate human health status. However, the exposome characterization of urinary molecules remains extremely challenging with current techniques. Herein, we develop an ExpoNano strategy based on hyper-cross-linked polymers (HCPs) to achieve ultrahigh-throughput measurement of exo/endogenous molecules in urine. The strategy includes a simple trapping-detrapping procedure (15 min) with HCPs in enzymatically treated urine, followed by mass spectrometer determination. Molecules that can be determined by ExpoNano have a wide range of molecular weight (75-837 Da) and Log Kow (octanol-water partition coefficient; -9.86 to 10.56). The HCPs can be repeatedly used five times without decreasing the trapping efficiency. Application of ExpoNano in a biomonitoring study revealed a total of 63 environmental chemicals detected in >50% of the urine pools collected from Chinese adults living in 13 cities, with a median concentration of 0.026-47 ng/mL, while nontargeted analysis detected an additional 243 exogenous molecules. Targeted and nontargeted analysis also detected 926 endogenous molecules in pooled urine. Collectively, the ExpoNano strategy demonstrates unique advantages over traditional urine analysis approaches, including a wide range of analytes, satisfactory trapping efficiency, high simplicity and reusability, and extremely reduced time demand and financial cost.

Highly Defective Zirconium-Based Metal-Organic Frameworks for the Efficient Adsorption and Detection of Sugar Phosphates in the Biological Sample.

Enrichment and quantification of sugar phosphates (SPx) in biological samples were of great significance in biological medicine. In this work, a series of zirconium-based metal-organic frameworks (MOFs) with different degrees of defects, namely, HP-UiO-66-NH2-X, were synthesized using acetic acid as a modulator and were utilized as high-capacity adsorbents for the adsorption of SPx in biological samples. The results indicated that the addition of acetic acid altered the morphology of HP-UiO-66-NH2-X, with corresponding changes in pore size (3.99-9.28 nm) and specific surface area (894.44-1142.50 m2·g-1). HP-UiO-66-NH2-10 showed the outstanding performance by achieving complete adsorption of all four SPx using only 80 µg of the adsorbent. The excellent adsorption efficiency of HP-UiO-66-NH2-10 was also obtained with a wide pH range and short adsorption time (10 min). Adsorption experiments demonstrated that the adsorption process involved chemical adsorption and multilayer adsorption. By utilizing X-ray photoelectron spectroscopy and density functional theory to explain the adsorption mechanism, it was found that various interactions (including coordination, hydrogen bonding, and electrostatic interactions) collectively contributed to the exceptional adsorption capability of HP-UiO-66-NH2-10. Those results indicated that the defect strategy not only increased the specific surface area and pore size, providing additional adsorption sites, but also reduced the adsorption energy between HP-UiO-66-NH2-10 and SPx. Moreover, HP-UiO-66-NH2-10 showed a low limit of detection (0.001-0.01 ng·mL-1), high precision (<13.77%), and accuracy (80.10-111.83%) in serum, liver, and cells, good stability, high selectivity (SPx/glucose, 1:100 molar ratio), and high adsorption capacity (292 mg·g-1 for SPx). The practical detection of SPx from human serum was also verified, prefiguring the great potentials of defective zirconium-based MOFs for the enrichment and detection of SPx in the biological medicine.

Hierarchical Magnetic Carbon Nanoflowers for Ultra-Efficient Electromagnetic Wave Absorption.

Porous carbon nanomaterials are widely applied in the electromagnetic wave absorption (EMWA) field. Among them, an emerging flower-like carbon nanomaterial, termed carbon nanoflowers (CNFs), has attracted tremendous research attention due to their unique hierarchical flower-like structure. However, the design of flower-like carbon nanomaterials with different magnetic cores for EMWA has rarely been reported. Herein, a general template method is proposed to achieve a set of high-quality magnetic CNFs, namely Co@Void@CNFs, CoNi@CNFs, and Ni@CNFs. The prepared magnetic CNFs have highly accessible surface area and internal space, rich heteroatom content, multi-scale pore system, and uniform and highly dispersed magnetic nanoparticles, as a result, deliver superior EMWA performance. Specifically, when the thickness is 2.6 mm, the Co@Void@CNFs exhibit a maximum refection loss (RLmax) of -56.6 dB and an effective absorption bandwidth (EAB) from 8.0 to 12.1 GHz covering the whole X band. The CoNi@CNFs have an RLmax of up to -57.6 dB and a wide EAB of 5.6 GHz at just 1.9 mm. For the Ni@CNFs, possess an ultra-broad EAB of 6.1 GHz, covering the entire Ku band at 2.0 mm. Overall, the hierarchical magnetic carbon nanoflowers proposed here offer new insights toward realizing multifunctional integrated carbon nanomaterials for EMWA.

Wood-Structured Nanomaterials as Highly Efficient, Self-Standing Electrocatalysts for Water Splitting.

Electrocatalytic water splitting (EWS) driven by renewable energy is widely considered an environmentally friendly and sustainable approach for generating hydrogen (H2), an ideal energy carrier for the future. However, the efficiency and economic viability of large-scale water electrolysis depend on electrocatalysts that can efficiently accelerate the electrochemical reactions taking place at the two electrodes. Wood-derived nanomaterials are well-suited for serving as EWS catalysts because of their hierarchically porous structure with high surface area and low tortuosity, compositional tunability, cost-effectiveness, and self-standing integral electrode configuration. Here, recent advancements in the design and synthesis of wood-structured nanomaterials serving as advanced electrocatalysts for water splitting are summarized. First, the design principles and corresponding strategies toward highly effective wood-structured electrocatalysts (WSECs) are emphasized. Then, a comprehensive overview of current findings on WSECs, encompassing diverse structural designs and functionalities such as supported-metal nanoparticles (NPs), single-atom catalysts (SACs), metal compounds, and heterostructured electrocatalysts based on engineered wood hosts are presented. Subsequently, the application of these WSECs in various aspects of water splitting, including the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), overall water splitting (OWS), and hybrid water electrolysis (HWE) are explored. Finally, the prospects, challenges, and opportunities associated with the broad application of WSECs are briefly discussed. This review aims to provide a comprehensive understanding of the ongoing developments in water-splitting catalysts, along with outlining design principles for the future development of WSECs.

Conjugated Microporous Polymers-Based Catalytic Membranes with Hierarchical Channels for High-Throughput Removal of Micropollutants.

Engineering a catalytic membrane capable of efficiently removing emerging organic microcontaminants under ultrahigh flux conditions is of significance for water purification. Herein, drawing inspiration from the functional attributes of lymphatic vessels involved in immunosurveillance and fluid transport with minimal energy consumption, a novel hierarchical porous catalytic membrane is engineered. This membrane, based on an innovative nitrogen-rich conjugated microporous polymer (polytripheneamine, PTPA), is synthesized using an electrospinning coupled in situ polymerization approach. The resulting bioinspired membrane with hierarchical channels comprises a thin layer (≈1.7 µm) of crosslinked PTPA nanoparticles covering the interconnected electrospun nanofibers. This unique design creates an intrinsic microporous angstrom-confined system capable of activating peroxymonosulfate (PMS) to generate 98.7% singlet oxygen (1O2), enabling durable and highly efficient degradation of microcontaminants. Additionally, the presence of a thin layer of mesoporous structure between PTPA nanoparticles and macroporous channels within the interwoven nanofibers enhances mass transfer efficiency and facilitates high flux rates. Notably, the prepared hierarchical porous organic catalytic membrane demonstrates enduring high-efficiency degradation performance with a superior permeance (>95% and >2500 L m-2 h-1 bar-1) sustained over 100 h. This work introduces an innovative pathway for the design of high-performance catalytic membranes for the removal of emerging organic microcontaminants.

Lab-on-Device Synthesis of Hierarchical Macro/Mesoporous WO3 Semiconducting Films for High-Performance H2S Sensing.

The performance consistency of the gas sensor is strongly dependent on the interface binding between the sensitive materials and the electrodes. Traditional powder coating methods can inevitably lead to differences in terms of substrate-film interface interaction and device performance, affecting the stability and lifetime. Thus, efficient growth of sensitive materials on device substrates is crucial and essential to enhance the sensing performance, especially for stability. Herein, hierarchically ordered macro/mesoporous WO3 films are in situ synthesized on the electrode via a facile soft/hard dual-template strategy. Orderly arrayed uniform polystyrene (PS) microspheres with tailored size (ca. 1.2 µm) are used as a hard template, and surfactant Pluronic F127 as a soft template can co-assemble with tungsten precursor into ordered mesostructure in the interstitials of PS colloidal crystal induced by solvent evaporation. Benefiting from its rich porosity and high stability, the macro/mesoporous WO3-based sensor shows high sensitivity (Rair/Rgas = 307), fast response/recovery speed (5/9 s), and excellent selectivity (SH2S/Smax > 7) toward 50 ppm H2S gas (a biomarker for halitosis). Significantly, the sensors exhibit an extended service life with a negligible change in sensing performance within 60 days. This lab-on-device synthesis provides a platform method for constructing stable nanodevices with good consistency and high stability, which are highly desired for developing high-performance sensors.

Hierarchically porous MOF@COF structures with ultrafast gas diffusion rate for C2H6/C2H4 separation.

For ethylene purification, C2H6-selective metal-organic frameworks (MOFs) show great potential to directly produce polymer-grade C2H4 from C2H6/C2H4 mixtures. Most C2H6-traping MOFs are ultra-microporous structures so as to strengthen multiple supramolecular interactions with C2H6. However, the narrowed pore channels of C2H6-traping MOFs cause large guest diffusion barriers, greatly hampering their practical applications. Herein, we present a feasible strategy by precisely constructing hierarchically porous MOF@COF core-shell structures to address this issue. Additional mesoporous diffusion channels were incorporated between MOF crystals through the construction of the COF shell, thereby enhancing the gas adsorption kinetics. Notably, designing a core-shell MOF@COF structure with an optimal coating amount of mesoporous COF shell will further improve the gas diffusion rate. Breakthrough experiments reveal that the tailored MOF@COF composites can effectively achieve C2H6/C2H4 separation and maintain its separation performance over five continuous measurement cycles. This investigation opens up a new avenue to solve the diffusion/transfer issues and provides more opportunities and potentials for MOF@COF composites in practical separation applications.

Facile and scalable synthesis of functionalized hierarchical porous polymers for efficient uranium adsorption.

Efficient uranium capture from wastewater holds great importance for the environmental remediation and sustainable development of nuclear energy, but it is a tremendous challenge. Herein, a facile and scalable approach is reported to fabricate functionalized hierarchical porous polymers (PPN-3) decorated with high density of phosphate groups for uranium adsorption. The as-constructed hierarchical porous structure could allow rapid diffusion of uranyl ions, while abundant phosphate groups that serve as adsorption sites could provide the high affinity for uranyl. Consequently, PPN-3 shows a high uranium adsorption uptake of 923.06 mg g-1 and reaches adsorption equilibrium within simply 10 min in uranium-spiked aqueous solution. Moreover, PPN-3 affords selective adsorption of uranyl over multiple metal ions and possesses a rapid and high removal rate of U(VI) in real water systems. Furthermore, this study offers direct polymerization strategy for the cost-effective fabrication of phosphate-functionalized porous organic polymers, which may provide promising application potential for uranium extraction.

Construction of a highly efficient adsorbent for one-step purification of recombinant proteins: Functionalized cellulose-based monolith fabricated via phase separation method.

Currently, purification step in the recombinant protein manufacture is still a great challenge and its cost far outweighs those of the upstream process. In this study, a functionalized cellulose-based monolith was constructed as an efficient affinity adsorbent for one-step purification of recombinant proteins. Firstly, the fundamental cellulose monolith (CE monolith) was fabricated based on thermally induced phase separation, followed by being modified with nitrilotriacetic acid anhydride through esterification to give NCE monolith. After chelating with Ni2+, the affinity adsorbent NCE-Ni2+ monolith was obtained, which was demonstrated to possess a hierarchically porous morphology with a relatively high surface area, porosity and compressive strength. The adsorption behavior of NCE-Ni2+ monolith towards ß2-microglobulin with 6 N-terminus His-tag (His-ß2M) was evaluated through batch and fixed-bed column experiments. The results revealed that NCE-Ni2+ monolith exhibited a relatively fast His-ß2M adsorption rate with a maximum adsorption capacity of 329.2 mg/g. The fixed-bed column adsorption implied that NCE-Ni2+ monolith showed high efficiency for His-ß2M adsorption. Finally, NCE-Ni2+ monolith was demonstrated to have an excellent His-ß2M purification ability from E. coli lysate with exceptional reusability. Therefore, the resultant NCE-Ni2+ monolith had large potential to be used as an efficient adsorbent for recombinant protein purification in practical applications.

Molecular-level insight into the chlorofluorocarbons adsorption by defective covalent organic polymers.

Halocarbons have important industrial applications, however they contribute to global warming and the fact that they can cause ozone depletion. Hence, the techniques that can capture and recover the used halocarbons with energy efficiency methods have recently received greater attention. In this contribution, we report the capture of dichlorodifluoromethane (R12), which has high global warming and ozone depletion potential, using covalent organic polymers (COPs). The defect-engineered COPs were synthesized and demonstrated outstanding sorption capacities, ~226 wt% of R12 combined with linear-shaped adsorption isotherms. We further identified the plausible microscopic adsorption mechanism of the investigated COPs via grand canonical Monte Carlo simulations applied to non-defective and a collection of atomistic models of the defective COPs. The modeling work suggests that significant R12 adsorption is attributed to a gradual increment of porosities due to isolated/interconnected micro-/meso-pore channels and the change of the long-range ordering of both COPs. The successive hierarchical-pore-filling mechanism promotes R12 molecular adsorption via moderate van der Waals adsorbate-adsorbent interactions in the micropores of both COPs at low pressure followed by adsorbate-adsorbate interactions in the extra-voids created at moderate to high pressure ranges. This continuous pore-filling mechanism makes defective COPs as promising sorbents for halocarbon adsorption.

Confined growth of Ultrathin, nanometer-sized FeOOH/CoP heterojunction nanosheet arrays as efficient self-supported electrode for oxygen evolution reaction.

Self-supported electrodes, featuring abundant active species and rapid mass transfer, are promising for practical applications in water electrolysis. However, constructing efficient self-supported electrodes with a strong affinity between the catalytic components and the substrate is of great challenge. In this study, by combining the ideas of in-situ construction and space-confined growth, we designed a novel self-supported FeOOH/cobalt phosphide (CoP) heterojunctions grown on a carefully modified commercial Ni foam (NF) with three-dimensional (3D) hierarchically porous Ni skeleton (FeOOH/CoP/3D NF). The specific porous structure of 3D NF directs the confined growth of FeOOH/CoP catalyst into ultra-thin and small-sized nanosheet arrays with abundant edge active sites. The active FeOOH/CoP component is stably anchored on the rough pore wall of 3D NF support, leading to superior stability and improved conductivity. These structural advantages contributed to a highly facilitated oxygen evolution reaction (OER) activity and enhanced durability of the FeOOH/CoP/3D NF electrode. Herein, the FeOOH/CoP/3D NF electrode afforded a low overpotential of 234 mV at 10 mA cm-2 (41 mV smaller than FeOOH/CoP grown on unmodified Ni foam) and high stability for over 90 h, which is among the top reported OER catalysts. Our study provides an effective idea and technique for the construction of active and robust self-supported electrodes for water electrolysis.

Hierarchically porous ZnO derived from zeolitic imidazolate frameworks for high-sensitive MEMS NO2 sensor.

Three-dimensional (3D) porous metal oxide nanomaterials with controllable morphology and well-defined pore size have attracted extensive attention in the field of gas sensing. Herein, hierarchically porous ZnO-450 was obtained simply by annealing Zeolitic Imidazolate Frameworks (ZIF-90) microcrystals at an optimal temperature of 450 °C, and the effect of annealing temperature on the formation of porous nanostructure was discussed. Then the as-obtained ZnO-450 was employed as sensing materials to construct a Micro-Electro-Mechanical System (MEMS) gas sensor for detecting NO2. The MEMS sensor based on ZnO-450 displays the excellent gas-sensing performances at a lower working temperature (190 °C), such as high response value (242.18% @ 10 ppm), fast response/recovery time (9/26 s) and ultralow limit of detection (35 ppb). The ZnO-450 sensor shows better sensing performance for NO2 detection than ZnO-based composites materials or commercial ZnO nanoparticles (NPs), which are attributed to its unique hierarchically structures with high porosity and larger surface area. This ZIFs driven strategy can be expected to pave a new pathway for the design of high-performance NO2 sensors.

Hierarchically porous surface of HA-sandblasted Ti implant screw using the plasma electrolytic oxidation: Physical characterization and biological responses.

The surface topological features of bioimplants are among the key indicators for bone tissue replacement because they directly affect cell morphology, adhesion, proliferation, and differentiation. In this study, we investigated the physical, electrochemical, and biological responses of sandblasted titanium (SB-Ti) surfaces with pore geometries fabricated using a plasma electrolytic oxidation (PEO) process. The PEO treatment was conducted at an applied voltage of 280 V in a solution bath consisting of 0.15 mol L-1 calcium acetate monohydrate and 0.02 mol L-1 calcium glycerophosphate for 3 min. The surface chemistry, wettability, mechanical properties and corrosion behavior of PEO-treated sandblasted Ti implants using hydroxyapatite particles (PEO-SB-Ti) were improved with the distribution of calcium phosphorous porous oxide layers, and showed a homogeneous and hierarchically porous surface with clusters of nanopores in a bath containing calcium acetate monohydrate and calcium glycerophosphate. To demonstrate the efficacy of PEO-SB-Ti, we investigated whether the implant affects biological responses. The proposed PEO-SB-Ti were evaluated with the aim of obtaining a multifunctional bone replacement model that could efficiently induce osteogenic differentiation as well as antibacterial activities. These physical and biological responses suggest that the PEO-SB-Ti may have a great potential for use an artificial bone replacement compared to that of the controls.

Investigation into the Structure and Properties of Biochar Co-Activated by ZnCl2 and NaHCO3 under Low Temperature Conditions.

Using sodium lignosulfonate as feedstock, ZnCl2 and NaHCO3 co-activated the hierarchical porous carbons (HPCs) were prepared by one-pot pyrolysis with different NaHCO3 dosages (0-4 g) and carbonization temperatures (400-600 °C). Subsequently, phosphotungstate (HPW) was supported with the resulting biochar for the α-pinene hydration reaction to produce α-terpineol. The optimum preparation conditions were determined according to the yield of α-terpineol. The formation mechanism and physicochemical properties of HPCs were analyzed through TG, SEM, XPS, XRD, FT-IR, and N2 adsorption-desorption isotherms. The results demonstrated that NaHCO3 underwent a two-step reaction which liberated a substantial quantity of CO2, thereby enhancing activated carbon's macroporous and mesoporous structures. Simultaneously, NaHCO3 mitigated strong acid gas (HCl) emissions during ZnCl2 activation. Compared with AC450-4:8:0 prepared by ZnCl2 activation alone, the total pore volume of AC450-4:8:2 prepared by co-activation is increased from 0.595 mL/g to 0.754 mL/g and the mesopore rate from 47.7% to 77.8%, which is conducive to reducing the steric hindrance of the hydration reaction and improving the selectivity. Hydration experiments show that the selectivity of α-terpineol is 55.7% under HPW/AC450-4:8:2 catalysis, higher than 31.0% for HPW and 47.4% for HPW/AC450-4:8:0.

Hierarchically porous magnetic biochar as an amendment for wheat (Triticum aestivum L.) cultivation in alkaline Cd-contaminated soils: Impacts on plant growth, soil properties and microbiota.

Hierarchically porous magnetic biochar (HMB) had been found to act as an effective amendment to remediate cadmium (Cd) in water and soil in a previous study, but the effects on wheat growth, Cd uptake and translocation mechanisms, and soil microorganisms were unknown. Therefore, soil Cd form transformation, soil enzyme activity, soil microbial diversity, wheat Cd uptake and migration, and wheat growth were explored by adding different amounts of HMB to alkaline Cd-contaminated soil under pot experiments. The results showed that application of HMB (0.5 %-2.0 %) raised soil pH, electrical conductivity (EC) and available Fe concentration, decreased soil available Cd concentration (35.11 %-50.91 %), and promoted Cd conversion to less bioavailable Cd forms. HMB treatments could reduce Cd enrichment in wheat, inhibit Cd migration from root to stem, rachis to glume, glume to grain, and promote Cd migration from stem to leaf and stem to rachis. HMB (0.5 %-1.0 %) boosted antioxidant enzyme activity, reduced oxidative stress, and enhanced photosynthesis in wheat seedlings. Application of 1.0 % HMB increased wheat grain biomass by 40.32 %. Besides, the addition of HMB (0.5 %-1.0 %) could reduce soil Cd bioavailability, increase soil enzyme activity, and increase the abundance and diversity of soil bacteria. Higher soil EC brought forth by HMB (2.0 %) made the wheat plants and soil bacteria poisonous. This study suggests that applying the right amount of HMB to alkaline Cd-contaminated soil could be a potential remediation strategy to decrease Cd in plants' edible parts and enhance soil quality.

Baking-inspired pore regulation strategy towards a hierarchically porous carbon for ultra-high efficiency cationic/anionic dyes adsorption.

Converting waste resource into porous carbon toward contaminant capturing is a crucial strategy for realizing "treating waste with waste". Inspired by bread baking process, the soybean meal activated carbon (SAC) with multimodal pore structures was developed via thermally remodeling the pores of waste soybean meal. The obtained SAC-3-800 has ultra-high specific surface area (3536.952 m2/g), as well as a hierarchically porous structure. SAC-3-800 exhibits extremely high adsorption capacity for methylene blue (MB) (3015.59 mg/g), methyl orange (MO) (6486.30 mg/g), and mixed dyes (8475.09 mg/g). The hierarchically porous structure enabled fast adsorption kinetics of SAC-3-800 for MB and MO (∼30 min). Additionally, SAC-3-800 shows excellent dynamic adsorption and regeneration performance, exhibiting great potential for industrial applications. This work showcases a feasible method for synthesizing hierarchically porous carbon with outstanding adsorption performance that can simultaneously achieve efficient treatment of dye-wastewater and value-added utilization of waste resources.

Hierarchically porous cellulose-based carbon aerogels with N-doped skeletons and encapsulated iron-based catalysts for efficient tetracycline catalytic degradation.

Three-dimensional interpenetrating and hierarchically porous carbon material is an efficient catalyst support in water remediation and it is still a daunting challenge to establish the relationship between hierarchically porous structure and catalytic degradation performance. Herein, a highly porous silica (SiO2)/cellulose-based carbon aerogel with iron-based catalyst (FexOy) was fabricated by in-situ synthesis, freeze-drying and pyrolysis, where the addition of SiO2 induced the hierarchically porous morphology and three-dimensional interpenetrating sheet-like network with nitrogen doping. The destruction of cellulose crystalline structure by SiO2 and the iron-catalyzed breakdown of glycosidic bonds synergistically facilitated the formation of electron-rich graphite-like carbon skeleton. The unique microstructure is confirmed to be favorable for the diffusion of reactants and electron transport during catalytic process, thus boosting the catalytic degradation performance of carbon aerogels. As a result, the catalytic degradation efficiency of tetracycline under light irradiation by adding only 5 mg of FexOy/SiO2 cellulose carbon aerogels was as high as 90 % within 60 min, demonstrating the synergistic effect of photocatalysis and Fenton reaction. This ingenious structure design provides new insight into the relationship between hierarchically porous structure of carbon aerogels and their catalytic degradation performance, and opens a new avenue to develop cellulose-based carbon aerogel catalysts with efficient catalytic performance.

Biomineralization-Inspired Confined-Space Fabrication of Polyimide Aerogels.

The biomineralization process endows biominerals with unique hierarchically porous structures and physical-chemical properties by filling the restricted microreaction space with amorphous phases before the growth of inorganic crystals. In this paper, a confined-space fabrication method inspired by biomineralization for preparing hierarchically porous polyimide (PI) aerogels and PI-derived carbon aerogels is introduced. The confined structure is established through a self-assembly method of vacuum impregnation and ultrasound-assisted freeze-drying. The hierarchically porous structure is controlled by adjusting the structure characteristics of the confined space and secondary aerogels. Subsequently, a variety of performance demonstrations are conducted to demonstrate the mechanical properties and application prospects in the fields of thermal insulation and electromagnetic shielding of the prepared aerogel.