Metal-organic frameworks (MOFs) are promising materials for sample pretreatment. The performance improvement of powdered MOFs is hindered by their aggregation and difficult recovery. To overcome these issues, a biodegradable lightweight spherical aerogel was used as a support for the in situ growth of copper-based MOFs (MOF-199). Furthermore, Fe3O4 nanoparticles were incorporated into the aerogel to achieve magnetic properties. Thus, hybrid aerogel spheres containing MOF-199 supported on magnetic oxidized cellulose nanofiber/carboxymethyl chitosan (MOF-199@mag-CNF/CMC) were fabricated. The effects of Fe3O4 loading amount and organic-ligand concentration on the properties (spherical geometry and mechanical strength) of the hybrid aerogel spheres were studied. Their potential application in the extraction of benzodiazepines (BZPs) from urine samples prior to liquid chromatography-mass spectrometry was evaluated. The highly dispersed MOF-199 crystals on the spherical aerogel effectively overcame the inherent structural shrinkage of the bare aerogel spheres; thus, the MOF-199@mag-CNF/CMC aerogel spheres were robust and could withstand repeated use for at least eight consecutive extraction cycles. Further, MOF-199@mag-CNF/CMC exhibited improved BZP extraction efficiency, which was 2.5-11.6 times higher than that of bare Cu2+@mag-CNF/CMC aerogel spheres, primarily due to additional π-π interaction and H-bonding as well as improved specific surface area. Parameters influencing the extraction and desorption processes were also comprehensively investigated. Under optimal conditions, this method provided a wide linear range of 0.1-10 µg/L (R2 > 0.995) and good precision (2.8-6.7% for intra-day; 1.9-7.8 % for inter-day). The limits of detection and quantification ranged from 0.02 to 0.11 µg/L and from 0.06 to 0.33 µg/L, respectively. The recoveries for the urine samples spiked with three concentrations of BZPs ranged from 73.9 % to 114.1 %. The proposed method is simple, sensitive and eco-friendly and can be used for the determination of BZPs from urine for clinical and forensic examinations.

Sulfate radical (SO4•-)-based advanced oxidation processes (SR-AOPs) have been studied to date by utilizing metal-organic frameworks as efficient catalysts to generate sulfate radicals by peroxymonosulfate (PMS) activation in water purification. It is important to select high-performance and reliable catalysts for efficient water remediation, and separation and recovery of catalysts are essential in the practical application of MOFs. Herein, we adapted thermally curable, shape-controllable, and cost-effective agarose (AG) as a smart matrix and ZIF-67, as a powerful catalyst to prepare nanoarchitectured aerogel (Z67@AG). This nanoporous aerogel composite can efficiently generate sulfate radicals and hydroxyl radicals by activating PMS in the nanopores. Z67@AG aerogel could be easily fabricated in various molds to make desired shapes. This approach enables its utilization for different filtering systems and demonstrates cost-effective and stable performance by mass production and reusability. In the SR-AOP, aerogel exhibited excellent catalytic decomposition performances of 95 % and 88 % efficiencies within 8 and 10 min for dye and levofloxacin, respectively. It is believed that the proposed highly catalytic nanoporous aerogel nanocomposite having cost-effectiveness, excellent catalytic activity, facile fabrication of desired shapes, and an excellent porous structure can be extended to the synthesis of various nanocomposites and emerging applications.

Functional gradient materials with material property anisotropy are one of the hotspots of current new material research. The gradient change of material properties comes from the change of the content of one or more components in the material, which is closely related to the preparation process of the material. Meanwhile, polysaccharide materials, as an environmentally friendly and green material, have attracted extensive attention from researchers. This paper focuses on the preparation process of functional gradient gel materials based on polysaccharides, analyzes the laws affecting the distribution of substances during the molding process from the basic principles of material molding, and clarifies the advantages and disadvantages of various methods, so as to promote the innovation of the theory of the preparation method of functional gradient gel materials. At the same time, the specific applications that can be realized by the gradient materials are introduced and compared with the traditional homogeneous materials to elucidate the enhancement of the usage properties brought by their unique gradient structure or properties, which will play a certain role as a reference for the direction of the application of the subsequent materials.

Electromagnetic wave absorption materials (EWAMs) have become an effective means to address electromagnetic (EM) radiation and enhance stealth technology, among which aerogels are valued for their lightweight nature and excellent designability. This study utilized environmentally friendly preparation and in-situ reduction techniques to fabricate bacterial cellulose (BC) / reduced graphene oxide (RGO) aerogels, achieving tailored EM wave loss capabilities by controlling the reduction time of ascorbic acid. Benefitting from the effects of freeze-casting, BC winding, hydrogen bond, and RGO layers coupling, the aerogel maintains their original structure after reduction and exhibits satisfactory EM wave absorption. The minimum reflection loss (RLmin) is -38.52 dB, with an effective absorption bandwidth (EAB) of 6.68 GHz and a maximum radar cross section (RCS) reduction of 44.69 dBsm. Additionally, the aerogel\'s lightweight (a low density of 9.03 mg/cm3) and outstanding thermal insulation properties enable it to adapt to complex conditions. Thus, the study provides a novel approach for the construction of industrialized and sustainable RGO-based EWAMs.

Wastewater contains various organic contaminants that pose great hazards to human health and the environment. A protein/polysaccharide-derived aerogel, namely, ICMA, was developed as a high-performance adsorbent for the simultaneous and efficient removal of diverse contaminants from wastewater, including melanoidin (MLE), Congo red (CR), and diclofenac (DIC). Metal organic framework (UiO-66-NH2), as a regulatory factor, significantly improved the porosity and pore volume of the ICMA to enhance the capture performance of contaminants. The ICMA exhibited outstanding adsorption efficiency owing to the incorporation of ample polyamine functional groups and its well-developed pore structure, large porosity and pore volume, and remarkable heat resistance. The equilibrium capture capacities of the ICMA were 1364, 2031, and 539 mg/g for MLE, CR, and DIC, respectively, with corresponding removal efficiencies all exceeding 90%. Furthermore, the ICMA can capture cationic dyes through MLE/CR/DIC-bridging interactions. After five cycles, the used ICMA can still maintain a high contaminant removal rate/amount, demonstrating good reusability. The classic adsorption model showed that the capture of contaminants by the ICMA is a double-layered and heterogeneous adsorption orientation. A brand new LWAMTM model demonstrated that the adsorption mass-transfer process is jointly determined by the external mass conveyance, pore diffusion, and adsorption on the active site. Multiple characterizations indicated that the contaminant adsorption onto the ICMA was mainly facilitated by charge interactions, with H-bonds playing a secondary role. Quantum chemical theory simulations further provide insights into the atomic-level mechanisms involved in the capture of contaminants. Hirshfeld surface analysis revealed that the ICMA functions as both an H-bond acceptor and a donor during contaminant adsorption. Scale-up and upgrade adsorption were performed to treat actual/simulated wastewater, establishing the groundwork for the industrial implementation of the ICMA.

Developing highly efficient electrocatalyst with heterostructure for hydrogen evolution and oxidation reactions (HER/HOR) in alkaline media is crucial to the fabrication and conversion of hydrogen energy but also remains a great challenge. Herein, the synthesis of ruthenium-nickel nanoparticles (Ru3-Ni NPs) with heterostructure for hydrogen electrocatalysis is reported, and studies show that their catalytic activity is improved by electron redistribution caused by the distinctly heterogeneous interface. Impressively, Ru3-Ni NPs possess the remarkable exchange current density (2.22 mA cm-2) for HOR. Additionally, an ultra-low overpotential of 28 mV is required to attain a current density of 10 mA cm-2 and superior stability of 200 h for HER. The highly efficient catalytic activity can be attributed to the electron transfer from Ni to Ru and the optimal adsorption of H* on Ru-Ni sites. Our study showcases a reliable heterostructure that boosts the HOR/HER activity of the catalyst in alkaline environments. This work provides a new pathway for designing high-performance electrocatalyst for energy storage and conversion.

Lightweight materials that combine high mechanical strength, insulation, and fire resistance are of great interest to many industries. This work explores the properties of environmentally friendly alginate aerogel composites as potential sustainable alternatives to petroleum-based materials. This study analyzes the effects of two additives (tannic acid and montmorillonite clay), the orientation that results during casting, and the crosslinking of the biopolymer with glutaraldehyde on the properties of the aerogel composites. The prepared aerogels exhibited high porosities between 90% and 97% and densities in the range of 0.059-0.191 g/cm3. Crosslinking increased the density and resulted in excellent performance under loading conditions. In combination with axial orientation, Young\'s modulus and yield strength reached values as high as 305 MPa·cm3/g and 7 MPa·cm3/g, respectively. Moreover, the alginate-based aerogels exhibited very low thermal conductivities, ranging from 0.038 W/m·K to 0.053 W/m·K. Compared to pristine alginate, the aerogel composites\' thermal degradation rate decreased substantially, enhancing thermal stability. Although glutaraldehyde promoted combustion, the non-crosslinked aerogel composites demonstrated high fire resistance. No flame was observed in these samples under cone calorimeter radiation, and a minuscule peak of heat release of 21 kW/m2 was emitted as a result of their highly efficient graphitization and fire suppression. The combination of properties of these bio-based aerogels demonstrates their potential as substituents for their fossil-based counterparts.

Polybenzoxazine (PBz) aerogels hold immense potential, but their conventional production methods raise environmental and safety concerns. This research addresses this gap by proposing an eco-friendly approach for synthesizing high-performance carbon derived from polybenzoxazine. The key innovation lies in using eugenol, ethylene diamine, and formaldehyde to create a polybenzoxazine precursor. This eliminates hazardous solvents by employing the safer dimethyl sulfoxide. An acidic catalyst plays a crucial role, not only in influencing the microstructure but also in strengthening the material\'s backbone by promoting inter-chain connections. Notably, this method allows for ambient pressure drying, further enhancing its sustainability. The polybenzoxazine acts as a precursor to produce two different carbon materials. The carbon material produced from the calcination of PBz is denoted as PBZC, and the carbon material produced from the gelation and calcination of PBz is denoted as PBZGC. The structural characterization of these carbon materials was analyzed through different techniques, such as XRD, Raman, XPS, and BET analyses. BET analysis showed increased surface of 843 m2 g-1 for the carbon derived from the gelation method (PBZGC). The electrochemical studies of PBZC and PBZGC imply that a well-defined morphology, along with suitable porosity, paves the way for increased conductivity of the materials when used as electrodes for supercapacitors. This research paves the way for utilizing heteroatom-doped, polybenzoxazine aerogel-derived carbon as a sustainable and high-performing alternative to traditional carbon materials in energy storage devices.

Cellulose nanofibers (NF) were extracted from kapok fibers using TEMPO oxidation, followed by a combination of mechanical grinding and ultrasonic processing. The TEMPO-mediated oxidation significantly impacted the mechanical disintegration behavior of the kapok fibers, resulting in a high NF yield of 98%. This strategy not only improved the fibrillation efficiency but also reduced overall energy consumption during NF preparation. An ultralight and highly porous NF-based aerogel was successfully prepared using a simple ice-templating technique. It had a low density in the range of 3.5-11.2 mg cm-3, high compressional strength (160 kPa), and excellent thermal insulation performance (0.024 W m-1 K-1). After silane modification, the aerogel displayed an ultralow density of 7.9 mg cm-3, good hydrophobicity with a water contact angle of 128°, and excellent mechanical compressibility with a high recovery of 92% at 50% strain. Benefiting from the silene support structure, it showed a high oil absorptive capacity (up to 71.4 g/g for vacuum pump oil) and a remarkable oil recovery efficiency of 93% after being reused for 10 cycles. These results demonstrate that our strategy endows nanocellulose-based aerogels with rapid shape recovery and high liquid absorption capabilities.

The mimesis of biological mechanisms by artificial devices constitutes the modern, rapidly expanding, multidisciplinary biomimetics sector. In the broader bioinspiration perspective, however, bioarchitectures may perform independent functions without necessarily mimicking their biological generators. In this paper, we explore such Bioarchitectonic notions and demonstrate three-dimensional photonics by the exact replication of insect organs using ultra-porous silica aerogels. The subsequent conformal systolic transformation yields their miniaturized affine \'clones\' having higher mass density and refractive index. Focusing on the paradigms of ommatidia, the compound eye of the hornet Vespa crabro flavofasciata and the microtrichia of the scarab Protaetia cuprea phoebe, we fabricate their aerogel replicas and derivative clones and investigate their photonic functionalities. Ultralight aerogel microlens arrays are proven to be functional photonic devices having a focal length f ~ 1000 μm and f-number f/30 in the visible spectrum. Stepwise systolic transformation yields denser and affine functional elements, ultimately fused silica clones, exhibiting strong focusing properties due to their very short focal length of f ~ 35 μm and f/3.5. The fabricated transparent aerogel and xerogel replicas of microtrichia demonstrate a remarkable optical waveguiding performance, delivering light to their sub-100 nm nanotips. Dense fused silica conical clones deliver light through sub-50 nm nanotips, enabling nanoscale light-matter interactions. Super-resolution bioarchitectonics offers new and alternative tools and promises novel developments and applications in nanophotonics and other nanotechnology sectors.