Hierarchical Pore Research Articles

Towards 3D Pore Structure of Porous Gypsum Cement Pozzolan Ternary Binder by Micro-Computed Tomography

A sophisticated characterisation of a porous material structure has been challenging in material science. Three-dimensional (3D) structure analysis allows the evaluation of a material’s homogeneity, pore size distribution and pore wall properties. Micro-computed tomography (micro-CT) offers a non-destructive test method for material evaluation. This paper characterises a novel ternary binder’s porous structure using micro-CT. Gypsum–cement–pozzolan (GCP) ternary binders are low-carbon footprint binders. Both natural and industrial gypsum were evaluated as a major components of GCP binders. Porous GCP binder was obtained by a foaming admixture, and the bulk density of the material characterised ranged from 387 to 700 kg/m3. Micro-CT results indicate that pores in the range from 0.017 to 3.0 mm can be effectively detected and described for porous GCP binders. The GCP binder structure proved to be dominant by 0.1 to 0.2 mm micropores. For GCP binders produced with natural gypsum, macropores from 2.2 to 2.9 mm are formed, while GCP binders with phosphogypsum possess pores from 0.2 to 0.6 mm. Micro-CT proved to be an effective instrument for characterising the homogeneity and hierarchical pore structure of porous ternary binders.

Graphene-based aerogel for efficient oil sorption and water pollution remediation

In the past few years, there has been a notable rise in the release of industrial waste oil, frequent oil spills at sea, and a significant escalation in the severity of water pollution. This issue has garnered global attention and is now recognised as a widespread concern. Hence, there is a pressing demand for an oil-absorbing material exhibiting high oil-absorption capabilities and robust mechanical properties. This study introduces a new aerogel characterised by a three-dimensional hierarchical pore size structure derived from natural corn stalk powder and graphene oxide (GO). The developed aerogel demonstrated notable sorption capacity ranging from 70.6 to 131.0 g/g, along with excellent compressibility and high elasticity. These properties enable effective oil-water separation and selective sorption. This study introduces a novel approach to treating agricultural waste and presents a straightforward, environmentally friendly, cost-effective method for synthesising high-performance graphene-based oil-absorbing agents.

Oxygen-Terminated Polycrystalline Boron-Doped Diamond Superhydrophobic Surface with Excellent Mechanical and Thermal Stabilities.

Superhydrophobic surfaces are of great interest because of their remarkable properties. Due to its maximal hardness and chemical inertness, diamond film has great potential in fabricating robust superhydrophobic surfaces. In the present study, an oxygen-terminated polycrystalline boron-doped diamond (O-PBDD) superhydrophobic surface with micro/nano-hierarchical porous structures is developed. The preparation method is very simple, requiring only sputtering and dewetting procedures. The former involves sputtering gold and copper particles onto the hydrogen-terminated polycrystalline boron-doped diamond (H-PBDD) to form gold/copper films, whereas the latter involves placing the samples in an atmospheric tube furnace to form hierarchical pores. By controlling the etching parameters, the wettability of the O-PBDD surface can be adjusted from hydrophilic to superhydrophobic, which is significantly different to the normal hydrophilicity feature of O-termination diamonds. The water contact angle of the obtained O-PBDD surface can reach 165 ± 5°, which is higher than the superhydrophobic diamond surfaces that are reported in the literature. In addition, the O-PBDD surface exhibits excellent durability; it can maintain satisfactory superhydrophobicity even after high-pressure, high-temperature, and sandpaper friction tests. This work provides a new research direction for fabricating robust superhydrophobic materials with diamond film.

Coupling bimetallic selenides with homogeneous mediators synergistically accelerating overall sulfur redox kinetics for high-performances lithium–sulfur batteries

The practical applications of lithium-sulfur batteries (LSBs) are hampered by poor electrical conductivity, severe shuttling of intermediate lithium polysulfides (LiPSs) and sluggish redox kinetics. Herein, we introduce a multifunctional catalytic system by integrating bimetallic ZnSe-CoSe2 with CoCp2 mediators, aimed at serving as redox kinetic accelerators in LSBs. In this design, the ZnSe-CoSe2 heterostructure with hierarchical pores and large surface area, is capable of immobilizing both soluble LiPSs and CoCp2 mediators, but also provides abundant active sites for catalyzing LiPSs conversions. Concurrently, the soluble CoCp2 mediators contribute to promoting the high-dimensional growth of Li2S and reducing the interface polarization. Electrochemical experiments and theoretical analyses reveal that the ZnSe-CoSe2/CoCp2 system synergistically accelerates overall sulfur redox kinetics. Consequently, the cell with the ZnSe-CoSe2/CoCp2 system under a sulfur loading of 2.3 mg cm−2 exhibits superior long-term cycling stability at 1.0C. Additionally, it achieves a remarkable areal capacity of 6.5 mAh cm−2 under a high sulfur loading of 8.0 mg cm−2 and a low electrolyte-to-sulfur ratio of 5.0 µL mg−1.

Designing Mesoporous Prussian Blue@zinc Phosphate Nanoparticles with Hierarchical Pores for Varisized Guest Delivery and Photothermally-Augmented Chemo-Starvation Therapy.

With the rapid development of nanotechnology, constructing a multifunctional nanoplatform that can deliver various therapeutic agents in different departments and respond to endogenous/exogenous stimuli for multimodal synergistic cancer therapy remains a major challenge to address the inherent limitations of chemotherapy. Herein, we synthesized hollow mesoporous Prussian Blue@zinc phosphate nanoparticles to load glucose oxidase (GOx) and DOX (designed as HMPB-GOx@ZnP-DOX NPs) in the non-identical pore structures of their HMPB core and ZnP shell, respectively, for photothermally augmented chemo-starvation therapy. The ZnP shell coated on the HMPB core, in addition to providing space to load DOX for chemotherapy, could also serve as a gatekeeper to protect GOx from premature leakage and inactivation before reaching the tumor site because of its degradation characteristics under mild acidic conditions. Moreover, the loaded GOx can initiate starvation therapy by catalyzing glucose oxidation while causing an upgradation of acidity and H2O2 levels, which can also be used as forceful endogenous stimuli to trigger smart delivery systems for therapeutic applications. The decrease in pH can improve the pH-sensitivity of drug release, and O2 can be supplied by decomposing H2O2 through the catalase-like activity of HMPBs, which is beneficial for relieving the adverse conditions of anti-tumor activity. In addition, the inner HMPB also acts as a photothermal agent for photothermal therapy and the generated hyperthermia upon laser irradiation can serve as an external stimulus to further promote drug release and enzymatic activities of GOx, thereby enabling a synergetic photothermally enhanced chemo-starvation therapy effect. Importantly, these results indicate that HMPB-GOx@ZnP-DOX NPs can effectively inhibit tumor growth by 80.31% and exhibit no obvious systemic toxicity in mice. HMPB-GOx@ZnP-DOX NPs can be employed as potential theranostic agents that incorporate multiple therapeutic modes to efficiently inhibit tumors.

3D porous SnO2/MXene as a superior anode material for Li-ion and Na-ion battery

In this paper, we synthesized the SnO2/MXene composite with unique three-dimensional(3D) porous framework by removing of polystyrene (PS) nanospheres as sacrificial templates. The SnO2 nanopaticles are evenly anchored in MXene nanosheets by electrostatic self-assembly. The composite demonstrates plenty of hierarchical pores and a greatly enlarged interfacial area, which can facilitate the permeation of electrolyte and provide more active sites for Li+/Na+ intercalation. The conductive porous structure can also promote the fast transport of electrons and ions, and maintain the structural stability of eletrode in the cycling. The SnO2/MXene composite shows increased reversible capacities and excellent cycling stability for dual storage of both Li+ and Na+. As anode material for lithium ion storage, it has long-life cycling performance of 373.7 mAh/g after 1400 cycles at 5 A/g, superior than most reported SnO2/carbide composites. For sodium ion storage, the conposite also shows a increased capacity of 236.8 mAh/g at 0.4 A/g after 100 cycles. This study provides a design strategy for preparing anode materials of advanced battery system with promising electrochemical performance.

Construction of chitosan/alginate aerogels with three-dimensional hierarchical pore network structure via hydrogen bonding dissolution and covalent crosslinking synergistic strategy for thermal management systems

To replace traditional petrochemical-based thermal insulation materials, in this work, the chitosan (CHI)/alginate (ALG) (CA) aerogels with three-dimensional hierarchical pore network structure were constructed by compositing CHI and ALG using a synergistic strategy of hydrogen bonding dissolution and covalent crosslinking. The structure and properties were further regulated by crosslinking the CA aerogels with epichlorohydrin (ECH). The CA aerogels exhibited various forms of covalent crosslinking, hydrogen bonding and electrostatic interactions, with hydrogen bonding content reaching 79.12 %. The CA aerogels showed an excellent three-dimensional hierarchical pore network structure, with an average pore size minimum of 15.92 nm. The structure regulation of CA aerogels obtained excellent compressive properties, with an increase of stress and strain by 137.61 % and 45.05 %, which can support a heavy object 5000 times its weight. Additionally, CA aerogels demonstrate excellent thermal insulation properties and low thermal conductivity, comparable to commercially available insulation materials. More importantly, CA aerogels have good cyclic insulation stability and thermal properties, and they have a flame retardancy rating of V-0, which shows the stability of insulation properties and excellent safety. CA aerogels provide new ideas for the development of biomass thermal insulation materials and are expected to be candidates for thermal management applications.

In English

The synthesis and characterization of heterostructure por-Ga2O3/GaAs represent a crucial advancement in nanomaterials, particularly in optoelectronic applications. Employing a two-stage electrochemical etching methodology, this research has elucidated the precise conditions required to fabricate such a heterostructure. The initial stage involves etching monocrystalline gallium arsenide (GaAs) using an aqueous nitric acid solution as the electrolyte. This process is governed by the redox reactions at the crystal-electrolyte interface, where GaAs are partially oxidized and selectively etched. The second stage introduces ethanol into the electrolytic solution. This chemical addition serves a dual purpose: Firstly, it modulates the electrochemical environment, allowing for controlling pore morphology in GaAs. Secondly, it facilitates the etching of the resultant oxide layer, which predominantly consists of gallium oxide (Ga2O3). The formation of this oxide layer can be attributed to the oxidation of GaAs, driven by the electrochemical potentials and resulting in the deposition of reaction by-products on the substrate surface. The fabricated nanocomposite was comprehensively characterized using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Analysis (EDX), and Raman Spectroscopy. SEM imaging revealed a range of agglomerated nanostructures dispersed across the surface, with dimensions ranging from 8–25 μm, 1–1.5 μm, and 70–100 nm. These observations suggest a hierarchical pore structure indicative of a complex etching mechanism modulated by the electrolyte composition. Raman spectroscopic analysis corroborated the presence of various phases in the heterostructure. Signals corresponding to bulk GaAs, serving as the substrate, were distinguishable. In addition, peaks indicative of porous GaAs and porous Ga2O3 were observed. A cubic phase in the Ga2O3 layer was particularly noteworthy, suggesting a higher degree of crystallinity. Notably, the absence of Raman-active modes associated with internal stresses implies that the fabricated heterostructure is of high quality.

Laser Additive Manufacturing of Three-Dimensional Ti/TiN Nanotube Arrays with Hierarchical Pore Structures and Promoted Supercapacitor Performances.

Titanium-based composites hold great promise in versatile functional application fields, including supercapacitors. However, conventional subtractive methods for preparing complex-shaped titanium-based composites generally suffer from several significant shortcomings, including low efficiency, strictly simple geometry, low specific surface area, and poor electrochemical performance of the products. Herein, three-dimensional composites of Ti/TiN nanotube arrays with hierarchically porous structures were prepared using the additive manufacturing method of selective laser melting combined with anodic oxidation and nitridation. The resultant Ti/TiN nanotube array composites exhibit good electrical conductivity, ultrahigh specific surface areas, and outstanding supercapacitor performances featuring the unique combination of a large specific capacitance of 134.4 mF/cm2 and a high power density of 4.1 mW/cm2, which was remarkably superior to that of their counterparts. This work is anticipated to provide new insights into the facile and efficient preparation of high-performance structural and functional devices with arbitrarily complex geometries and good overall performances.

Monolithic polar conjugated microporous polymers: Optimisation of adsorption capacity and permeability trade-off based on process simulation of flue gas separation

The challenge in developing porous materials that significantly reduce energy consumption in industrial gas separation lies in striking a balance between adsorption capacity and permeability. Herein, the precise anchoring of polar oxygen adsorption sites in a robust porous conjugated backbone is achieved through the directed self-assembly of building blocks, resulting in the formation of oxygen-enriched conjugated microporous polymers (O-CMPs). O-CMPs serve as attractive porous hosts for the synergistic separation of CO2 and PM in exhaust gases emitted from point sources. As analyzed by surface electrostatic potential, the introduction of oxygen-doped π-conjugated systems induced surface charge redistribution, enhancing the CO2 quadrupole-dipole effect within a widely distributed microporous network. The O-CMPs exhibited a high CO2 adsorption capacity of 125.84 mg/g at 273 K and 1.0 bar. The monolithic O-CMPs incorporate permanently integrated hierarchical pores with a high micropore ratio. This transport channel can enhance the transfer rate of gas flow while selectively intercepting CO2 and PM. The rigid conjugated molecular chains and hollow nanotube microstructure effectively prevent material densification, yielding a minimal gas permeation resistance of only 5 Pa. Additionally, O-CMPs also demonstrate outstanding stability and PM separation performance under humid and acid/alkaline condition. The visual process simulations serve to further validate that aforementioned design strategy can optimize the trade-off between adsorption capacity and permeability.

Mass-Transfer Enhancement in the CO2 Oxidative Dehydrogenation of Propane over GaN Supported on Zeolite Nanosheets with a Short b-Axis and Hierarchical Pores

Mass-Transfer Enhancement in the CO₂ Oxidative Dehydrogenation of Propane over GaN Supported on Zeolite Nanosheets with a Short <i>b</i>-Axis and Hierarchical Pores

Enzyme-catalyzed hydrolysis of surface polycaprolactone for enhanced cell adhesion on polycaprolactone-based composite scaffolds

In this study, a porous polycaprolactone (PCL) −based scaffold was treated with lipase to create a hierarchical pore structure. The lipase treatment increased the surface roughness and hydrophilicity, leading to enhanced cell adhesion compared to the untreated scaffold. The hierarchical pore structure of the lipase-treated scaffold shows promise for bone regeneration. This lipase treatment approach offers a new method for designing tissue engineering scaffolds.

N/S co-doped interconnected hierarchical porous carbon cathode for zinc-ion hybrid capacitors with high energy density

Porous carbon materials (PCMs) are regarded as one of the most promising cathode materials for zinc-ion hybrid capacitors (ZIHCs) because of their low cost and abundant resource. Nevertheless, it is still a major challenge to enhance the energy density of PCMs-based ZIHCs. Herein, N/S co-doped interconnected hierarchical porous carbons (NS–IHPCs) are prepared from coal tar pitch (CTP) via a MgO@ZIF-8 double-template, in situ activation and N/S doping strategy to tune the microstructure and chemical composition. The as-prepared NS-IHPC1.5 features high specific surface area of 1273 m2 g−1, hierarchical pore structure and suitable heteroatom doping. Consequently, as a cathode, the NS-IHPC1.5-based ZIHC exhibits a high energy density of 125.3 Wh kg−1 at 134.5 W kg−1 and still remains 85.3 Wh kg−1 at 14096.1 W kg−1. The calculation results of density functional theory (DFT) demonstrate that the combination of pyrrole nitrogen and ortho-oxidized sulfur in samples achieves more negative Zn2+ adsorption energy. Correspondingly, the high capacity (166.5 mAh g−1 at 0.2 A g−1) and long cycle stability (94.0 % capacitance retention at 5 A g−1 after 20,000 cycles) are achieved for NS-IHPC1.5. This work offers a reliable way for synthesizing remarkable cathode materials from coal chemical by-products for energy storage.

Easily recyclable pd-decorated hierarchically porous nanofibers for the selective hydrogenation of phenol

The electrospun nanofibers are good candidates for the catalyst carriers, however the fabrication of electrospun nanofibers with well-developed porous structures is still a big challenge. Herein, the SiO2 nanofibers obtained by electrospinning and pyrolysis are functionalized with polydopamine (PDA) and UiO-66-NH2, and after Pd loading the hierarchically porous Pd/UiO-SiO2 nanofiber catalysts were developed. The surface properties and microstructures of the Pd/UiO-SiO2 nanofiber catalysts were regulated by adjusting the concentrations of dopamine (DA) and zirconium tetrachloride (ZrCl4), and the catalytic performance was tested in the selective hydrogenation of phenol to cyclohexanone. The as-prepared Pd/UiO-SiO2-3–21.44 has abundant hierarchical pores and amino groups, high Pd content with good dispersion, and rich Pd(0), thus exhibiting a superior specific activity of 47.3 h−1 higher than most Pd-based catalysts. Most importantly, the Pd/UiO-SiO2-3–21.44 nanofiber catalyst can be directly taken out from the reaction solution and used for the next run, and has good catalytic stability.

Lightweight polyimide composite foams with anisotropic hierarchical pore structure for enhanced mechanical, flame retardancy and thermal insulation purposes

In this study, lightweight polyimide foam (PIF) with anisotropic pore structure were fabricated by adopting microwave-assisted foaming technique. Afterward, lightweight PIF/PI aerogel/silica aerogel (PIF/PIA/SiA) composite foams with anisotropic hierarchical pore structures was prepared by impregnation and directional freeze-drying method. The directional growth of foam pores and ice crystals endowed PIF/PIA/SiA composite foams with anisotropic skeleton structures and hierarchical porous filling structures, leading to anisotropic mechanical and thermal insulation performances. PIF/PIA/SiA composite foams presented mechanical robustness in vertical direction and mechanical flexibility in horizontal direction due to its unique pore structure. In addition, PIF/PIA/SiA composite foams showed outstanding thermal stability and flame retardancy, suggesting a promising application in the field of high temperature fire protection. The PIF/PIA/SiA composite foams exhibited superior thermal insulation performance with thermal conductivities ranging from 0.0253 to 0.0523 W/(m·K) between 25 and 300 °C. Therefore, a facile strategy was developed to fabricate PIF-based composite foams for mechanical, flame retardancy and thermal insulation applications in high-end engineering fields.

Study of the Suitability of Corncob Biochar as Electrocatalyst for Zn–Air Batteries

There has been a recent increasing interest in Zn–air batteries as an alternative to Li-ion batteries. Zn–air batteries possess some significant advantages; however, there are still problems to solve, especially related to the tuning of the properties of the air–cathode which should carry an inexpensive but efficient bifunctional oxygen reduction (ORR) and oxygen evolution (OER) reaction electrocatalyst. Biochar can be an alternative, since it is a material of low cost, it exhibits electric conductivity, and it can be used as support for transition metal ions. Although there is a significant number of publications on biochars, there is a lack of data about biochar from raw biomass rich in hemicellulose, and biochar with a small number of heteroatoms, in order to report the pristine activity of the carbon phase. In this work, activated biochar has been made by using corncobs. The biomass was first dried and minced into small pieces and pyrolyzed. Then, it was mixed with KOH and pyrolyzed for a second time. The final product was characterized by various techniques and its electroactivity as a cathode was determined. Physicochemical characterization revealed that the biochar had a hierarchical pore structure, moderate surface area of 92 m2 g−1, carbon phase with a relatively low sp2/sp3 ratio close to one, and a limited amount of N and S, but a high number of oxygen groups. The graphitization was not complete while the biochar had an ordered structure and contained significant O species. This biochar was used as an electrocatalyst for ORR and OER in Zn–air batteries where it demonstrated a satisfactory performance. More specifically, it reached an open-circuit voltage of about 1.4 V, which was stable over a period of several hours, with a short-circuit current density of 142 mA cm−2 and a maximum power density of 55 mW cm−2. Charge–discharge cycling of the battery was achieved between 1.2 and 2.1 V for a constant current of 10 mA. These data show that corncob biochar demonstrated good performance as an electrocatalyst in Zn–air batteries, despite its low specific surface and low sp2/sp3 ratio, owing to its rich oxygen sites, thus showing that electrocatalysis is a complex phenomenon and can be served by biochars of various origins.

Mn single atoms coordinated with N and O and embedded in activated carbon for supercapacitor and oxygen evolution reaction applications

With the aim of increasing the potential applications of activated carbon (AC) in supercapacitors and zinc-air batteries, the present work prepared AC composites doped with Mn, N and O using various methods. These materials exhibited superior capacitive and oxygen evolution reaction (OER) electrocatalytic activity. Analytical characterizations and density functional theory calculations demonstrated that the specimen subjected to calcination and heating under N2 and NH3 (AC-Mn-3) had a higher specific surface area, an optimized distribution of pyridinic and pyrrolic N and single Mn atom active sites. These factors improved the supercapacitor performance and OER catalytic activity of this material. The hierarchical pore structure of the AC matrix also facilitated electrolyte transport while simultaneously reducing internal resistance and protecting the electrode structure during cycling. An AC-Mn-3 electrode provided a high specific capacitance of 516.20 F/g at 1 A/g while a symmetric supercapacitor based on this electrode delivered an exceptional energy density of 71.69 Wh/kg at a power density of 500 W/kg. When applied to the OER, the AC-Mn-3 achieved a low overpotential of 270.21 mV at 10 mA/cm2 in 1 M KOH. Theoretical calculations suggested that single Mn atoms coordinated with N and O effectively bound oxygenated intermediates to lower the adsorption energy barrier associated with the OER rate-determining step going from OH* to O*. These results provide new insights concerning the mechanism by which improved supercapacitor performance and OER catalytic activity can be realized and demonstrate an effective strategy for AC modification.

Supramolecular cross-linking affords superelastic and fatigue-resistant cellulose-based nanocomposites with excellent thermomechanical properties and waterproofing performance

Nanocellulose is one of the most abundant renewable resources on earth and is used in many applications due to its excellent physical and chemical properties, and it is an important biopolymer raw material to support human well-being. However, current cellulose-based aerogel nanocomposites are plagued by irreconcilable contradictions between thermomechanical and waterproofing characteristics due to their hygroscopicity. Herein, sustainable insulating cellulose aerogel nanocomposites are prepared from tempo-oxidized bamboo cellulose nanofibrils (CNFs) and polyvinyl alcohol (PVA) with a continuous orientation-free pore architecture formed by CNFs/PVA pre-hydrogel aggregates, which combine to become the basic structural unit for producing superelastic properties. The resulting lightweight CNFs/PVA aerogels (CNPA) with a hierarchical orientation-free pore architecture and density about 5–20 kg m3 achieve an optimal thermomechanical and insulation trade-off, demonstrating temperature-invariant compressibility (–100–500 ℃) and a low thermal conductivity of 38.2 mW m–1 K–1 at 300 ℃. Particularly, the flyweight CNPA retained its structural integrity after more than 106 cycles at ɛ=20 %, 105 cycles at ɛ=50 %, and 104 cycles at ɛ=80 %. Furthermore, CNPA also exhibits robust liquid-repellency with a WCA exceeding 160.3°. This lightweight cellulose-based nanocomposites, although constructed using an intrinsically hygroscopicity nanocellulose-constituent, is simultaneously superelastic, fatigue-resistant, thermomechanical, and waterproofing performance.

Portable electrochemical sensing platform based on amidated GO-MOF and PEDOT:PSS for high-efficient detection of ponceau 4R.

Apromising electrochemical sensing platform for the detection of ponceau 4R in food has been fabricated based on the carboxylated graphene oxide (GO-COOH), metal-organic framework (MOF) UIO-66-NH2, and poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). To this endGO-COOH was covalently coupled with UIO-66-NH2 through amide reaction, endowing the material (GO-CONH-UIO-66) unique hierarchical pores and high chemical stability and as a result improving the conductivity of MOF and the dispersion of GO. After the addition of PEDOT:PSS into GO-CONH-UIO-66, the continuity and conductivity of the composite (PEDOT:PSS/GO-CONH-UIO-66) have been further enhanced, due to the high conductivity, favorable film-forming, and hydrophilic properties of PEDOT:PSS. Systematic electrochemical experiments confirm that the PEDOT:PSS/GO-CONH-UIO-66/GCE shows satisfactory electrochemical sensing properties towards the detection of ponceau 4R, with a wide linear detection range of 0.01-30μM, a low limit of detection of3.33nM, and a high sensitivity of 0.606 μA μM-1cm-2. ThePEDOT:PSS/GO-CONH-UIO-66 sensing platform was successfully used to detect ponceau 4R in beverage, and the detection results were compared with high-performance liquid chromatography. As a result, the PEDOT:PSS/GO-CONH-UIO-66 composite shows a promising application prospect for rapid detection of ponceau 4R in food and will play significant role in food safety detection and supervision.

Bio‐inspired hierarchical bamboo‐based air filters for efficient removal of particulate matter and toxic gases

AbstractAir pollution is caused by the perilous accumulation of particulate matter (PM) and harmful gas molecules of different sizes. There is an urgent need to develop highly efficient air filtration systems capable of removing particles with a wide size distribution. However, the efficiency of current air filters is compromised by controlling their hierarchical pore size. Inspired by the graded filtration mechanisms in the human respiratory system, microporous ZIF‐67 is in situ synthesized on a 3D interconnected network of bamboo cellulose fibers (BCFs) to fabricate a multiscale porous filter with a comprehensive pore size distribution. The macropores between the BCFs, mesopores formed by the BCF microfibers, and micropores within the ZIF‐67 synergistically facilitate the removal of particulates of different sizes. The filtration capabilities of PM2.5 and PM0.3 could reach 99.3% and 98.6%, respectively, whereas the adsorption of formaldehyde is 88.7% within 30 min. In addition, the filter exhibits excellent antibacterial properties (99.9%), biodegradability (80.1% degradation after 14 days), thermal stability, and skin‐friendly properties (0 irritation). This study may inspire the research of using natural features of renewable resources to design high‐performance air‐filtration materials for various applications.