Hierarchical Porous Structure Research Articles

A networked iron and nitrogen-doped ZIF-8/MWCNTs heterostructure for oxygen reduction reaction.

Zeolitic Imidazolate Frameworks-8 (ZIF-8) is commonly used as an ideal precursor for non-noble metal catalysts because of its high specific surface area, ultra-high porosity, and N-rich content. Upon pyrolyzing ZIF-8 at 900 °C in Ar, the resulting material, referred to as Z8, displayed good activity toward the oxygen reduction reaction (ORR). Then the ZIF-8 was mixed with various conductive carbon materials, such as multiwall carbon nanotubes (MWCNTs), Acetylene black (ACET), Vulcan XC-72R (XC-72R), and Ketjenblack EC-600JD (EC-600JD), to form Z8 composites. The Z8/MWCNTs composite exhibited enhanced ORR activity owing to its network structure, meso-/microporous hierarchical porous structure, improved electrical conductivity, and graphitization. Subsequently, iron and nitrogen co-doping is achieved through the pyrolysis of a mixture comprising Fe, N precursor, and ZIF-8/MWCNTs, which is denoted as FeN-Z8/MWCNTs. The intrinsically high electrical conductivity of MWCNTs facilitated efficient electron transfer during the ORR, while the meso-/microporous hierarchical porous structure and network structure of Fe, N co-doped ZIF-8/MWCNTs promoted oxygen transport. The presence of Fe-containing species in the catalyst acted as activity centers for ORR. This strategy of preparing Z8 composites and modifying them with Fe, N co-doping offers an insightful approach to designing cost-effective electrocatalysts.

Simulation of Hydrogen Adsorption in Hierarchical Silicalite: Role of Electrostatics and Surface Chemistry.

Adsorption in nanoporous materials is one strategy that can be used to store hydrogen at conditions of temperature and pressure that are economically viable. Adsorption capacity of nanoporous materials depends on surface area which can be enhanced by incorporating a hierarchical pore structure. We report grand canonical Monte Carlo (GCMC) simulation results on the adsorption of hydrogen in hierarchical models of silicalite that incorporate 4 nm wide mesopores in addition to the 0.5 nm wide micropores at 298 K, using different force fields to model hydrogen. Our results suggest that incorporating mesopores in silicalite can enhance adsorption by at least 20% if electrostatic interactions are not included and up to 100% otherwise. Incorporating electrostatic interactions results in higher adsorption by close to 100% at lower pressures for hierarchical silicalite whereas for unmodified silicalite, it is less significant at all pressures. Hydroxylating the mesopore surface in hierarchical silicalite results in an enhancement in adsorption at pressures below 1 atm and suppression by up to 20% at higher pressures. Temperature dependence at selected pressures exhibits expected decrease in adsorption amounts at higher temperatures. These findings can be useful in the engineering, selection, and optimization of nanoporous materials for hydrogen storage.

Lysis-Free Isolation and Direct Amplification of Pathogenic Bacterial DNA Using Diatom Frustules.

DNA has been implicated as an important biomarker for the diagnosis of bacterial infections. Herein, we developed a streamlined methodology that uses diatom frustules (DFs) to liberate and capture bacterial DNA and allows direct downstream amplification tests without any lysis, washing, or elution steps. Unlike most conventional DNA isolation methods that rely on cell lysis to release bacterial DNA, DFs can trigger the oxidative stress response of bacterial cells to promote bacterial membrane vesicle formation and DNA release by generating reactive oxygen species in aqueous solutions. Due to the hierarchical porous structure, DFs provided high DNA capture efficiency exceeding 80% over a wide range of DNA amounts from 10 pg to 10 ng, making only 10 μg DFs sufficient for each test. Since laborious liquid handling steps are not required, the entire DNA sample preparation process using DFs can be completed within 3 min. The diagnostic use of this DF-based methodology was illustrated, which showed that the DNA of the pathogenic bacteria in serum samples was isolated by DFs and directly detected using polymerase chain reaction (PCR) at concentrations as low as 102 CFU/mL, outperforming the most used approaches based on solid-phase DNA extraction. Furthermore, most of the bacterial cells were still alive after DNA isolation using DFs, providing the possibility of recycling samples for storage and further diagnosis. The proposed DF-based methodology is anticipated to simplify bacterial infection diagnosis and be broadly applied to various medical diagnoses and biological research.

Preparation of amorphous coal-based activated coke via a two-step process of carbonization and steam activation

The coal-based activated coke (AC) is suitable for desulfurization and denitrification in coal-fired power plants. However, the current studies on millimeter-sized amorphous AC are limited. To evaluate the preparation parameters of millimeter-sized amorphous AC, two typical middle-low rank coal samples, Fugu coal and Datong coal, are selected as the raw materials. The effects of carbonization/activation parameter, particle size and steam flow rate on the yield and pore structure of AC are studied. Samples are analyzed by the synchronous thermal analyzer and the fully automatic rapid specific surface and porosity analyzer. The results show that carbonization and the long-time steam activation at a low temperature can make the internal pores of samples fully developed, significantly increasing the specific surface area and pore volume. The coke yield, specific surface area and mesoporous proportion of Fugu AC obtained by activation at 700 °C for 3 h are 60.95 %, 429.54 m2/g and 29.60 %, respectively. The corresponding values of Datong AC obtained at 850 °C for 3 h are 53.19 %, 892.20 m2/g and 23.01 %, separately. Both of Fugu AC and Datong AC belong to the hierarchical porous AC. The influence of particle sizes on the performance of AC at the millimeter level is within the acceptable range. Therefore, the same carbonization and activation parameters can be chosen to prepare Fugu AC and Datong AC with different particle sizes, respectively. The water vapor flow rate has a significant effect on the pore structure of AC. There is a moderate flow rate (0.03 mL min−1 at this study’s experimental conditions) for preparing the hierarchical porous amorphous AC. The study shows that it is feasible to prepare the amorphous AC with the hierarchical pore structure by employing the millimeter-sized medium–low rank coal particles. The AC could be applied for the pollutants removal in the coal-fired power plants.

Porous TiN-based ceramic electrode with N-modified Co-based Nanorods/TiN heterointerfaces for efficient overall water splitting

The development of high-performance electrocatalytic electrodes for overall water splitting is a crucial issue to realize renewable hydrogen production. This paper presents the in situ growth of N-modified Co-based nanorods on porous TiN ceramic membranes using the hydrothermal method and thermal NH3 treatment, resulting in a novel self-supported electrocatalytic electrode with abundant heterointerfaces, denoted as NCTN-x-y (x: nitridation temperature; y: nitridation time). In the alkaline medium (1 M KOH), the NCTN-350-2 electrode displays the best hydrogen evolution reaction (HER) activity (ƞ10 = 66 mV), and the NCTN-250-3 electrode manifests the best oxygen evolution reaction (OER) performance (ƞ10 = 270 mV). Accordingly, these two electrodes comprise an electrolyzer, which features a current density of 10 mA cm−2 at a low cell voltage of 1.63 V. The good electrocatalytic performance can be attributed to the abundant heterointerfaces formed between the porous TiN ceramic membrane and the N-modified Co-based nanorods, in conjunction with the hierarchical pore structure of the TiN ceramic membrane. Theoretical calculations identify that the construction of heterointerfaces modulates the electronic structure of active sites, thereby promoting the dissociation of H2O, optimizing the H* adsorption energy (ΔGH*), and accelerating the reaction kinetics, which ultimately improve the electrocatalytic activity of electrode.

Advancing carbon dioxide capture: Unravelling structure-property-performance dynamics in graphene related two-dimensional materials

Efficient design of adsorbents for carbon dioxide (CO2) capture is imperative in addressing the challenges caused by climate change. In this study, a comprehensive exploration of solid adsorbents derived from graphene-related two-dimensional materials (GR2Ms) with tunable surface chemistry and structures was undertaken to unravel the intricate structural-property-activity relationships essential for optimizing their CO2 adsorption. Nine key GR2Ms and carbon materials, including two types of (few-layer graphene (FLG), graphene oxide (GO) reduced graphene oxide (rGO) materials), expanded graphite (Exp Gft), rGO-Exp Gft and graphite (Gft), were methodically characterized alongside benchmarked materials such as activated carbon (AC) and molecular sieves (MS). Characterization parameters, i.e. morphology, particle size, interlayer distance, crystallite size, defect density, specific surface area (SSA), total pore volume, micropore volume and pore size, are correlated with CO2 adsorption capacity. Results revealed that the dominant properties influencing CO2 adsorption in GR2Ms are hierarchical porous morphology, defect density (up to 2.38 × 1011 cm−2), SSA (up to ∼271 m2/g), total pore volume (up to 0.86 cm3/g), and micropore volume (up to 0.03 cm3/g), all of which have established positive linear relationships. Conversely, crystallite size (0.38–48 nm) exhibited an inverse (non-linear) relationship with CO2 adsorption capacity under ambient conditions (25 °C and 1 atm). Particle size (8–52 μm), interlayer distance (0.33–0.89 nm) and pore size (4.2–13.3 nm) of GR2Ms showed negligible impact on CO2 adsorption capacity. Remarkably, porous rGO emerged as the top-performing CO2 adsorbent with an enhanced adsorption capacity (5.38 mmol/g) , in comparison with activated carbon (AC, 1.79 mmol/g) and molecular sieve (MS, 1.48 mmol/g). This study establishes a comprehensive structure-property-performance relationship, highlighting the significance of a three-dimensional (3D) hierarchical, open and interconnected pore structure within the graphene network, along with the largest pore volume and minimum crystallite size of rGO. These findings underscore the critical role of structural and porosity attributes of GR2Ms in CO2 adsorption, providing fundamental insights into the interplay between the structure and properties on their CO2 adsorption behavior. This study emphasizes the key pillars for effective adsorbent design and underlines the necessity of optimised control over the structural characteristics and porosity of GR2Ms to enhance their CO2 adsorption capabilities, contributing towards the ambitious net-zero target by 2050.

Tuning of the acid sites in the zeolite-alumina composite Ni catalysts and their impact on the palm oil hydrodeoxygenation reaction

The hydrodeoxygenation (HDO) of bio-oil is one of the potential approaches to produce green diesel. However, HDO catalyst requires the development of bifunctionality which translates to the simultaneous presence of acidic and metal sites for desired catalytic activity and selectivity. Zeolites and their composites are attractive candidates for the conversion of biomass to fuels. In the present work, a series of Ni-incorporated Al2O3-zeolite beta bifunctional composite catalysts with distinct Al2O3 (25–75 wt%) and Ni contents (5–15 wt%) were synthesized via a facile one-pot method directly from nickel acetate, nano-boehmite (γ-AlO(OH)) and the NH4+ form of beta zeolite (NH4+-BZ). The nano-boehmite particles, due to the positive charges on their surface, electrostatically attract negatively charged beta zeolite crystals, which leads to the assembly of a hierarchical pore structure upon calcination. Interestingly, the composite catalysts synthesized were quite homogeneous with uniform dispersion of Ni particles. All composite catalysts were thoroughly characterized using XRD, SEM-EDX, SEM-mapping, HR-TEM, H2-TPR, H2-TPD, NH3-TPD, XPS, 31P MAS NMR, 27Al MAS NMR and N2 sorption analysis. The synthesized composite catalysts with distinct Al2O3 contents showed diverse textural properties, distinct nature of acid sites and improved performance in hydrodeoxygenation of palm oil. Particularly, the Ni/BZ-Al50 (with BZ:Al2O3 = 50:50) composite catalyst significantly enhanced the conversion of palm oil (up to 90%) and yield of n-C15-C18 hydrocarbons (up to 69%) at moderate temperature of 375 °C as compared to 10Ni/BZ catalyst (Conv. = 75%, yield of n-C15-C18 = 52%). The higher catalytic performance realized with composite catalysts can be ascribed to its hierarchical pore structure, moderate acidity (chemisorption studies), tuned acid sites nature (solid state NMR) and homogeneous distribution of active Ni sites (H2 chemisorption) which helps to improve product selectivity by minimizing side reactions. The time-on-stream (TOS) experiments were carried out up to 20 h which clearly showed that composite catalysts are more stable suggesting the lower amount of coke deposition (TPO studies) and suppression of metal sintering.

Hierarchical Co-doped hollow Ti3C2Tx tubes with built-in electron/ion transport network for high-performance lithium sulfur batteries

A crucial approach to enhancing the electrochemical performance of lithium-sulfur batteries (LSBs) is to develop a dependable sulfur host material possessing reasonable structure, high electrical conductivity, and exceptional adsorption/catalytic capabilities towards lithium polysulfides (LiPSs). Herein, Co-doped hollow Ti3C2Tx tubes with in-situ grown CNTs as a built-in electron/ion transport network (HTCTs/Co/CNTs) are prepared via electrospinning technique combined with the self-catalyzed growth strategy. The unique hierarchical porous structure of HTCTs/Co/CNTs not only increases the sulfur loading and alleviates the volume expansion, but also effectively suppresses the shuttling effect of LiPSs through the synergism between physical confinement and chemical adsorption. It is revealed that the combination of Ti3C2Tx MXene and metallic Co enhances the LiPSs absorbability and accelerates the catalytic conversion of sulfur species, thereby improving sulfur utilization and electrochemical reversibility. The corresponding cells with HTCTs/Co/CNTs/S cathode retain high capacities of 901.9 mAh g−1 after 100 cycles at 0.2 C and 725.9 mAh g−1 after 500 cycles at 1.0 C. More importantly, a high areal capacity of 4.83 mAh cm−2 is achieved under a high sulfur loading of 5.8 mg cm−2 and a low E/S ratio of 4.3 µL mg−1 after 50 cycles at 0.1 C.

β‐Ketoenamine‐Linked Covalent Organic Frameworks Synthesized via Gel‐to‐Gel Monomer Exchange Reaction: From Aerogel Monoliths to Electrodes for Supercapacitors

AbstractCovalent organic frameworks (COFs) possess intrinsic nanoscale pores, limiting mass transport and impacting their utility in many applications, such as catalysis, supercapacitors, and gas storage, demanding efficient diffusion throughout the material. Hierarchical porous structures, integrating larger macropores with inherent micro‐/meso‐pores, facilitate rapid mass transport. Recently, the fabrication of aerogel monoliths is reported exclusively from imine‐linked COFs, offering flexibility in aerogel composition. However, challenges in synthesizing robust β‐ketoenamine‐based COFs with comparable surface areas prompted innovative synthetic approaches. Leveraging the dynamic nature of COF bonds, in this work efficient monomer exchange from imine to partially β‐ketoenamine‐linked COFs within the gel phase is demonstrated. These aerogels can be transformed into electrodes using the compression technique. The new flexible electrodes‐based β‐ketoenamine‐linked COF composites with C super P exhibit superior durability and redox activity. Through supercapacitor assembly, the β‐ketoenamine‐linked COF electrodes outperform their imine‐based counterparts, showcasing enhanced capacitance (88 mF cm−2) and stability at high current densities (2.0 mA cm−2). These findings underscore the promise of β‐ketoenamine‐linked COFs for pseudocapacitor energy storage applications.

Gel-confined fabrication of fully bio-based filtration membrane for green capture and rapid detection of airborne microbes

Air filtration has become a desirable route for collecting airborne microbes. However, the potential biotoxicity and sterilization of current air filtration membranes often lead to undesired inactivation of captured microbes, which greatly limits microbial non-traumatic transfer and recovery. Herein, we report a gel-confined phase separation strategy to rationally fabricate a fully bio-based filtration membrane (SGFM) using soluble soybean polysaccharide and gelatin. The versatile SGFM features fascinating honeycomb micro-nano architecture and hierarchical interconnected porous structures for microbial capture, and achieves a lower pressure drop, higher interception efficiency (99.3%), and superior microbial survivability than commercial gelatin filtration membranes. Particularly, the water-dissolvable SGFM can greatly simplify the elution and extraction process after bioaerosol sampling, thereby bringing about maximum sample transfer and vigorous recovery of collected microbes. Meanwhile, green capture coupled with ATP bioluminescence endows the SGFM with rapid and quantitative detection capability for airborne microbes. This work may pave the way for designing green protocols for the detection of bioaerosols.

Synthesis of Granular MCM-22 Zeolite with a Hierarchical Porous Structure

Synthesis of Granular MCM-22 Zeolite with a Hierarchical Porous Structure

Ultrafast high-capacitance supercapacitors employing carbons derived from Al-based metal-organic frameworks

Compact supercapacitors (SCs) have garnered significant attention due to their potential to replace bulky aluminum electrolytic capacitors (AECs) in alternating current (AC) line filtering applications. However, the slow response speeds of conventional SCs based on activated carbons are inadequate for such high-frequency applications. Therefore, this paper presents a study on high-frequency SCs using metal-organic framework (MOF)-derived carbon (MDC) electrode materials. Here, the carbonization of the selected MOF results in highly conductive carbons with hierarchical pore structures that offer substantial advantages for use as electrode materials in ultrafast SC applications. Consequently, the as-fabricated MDC SCs exhibit significant areal and volumetric capacitances of 2.41 mF cm–2 and 5.74 F cm–3, respectively, at 120 Hz, coupled with a rapid response speed indicated by a phase angle of –80.1°. Notably, this performance is superior to that of the state-of-the-art high-frequency SCs based on carbon materials. The results underscore the potential of MDCs as electrode materials for use in ultrafast SCs, with eventual implications for the miniaturization of electronic devices.

Nanoporous Carbon Materials Derived from Zanthoxylum Bungeanum Peel and Seed for Electrochemical Supercapacitors.

In order to prepare biomass-derived carbon materials with high specific capacitance at a low activation temperature (≤700 °C), nanoporous carbon materials were prepared from zanthoxylum bungeanum peels and seeds via the pyrolysis and KOH-activation processes. The results show that the optimal activation temperatures are 700 °C and 600 °C for peels and seeds. Benefiting from the hierarchical pore structure (micropores, mesopores, and macropores), the abundant heteroatoms (N, S, and O) containing functional groups, and plentiful electrochemical active sites, the PAC-700 and SAC-600 derive the large capacities of ~211.0 and ~219.7 F g-1 at 1.0 A g-1 in 6 M KOH within the three-electrode configuration. Furthermore, the symmetrical supercapacitors display a high energy density of 22.9 and 22.4 Wh kg-1 at 7500 W kg-1 assembled with PAC-700 and SAC-600, along with exceptional capacitance retention of 99.1% and 93.4% over 10,000 cycles at 1.0 A g-1. More significantly, the contribution here will stimulate the extensive development of low-temperature activation processes and nanoporous carbon materials for electrochemical energy storage and beyond.

Application of Hierarchically Porous Chitosan Monolith for Enzyme Immobilization.

Enzyme immobilization is a crucial technique for improving the stability of enzymes. Compared with free enzymes, immobilized enzymes offer several advantages in industrial applications. Efficient enzyme immobilization requires a technique that integrates the advantages of physical absorption and covalent binding while addressing the limitations of conventional support materials. This study offers a practical approach for immobilizing α-amylase on a hierarchically porous chitosan (CS) monolith. An optimized CS monolith was fabricated using chemically modified chitin by thermally induced phase separation. By combining physical adsorption and covalent bonding, this technique leverages the amino and hydroxy groups present in CS to facilitate effective enzyme binding and stability. α-Amylase immobilized on the CS monolith demonstrated excellent stability, reusability, and increased activity compared to its soluble counterpart across various pH levels and temperatures. In addition, the CS monolith exhibited a significant potential to immobilize other enzymes, namely, lipase and catalase. Immobilized lipase and catalase exhibited higher loading capacities and enhanced activities than their soluble forms. This versatility highlights the broad applicability of CS monoliths as support materials for various enzymatic processes. This study provides guidelines for fabricating hierarchical porous monolith structures that can provide efficient enzyme utilization in flow systems and potentially enhance the cost-effectiveness of enzymes in industrial applications.

3D-interconnected N-doped porous carbon with hierarchical pore structure as a high-efficiency catalyst for H2S oxidation at room temperature

Nitrogen-doped porous carbons (NPCs) have been regarded as an efficient metal-free catalyst for H2S oxidation. However, critical factors affecting their desulfurization ability are still unclear, making it difficult to accurately adjust their desulfurization performance to meet industrial requirements. Herein, a novel 3D-interconnected NPC with hierarchical pore structure was synthesized by one-step “leavening” strategy using rice husk and (NH4)2C2O4 as a carbon source and foaming agent, respectively, for H2S oxidation at room temperature. Pyrolysis temperature is the major factor for physicochemical properties of NPCs, and breakthrough sulfur capacity of the optimal NPC reaches up to 1036.68 mg/g, which can remain stable during three desulfurization-regeneration cycles. Comparative experiment shows that H2S capacity of NPC is 1.8 and 4.0 times those of PC and NC, respectively, revealing the excellent desulfurization performance of NPC. The structure-effect relationships between H2S and NPC reveal that both textural and chemical properties of NPC, especially specific surface area, structural defect, and pyrrolic N, play dominant roles in H2S removal. It is very necessary to balance the relationship between textural performances and pyrrolic N to synthesize optimal NPC catalyst. This work provides a valuable reference for rational design of high-efficiency carbon-based catalysts for persistent desulfurization at room temperature.

Flower-like covalent organic frameworks as host materials for high-performance lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries have emerged as a promising alternative energy storage system due to their high energy density and cost-effectiveness. However, practical applications of Li-S batteries are hindered by challenges such as the shuttle effect and sluggish redox kinetics. In this study, a three-dimensional (3D) flower-like diaminoanthraquinone (DAAQ)-covalent organic framework (COF) was developed, featuring nanorod-like petals and enriched with abundant N and O adsorption sites, serving as a host material for the sulfur cathode of Li-S batteries. Through a process of sulfur melting-diffusion, the resulting DAAQ-COF@S cathode material demonstrated a stable 3D cross-linked morphology with a hierarchical pore structure, maximizing the exposure of N/O adsorptive sites and facilitating rapid ion diffusion. This effectively inhibited the shuttling effect of lithium polysulfides (LiPSs) and enhanced rate performance. Consequently, DAAQ-COF@S cathodes exhibited a high initial discharge capacity of 1182.0 mAh g−1 at 0.1 C, with a capacity retention rate of 79.6% after 500 cycles at 2 C. Even at a high current density of 4 C, they maintained a high capacity of 616.8 mAh g−1, surpassing the majority of previously reported COF-based host materials for Li-S batteries. This work underscores the significance of COF micromorphology and advances the development of high-performance cathodes for Li-S batteries.

Efficient Template-Catalyzed In Situ Polymerization for Carbon Xerogels with Large Specific Surface Area and High Adsorption.

The limited specific surface area (SSA), long preparation period, and high cost are significant challenges for carbon xerogels (CXs). To overcome these limitations, we propose an approach to prepare tannin-resorcinol-formaldehyde-based CXs through template-catalyzed in situ polymerization. ZnCl2 acts as a catalyst and significantly accelerates the polymerization reaction through the coordination of Zn2+ to the carbonyl group in formaldehyde, while atmospheric drying instead of special drying and without solvent exchange reduces the preparation period to 24 h. In addition, ZnCl2 acts as an activator for the formation of many pores. Plant-derived tannins not only reduce the preparation cost but also regulate the pore structure. The resulted CXs with hierarchical porous structures show an optimal SSA of 1308 m2/g, high adsorption capabilities (for cationic, nitrosoaniline dyes, metal, and nonmetallic ions, especially for methylene blue with 454.93 mg/g), low shrinkage down to 10%, and reusability with 92.9% retention after 5 cycles. This work provides a promising and cost-effective method for the large-scale preparation of porous carbon materials with large SSA, offering potential applications in adsorption, energy storage, and catalysis.

Imidazole-based organic polymer frameworks as metal- and halogen-free heterogeneous platforms for efficient CO2 cycloaddition

Developing effective metal- and halogen-free heterogeneous catalysts for the CO2 cycloaddition remains a challenge. In this study, novel imidazole-based hyper-crosslinked polymers (HCP-BZ, HCP-BP and HCP-TBZ) with abundant N sites were constructed via a one-pot polymerization, and employed as heterogeneous catalysts for the CO2 cycloaddition reaction. The special skeletal pore structure with abundant hierarchical pore structures and uniformly distributed active sites were demonstrated by various characterization technologies. The optimal HCP-TBZ(16:1) exhibits a good CO2 selective adsorption performance with a CO2 adsorption capacity of 2.23 mmol/g and CO2/N2 adsorption selectivity of 41 at 273 K and 0.1 MPa. Additionally, the resulting catalyst HCP-TBZ(16:1) achieves an excellent catalytic performance with 96 % yield and 99 % selectivity without metal, halogen, cocatalyst and solvent additions (120 °C, 1.0 MPa CO2, 5 h). Moreover, the HCP-TBZ(16:1) also exhibits a satisfactory catalytic activity under the mild conditions (70 °C, 1.0 MPa CO2), and can effectively catalyze the cyclic carbonate preparation from the dilute CO2 (15 %CO2/85 %N2). The comparable catalytic activity and the determined structural stability, reusability and universality make the prepared imidazole-based HCPs a potential heterogeneous catalyst candidate for the CO2 cycloaddition. This study will provide some guidance for developing metal-free and halogen-free CO2 adsorption and conversion platforms.

Indirect 3D printing CDHA scaffolds with hierarchical porous structure to promote osteoinductivity and bone regeneration

Hierarchical porous structures, which include macropores, minor pores, and micropores in scaffolds, are essential in the multiple biological functions of bone repair and regeneration. In this study, patient-customized calcium-deficient hydroxyapatite (CDHA) scaffolds with the three-level hierarchical porous structure were fabricated by indirect 3D printing technology and particulate leaching method. The sacrificial template scaffolds were fabricated using a photo-curing 3D printer, which provided a prerequisite for the integral structure and interconnected macro pores of CDHA scaffolds. Additionally, the 20 wt% pore former was incorporated into the slurry to enhance the content of smaller pores within the CDHA-2 scaffolds, and then the CDHA-2 scaffolds were sintered to remove the sacrificial template scaffolds and pore former. The obtained CDHA-2 scaffolds exhibited interconnected macropores (300–400 μm), minor pores (∼10–100 μm), and micropores (< 10 μm) distributed throughout the scaffolds, which could promote bone tissue ingrowth, increase surface roughness, and enhance protein adsorption of scaffolds. In vitro studies identified that CDHA-2 scaffolds had nanocrystal grains, high specific surface area, and outstanding protein adsorption capacity, which could provide a microenvironment for cell adhesion, spreading, and proliferation. In addition, the murine intramuscular implantation experiment suggested that CDHA-2 scaffolds exhibited excellent osteoinductivity and were superior to traditional BCP ceramics under conditions without the addition of live cells and exogenous growth factors. The rabbit calvarial defect repair results indicated that CDHA-2 scaffolds could enhance in situ bone regeneration. In conclusion, these findings demonstrated that the hierarchical porous structure of CDHA scaffolds was a pivotal factor in modulating osteoinductivity and bone regeneration, and CDHA-2 scaffolds were a potential candidate for bone regeneration.

A hierarchical porous structure and nitrogen-doping jointly enhance the lithium-ion storage capacity of biomass-derived carbon materials

Biomass-derived carbon materials are considered potential lithium-ion anode materials because they are sustainable, renewable, economical, and environmentally friendly and have tunable microstructures. However, biomass-derived carbon materials have low specific capacity and show capacity degradation during long-term electrochemical cycling, which prevents their application in high-performance lithium-ion batteries. Hence, in this paper, nitrogen-doped hierarchical porous carbon (NHPC) is synthesized from a biomass waste material, corncob, through one-step activation and carbonization procedures. N-doping in the NHPC modifies the electron distribution on the surface of carbon, resulting in the generation of additional lithium-ion storage sites and enhancing electrode wettability to increase the conductivity. Additionally, the doping procedure results in a hierarchical porous structure with an increased specific surface area and pore volume, which facilitates ion transport and provides remarkable cycling stability. The electrochemical performance of NHPC is improved by the jointly beneficial combination of N-doping and the hierarchical porous structure. The optimized NHPC electrode provides a reversible specific capacity of 700 mAh g−1 after 100 cycles at 100 mA g−1. This study provides a simple and efficient method for improving the electrochemical properties of biomass-derived carbon materials through elemental doping and modulation of microscopic morphology and structure.