Abundant Meso Research Articles

Enhanced Capacitive Deionization of Hollow Mesoporous Carbon Spheres/MOFs Derived Nanocomposites by Interface-Coating and Space-Encapsulating Design.

Exploring new carbon-based electrode materials is quite necessary for enhancing capacitive deionization (CDI). Here, hollow mesoporous carbon spheres (HMCSs)/metal-organic frameworks (MOFs) derived carbon materials (NC(M)/HMCSs and NC(M)@HMCSs) are successfully prepared by interface-coating and space-encapsulating design, respectively. The obtained NC(M)/HMCSs and NC(M)@HMCSs possess a hierarchical hollow nanoarchitecture with abundant nitrogen doping, high specific surface area, and abundant meso-/microporous pores. These merits are conducive to rapid ion diffusion and charge transfer during the adsorption process. Compared to NC(M)/HMCSs, NC(M)@HMCSs exhibit superior electrochemical performance due to their better utilization of the internal space of hollow carbon, forming an interconnected 3D framework. In addition, the introduction of Ni ions is more conducive to the synergistic effect between ZIF(M)-derived carbon and N-doped carbon shell compared with other ions (Mn, Co, Cu ions). The resultant Ni-1-800-based CDI device exhibits excellent salt adsorption capacity (SAC, 37.82mg g-1) and good recyclability. This will provide a new direction for the MOF nanoparticle-driven assembly strategy and the application of hierarchical hollow carbon nanoarchitecture to CDI.

Disinfectant-Assisted Preparation of Hierarchical ZSM-5 Zeolite with Excellent Catalytic Stabilities in Propane Aromatization.

A series of quaternary ammonium or phosphonium salts were applied as zeolite growth modifiers in the synthesis of hierarchical ZSM-5 zeolite. The results showed that the use of methyltriphenylphosphonium bromide (MTBBP) could yield nano-sized hierarchical ZSM-5 zeolite with a "rice crust" morphology feature, which demonstrates a better catalytic performance than other disinfect candidates. It was confirmed that the addition of MTBBP did not cause discernable adverse effects on the microstructures or acidities of ZSM-5, but it led to the creation of abundant meso- to marco- pores as a result of aligned tiny particle aggregations. Moreover, the generation of the special morphology was believed to be a result of the coordination and competition between MTBBP and Na+ cations. The as-synthesized hierarchical zeolite was loaded with Zn and utilized in the propane aromatization reaction, which displayed a prolonged lifetime (1430 min vs. 290 min compared with conventional ZSM-5) and an enhanced total turnover number that is four folds of the traditional one, owing to the attenuated hydride transfer reaction and slow coking rate. This work provides a new method to alter the morphological properties of zeolites with low-cost disinfectants, which is of great potential for industrial applications.

Aerogel-glass fiber composite filter media for effective separation of emulsified water droplets from diesel fuel

This work evaluates several mechanisms of separation of surfactant-stabilized emulsified water droplets from diesel fuel using high surface area (50–370 m2/g) and high porosity (>90 %) filter media fabricated by combining aerogels and glass fiber mats. Specifically, high surface area, porous gels of syndiotactic polystyrene (sPS) and silica are developed inside glass fiber mats via dip coating in corresponding sol followed by sol–gel transition. The resultant materials are supercritically dried to obtain aerogel-coated separation media. The abundant meso- and macropores of the aerogel network and the different surface energy of sPS and silica produce cooperative functioning of the mechanisms of size exclusion, coalescence filtration, surfactant adsorption, and volumetric water absorption for removal of emulsified water droplets from ultralow sulfur diesel fuel under continuous flow conditions. The role of each separation mechanism is elucidated in this paper. The results reveal high water separation efficiency of ∼92 % compared to ∼30 % for the glass fiber mats.

An energy-efficient method inspired by nutrient transport during the growth of tree to prepare free-standing wood/MXene electrodes

Wood has been increasingly used as free-standing electrodes for supercapacitors, but the urgent issues in common preparation are high energy consumption and long duration, especially destruction of wood structure, greatly limiting further development. Abundant meso−/macropores and O-containing functional groups in wood can facilitate nutrient transport by capillarity and transpiration effects. Inspired by this phenomenon, this work innovatively develops a modified energy-efficient method using Ti3C2Tx (a typical MXene) droplets to prepare free-standing wood/Ti3C2Tx (WT) electrodes. Ti3C2Tx, with ultra-high conductivity and good electrochemical activity is loaded into wood to compensate for the electrical isolation of wood and contribute large capacitance. The pores in wood not only act as capillary tubes to transport Ti3C2Tx and provide loading space for compositing abundant Ti3C2Tx, but also serve as routes for rapid ion transport during charging-discharging process. The heating panel is applied to ensure continuous absorption of Ti3C2Tx by bringing in transpiration effect by fast evaporating water and reaching unsaturated state of wood. Resultantly, an all-wood supercapacitor assembled by two WTs electrodes and one wood separator exhibits good specific capacitance (623 mF cm−2 at 0.5 mA cm−2), high rate capability (80% at 20 mA cm−2), and large energy density (15.11 μWh cm−2 at 11.70 μW cm−2).

Biobased hierarchically porous carbon featuring micron-sized honeycomb architecture for CO2 capture and water remediation

Hierarchically porous carbon (HPC) has exhibited exceptional performance in environmental-related applications; however, the synthesis of high-efficient biobased HPCs remains a challenge because of the inherent structure and chemical composition complexities of biomass. Here, we prepare high-efficient biobased HPC sorbents featuring uniform micron-sized (~20 µm) honeycomb cells and abundant meso- and micropores through combining the selection of biomass precursors and the corresponding synthetic strategies. Cork is selected as the precursor because of its distinctive hollow polyhedral cellular structure and unique chemical composition composed of suberin. ZnCl2 is selected as the activation reagent due to its mild activation effect with less carbon etching and recyclability. The sequential low-temperature pretreatment and ZnCl2 activation processes produce high-efficient HPC sorbent for CO2 capture and water decontamination. Results show that cork-based HPC poses high carbon yield (> 80 wt%), large specific surface area (up to 1853 m2/g), and high pore volume (up to 0.839 cm3/g). Accordingly, cork-based HPC exhibit high CO2 capture performance (e.g., 4.64 mmol/g at 0 °C), superior adsorption capacity for methylene blue (887.7 mg/g) and lead ion (Pb2+, 74.3 mg/g), and fast uptake speed for contaminants (i.e., < 5 min). Moreover, approximately 80% of ZnCl2 can be recycled and reused. This study demonstrates a sustainable and cost-effective process for producing high-efficient HPCs from cork for environmental applications.

The role of hydrodynamic fluctuations and wind intensity on the distribution of plastic debris on the sandy beaches of Paraná River, Argentina

Plastic in the environment is considered an emerging pollutant of global concern. In spite of intensive research, many questions remain open, such as the processes that drive the deposition and remobilization of plastic debris on river beaches. The objectives of this study were: i) to analyze the influence of the natural hydrological fluctuations and wind intensity on the distribution of mesoplastic (0.5–2.5 cm) and macroplastic (>2.5 cm) debris in beach sediments of a large river, ii) to describe the type of plastic debris found and iii) to explore potential relations between the number of items and weight of macro- and mesoplastics.Our results suggest that, during lowering water levels, flow removes the plastic debris and transports it further downstream. Conversely, when the beach sediments remain exposed during long periods, the plastic debris accumulates considerably. Nevertheless, the influence of wind intensity on plastic debris transport was comparatively negligible. In other words, in our study the water flow had a greater capacity to remobilize and transport plastic debris than the wind.The most abundant mesoplastic items were foam, hard plastic, film and small fragments of fishing line. The dominant macroplastic items recorded were pieces of fishing line (nylon) and cigarette filters (cellulose acetate), typically discarded by beach users. Other items found in large quantities were soft packaging elements (expanded polystyrene), hard plastic containers (polystyrene, polyethylene terephthalate) and beverage bottles (polyethylene terephthalate), typical items of domestic use in the Paraná River region.Finally, we found that the density of macroplastic items is highly correlated to the density of mesoplastic items, serving as surrogate for further estimations. Our results could help to develop better mitigation strategies in seasonal riverscapes, based on the influence of the hydrological cycle and the characteristics of the most abundant meso- and macroplastics.

Embedding Co9S8 nanoparticles into porous carbon foam with high flexibility and enhanced lithium ion storage

Co9S8 nanoparticles embedded in two dimensional/three dimensional (2D/3D) porous carbon foams are synthesized from carbonized melamine foam (CMF) @Co-ZIF-L. Due to the vertical-growth of 2D Co-ZIF-L on the carbonized 3D melamine foam wires, abundant meso- and macropores are formed among Co-ZIF-L nanosheets with sufficient micropores created from the carbonization of ZIF-L; thus 2D/3D carbon foam with hierarchical pores can be obtained. Meanwhile, Co9S8 nanoparticles are formed and uniformly dispersed into porous carbon, and such carbon wrapping can effectively alleviate the volume expansion of metal sulfide; thus high electrochemical performance can be achieved. For example, the specific capacity is as high as 615 mAh g−1 at 500 mA g−1 after 450 cycles, much higher than that of pristine CMF (79.5 mAh g−1). Moreover, due to the excellent flexibility of carbonized melamine foam, such composite can be directly used as free-standing binder-free electrode for lithium ion batteries, which exhibits great potential to be used in wearable electronics.

Preparation of C/SnO2 composite with rice husk-based porous carbon carrier loading ultrasmall SnO2 nanoparticles for anode in lithium-ion batteries

C/SnO2 composite with porous carbon as the carrier is usually prepared for stable SnO2 anodes in lithium-ion batteries. However, the application of present porous carbon materials is limited with high cost and complex preparation procedures. In our article, a C/SnO2 composite anode was fabricated using a low-cost and easily obtained rice-husk based porous carbon (RHPC). The RHPC material can be easily and cheaply obtained by convenient carbonization and activation of rice husk. Subsequently, a RHPC/SnO2 composite was prepared via a simple melt-impregnation method with heat treatment route. The HRTEM image revealed that the RHPC displayed abundant meso- and micro-pore structures. The SnO2 nanoparticles can be loaded on the RHPC matrix with the average size of ca. 4 nm. The cyclic measurement showed that the fifty discharge capacity of RHPC/SnO2 anodes at the current density of 100 mA g−1 was 550 mAh g−1 (180 mAh g−1 for SnO2 anodes), It demonstrates that the cyclic performance of RHPC/SnO2 anodes is a remarkable enhancement by introducing the RHPC matrix in comparison with the SnO2 anodes. Moreover, the easy obtainment method of RHPC and the improved stability of SnO2 anodes promote the RHPC/SnO2 as a promising anode material in lithium-ion batteries.

Geologic and geochemical characteristics of the Cambrian marine shale in the Tarim Basin of China and their implication for the prediction of shale-gas resources

Although the Cambrian marine shale in the Tarim Basin is usually considered to be the source rocks for overlying conventional reservoirs, its unconventional shale-gas potential has not yet been evaluated. To indicate the unconventional resource play potential and highlight more favorable zones, we conducted a comprehensive lithologic, petrophysical, and geochemical analysis of 228 drill core samples from 14 wells and 167 outcrop samples from eight geologic sections in the basin. The results indicate that the Cambrian marine shale was deposited in basinal and slope environments dominated by shale and siliceous shale. The average total organic carbon (TOC) content of the Є1xd (Xidashan) and Є2m (Moheershan) Formations ranges from 0.5% to 2.5%, and that of the Є1y (Yuertusi) Formation ranges from 1.0% to 7.0%. Phytoplankton is dominant in the Є1xd and Є2m Formations, whereas benthic algae are more prevalent in the Є1y Formation. The organic matter ranges in maturity from high to postmature. The shale consists of abundant meso- and macropores. The mineral matter is mostly composed of quartz ([Formula: see text] in most samples) followed by carbonate minerals, with minor contributions made by clay minerals ([Formula: see text]). The analysis of methane adsorption isotherm indicates a positive correlation between the gas and TOC content and a negative correlation between the gas content and burial depth implying the good adsorption capacity of the shale-gas play. Resource estimation of the Middle-Lower Cambrian indicates that the Yuli and Ruoqiang areas contain a potential [Formula: see text] of shale gas, and they are the most favorable zones for further exploitation.

Meso-/microporous carbon as an adsorbent for enhanced performance in solid-phase microextraction of chlorobenzenes

There is urgent demand for the design of advanced coating materials for solid-phase microextraction (SPME) for water quality monitoring and assessment because of the global occurrence of chlorobenzenes (CBs). In this study, we proposed a dual-order activation method in which potassium hydroxide is used to modify pre-activated calcium citrate to synthesize a highly developed meso-/microporous carbon (MMC). The as-obtained MMC presented well-developed porosity with a super-high specific surface area (2638.09 m2 g−1), abundant meso-/micropores (0.5–10 nm), high hydrophobicity, excellent thermal stability (>720 °C), and a partly graphitized structure. As a coating material for headspace-SPME, the MMC-coated fiber exhibited outstanding extraction capability for CBs (up to 48.5 times higher than that of commercial fibers), which may be attributed to multiple interactions between the MMC and the pollutants, including size selectivity, micropore filling, π-π stacking and hydrophobicity. Finally, a satisfactory method using an MMC-coated fiber coupled with gas chromatography and electron capture detection was developed with good linearity (1–1000 ng L−1, R2 > 0.9982), high enrichment efficiencies (enrichment factors, 861–7819), low limits of detection (0.003–0.072 ng L−1), excellent repeatability (0.7–5.3%) and reproducibility (1.7–5.1%), and outstanding recoveries (90.18–103.02%) when applied to determine trace CBs in real water samples. These results suggest that MMC is a promising coating material for the SPME of CBs.

Organized cryogel composites with 3D hierarchical porosity as an extraction adsorbent for nucleosides.

Macroscopic monoliths are highly desirable in many fields of application. Herein, well organized organic-inorganic cryogel composite with a three-dimensional hierarchical meso- and macroporous structure are presented, which were produced by in situ copolymerization of mesoporous multifunctional silica (size: 1-20μm; pore: 2-20nm mostly) and monomers (hydroxyethyl methacrylate and diallyldimethylammonium chloride) in water below the freezing point. This copolymerization method effectively adjusted the macropores of the basic cryogel, and the nanosilica was more homogeneously dispersed in the basic cryogel. The specific surface area of the cryogel composite was increased 17 times versus than that of the basic cryogel. The abundant meso- and macroporous pores on the cryogel composite provided sufficient reactive sites favorable for the efficient mass transport of target compounds. When the cryogel composite, as solid phase extraction adsorbent, was coupled with high-performance liquid chromatography, an analytical tool, the nucleosides were quantified with good selectivity, lower detection limits (0.9-1.3ng/mL) and satisfactory recoveries of greater than 80% from spiked human serum.

Defluorination-assisted heteroatom doping reaction with ammonia gas for synthesis of nitrogen-doped porous graphitized carbon

Nitrogen-doped porous graphitized carbon (N-F-PREGO) were synthesized by doping the fluorinated porous graphitized carbon with ammonia gas at reaction temperatures of 400–850 °C. In N-F-PREGO synthesized at 400 °C, nitrogen atoms were introduced into the porous graphene framework at a concentration of 7.9 at.%. Among which, the concentrations of the pyridinic-, pyrrolic-, and graphitic-type nitrogen species were 5.14, 1.78, and 0.99 at.%, respectively, and their percentages with respect to the total nitrogen species were 65.0, 22.5, and 12.5%, respectively. Meanwhile, the original specific surface area of 2022 m2/g and abundant meso- and microporous were well-preserved after doping process. Herein, the specific capacitance of the nitrogen-doped PREGOs was improved from 103 F/g to 294.2 F/g at a current density of 1.0 A/g. At 10 A/g, the specific capacitance was reserved at 272.5 F/g, and well retained even after 10,000 cycles at 5 A/g.

Morphology Control of Carbon-Free Spinel NiCo2O4 Catalysts for Enhanced Bifunctional Oxygen Reduction and Evolution in Alkaline Media

Spinel NiCo2O4 is considered a promising precious metal-free catalyst that is also carbon-free for oxygen electrocatalysis applications. Current efforts mainly focus on optimal chemical doping and substituent to tune its electronic structures for enhanced activity. Here, we study its morphology control and elucidate the morphology-dependent catalyst performance for bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Three types of NiCo2O4 catalysts with significantly different morphologies were prepared using temple-free, Pluronic-123 (P-123) soft, and SiO2 hard templates, respectively, via hydrothermal methods following by a calcination. While the hard-template yields sphere-like dense structures, soft-template assists the formation of a unique nano-needle cluster and flower-like assembly containing abundant meso- and macro pores. Then, the effect of morphology of NiCo2O4 on their corresponding bifunctional catalytic performance was systematically investigated. The flower-like nano-needle assembly NiCo2O4 catalyst via the soft template method exhibited the highest catalytic activity and stability for both ORR and OER. In particular, it exhibited an onset and half-wave potentials of 0.94 and 0.82 V vs. RHE, respectively, for the ORR in alkaline media. Although it is still inferior to Pt, the NiCo2O4 represents one of the best ORR catalyst compared to other reported carbon-free oxides. Meanwhile, remarkable OER activity and stability were achieved with an onset potential of 1.48 V and a current density of 15 mA/cm2 at 1.6 V, showing no activity loss after 20,000 potential cycles (0 to 1.9 V). The demonstrated stability is even superior to Ir for the OER. The morphology-controlled approach provides an effective solution to create a robust 3D architecture with increased surface areas and enhanced mass transfer. Importantly, the soft template can yield high degree of spinel crystallinity with ideal stoichiometric ratios between Ni and Co, thus promoting structural integrity with enhanced electrical conductivity and catalytic properties. The high performance bifunctional oxide catalyst is carbon free and can eventually overcome the stability issue resulting from carbon corrosion in reversible fuel cells and metal-air batteries.

Morphology Control of Carbon-Free Spinel NiCo2O4 Catalysts for Enhanced Bifunctional Oxygen Reduction and Evolution in Alkaline Media.

Spinel NiCo2O4 is considered a promising precious metal-free catalyst that is also carbon-free for oxygen electrocatalysis. Current efforts mainly focus on optimal chemical doping and substituent to tune its electronic structures for enhanced activity. Here, we study its morphology control and elucidate the morphology-dependent catalyst performance for bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Three types of NiCo2O4 catalysts with significantly distinct morphologies were prepared using temple-free, Pluronic-123 (P-123) soft, and SiO2 hard templates, respectively, via hydrothermal methods followed by calcination. Whereas the hard-template yields spherelike dense structures, soft-template assists the formation of a unique nanoneedle cluster assembly containing abundant meso- and macropores. Furthermore, the effect of morphology of NiCo2O4 on their corresponding bifunctional catalytic performance was systematically investigated. The flowerlike nanoneedle assembly NiCo2O4 catalyst via the soft-template method exhibited the highest catalytic activity and stability for both ORR and OER. In particular, it exhibited an onset and half-wave potentials of 0.94 and 0.82 V versus reversible hydrogen electrode, respectively, for the ORR in alkaline media. Although it is still inferior to Pt, the NiCo2O4 represents one of the best ORR catalyst compared to other reported carbon-free oxides. Meanwhile, remarkable OER activity and stability were achieved with an onset potential of 1.48 V and a current density of 15 mA/cm2 at 1.6 V, showing no activity loss after 20 000 potential cycles (0-1.9 V). The demonstrated stability is even superior to Ir for the OER. The morphology-controlled approach provides an effective solution to create a robust three-dimensional architecture with increased surface areas and enhanced mass transfer. Importantly, the soft template can yield a high degree of spinel crystallinity with ideal stoichiometric ratios between Ni and Co, thus promoting structural integrity with enhanced electrical conductivity and catalytic properties.

Hierarchically porous Fe-N-doped carbon nanotubes as efficient electrocatalyst for oxygen reduction

A hierarchically meso/micro-porous Fe-N-doped carbon nanotube electrocatalyst (meso/micro-Fe-N-CNT), for the first time, was synthesized. Anodic aluminum oxide (AAO) was used as a template to cast the CNT framework and Fe(NO)3 was filled in the AAO nanochannels as both a mesopore template in CNT walls and the iron source to form Fe-N-C active sites. Subsequent NH3 activation was carried out to create abundant micropores and active sites to produce the meso/micro-Fe-N-CNT. This hybrid material has a unique characteristic of a high-conductivity CNT framework, an ultrahigh surface area of 2137 m2 g−1, a high density of Fe-N-C catalytic active sites, and abundant meso- and micropores for efficient mass transport channels. As a consequence, excellent oxygen reduction reaction performance under acidic conditions and even better performance under alkaline conditions were demonstrated that are comparable to that of Pt/C.

Facile Synthesis and Tunable Porosities of Imidazolium‐Based Ionic Polymers that Contain In Situ Formed Palladium Nanoparticles

AbstractA series of porous imidazolium‐based ionic polymers that contain in situ formed Pd nanoparticles (Pd@PIPs) was synthesized by a Suzuki–Miyaura cross‐coupling reaction in the presence of SiO2 particles. The hierarchical porosities of Pd@PIPs can be regulated well by adjusting the dosage of SiO2. Pd nanoparticles are formed concomitantly and encapsulated uniformly within the pores of the polymers. The appropriate usage of SiO2 templates results in a clear enhancement of the catalytic activity in the hydrogenation of nitroarenes without the addition of extra Pd species. The excellent catalytic performances are attributed to abundant meso‐ and macropores that facilitate the mass transfer of substrates during catalytic reactions.

Palynological implication of Holocene vegetation and environment in Pyeongtaek wetland, Korea

Vegetational and depositional environmental changes were interpreted from a trench in ca. 10 000 cal BP sediments in the Pyeongtaek wetland, Korea, based on palynomorph and grain size analysis. From ca. 10 400−8000 cal BP, cool, dry, temperate conditions encouraged Quercus-dominated deciduous broadleaved forest, with conifers and cool-tolerant birch prevailing on hills and in mountainous areas as postglacial warming began. Halophytic Chenopodiaceae pollen and marine dinoflagellates indicate the depositional environment was an intertidal flat. Conditions became warm and wet between ca. 8000 and ca. 6000 cal BP: areas still contained Quercus-dominated deciduous broadleaved forest but with decreased conifers and cool-tolerant birch. The absence of marine dinoflagellates and abundant meso- to hypersaline salt marshes of Gramineae, with a later increase of mesosaline Cyperaceae marshes, indicate a transition from intertidal flat to freshwater swamp. From ca. 6000 to ca. 4500 cal BP, Quercus-dominated forests were replaced by mixed conifer–deciduous broadleaved forests under climatic deterioration. Aquatic genera and freshwater algae indicate that the study area completely changed to freshwater swamp. The directional sequence in relative abundance of taxa (maximum percentage of pollen of Chenopodiaceae followed by Gramineae, Cyperaceae, and aquatics) suggests a gradational pattern indicative of marked environmental clines typical of intertidal habitats.

Synthesis of Meso-/Macroporous Zeolite (Fe,Al)-ZSM-5 Microspheres from Diatomite

Abstract Microspheres of (Fe,Al)-ZSM-5 crystallite aggregates with abundant meso-/macropores have been synthesized by hydrothermal treatment of natural diatomite in a NaCl-containing solution. It was found that the addition of NaCl would lead to the formation of spherical product as well as promoting the incorporation of the Fe originally existed in diatomite into zeolitic framework.

Palaeoproterozoic regional-scale non-coaxial deformation: an example from eastern Eyre Peninsula, South Australia

Regional-scale high-grade structures preserved in an Archaean–Palaeoproterozoic gneissic belt, in eastern Eyre Peninsula, are attributed to the development of the Kalinjala Shear Zone. The Kalinjala Shear Zone is an ∼200km long high-grade dextral transpressional shear zone that formed during the ∼1730–1700Ma Kimban Orogeny (KD1 and KD2). The first deformation event, KD1, involved a large component of northeast–southwest sub-horizontal stretching (parallel to X) and formed abundant meso- to macro-scale sheath folds and a well-developed prolate >10:1:1 (X>Y>Z) L-fabric (KL1; L⪢S) during transitional granulite facies conditions. The second event, KD2, was dominated by bulk sub-horizontal flattening along the east–west Z-axis following KD1. KD2 formed variably-dipping and mutually overprinting reverse and strike–slip shear zones, upright, tight-isoclinal folds and plane strain ∼12:3:1 marker clasts. The strain studies indicate the primary role of constrictional strains during the transpressional deformation and the smaller degree of flattening recorded in the amphibolite to granulite facies shear belt. The size of this Proterozoic shear belt is akin to those of modern orogens involved in significant plate reorganisation.