Open Pore Structure Research Articles

ZrC-SiC closed-cell ceramics with low thermal conductivity: Exploiting unique spherical closed-cell structure through tape casting and CVI techniques

Porous ultra-high temperature ceramics (UHTCs) are recognized as novel candidates for fulfilling the requirements of thermal protection systems of hypersonic aircrafts, as they possess excellent high-temperature resistance and low thermal conductivity. Currently, the reported porous UHTCs predominantly exhibit an open pore structure. By contrast, closed-cell UHTCs, formed by employing ceramic hollow microspheres (HMs) as pore-forming agents, hold great potential for achieving superior thermal insulation performance. Unfortunately, the implementation of this strategy has been hindered by the scarcity of raw materials and preparation techniques.In this paper, ZrC-SiC closed-cell ceramics were first successfully prepared through a combination of tape casting and chemical vapor infiltration (CVI) techniques, utilizing the self-developed ZrC HMs as the primary raw material. The morphology, microstructure, and thermal insulation properties of the obtained ZrC-SiC closed-cell ceramics were investigated. The results indicate that when the content of ZrC HMs is 30 vol.%, the density of the prepared porous ceramics is 2.09 g cm–3, with a closed porosity of 14.05% and a thermal conductivity of 1.69 W (m K)–1. The results clearly prove that the CVI process can successfully convert ZrC HMs into closed pore structures within porous ceramics. The introduction of ZrC HMs suppresses the contribution of free electrons to thermal conductivity and brings about a large number of solid-gas interfaces, which increases the interfacial thermal resistance and significantly reduces the phonon thermal conductivity. Consequently, the as-prepared ZrC-SiC closed-cell ceramics show excellent thermal insulation properties. This study provides a new idea and method for the development of porous UHTCs and offers a more reliable material choice for thermal protection systems.

3D-printed wound dressing platform for protein administration based on alginate and zinc oxide tetrapods

Wound treatment requires a plethora of independent properties. Hydration, anti-bacterial properties, oxygenation and patient-specific drug delivery all contribute to the best possible wound healing. Three-dimensional (3D) printing has emerged as a set of techniques to realize individually adapted wound dressings with open porous structure from biomedically optimized materials. To include all the desired properties into the so-called bioinks is still challenging. In this work, a bioink system based on anti-bacterial zinc oxide tetrapods (t-ZnO) and biocompatible sodium alginate is presented. Additive manufacturing of these hydrogels with high t-ZnO content (up to 15 wt.%) could be realized. Additionally, protein adsorption on the t-ZnO particles was evaluated to test their suitability as carriers for active pharmaceutical ingredients (APIs). Open porous and closed cell printed wound dressings were tested for their cell and skin compatibility and anti-bacterial properties. In these categories, the open porous constructs exhibited protruding t-ZnO arms and proved to be anti-bacterial. Dermatological tests on ex vivo skin showed no negative influence of the alginate wound dressing on the skin, making this bioink an ideal carrier and evaluation platform for APIs in wound treatment and healing.

Enhanced Low-Density Silicone Foams Blown by Water-Hydroxyl Blends.

Water, alcohols, diols, and glycerol are low-cost blowing agents that can be used to create the desired silicone foam structures. Although their combined use can be beneficial, it remains unclear how it affects the physical properties of the resulting materials. We conducted a comparative study of these hydroxyl-bearing blowing agents in fumed silica- and mica-filled polymer composite systems for simultaneous blowing and crosslinking to obtain a low-density, uniform porosity and superior mechanical properties. The foams were optimized for a uniform open-pore structure with densities ranging from 75 to 150 kg‧m-3. Varying the diol chain length (Cn) from one to seven carbons can alter the foam density and structure, thereby enhancing the foam tensile strength while maintaining a low density. Replacing 10 mol% of water with 1,4-butanediol decreased the density by 26%, while increasing the specific strength by 5%. By combining glycerol and water blowing, the resulting foams exhibited a 30% lower apparent density than their water-blown analogs. The results further showed that Cn > 4 alkane chain diols had an odd-even effect on the apparent density and cell wall thickness. All foamable compositions had viscosities of approximately 7000 cSt and curing times below 2 min, allowing for quick dispensing and sufficient time for the foam to cure in semi-industrial volumes.

A quadruple-strategy of modification on carbon nitride boosts oxygen reduction for high performance photocatalytic hydrogen peroxide production

This paper reports a quadruple-strategy for material design, simultaneously applying morphology control, group modification, defect engineering and alkali metal doping to the design of catalysts, and successfully constructing irregular clusters of carbon nitride (pMNK-CN) with excellent photogenerated carrier separation performance and structural stability. The pMNK-CN is an irregular flower cluster-like morphology with a nanosheet structure on the surface, and the repolymerization process of the prepolymer in the microvoid of the metal salt gives it an open pore structure. With the help of essential characterization, it was confirmed that the heptazine unit in the backbone underwent partial decomposition due to the etching of metal salts at high temperatures, reducing the overall polymerization and introducing cyano and nitrogen vacancies. Meanwhile, the potassium ion embedded in the lattice can induce the growth of ordered structures and thus improve the short-range order. The pMNK-CN possesses a hydrogen peroxide production efficiency of 240.0 μmol·g−1·h−1 in pure water, which is 31 times higher than that of bulk carbon nitride. And the apparent quantum efficiencies of pMNK-CN in the 380 and 420 nm bands are 17.5 % and 14.8 % in the presence of isopropanol. The effects of each modification strategies on the electronic structure of carbon nitride were investigated using First-Principles, and it was demonstrated that the multiple modification strategies synergistically enhanced the optical absorption, photogenerated charge separation efficiency, and lowered the reaction energy barrier, thus greatly contributing to the oxygen reduction to hydrogen peroxide performance.

Manufacturing and characterization of an interpenetrating metal matrix composite reinforced with a 3D-printed metallic glass lattice structure (Ni60Nb20Ta20)

Metallic glasses (MG) exhibit remarkable properties, like high strength, hardness, and elastic strain limit due their amorphous structure. But they also exhibit low ductility and brittle behavior, making them less suitable for monolithic components. Therefore, MG offer high potential for use as a reinforcing phase in a ductile matrix. Especially interpenetrating metal matrix composites (MMCs) are suitable, since good interfacial adhesion can be achieved due to the metallic character of the MG and mechanical properties can be further enhanced by the interpenetrating structure. Temperature during manufacturing process must be below crystallization temperature of the MG. Until now, interpenetrating MMCs have been manufactured by infiltrating the metal matrix foam with MG, requiring a high melting temperature of the matrix and thus excludes lightweight metals. In this work it was possible to infiltrate an open porous lattice structure of MG (Ni60Nb20Ta20) due to its high crystallization temperature with AlSi12 by gas pressure infiltration resulting in a novel MMC. X-ray diffraction measurements confirm that no crystallization occurred during infiltration. Micrographs show a good infiltration quality and interfacial bonding between both phases. An increase in Young's modulus of 28 % and compressive strength in the MMC can be achieved compared to the AlSi12-matrix.

Indoor water splitting for hydrogen production through electrocatalysis using composite metal oxide catalysts

This study explores an optimistic approach for large-scale hydrogen production by employing electrocatalysts based on nickel, cobalt, iron, and aluminum oxides as alternatives to costlier metals. This approach offers a cost-effective solution to electrolysis in water media for hydrogen production. This investigation is focused on the electrolysis process, engaging NiO–Al2O3–CoO–Fe2O3 in 1M solution of NaOH and KOH. The environmental and economic analyses are conducted to evaluate the overall effect and cost-effectiveness of the electrolysis process. These findings provide valuable insights into the performance, feasibility, and challenges of using oxides of aluminum, nickel, iron, and cobalt in electrolysis for hydrogen production. The structural and morphological analyses of metal oxides are conducted using XRD and SEM tools, which showed reduced crystallinity and open pore structure of the samples. Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS), and Linear Sweep Voltammetry (LSV) revealed a higher electrocatalytic activity, a larger electrochemical active surface area, a higher current density, and a high density of active sites of NiO–Al2O3–CoO–Fe2O3 composite. Electrode 1 of the composite catalyst produced 500 ml of hydrogen after 30 min of the process, while electrodes 2 and 3 produced 263 and 249 ml of hydrogen, respectively. This study also elucidated the electrocatalytic mechanism involved in water splitting using these composite materials.

The Ionomer–Carbon Interaction: A Key Parameter in the Power Performance of Anion Exchange Membrane Fuel Cell

Compared to the remarkable advances in anion exchange ionomers (AEIs), the catalyst layer (CL) of the anion exchange membrane fuel cell (AEMFC) has not been sufficiently engineered. Our molecular simulations reveal that the AEIs widely used in this field have weak interaction with the carbon support, presenting the possibility of significant ionomer aggregation in CL. To demonstrate the issue of ionomer–carbon interaction, we investigated CL morphology for various AEIs including polycarbazole-based ionomer (QPC-TMA), FAA-3, PiperION, Sustainion, and compared them with Nafion ionomer that has strong interaction with carbon. In contrast to the uniform Nafion distribution and open-pore structure of Nafion-based CLs, these AEIs are locally aggregated in CL and clog the interstitial pores between the catalyst particles. Furthermore, the comparison of two AEIs with distinct ionomer–carbon interaction energies exhibits that the ionomer with a lower ionomer–carbon interaction energy leads to larger kinetic and mass transport overvoltages. This study provides a fresh perspective that ionomer–carbon support interaction has a significant effect on the structure and performance of the CL.

Process Development of a Generative Method for Partial and Controlled Integration of Active Substances into Open-Porous Matrix Structures.

A special generative manufacturing (AM) process was developed for the partial integration of active ingredients into open-porous matrix structures. A mixture of a silver-containing solution as an antibacterial material with an alginate hydrogel as a carrier system was produced as the active ingredient. The AM process developed was used to introduce the active ingredient solution into an open-porous niobium containing a β-titanium matrix structure, thus creating a reproducible active ingredient delivery system. The matrix structure had already been produced in a separate AM process by means of selective laser melting (SLM). The main advantage of this process is the ability to control porosity with high precision. To determine optimal surface conditions for the integration of active ingredients into the matrix structure, different surface conditions of the titanium substrate were tested for their impact on wetting behaviour of a silver-containing hydrogel solution. The solution-substrate contact angle was measured and evaluated to determine the most favourable surface condition. To develop the generative manufacturing process, an FDM printer underwent modifications that permitted partial application of the drug solution to the structure in accordance with the bioprinting principle. The modified process enabled flexible control and programming of both the position and volume of the applied drug. Furthermore, the process was able to fill up to 95% of the titanium matrix body pore volume used. The customised application of drug carriers onto implants as a drug delivery system can be achieved via the developed process, providing an alternative to established methods like dip coating that lack this capability.

Nanoporous Cu-based metamaterial for fenton-like catalysis

Nanoporous metals are considered as the ideal catalysts owing to their open pore structure and high surface area. In the present work, a series of nanoporous Cu-based metamaterial (nano-Cu/MM) catalysts with triply periodic minimal surface (TPMS) were developed by the selective laser melting (SLM) and chemical dealloying process. The TPMS structure endowed the porous metamaterial with an excellent mechanical property and an abundant pathway for mass transfer. The as-prepared nano-Cu/MM was applied as a Fenton-like catalyst in the advanced oxidation process, and the degradation rate of methylene blue (MB) was as high as 99 % in 10 min. In addition, the catalyst showed a good applicability, which could effectively degrade the complex dyes and tetracycline drugs. To meet the practical application, a TPMS-structured coaxial circular with nanoporous structure was designed and prepared by the same process, which could be simply assembled with an electric motor to achieve a continuous catalytic degradation, demonstrating its potential for the industrial applications.

Charge-controlled swelling gradients at 200-µm resolution in an open-porous polymeric structure for compliance modulation

Plants combine active and passive liquid-mediated mechanisms across broad spatial and temporal scales, inspiring technological developments, in particular involving variable stiffness. Swelling is of particular interest due to the abundance of plant models and applicable (bio)materials, yet existing control by environmental humidity sorption limits its applications. This work combined swellable polymeric structures with electroactive control: we considered an open-porous polymeric laminate that hosted an electrokinetic medium also co-acting as a swelling agent for the same polymer. A constant volume of liquid (an electrolytic solution) was electrokinetically pumped between the symmetrical laminate’s interior and surface layers: as the second moment of inertia increases from the centre to the surface, the pumping of liquid towards the surface decreases the laminate’s bending stiffness, and vice versa. Ion electrosorption on high-specific-surface-area carbon electrodes, deposited in three layers in the laminate by simple additive spraying, facilitated the ion current necessary for the electrokinetic pumping. Flexural rigidity of the 400 µm thick laminate varied by 7% in response to 2-V input, evidencing swelling gradients forming at half-laminate (i.e., 200-µm) resolution. Charge-driven local rearrangement of liquid allows for broader adoption of bioinspired (and biological) porous architectures, where the channels are defined collectively, not individually as in, e.g., soft lithography. Sub-mm resolution and low-voltage control of liquid offer a high level of integration at minimal assembly, positioning active swelling as a promising solution for wearable and bioinspired soft robotic applications.

Tailored porous structure and CO2 adsorption capacity of Mg-MOF-74 via solvent polarity regulation

Metal-organic frameworks (MOFs) are promising materials for CO2 adsorption and capture. The unique crystal structure and the open porous structure of MOFs are key factors affecting their CO2 adsorption performance, but the precise tuning of MOF structures remains a challenge. Herein, we applied the Kamlet-Taft method to investigate the effect of solvent proton-supplying/accepting capaity (β/α parameters) on the structure and CO2 adsorption performance of Mg-MOF-74 by tuning the reaction solvent polarity. It was found that the ratio of the nucleation rate/growth rate of Mg-MOF-74 could be effectively controlled by adjusting the β/α value of the solvent, realizing the regulation of the crystal structure and morphology of Mg-MOF-74. In addition, the size of solvent molecules played a crucial role in the pore size of Mg-MOF-74. Interestingly, the solvent molecules were competitively coordinated with ligands and participate in the growth of Mg-MOF-74 upon decreasing the β/α value. The crystal structure, morphology and pore size of Mg-MOF-74 could be precisely regulated by the β/α value and molecular size of the reaction solvent, and the highest performing Mg-MOF-74 exhibited a CO2 adsorption capacity of 7.38 mmol/g.

Exploring the potential of porous organic cage membranes: Recent advances and applications

Porous organic cages (POCs) emerge as a new category of crystalline extended solids —assembled by discrete organic molecules— featuring cage-shaped architectures and inherent cavities. The unique synthesis and assembly of cage molecules endow POCs with intriguing strengths of high porosity, amendable open-pore structures, and favored solution processability. This yields multiple options for designs and fabrications of POC-based membranes with huge potential in advanced gas/liquid separations. This review highlights crucial characteristics of POCs such as window-cavity structure and tunable porosity, processability, hydrophilicity, and surface charge for membrane design and performance. A further discussion on the fabrication of POC membranes based on molecular designs is directed towards structure–property correlation analyses of POC membranes. Applications of reported POC membranes in gas separation, liquid separation, and other related separations are explored. Current challenges and future outlook on POC membranes are given to provide a guidance for design and fabrication of functional POC membranes with a broader range of customized separations.

Controlled Release of Mahaad Extract Using Span 80 Co-Loaded on a Dendritic Fibrous Silica

Mahaad (Artocarpus lakoocha Roxb.) is a plant variety that can be found in Southern and Eastern Asia. Its extract contains a major component, oxyresveratrol (ORES), and a minority component, resveratrol (RES), both of which are important cosmetic compounds with antioxidant and skin-brightening properties. However, both ORES and RES are easily degraded by light, heat, and oxygen, making proper storage necessary for effective use in cosmetics. In this study, dendritic fibrous silica was selected as the carrier to protect the active compounds due to its high porosity and surface area with a unique open pore structure, as well as its low toxicity. The synthesized silica was characterized using various techniques, including SEM, FE-SEM, XRD, N2 adsorption-desorption, and FTIR. The synthesized silica had a particle size, specific surface area, pore size, and pore volume of 500-600 nm, 703 m2/g, 6.21 nm, and 1.09 cm3/g, respectively. The Mahaad extract was co-loaded with Span 80, a non-ionic surfactant widely used in cosmetics in different ratios on KCC-1. The FTIR results confirmed successful loading of Mahaad and surfactant onto the KCC-1 carrier, and we observed that the release rate of Mahaad decreased with an increase in the Span 80-to-drug ratio. These findings suggest that co-loading Span 80 with the drug on a silica surface can provide a controlled and tunable drug release rate that is desirable for cosmetic applications.

Multiscale enhancement of refrigerant falling film boiling by combining commercially enhanced tubes with nanostructures

Multiscale surface structures offer the opportunity to combine the heat transfer enhancement provided by microscale structures with the dryout benefits provided by some nanostructures, which is particularly attractive for falling film evaporators, who have to prevent dryout to ensure high heat transfer coefficients can be maintained.In this study commercially produced plain, low-finned and 3D enhanced commercially produced tubes were tested uncoated as well as coated with fibrous nanostructures that induce wicking on the surface to investigate the opportunity that multiscale enhancements might offer falling film boiling evaporators. Single tubes were heated internally by water and tested in the horizontal position with refrigerant R-134a drizzled over the outside of the tube surface at saturation temperatures of 5 and 25 °C, heat fluxes from 20 to 100 kW/m2 and film Reynolds numbers of up to 2000. The tubes tested were a roughened plain tube, a low-finned Gewa-KS tube and two different 3D enhanced tubes, an Gewa-B5 and an Turbo EHPII, that have networks of re-entrant cavities.The uncoated 3D enhanced tubes achieved the highest heat transfer coefficients, outperforming a roughened plain tube by up to 500 %. The uncoated low-finned tube had heat transfer coefficients that were up to 140 % higher than the roughened plain tube, despite having only an 80 % larger surface area, thought to be due to bubbles sliding down the channels between the fins, increasing the surface area of the bubbles in contact with the surface and thus allowing for increased microlayer evaporation.The application of the copper oxide coating benefitted the low-finned tube, with heat transfer enhancement of up to 60 %, possibly due to liquid wicked underneath the sliding bubbles and onto the fin tips. However, the nanocoating largely decreased the heat transfer of the roughened plain tube and the 3D enhanced tubes, thought to be due flooding of nucleation sites on the roughened tube and interference with the hydraulics of the re-entrant cavity network on the surface of the 3D enhanced surfaces.The low-finned tube also benefitted the most from the falling film boiling heat transfer mode compared to previous pool boiling results, with heat transfer increased by up to 80 and 460 % for the uncoated and coated low-finned tube respectively, again likely due to the bubbles sliding in the fin channels under falling film conditions.The Gewa-B5 tubes had the best dryout performance, followed by the Turbo EHPII tubes and then the low-finned Gewa-KS tube. The open pore structure of the Gewa-B5 likely aided it in dryout prevention, while the fins of the Gewa-KS are thought to have prevented lateral fluid distribution and thus worsen dryout.The dryout performance of the tubes we not markedly improved by the nanocoating, highlighting the difficulty in improving wettability on high wetting low surface tensions fluids such as refrigerants. Microscale enhancements were thus shown to have significant influence on dryout performance, while nanoscale enhancements had little effect in this study.

Organic Intercalation Induced Kinetic Enhancement of Vanadium Oxide Cathodes for Ultrahigh-Loading Aqueous Zinc-Ion Batteries.

Vanadium-based oxides have attracted much attention because of their rich valences and adjustable structures. The high theoretical specific capacity contributed by the two-electron-transfer process (V5+ /V3+ ) makes it an ideal cathode material for aqueous zinc-ion batteries. However, slow diffusion kinetics and poor structural stability limit the application of vanadium-based oxides. Herein, a strategy for intercalating organic matter between vanadium-based oxide layers is proposed to attain high rate performance and long cycling life. The V3 O7 ·H2 O is synthesized in situ on the carbon cloth to form an open porous structure, which provides sufficient contact areas with electrolyte and facilitates zinc ion transport. On the molecular level, the added organic matter p-aminophenol (pAP) not only plays a supporting role in the V3 O7 ·H2 O layer, but also shows a regulatory effect on the V5+ /V4+ redox process due to the reducing functional group on pAP. The novel composite electrode with porous structure exhibits outstanding reversible specific capacity (386.7 mAh g-1 , 0.1 A g-1 ) at a high load of 6.5mg cm-2 , and superior capacity retention of 80% at 3 A g-1 for 2100 cycles.

Mesoporous Dual-Semiconductor ZnS/CdS Nanocomposites as Efficient Visible Light Photocatalysts for Hydrogen Generation.

The development of functional catalysts for the photogeneration of hydrogen (H2) via water-splitting is crucial in the pursuit of sustainable energy solutions. To that end, metal-sulfide semiconductors, such as CdS and ZnS, can play a significant role in the process due to their interesting optoelectronic and catalytic properties. However, inefficient charge-carrier dissociation and poor photochemical stability remain significant limitations to photocatalytic efficiency. Herein, dual-semiconductor nanocomposites of ZnS/CdS nanocrystal assemblies (NCAs) are developed as efficient visible light photocatalysts for H2 generation. The resultant materials, synthesized via a polymer-templated self-polymerization method, comprise a unique combination of ~5-7 nm-sized metal-sulfide nanoparticles that are interlinked to form a 3D open-pore structure with large internal surface area (up to 285 m2 g-1) and uniform pores (circa 6-7 nm). By adjusting the ratio of constituent nanoparticles, the optimized ZnS/CdS catalyst with 50 wt.% ZnS content demonstrates a remarkable stability and visible light H2-evolution activity (~29 mmol g-1 h-1 mass activity) with an apparent quantum yield (AQY) of 60% at 420 nm. Photocatalytic evaluation experiments combined with electrochemical and spectroscopic studies suggest that the superior photocatalytic performance of these materials stems from the accessible 3D open-pore structure and the efficient defect-mediated charge transfer mechanism at the ZnS/CdS nanointerfaces. Overall, this work provides a new perspective for designing functional and stable photocatalytic materials for sustainable H2 production.

Durability of antireflective SiO2 coatings with closed pore structure

The use of antireflective coatings to increase the transmittance of the cover glass is a central aspect of achieving high efficiencies for solar collectors and photovoltaics alike. Considering an expected lifetime of 20–30 years for solar energy installations, the durability of the antireflective surfaces is essential. Here, a novel antireflective SiO2 coating with a hexagonally ordered closed pore structure, produced with an aerosol-based sol-gel method is benchmarked against two commercial coatings; produced with acid etching and sol-gel roll coating. The optical and mechanical properties together with contact angle characteristics were evaluated before and after various durability tests, including climate chamber tests, outdoor exposure, and abrasion. Compared to the commercial antireflective coatings with open pore structures, the novel coating performed in parity, or better, in all tests. Based on the results of humidity freeze and industrial climate chamber tests, it appears that the coating with closed pore structure has a better ability to prevent water adsorption. Additionally, the closed pore structure of the coating seems to minimize the accumulation of dirt and deposits. The abrasion and cleanability test further confirm the advantages of a closed pore structure, showcasing the coating's mechanical durability. While the coatings exhibit similar hardness and reduced elastic modulus, the closed pore coating proves to be even harder after undergoing the industrial climate chamber test, but also slightly more brittle, as indicated by the probability of crack initiation. In summary the closed pore structure is well suited for tempered and arid climates, making it a truly competitive alternative to existing antireflective coatings.

Influence of β-Stabilizer Element on Microstructure and Mechanical Behavior of Porous Titanium Alloy Synthesized by Liquid Metal Dealloying.

The metallic implant materials for load-bearing applications typically possess a significantly higher stiffness when compared with that of human bone. In some cases, this stiffness mismatch leads to a stress-shielding effect and eventual loosing of the implant. Porous metallic materials are suitable candidates to overcome this problem. In this study, we synthesized low modulus open porous TiFe alloy by liquid metal dealloying of the precursor Ti47.5Fe2.5Cu50 (at.%) material in liquid Mg. Upon liquid metal dealloying, Cu was selectively dissolved from the precursor, and the remaining Ti and Fe elements were reorganized into a bicontinous porous structure. The synthesized TiFe alloy is composed of α-titanium and β-titanium phases. The average measured ligament size is in the micrometer range. It was found that a higher dealloying temperature leads to a pronounced coarsening of the microstructure. The open porous TiFe alloy possesses a low elastic modulus of about 6.4-6.9 GPa. At the same time, its yield strength value reaches about 185 MPa due to the α + β microstructure. Its attractive mechanical properties for biomedical applications, together with its open porous structure, indicate the potential of porous TiFe alloys to be used as implants.

Evolution of the porous structure for phosphoric acid etching carbon as cathodes in Li–O2 batteries: Pyrolysis temperature‐induced characteristics changes

AbstractAlthough biomass‐derived carbon (biochar) has been widely used in the energy field, the relation between the carbonization condition and the physical/chemical property of the product remains elusive. Here, we revealed the carbonization condition's effect on the morphology, surface property, and electrochemical performance of the obtained carbon. An open slit pore structure with shower‐puff‐like nanoparticles can be obtained by finely tuning the carbonization temperature, and its unique pore structure and surface properties enable the Li–O2 battery with cycling longevity (221 cycles with 99.8% Coulombic efficiency at 0.2 mA cm−2 and controlled discharge–charge depths of 500 mAh g−1) and high capacity (16,334 mAh g−1 at 0.02 mA cm−2). This work provides a greater understanding of the mechanism of the biochar carbonization procedure under various pyrolysis conditions, paving the way for future study of energy storage devices.

Hierarchical porous loofah-like carbon with sulfhydryl functionality for electrochemical detection of trace mercury in water

Mercury is a common contaminant found in natural waters, which is highly toxic to human health. Thus, the facile and reliable monitoring of mercury in waters is of great significance. In this study, we fabricated a novel loofah-like hierarchical porous carbon with sulfhydryl functionality (S-LHC), and applied it as an ultrasensitive sensor for the electrochemical detection of mercury in water. The S-LHC was prepared through the direct pyrolysis of a triazole-rich metal-organic framework (MOF), followed by chemical modification using thioglycolic acid. The highly conductive N-doped carbon framework of S-LHC facilitated the electron transfer in mercury electrochemical sensing. Meanwhile, the open hierarchical pore structure and abundant sulfhydryl groups allowed the fast diffusion and effective enrichment of mercury ions. Consequently, the S-LHC sensor exhibited an exceptionally high sensitivity for mercury ions, with the mercury detection limit (0.36 nM) orders of magnitude lower than the regulated values in drinking water (typically 10∼30 nM). The constructed sensor also afforded good anti-interference ability and excellent stability for long-term detection of mercury in a variety of complex real water samples. The present study provides not only a facile method for mercury detection, but also a new idea for the construction of highly sensitive electrochemical sensors.