Unique Porosity Research Articles

Advanced Polymer Composites for Effective Removal of Perfluorooctanoic Acid (PFOA) Pollutants From Aqueous Solutions.

Perfluorooctanoic acid (PFOA) is extensively utilized in industrial applications, posing significant environmental and health risks because of its persistence and toxicity. Effective elimination methods are vital to mitigate its adverse effects on ecosystems and human health. In this study, we investigate the potential of biomass-derived polymer composite for PFOA adsorption in aqueous solution. Due to its unique surface interaction and porosity, the polymer-based composite derived from sustainable biomass sources exhibits favorable adsorption characteristics. The physicochemical properties of polymer composites were characterized using FTIR, XRD, SEM-EDS, XPS, and BET analysis. The polymer composites reached a maximum PFOA adsorption efficiency about 93.3% under optimized conditions determined by Box Behnken Design. The Langmuir isotherm model revealed and provided an adsorption capacity of PFOA about 13.98 mg g-1. Moreover, the polymer-based composites demonstrated reusability, with removal rates of PFOA ranging from 93.3% to 52% over the course of four cycles after desorption. Our findings underscore the possibility of biomass-derived polymer composites as long-term and effective adsorbents for PFOA removal from aqueous environments.

Two-dimensional hierarchically porous C3N4 for photocatalysis: perspective and challenges

Owing to its unique structure, porosity and photoresponse properties, two-dimensional hierarchically porous (2D-HP) C3N4 has attracted wide attention in environmental remediation and sustainable energy evolution fields. Up to today, 2D-HP C3N4 has been developed as an efficient photocatalyst for various environmental/energy photocatalytic applications. Its advantages in promoting light harvesting, reactant diffusion and transportation, surface molecule activation and photoinduced carrier separation have been verified. In this perspective, we highlighted the advantages of 2D-HP C3N4 in various photocatalytic reactions such as water splitting and H2O2 production. The relevant mechanism was simultaneously discussed. Moreover, the prospects and obstacles for the industrial utilization of 2D-HP C3N4-based photocatalysts are outlined and summarized. Finally, we envision available approaches for the deployment of 2D-HP C3N4-based materials to promote its practical application.

Simultaneous construction of Zr-β zeolite with high content and high accessibility of framework Zr sites in the conversion of ethanol to 1,3-butadiene: Mechanisms and synergistic effects

Metallosilicate zeolites, represented by Zr-β zeolite, possess unique porosity and tunable acidity, showing great potential in the conversion of ethanol to 1,3-butadiene. However, there still remains potential for further improvement of catalytic activity and stability by breaking the bottleneck framework metal site content and microporosity diffusion. In this paper, a novel Zr-β zeolite with both high content and high accessibility of framework Zr sites was successfully synthesized via the combination strategy of “Improved Decomposition Reconstruction” and “Silanization.” Based on the activity evaluation experiments of key reaction steps and in situ DRIFTS in the conversion of ethanol to 1,3-butadiene, the enhanced activity and stability are due to the synergistic effects of the content and accessibility of framework Zr sites, which both facilitate reactant conversion and inhibit the covering of active sites or the plugging of pore channels by polymerized heavy compounds. The prepared zeolite demonstrates excellent performance with a total conversion of 66 % and a 1,3-butadiene selectivity above 67 % in 100 h, along with good regenerability.

A porous three-dimensional Cu-MOF: Preparation and application in supercapacitors, low temperature hydrogen storage and gas separation

Due to its unique porosity, metal–organic frameworks (MOFs) have great application prospects in the fields of gas adsorption and separation. However, the synthesis of multi-functional MOFs is still a great challenge. Herein, a multi-functional Cu-MOF of {[Cu2(TPTA)(H2O)2]·2DMF·NMP·4H2O}n with a porosity of 62.0 % was designed and synthesized. The H2 adsorption amount of Cu-MOF is about 289.2 cm3 g−1 at 77 K and 1 bar. Meanwhile, the selectivity adsorption of Cu-MOF towards CO2 over CH4 (V:V = 0.5:0.5), CO2/N2 (V:V = 0.5:0.5) and CO2/H2 (V:V = 0.5:0.5) is 95.1, 139.2 and 147.5, respectively, which is 1.5 times higher than the previously reported Cu-MOFs. The Cu-MOF@NF//AC asymmetric supercapacitor demonstrates high specific capacitance (53.4 F g−1) and stability (90.3 % after 2000 cycles). Furthermore, this work presents a novel approach to design multifunctional materials with low temperature hydrogen storage, gas separation and energy storage properties.

Multiwalled Carbon Nanotube-Templated Nickel Porphyrin Covalent Organic Framework for Pencil-Drawn Noninvasive Respiration Sensors.

Paper-integrated configuration with miniaturized functionality represents one of the future main green electronics. In this study, a paper-based respiration sensor was prepared using a multiwalled carbon nanotube-templated nickel porphyrin covalent organic framework (MWCNTs@COFNiP-Ph) as an electrical identification component and pencil-drawn graphite electric circuits as interdigitated electrodes (IDEs). The MWCNTs@COFNiP-Ph not only inherited the high gas sensing performance of porphyrin and the aperture induction effect of COFs but also overcame the shielding effect between phases through the MWCNT template. Furthermore, it possessed highly exposed M-N4 metallic active sites and unique periodic porosity, thereby effectively addressing the key technical issue of room-temperature sensing for the respiration sensor. Meanwhile, the introduction of a pencil-drawing approach on common printing papers facilitates the inexpensive and simple manufacturing of the as-fabricated graphite IDE. Based on the above advantages, the MWCNTs@COFNiP-Ph respiration sensor had the characteristics of wide detection range (1-500 ppm), low detection limit (30 ppb), acceptable flexibility for toluene, and rapid response/recovery time (32 s/116 s). These advancements facilitated the integration of the respiration sensor into surgical masks and clothes with maximum functionality at a minimized size and weight. Moreover, the primary internal mechanism of COFNiP-Ph for this efficient toluene detection was investigated through in situ FTIR spectra, thereby directly elucidating that the chemisorption interaction of oxygen modulated the depletion layers, resulting in alterations in sensor resistance upon exposure to the target gas. The encouraging results revealed the feasibility of employing a paper-sensing system as a wearable platform in green electronics.

Biomimetic 3D-printed Composites: Ballistic Impact Resistance with Nacre-Inspired and Tubulane Structures

This research delves into nature-inspired designs for creating materials with exceptional impact resistance, leveraging cutting-edge 3D printing techniques. Our composite design features a nacre-like outer layer combined with a tubulane-resembling core, aiming to enhance energy dissipation significantly. By emulating the dense aragonite structure found in natural nacre and the unique porosity of tubulane, to enhance ballistic impact resistance. To validate its effectiveness, we conducted ballistics tests using a 40-grain lead-tipped .22 LR bullet at an initial velocity of 330.7 m/s, with a specialized chronograph setup to measure both initial and post-penetration bullet velocities, quantifying energy absorption precisely. This study opens new frontiers in aviation safety, structural engineering, and personal protective equipment, showcasing the transformative potential of biomimicry and additive manufacturing in advancing public safety and material science.

Carbon quantum dots assemblies integrated with spatial confined Co nanoparticles for antibiotic degradation via peroxymonosulfate activation

Heterogeneous Co-based materials are well-known for their exceptional catalytic properties in activating peroxymonosulfate (PMS) for the degradation of antibiotic pollutants. However, the potential applications of these materials are often hindered by significant Co nanoparticle aggregation and ion leaching. In this study, a carbon quantum dot-mediated self-assembly strategy was used to fabricate three-dimensional porous sponge-like Co@CDs-x (x represents the calcination tempeatures) catalysts with spatially confined Co nanoparticles. Among the samples, Co@CDs-900 exhibited a remarkable 97.8 % removal efficiency of TC in 11 minutes, with an apparent rate constant of 0.313 min−1. The exceptional performance of Co@CDs-900/PMS can be attributed to its large specific surface area, unique porosity, and abundant catalytically active sites, which generate ample reactive oxygen species for TC degradation. The catalyst demonstrated good degradation capabilities across a wide pH range of 3–11 and various organic pollutants such as tetranitrophenol, oxytetracycline, ciprofloxacin, methyl orange, and rhodamine B. Moreover, Co@CDs-900 maintained high activity even after the 5th cycle due to its magnetic property and spatial confinement effect, preventing catalyst loss and ion leaching during recycling tests. The degradation mechanism involved both free-radical and non-free radical pathways, with SO4•− and 1O2 identified as the primary reactive oxygen species. The degradation intermediates of TC were identified and a plausible degradation pathway was proposed. Toxicity assessment revealed that the Co@CDs-900/PMS system effectively reduced the toxicity of TC post-degradation. This study presents an effective approach for developing sponge-like CDs assemblies with spatially confined metal nanoparticles for activating PMS in antibiotic degradation.

Poly acrylonitrile Schiff-bases nanofibers: Antibacterial and dye removal potency

Polymer nanofibers exhibit a diverse range of applications in both biological and environmental contexts owing to their unique surface structure and porosity. This study investigates the synthesis of polyacrylonitrile (PAN) Schiff base nanofibers utilizing an electrospinning protocol and their antibacterial potency as well as their dye-removing capability. Schiff bases were created from the reaction of modified PAN with vanillin PANVan and cinnamaldehyde PANCinn. X-ray diffraction analysis (XRD), Fourier transform infrared (FTIR), Thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) were employed to elucidate the structure of the resultant Schiff bases. Each compound's capability to inhibit bacterial growth and eliminate methylene blue dye (MB) from aqueous solutions was assessed. The fabricated PAN Schiff bases were able to inhibit the bacterial growth of both Gram-negative bacteria with inhibitory zone diameters ranging from 8.5 to 12.3 mm and Gram-positive bacteria with inhibitory zone diameters ranging from 9 to 15.6 mm. Furthermore, 77.8 % of the MB dye was found to be removed by PANVan nanofibers. This dye removal process was discovered to be endothermic, following the Langmuir isotherm model and having pseudo-second-order kinetics as a description. It has been discovered that PANVan nanofibers can be reused for dye removal. Simulated adsorption and docking studies were found to agree with dye removal and antibacterial studies. These synthesized Schiff bases could demonstrate their promise as bactericidal agents and useful materials for environmental applications involving the removal of dyes.

Recent progress on construction and applications of metal‐organic frameworks‐based materials for lithium‐ion batteries and supercapacitors

AbstractMetal‐organic frameworks (MOFs), a special sort of three‐dimensional crystalline porous lattices composed of organic multi‐site connectors and metal nodes, are characterized by unique porosity and high specific surface area, which have attracted a wide range of interest as electrode materials for the electrochemical energy storage devices in recent years. In this contribution, we outline the current research progress on the construction of pristine MOFs, MOF composites, and MOF derivatives and their applications as electrode materials in supercapacitors (SCs) and lithium‐ion batteries (LIBs). Specifically, we discuss the shortcomings of MOFs‐based electrode materials for SCs and LIBs. The innovative work on performance improvements by combining MOFs with other conductive materials and derivating MOFs into metal sulfides, metal oxides, metal phosphides, and porous carbon is also presented in detail. Finally, our perspectives on the challenges in the future for a grasp of the potential mechanisms are tentatively provided. This review will inspire more developments and applications of MOFs‐based electrode materials for electrochemical energy storage.

Advancing 3D Dental Implant Finite Element Analysis: Incorporating Biomimetic Trabecular Bone with Varied Pore Sizes in Voronoi Lattices.

The human mandible's cancellous bone, which is characterized by its unique porosity and directional sensitivity to external forces, is crucial for sustaining biting stress. Traditional computer- aided design (CAD) models fail to fully represent the bone's anisotropic structure and thus depend on simple isotropic assumptions. For our research, we use the latest versions of nTOP 4.17.3 and Creo Parametric 8.0 software to make biomimetic Voronoi lattice models that accurately reflect the complex geometry and mechanical properties of trabecular bone. The porosity of human cancellous bone is accurately modeled in this work using biomimetic Voronoi lattice models. The porosities range from 70% to 95%, which can be achieved by changing the pore sizes to 1.0 mm, 1.5 mm, 2.0 mm, and 2.5 mm. Finite element analysis (FEA) was used to examine the displacements, stresses, and strains acting on dental implants with a buttress thread, abutment, retaining screw, and biting load surface. The results show that the Voronoi model accurately depicts the complex anatomy of the trabecular bone in the human jaw, compared to standard solid block models. The ideal pore size for biomimetic Voronoi lattice trabecular bone models is 2 mm, taking in to account both the von Mises stress distribution over the dental implant, screw retention, cortical bone, cancellous bone, and micromotions. This pore size displayed balanced performance by successfully matching natural bone's mechanical characteristics. Advanced FEA improves the biomechanical understanding of how bones and implants interact by creating more accurate models of biological problems and dynamic loading situations. This makes biomechanical engineering better.

Unlocking High Porosity: Post-Synthetic Solvothermal Treatment of Cu-Paddlewheel Based Metal-Organic Cages.

Metal-organic cages (MOCs) have garnered significant attention due to their unique discrete structures, intrinsic porosity, designability, and tailorability. However, weak inter-cage interactions, such as van der Waals forces and hydrogen bonding can cause solid-state MOCs to lose structural integrity during desolvation, leading to the loss of porosity. In this work, a novel strategy to retain the permanent porosity of Cu-paddlewheel-based MOCs, enabling their use as heterogeneous catalysts is presented. Post-synthetic solvothermal treatments in non-coordinating solvents, mesitylene, and p-xylene, effectively preserve the packing structures of solvent-evacuated MOCs while preventing cage agglomeration. The resulting MOCs exhibit an exceptional N2 sorption capacity, with a high surface area (SBET=1934m2g-1 for MOP-23), which is among the highest reported for porous MOCs. Intriguingly, while the solvothermal treatment reduced Cu(II) to Cu(I) in the Cu-paddlewheel clusters, the MOCs with mixed-valenced Cu(I)/Cu(II) maintained their crystallinity and permanent porosity. The catalytic activities of these MOCs are successfully examined in copper(I)-catalyzed hydrative amide synthesis, highlighting the prospect of MOCs as versatile reaction platforms.

Facile preparation of sodium alginate/poly(vinyl alcohol)/graphite hybrid porous hydrogel for efficient solar desalination

Porous hydrogel incorporated with the photothermal conversion materials has been the key component of the interfacial solar evaporation device. However, the preparation of high-performance porous hydrogel for the interfacial solar evaporation device still existed some limitation, like the widely available and cheap photothermal conversion material, the ease and scalability of porous structure construction in the hydrogel. In this work, a porous biomass-derived hydrogel evaporator with interconnected pore structure were developed via the simple and effective foaming-freezing-crosslinking three-step method using sodium alginate and poly(vinyl alcohol) as matrix materials and commercial graphite as the photothermal material. It has excellent photothermal conversion and water transport capabilities, with an evaporation rate of 3.15 kg m-2h−1 and an evaporation efficiency of 91 % at a solar irradiation intensity of 1 kW m−2. The evaporator also has excellent salt rejection performance due to its unique porosity. The evaporator shows good stability and long-term durability when evaporating in brine cycles. This easily prepared, inexpensive and biocompatible hydrogel evaporator has great potential in the field of solar desalination.

Enhanced atmospheric water harvesting efficiency through green-synthesized MOF-801: a comparative study with solvothermal synthesis

Adsorption-based atmospheric water harvesting has emerged as a compelling solution in response to growing global water demand. In this context, Metal–organic frameworks (MOFs) have garnered considerable interest due to their unique structure and intrinsic porosity. Here, MOF 801 was synthesized using two different methods: solvothermal and green room temperature synthesis. Comprehensive characterization indicated the formation of MOF-801 with high phase purity, small crystallite size, and excellent thermal stability. Nitrogen adsorption–desorption analysis revealed that green-synthesized MOF-801 possessed an 89% higher specific surface area than its solvothermal-synthesized counterpart. Both adsorbents required activation at a minimum temperature of 90 °C for optimal adsorption performance. Additionally, green-synthesized MOF-801 demonstrated superior adsorption performance compared to solvothermal-synthesized MOF-801, attributed to its small crystal size (around 66 nm), more hydrophilic functional groups, greater specific surface area (691.05 m2/g), and the possibility of having a higher quantity of defects. The maximum water adsorption capacity in green-synthesized MOF-801 was observed at 25 °C and 80% relative humidity, with a value of 41.1 g/100 g, a 12% improvement over the solvothermal-synthesized MOF-801. Remarkably, even at a 30% humidity level, green-synthesized MOF-801 displayed a considerable adsorption capacity of 31.5 g/100 g. Importantly, MOF-801 exhibited long-term effectiveness in multiple adsorption cycles without substantial efficiency decline.

Lightweight Triboelectric Nanogenerators Based on Hollow Stellate Cellulose Films Derived from Juncus effusus L. Aerenchyma

AbstractThis study reports a facile delignification and natural drying process for synthesizing cellulose films using the unique surface roughness, porosity, and lightness of the hollow stellate cellulose (HSC) united aerenchyma of the wetland weed Juncus effusus L. By controlling the grafted amino/fluorine‐bearing group content of various silane coupling agents, this work successfully manipulates the triboelectric polarities of HSC films after silanization. Subsequently, a layer of Ag nanowire electrodes is coated on one side of the silanized HSC friction layers, resulting in flexible, lightweight, semi‐transparent HSC‐based triboelectric nanogenerators (HSC‐TENGs) featuring both macro‐scale surface roughness and micro‐nano inner pores. These all‐in‐one HSC‐TENGs achieve the highest output voltage of 4.86 V, which is 28 times that of TENGs employing two pristine HSC films as triboelectric layers (PHSC‐TENG). Finally, the HSC‐TENG with the optimum output power is applied as a wearable self‐powered sensor for gait analysis, demonstrating stable and sustainable performances in distinguishing different body motions such as walking, running, jumping, and calf raising. This study not only proposes a new cellulose‐based TENG for future in‐depth body locomotion analysis but also paves the way for converting differently structured aerenchyma from abundant problematic aquatic or wetland weeds into promising structural templates in multifunctional cellulose‐based applications.

3D Printable Gelatin Methacryloyl (GelMA)-Dextran Aqueous Two-Phase System with Tunable Pores Structure and Size Enables Physiological Behavior of Embedded Cells In Vitro.

The restricted porosity of most hydrogels established for in vitro 3D tissue engineering applications limits embedded cells with regard to their physiological spreading, proliferation, and migration behavior. To overcome these confines, porous hydrogels derived from aqueous two-phase systems (ATPS) are an interesting alternative. However, while developing hydrogels with trapped pores is widespread, the design of bicontinuous hydrogels is still challenging. Herein, an ATPS consisting of photo-crosslinkable gelatin methacryloyl (GelMA) and dextran is presented. The phase behavior, monophasic or biphasic, is tuned via the pH and dextran concentration. This, in turn, allows the formation of hydrogels with three distinct microstructures: homogenous nonporous, regular disconnected-pores, and bicontinuous with interconnected-pores. The pore size of the latter two hydrogels can be tuned from ≈4 to 100µm. Cytocompatibility of the generated ATPS hydrogels is confirmed by testing the viability of stromal and tumor cells. Their distribution and growth pattern are cell-type specific but are also strongly defined by the microstructure of the hydrogel. Finally, it is demonstrated that the unique porous structure is sustained when processing the bicontinuous system by inkjet and microextrusion techniques. The proposed ATPS hydrogels hold great potential for 3D tissue engineering applications due to their unique tunable interconnected porosity.

Coupling thermal and catalytic cracking of polymer wastes to boost carbon nanotubes production: Effects of HZSM-5 zeolites

The efficient synthesis of carbon nanotubes from polymer wastes has been considered one promising technology for the effective management of current environment crisis. In the two-stage reaction system, HZSM-5 zeolites were introduced into the two-stage reaction system between the upper and lower stages, which was expected to upgrade the pyrolysis gas from polymer wastes and boost the growth of carbon nanotubes on Fe-Al2O3 catalyst. The physicochemical properties of HZSM-5 zeolites, Fe-Al2O3 catalyst and the as-obtained carbon materials were systematically characterized by XRD, N2 physisorption, 27Al MAS NMR, NH3-TPD, H2-TPR, SEM, TEM, TG-DSC and Raman. It was found that the presence of HZSM-5 zeolites increased the length and yield, and narrowed the diameter of carbon nanotubes. In the absence of HZSM-5 zeolites, the yield of carbon nanotubes was 34 mg/g with an average diameter of 19 nm. The introduction of HZSM-5 and meso-HZSM-5 increased the yield of carbon nanotubes to 109 mg/g and 90 mg/g, and recduced the average diameter to 15 nm and 13 nm, respectively. The improvement of HZSM-5 zeolites on the synthesis of carbon nanotubes was observed for divrese polymer wastes inlcluding LDPE, HDPE and PP. It was attributed to the unique acidity and porosity of HZSM-5 zeolites, which enhanced the secondary cracking of the pyrolysis gas and the formation of light hydrocarbons.

Unique Duplex Microstructure and Porosity Effect on Mechanical Properties of AlCoCrFeNi2.1 Eutectic High-Entropy Alloys Processed by Selective Laser Melting

Unique Duplex Microstructure and Porosity Effect on Mechanical Properties of AlCoCrFeNi2.1 Eutectic High-Entropy Alloys Processed by Selective Laser Melting

Synthesis of PHI-type zeolite harmotome using barium as an inorganic structure-directing agent inspired from natural mineral compositions

Zeolites are nanoporous aluminosilicates widely used as commercial adsorbents, heterogeneous catalysts, and ion-exchange materials due to their unique porosity, acidity, and thermal stability. The vast majority of synthetically-realized zeolite structures are prepared under hydrothermal conditions in alkaline media, and often in the presence of an organic structure-directing agent that facilitates the crystallization of diverse porous networks. Due to economic and environmental disadvantages of organic-based syntheses, it is often desirable to produce zeolites in organic-free media using alkali metal ions as the most commonly employed inorganic structure-directing agents (ISDAs). In this study, we were inspired by the elemental compositions of natural zeolite minerals to examine the use of an alkaline earth metal ion as the ISDA to prepare zeolites with the PHI framework type. Two natural minerals exhibiting this crystal structure are phillipsite and harmotome. Both structures contain sodium and potassium as extra-framework cations, but only harmotome contains barium cations. Here we examined how the combination of alkali and alkaline earth ISDAs promote the formation of PHI-type zeolites. Our findings reveal that each isostructure is prepared under different synthesis conditions where simply adding barium to a growth mixture does not always lead to harmotome formation. Harmotome is formed in more dilute and alkaline growth media; however, time-resolved analyses of zeolite crystallization reveal that harmotome can be synthesized at low temperatures (ca. 65 °C) with rates that are 5-times faster than syntheses of phillipsite. This seemingly indicates that barium reduces the energetic barrier for PHI-type zeolite nucleation in ways that are not fully understood. Moreover, harmotome crystals exhibit an average particle size of ca. 60 nm, which is nearly 40-fold smaller than phillipsite crystals prepared under similar conditions. Collectively, these findings identify routes to control crystallization of PHI-type zeolites and may provide a broader strategy for using the composition of natural zeolite minerals to optimize the preparation of synthetic analogues.

Microporous melamine-formaldehyde networks loaded on rice husks for dynamic removal of organic micropollutants

The alteration of agricultural wastes into novel adsorbents can stimulate their scalability in realistic application, showing great economic and environmental advantages. Here, we proposed a strategy to engineer rice husk (RH) with microporous melamine-formaldehyde networks (MFNs) resins and the utilization for dynamic removal of organic micropollutants rapidly and efficiently. was pre-treated to acquire attractive surface and unique hierarchical porosity, endowing with surface functionalization and essential filtering properties. MFNs can be uniformly generated in-situ on the fully exposed cellulose backbones of the pre-treated RH. MFNs granules functionalized RH (RH@MFNs) exhibited high removal efficiencies over 90% within 30 min for the adsorption of hazardous organic compounds (e.g., phenolic and antibiotic micropollutants) in static tests. Experiment results and density functional theory (DFT) simulation revealed that the synergy of hydrogen bonding, π-πinteraction, and micropore preservation dominates the adsorption. Further dynamic adsorption experiments showed that the removal efficiency and equilibrium removal capacity towards bisphenol A by RH@MFNs packed bed up-flow column were 2.6 and 67 times higher than that of raw RH, respectively. The column adsorption fits well with the Thomas model and bed depth service time (BDST) kinetic model. The inherent macropores inside RH and the roughness caused by the spiky structures and mesopores outside RH, as well as the accumulated MFNs granules, can lead to local turbulence of water flow around RH@MFNs, enabling fast and efficient adsorption. This sustainable and cost-effective preparation of RH-based adsorbents sheds light on the rational design of biomass waste adsorbents for realistic wastewater.

Preparation of hierarchical porous carbon through one-step KOH activation of coconut shell biomass for high-performance supercapacitor

Here we report an effective and facile method for preparing porous carbons (CSCK-T-x) with highly developed hierarchical porosity for high-performance supercapacitor by one-step KOH activation of coconut shell carbon. The effects of carbonization temperature (T, °C) and KOH/C ratio (x) on the structure and electrochemical properties were studied systematically. As the KOH/C ratio and activation temperature increase, the SBET rapidly increases and then decreases and reaches a maximum (2143.6m2 g−1) at 800 °C with a KOH/C ratio of 2. Furthermore, CSCK-800-2 displayed abundant micropores and two concentrated mesopores at 4 nm and 14 nm. In a three-electrode test system, CSCK-800-2 exhibits a high specific capacitance of 317 F g−1 at a current density of 0.5 A g−1 and considerable rate retention of 68% at 20 A g−1. The symmetrical supercapacitor that was based on CSCK-800-2 showed a maximum energy density of 13.5 Wh kg−1 at 0.5 A g−1 with a superior cycling stability (99.7% of the capacitance retention after 10,000 cycles at 5 A g−1) in 6 M KOH electrolyte. The large specific surface area and unique hierarchical porosity of CSCK-800-2 enable it to have high ion-accessible surface and low-ion transport resistance. This one-step activation method provides an approach to convert biological waste into high-value hierarchical porous carbon material for electric double-layer capacitors.