Fast Conversion of Ionic Liquids and Poly(Ionic Liquid)s into Porous Nitrogen-Doped Carbons in Air.
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ABSTRACT:
SUBMITTER: Men Y
PROVIDER: S-EPMC4848988 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:A soluble and easily dispersive cross-linked poly(ionic liquid), copolymer of 1-vinyl-3-butylimidazolium bromide ([VBIM][Br]) and divinylbenzene (DVB), was used as a precursor for nitrogen doped porous carbons (NPCs) with SiO2 (from tetraethyl orthosilicate) as a template. The NPCs were characterized by infrared (IR) spectroscopy, nitrogen adsorption-desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, thermo gravimetric analysis (TGA), elemental analysis and X-ray photoelectron spectroscopy (XPS). The specific surface area and porosity of NPCs depended on the carbonization temperature, the SiO2/[VBIM][Br] ratio and the precursors. Under the optimized conditions, the NPC prepared from cross-linked poly(ionic liquid), P([VBIM][Br]-0.1DVB), gave a high specific surface area up to 1324 m2 g-1. XRD indicated that amorphous and disordered graphitic layers were dominant in NPCs. The nitrogen content was about 4-5 wt% in NPCs, and the nitrogen bonding state observed using XPS analysis was mainly pyridinic- and pyrrolic-N. Meanwhile, the cyclic voltammetry, gravimetric charge-discharge curves and electrochemical impedance spectroscopy of the NPCs were also investigated, the specific capacitance was up to 243 F g-1 at 0.1 A g-1, and the retention ratio was nearly 100% after charge-discharge cycling 2400 times at 2 A g-1 in 6 M KOH electrolyte.
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Project description:Nitrogen-doped carbon materials with a large specific surface area, high conductivity, and adjustable microstructures have many prospects for energy-related applications. This is especially true for N-doped nanocarbons used in the electrocatalytic oxygen reduction reaction (ORR) and supercapacitors. Here, we report a low-cost, environmentally friendly, large-scale mechanochemical method of preparing N-doped porous carbons (NPCs) with hierarchical micro-mesopores and a large surface area via ball-milling polymerization followed by pyrolysis. The optimized NPC prepared at 1000 °C (NPC-1000) offers excellent ORR activity with an onset potential (Eonset) and half-wave potential (E1/2) of 0.9 and 0.82 V, respectively (vs. a reversible hydrogen electrode), which are only approximately 30 mV lower than that of Pt/C. The rechargeable Zn-air battery assembled using NPC-1000 and the NiFe-layered double hydroxide as bifunctional ORR and oxygen evolution reaction electrodes offered superior cycling stability and comparable discharge performance to RuO2 and Pt/C. Moreover, the supercapacitor electrode equipped with NPC prepared at 800 °C exhibited a high specific capacity (431 F g-1 at 10 mV s-1), outstanding rate, performance, and excellent cycling stability in an aqueous 6-M KOH solution. This work demonstrates the potential of the mechanochemical preparation method of porous carbons, which are important for energy conversion and storage.
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Project description:Currently, finding high capacity adsorbents with large selectivity to capture Xe is still a great challenge. In this work, nitrogen-doped porous carbons were prepared by programmable temperature carbonization of zeolitic imidazolate framework-8 (ZIF-8) and ZIF-8/xylitol composite precursors and the resultant samples are marked as Carbon-Z and Carbon-ZX, respectively. Further adsorption measurements indicate that ZIF-derived nitrogen-doped Carbon-ZX exhibits extremely high Xe capacity of 4.42 mmol g(-1) at 298 K and 1 bar, which is higher than almost all other pristine MOFs such as CuBTC, Ni/DOBDC, MOF-5 and Al-MIL-53, and even more than three times of the matrix ZIF-8 at similar conditions. Moreover, Carbon-ZX also shows the highest Xe/N2 selectivity about ~120, which is much larger than all other reported MOFs. These remarkable features illustrate that ZIF-derived nitrogen-doped porous carbon is an excellent adsorbent for Xe adsorption and separation at room temperature.
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Project description:Nitrogen-doped and heteroatom multi-doped carbon materials are considered excellent metal-free catalysts, superior catalyst supports for transition metal particles and single metal atoms (single-atom catalysts), as well as efficient sorbents for gas- and liquid-phase substances. Acid-catalyzed sol-gel polycondensation of hydroxybenzenes with heterocyclic aldehydes yields cross-linked thermosetting resins in the form of porous organic polymers (i.e., organic gels). Depending on the utilized hydroxybenzene (e.g., phenol, resorcinol, phloroglucinol, etc.) and heterocyclic aldehyde variety of heteroatom-doped organic polymers can be produced. Upon pyrolysis, highly porous and heteroatom-doped carbons are obtained. Herein, polycondensation of phloroglucinol with imidazole-2-carboxaldehyde (and other, similar heterocyclic aldehydes with two heteroatoms in the aromatic ring) is utilized to obtain porous, N-doped organic and carbon gels with N-content of up to 16.5 and 12 wt.%, respectively. Utilization of a heterocyclic aldehyde with two different heteroatoms yields dually-doped carbon materials. Upon pyrolysis, the porous polymers yield ultramicroporous N-doped and N,S co-doped carbons with specific surface areas of up to 800 m2g-1. The influence of the initial composition of reactants and the pyrolysis temperature on the structure and chemical composition of the final doped organic and carbon materials is studied in detail.
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Project description:Electroactive soft actuators and bioinspired artificial muscles have received burgeoning interest as essential components in future electronic devices such as soft haptic-feedback systems, human-friendly wearable electronics, and active biomedical devices. However, important challenging issues including fast response time, ultralow input power, robust operation in harsh environments, high-resolution controllability, and cost-effectiveness remain to be resolved for more practical applications. Here, an electroionic antagonistic artificial muscle is reported based on hierarchically porous nitrogen-doped carbon (HPNC) electrodes derived from a microporous poly(triazine-triptycene) organic framework (PtztpOF). The HPNC, which exhibits hierarchically micro- and mesoporous structures, high specific capacitance of 330 F g-1 in aqueous solution, large specific surface area of 830.46 m2 g-1, and graphitic nitrogen doping, offers high electrical conductivity of 0.073 MS m-1 and outstanding volumetric capacitance of 10.4 MF m-3. Furthermore, it is demonstrated that a novel electroionic antagonistic muscle based on HPNC electrodes successfully displays extremely reliable and large bending deformations and long-term durability under ultralow input voltages. Therefore, microporous polymer or covalent organic frameworks can be applied to provide significant improvements in electroactive artificial muscles, which can play key roles as technological advances toward bioinspired actuating devices required for next-generation soft and wearable electronics.
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Project description:Carbon-based materials, as electrodes for supercapacitors, have attracted tremendous attention. Therefore, nitrogen-doped porous carbons (NPCs) were prepared through a facile carbonization/activation strategy by treating different mass ratios of melamine-urea-formaldehyde resin and KOH. It is clearly demonstrated that because of the introduction of KOH, the resulting NPCs were shown to have increased specific surface area and a rich pore structure, and the best sample possessed a large specific surface area of 2248 m2 g-1 and high N content, which contributed to the good electrochemical performance for supercapacitors. Accordingly, a three-electrode system assembles NPCs as an electrode using aqueous KOH solution; the specific capacitance was 341 F g-1 under the current density of 1 A g-1 and retained a specific capacitance of almost 92% after 5000 cycles. The maximum energy output for a symmetrical solid-state supercapacitor with NPCs as the electrode material was 9.60 W h kg-1 at 1 A g-1. NPCs have promising applications on high-performance supercapacitors and other energy-storage devices.
| S-EPMC6776963 | biostudies-literature
Project description:Biomass-derived activated carbon materials with hierarchically nanoporous structures containing nitrogen functionalities show excellent electrochemical performances and are explored extensively in energy storage and conversion applications. Here, we report the electrochemical supercapacitance performances of the nitrogen-doped activated carbon materials with an ultrahigh surface area prepared by the potassium hydroxide (KOH) activation of the Nelumbo nucifera (Lotus) seed in an aqueous electrolyte solution (1 M sulfuric acid: H2SO4) in a three-electrode cell. The specific surface areas and pore volumes of Lotus-seed-derived carbon materials carbonized at a different temperatures, from 600 to 1000 °C, are found in the range of 1059.6 to 2489.6 m2 g-1 and 0.819 to 2.384 cm3 g-1, respectively. The carbons are amorphous materials with a partial graphitic structure with a maximum of 3.28 atom% nitrogen content and possess hierarchically micro- and mesoporous structures. The supercapacitor electrode prepared from the best sample showed excellent electrical double-layer capacitor performance, and the electrode achieved a high specific capacitance of ca. 379.2 F g-1 at 1 A g-1 current density. Additionally, the electrode shows a high rate performance, sustaining 65.9% capacitance retention at a high current density of 50 A g-1, followed by an extraordinary long cycle life without any capacitance loss after 10,000 subsequent charging/discharging cycles. The electrochemical results demonstrate that Nelumbo nucifera seed-derived hierarchically porous carbon with nitrogen functionality would have a significant probability as an electrical double-layer capacitor electrode material for the high-performance supercapacitor applications.
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Project description:Heteroatom-doped porous carbon membranes (HPCMMs) with a tailor-made pore architecture, chemical composition, atomic structural order, and surface state represent an exciting family of porous carbon materials for diverse potential applications in catalysis, water treatment, biofiltration, energy conversion/storage, and so forth. Conventional porous carbon membranes possess intrinsic structural integrity, interconnectivity, and chemical purity across the atomic-to-macro world and have been popularly incorporated into devices as separators or chemically inert conductive supports, circumventing otherwise the inevitable complicated processing and structure weakness of their fine powderous counterpart. Motivated by the distinguished heteroatom-doping effect that revolutionizes the chemical and physical nature of carbon materials, the HPCMM research surges very recently, and focuses not only on the eminent conductive supports or separators but also on electro(co)catalysts in energy devices. Synergy of the porous nature, incorporation of heteroatoms, and the membrane state creates a vivid profile pattern and new task-specific usage. It is also noteworthy that the inherent structural merits of HPCMMs plus a high electron conductivity imbue them as a reliable binder-free model electrode to derive the intrinsic structure-property relationship of porous carbons in electrochemical environments, excluding the complex and adverse factors in association with polymer binders in carbon powder-based electrodes. HPCMMs are of both intense academic interest and practical value because of their well-defined properties endowed by controllable structure and porosity at both atomic and macroscopic scales in a membrane form. The sole aim of this article is to bring this group of porous carbon materials to the forefront so their comprehensive properties and functions can be better understood to serve the carbon community to address pressing materials challenges in our society. In this Account, we highlight the latest discovery and proceedings of HPCMMs, particularly the advancements in how to tailor structures and properties of HPCMMs by rational structure design of porous polymer membranes as sacrificial template built up especially from heteroatom-rich poly(ionic liquid)s (PILs). We will also stress the carbonization craft and the state-of-the-art electrochemical applications for HPCMMs. Key factors and thoughts in heteroatom doping and porous systems in HPCMMs are discussed. A future perspective of the challenges and promising potential of HPCMMs is cast on the basis of these achievements.
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Project description:Lithium-sulfur (Li-S) batteries have attracted considerable attention due to their ultra-high specific capacity and energy density. However, there are still problems to be resolved such as poor conductivity of sulfur cathodes and dissolution of polysulfides in organic electrolytes. Herein, a novel ZIF-8-derived nitrogen-doped connected ordered macro-microporous carbon (COM-MPC) was developed by a dual solvent-assisted in situ crystallization method within a face-centered cubic stacking sphere template, which acts as an advanced sulfur host for enhanced Li-S battery performance. Compared with the conventional predominant microporous C-ZIF-8, the unique hierarchical macro-microporous structure with nitrogen doping not only renders polysulfide intermediates enhanced entrapment by confining the effect of micropores and chemisorption of doping N atoms, but also facilitates electrolyte accessibility and efficient ion transport owing to the ordered macroporous structure. Benefitting from this, the COM-MPC@S cathode delivers a high initial specific capacity of 1498.5 mA h g-1 and a reversible specific capacity of 1118.9 mA h g-1. Moreover, the COM-MPC@S cathode exhibits 82.3% of capacity retention within 10th to 50th cycle at 0.5C and a large capacity of 608.5 mA h g-1 after 50 cycles at a higher rate of 1C, and this enhanced cycling stability and rate capability demonstrate great practical application potential in Li-S battery systems.
| S-EPMC9057854 | biostudies-literature
Project description:The synthesis of biomass-derived porous carbons (PCs) for supercapacitors by conventional two-steps method (chemical activation after carbonization) is complicated and time-consuming. In this study, we present a one-step microwave activation strategy to prepare hierarchically PCs from waste palm boosted by activated carbons (ACs). ACs with various specific surface areas (14, 642, and 1344 m²·g-1) were used for the first time to fast absorb microwave energy for converting waste palm into hierarchically PCs, that is, PC1, PC2, and PC3, respectively. The morphological and structural characterizations of PCs were studied. Also, the electrochemical performances of supercapacitors based on PCs as electrodes were further investigated. The results showed that the PC (PC1) boosted by AC with the lowest specific surface area possessed a porous structure (containing micro-, meso-, and macro- pores) with the largest specific surface area (1573 m²·g-1) and the highest micropore volume (0.573 cm³·g-1), as well as the suitable mesoporosity (29.69%). The as-prepared PC1 supercapacitor even in a gel electrolyte (PVA/LiCl) exhibited a high specific capacitance of 226.0 F·g-1 at 0.5 A·g-1 and presented excellent charge-discharge performance with an energy density of 72.3 Wh·kg-1 at a power density of 1.4 kW·kg-1 and 50.0 Wh·kg-1 at 28.8 kW·kg-1. Moreover, this promising method exhibited a simple, rapid, and cost-effective preparation of carbon materials from renewable biomass for energy storage applications.
| S-EPMC6473988 | biostudies-literature