Nitrogen-doped Microporous Carbon Research Articles

Nitrogen-Doped Microporous Carbon Prepared by One-Step Carbonization: Rational Design of a Polymer Precursor for Efficient CO2 Capture

Nitrogen-doped microporous carbon using carboxylic acid-functionalized imidazole-type polymers (PDVA) as a carbon precursor was fabricated by a one-step carbonization method without an additional activator. The introduction of acrylic acid was beneficial to promote the formation of microporous structures during the pyrolysis process. By changing the carbonization temperature, the textural properties and surface nitrogen content of the carbon materials were tuned. The synergistic effect of the microporous structure and basic nitrogen sites was conducive to enhancing the CO₂ adsorption performance of porous carbon materials. The CO₂ adsorption quantity of PDVA-C-800 obtained without an additional activator reached 3.18 mmol·g–¹ under 1 bar at 25 °C, which was comparable to that of the reported carbon materials. Besides, PDVA-C-800 possessed excellent cycle stability and recyclability. The fabrication of microporous nitrogen-doped carbon derived from carboxylic acid-functionalized imidazole-type polymers provided an original idea for CO₂ uptake.

Molecular Level Design of Nitrogen-Doped Well-Defined Microporous Carbon Spheres for Selective Adsorption and Electrocatalysis.

Nitrogen-doped porous carbon spheres have attracted great interest in diversified fields owing to their unique physical and chemical properties. However, the synthesis of nitrogen-doped porous carbon spheres with hierarchical superstructures and refined micropore structures is still a challenge. Herein, we develop a molecular-scale silica templating strategy to prepare nitrogen-doped microporous carbon spheres (MCSSs) with high porosity and a well-defined micropore structure. Octa(aminophenyl) polyhedral oligomeric silsesquioxane is used as a building block in MCSS precursors to provide precise molecular-scale templating and nitrogen doping. The morphology of MCSSs can be easily tuned by choosing the proper solvent. The as-synthesized MCSS with a large surface area (2036 m2 g-1), narrow micropore size distribution, nitrogen doping, and hierarchical geometry can serve as an efficient selective adsorbent for CO2 and organic pollutants. Furthermore, the MCSS decorated with Fe-N-C active sites (MCSS-Fe) shows enhanced electrocatalytic ORR activity in alkaline solution. This novel approach may open a new avenue for controllable fabrication of porous carbon spheres with desired geometry and well-designed pore structure and show potential applications in selective adsorption and catalysis.

Nitrogen-doped microporous carbon with narrow pore size distribution as sulfur host to encapsulate small sulfur molecules for highly stable lithium-sulfur batteries

Lithium-sulfur (Li-S) battery with high theoretical energy density has been considered as an important energy storage system. However, its application has been limited by low cycling stability and rapid capacity decay due to the shuttle of lithium polysulfide (Li2Sn, n > 5). These problems can be solved using small sulfur molecules (S2–4) as the active material, while synthesis of carbon hosts with suitable pores size and narrow pore distribution to encapsulate small sulfur molecules are still challenging. Here, we report a novel nitrogen-doping microporous carbon (NDMC) sulfur host with narrow micropore unimodal size distribution centered at 0.57 nm. By accommodating small sulfur molecules (S2–4) within the subnanopores of NDMC, the formation and shuttle of soluble lithium polysulfide (LiPS) can be avoided. The cathode shows only a long potential plateau due to the direct conversion from S2–4 to Li2S. In carbonate-based electrolyte, the NDMC/S-2 cathode remains a stable and reversible capacity of 902 mAh g−1 at 0.2 C with 100% Coulombic efficiency after 500 cycles, and capacity fading per cycle is only around 0.02%. Besides, an excellent capacity of 511.8 mAh g−1 is achieved even at an ultrahigh rate of 10 C, demonstrating a superior rate capability performance. This NDMC/S composite also shows excellent cycling stability in ether-based electrolyte. All the above demonstrate the NDMC has great potential application in Li-S batteries.

Nitrogen-Doped Microporous Carbon Materials Derived from DBU-Modified Carboxylic Acid Polymers for CO <sub>2</sub> Capture

Nitrogen-Doped Microporous Carbon Materials Derived from DBU-Modified Carboxylic Acid Polymers for CO <sub>2</sub> Capture

Nitrogen-doped microporous carbon coated on carbon nanotubes for high performance supercapacitors

Abstract Core-shell structure composite using carbon nanotubes as conductive core and nitrogen-doped microporous carbon as energy storage shell was synthesized by carbonization of polyaniline coated carbon nanotubes and followed by KOH activation. The optimized samples (CNTs@NC-4) possess unique core-shell structure with high specific surface area and rich heteroatoms. Consequently, the CNTs@NC-4 electrode displays a specific capacitance of 310 F g−1 at 0.5 A g−1, superior rate capability and good cycling durability. More interestingly, the assembled CNTs@NC-4//CNTs@NC-4 symmetric supercapacitor shows a high energy density of 18.6 Wh kg−1, excellent rate capability and good cycling durability in 1 M Na2SO4 aqueous electrolyte.

Nitrogen-doped microporous carbon material decorated with metal nanoparticles derived from solid Zn/Co zeolitic imidazolate framework with high selectivity for CO2 separation

To enhance CO2 separation selectivity and adsorption capacity for CCS applications, a core-shell Zn/Co zeolitic imidazolate framework (ZIF) synthesized through solvent-thermal reactions at 120 ℃ was pyrolyzed at different temperatures (ranging from 600 to 725 ℃) to obtain nanoporous carbon (NPC) materials with increased metal-N2 active sites and enhanced moisture stability. The NPC sample pyrolyzed (at 725 ℃) showed the highest CO2 uptake (3.22 mmol/g at 273 K and 1 bar), which was 2.13 times higher than that of the raw core-shell Zn/Co ZIF. In addition, it also exhibited the highest heat of adsorption towards CO2 (40 kJ/mol) and superior moisture stability compared to the other samples. Ideal adsorbed solution theory (IAST) calculations showed that this sample also possessed the highest CO2 separation selectivities of 24.3 and 40.2 for model biogas (CO2/CH4, volume ratio = 40:60) and coal-fired flue gas (CO2/N2, volume ratio = 15:85) mixtures, respectively, which were much higher than the corresponding values (2.11 and 3.71) for the raw core-shell Zn/Co ZIF. Through a combination of XPS, FTIR, PXRD, N2 adsorption-desorption, SEM, and TEM experimental techniques, it was demonstrated that the unsaturated metal sites (Me-N2) and pyridinic nitrogen groups were dominant active sites for CO2 adsorption via strong electrostatic interactions. The results obtained herein demonstrate that nitrogen-doped NPCs derived from core-shell Zn/Co ZIF are promising solid CO2 separation materials for industrial power plant flue gas and biogas purification applications.

Nitrogen-doped microporous carbon materials with uniform pore diameters: Design and applications in CO2 and H2 adsorption

Abstract Nitrogen-doped microporous carbon materials (N-MCs) with uniform pore diameters have promising applications in gas absorption, however their fabrication is challenging. Herein, we report a new approach to prepare N-MCs with uniform pore size using azo-linked organic polymers (AOPs) as the N-containing precursors. The AOPs were synthesized via the reactions of 1,3,5-tris(4-nitrophenyl)benzene (TNPB) and melamine (MA), and their N contents were tuned by changing the molar ratios of MA to TNPB. Followed by calcination of the resultant precursors at 800 °C, porous N-MCs were produced, which were characterized by means of different techniques including FT-IR analysis, N2 sorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and elemental analysis. It was demonstrated that the pore diameters of N-MCs could be tuned by changing the MA: TNPB ratio for preparing azo-polymer precursors, and N-MCs with pore size centered at 0.72 and 1.06 nm were obtained. The resultant N-MCs showed excellent CO2 uptake capacity up to 191 mg g−1 at 1 bar and 273 K, with a CO2/N2 selectivity of 58 at 298 K and good H2 adsorption capacity of 14.7 mg g−1 at 77 K.

Developing Platinum Group Metal Free Catalysts with Multiple Metal Centers for the Oxygen Reduction Reaction in Acid

Remarkable advancement of Platinum group metal-free (PGM-free) catalysts for the oxygen reduction reaction (ORR) in acidic media makes it potentially feasible as an alternate to Pt-based catalysts in polymer electrolyte fuel cells (PEMFCs). The current leading PGM-free catalysts are composed of single transition metal atoms embedded in microporous nitrogen-doped carbon matrix (M-N-C). The commercialization of M-N-C catalysts in PEMFCs has been impeded by the insufficient activity and particularly durability. The limited ORR performance is likely owing to the single metal center configuration that causes low active site density, undesired O2 binding configuration and energy toward the metal center, etc. These inherent limitations of M-N-C catalysts motivate us to move toward Mx-N-C with multiple metal center (MMC) sites. On account of this, herein a multidentate ligand platform is utilized to prepare a series of bimetallic coordination complexes. These complexes were then used as the metal precursors to produce Mx-N-C with MMC sites by incorporating them into microporous nitrogen-doped carbon matrix via both pyrolysis and surface deposition approaches without breaking the pre-existing multiple nuclear structure. The formation of MMC sites is supported by multiple characterizations. The high ORR activity achieved is tentatively related to MMC sites that promotes the desorption of oxygen adsorbates and suppress the site-blocking effect at elevated potentials. Further improvement, however, is limited by the low concentration of MMC sites. densification of MMC sites is undergoing. Acknowledgement This work was supported by the US Department of Energy under award number DE-EE0008416. The authors declare no competing financial interests. MRCAT operations are supported by the Department of Energy and the MRCAT member institution. This research used resources of the Advanced Photon Source, a DOE Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.

Three-Dimensional Interconnected Microporous Carbon Network Derived from Aniline Formaldehyde Resin/Sodium Polyacrylate Interpenetrating Polymer Networks (AF/PAAS IPNs) with Controllable Porosity for Supercapacitors

A facile strategy for the synthesis of three-dimensional nitrogen-doped microporous carbon (MC-IPNx) is reported here. We adopt the advantages of cross-linking individually of interpenetrating poly...

N-doped microporous carbon hollow spheres with precisely controlled architectures for supercapacitor

In the past decades, much effort has been denoted on the synthesis of porous hollow carbon spheres for many applications. However, the research for the precisely control of structure remains insufficient. Herein, nitrogen-doped microporous carbon hollow spheres with controllable architectures were synthesized with a facile one-pot synthetic route. Ethylenediamine (EDA) acts as a base catalyst for the condensation procedure and as a nitrogen precursor as well. Tetrapropyl orthosilicate (TPOS) and resorcinol/formaldehyde (RF) were used as the silica and carbon precursors, respectively. By the control of the EDA addition, the molar ratio of TPOS/tetraethyl orthosilicate (TEOS) and volume ratio of ethanol/DI water, the particles showed high surface area, large pore volume, good nitrogen content, precisely controllable pore size, shell thickness, diameter of cavity. In addition, the materials exhibited excellent properties for supercapacitor. We believe that the precisely controllable architectures of the N-doped microporous carbon hollow spheres in this method offers great opportunities for designing synthesis.

Tremella-like nitrogen-doped microporous carbon derived from housefly larvae for efficient encapsulation of small S2–4 molecules in Li-S batteries

The commercialization of rechargeable lithium-sulfur batteries (LSBs) has been severely restricted due to the electrically insulating nature of sulfur and the dissolution of polysulfides Li2Sn (4 ≤ n ≤ 8). Herein, we demonstrated a sustainable and proficient strategy to synthesize a unique and cost-effective tremella-like nitrogen-doped microporous carbon (TNMC) materials derived from housefly larvae. The key feature of TNMC is that it possesses interconnected 3D channels with voids, high surface area (>1000 m2 g−1) along with large volume (0.62 cm3 g−1). Particularly, a high portion of ultra-micropore and the predominant pore width of ∼0.54 nm play important roles in confining the metastable small sulfur molecules (S2–4) physically. More importantly, TNMCs with sufficient nitrogen doping (6–8 wt%) not only improve the conductivity of sulfur electrode materials but also act as an active site for adsorbing S2–4 chemically and reducing the shuttle effect efficiently. Beneficial from the unique 3D microstructures with ultra-micropore and inherent nitrogen doping, the resultant LSBs show high reversible capacity with a stable Coulombic efficiency.

Nitrogen-doped microporous carbon derived from a biomass waste-metasequoia cone for electrochemical capacitors

Naturally nitrogen-doped porous carbon is acquired from the fruit of Metasequoia (dawn redwood cone) by two facile steps of pre-carbonization and chemical activation. Current collectors coated with the porous carbon as electrodes are evaluated in 6.0 M basic electrolyte for the application of electrochemical capacitors. Results show that the porous carbon obtained with an activated temperature of 700 °C keeps the highest specific surface area (1,831 m2 g−1) and the largest pore volume (0.92 cm3 g−1). In three-electrode test, the carbon based electrode not only possesses an outstanding capacitive performance up to 326 F g−1 and 236 F g−1 at current densities of 0.5 A g−1 and 10 A g−1, respectively, but also shows a stable cycling characteristic. The two-electrode symmetric device also harvests a specific capacitance of 197 F g−1 at a current density of 1.0 A g−1 and an excellent energy density as high as 7.6 W h kg−1. Our study suggests that the cone can be applied as a promising and almost zero-cost precursor in fabricating porous carbon samples for supercapacitor, thanks to the abundance of resources.

Synthesis of triazine-based porous organic polymer: A new material for double layer capacitor

In this report, we prepared nitrogen-doped microporous carbon (N-MPC) via carbonization of a precursor triazine-based porous organic polymer (POP). The as-prepared POP and N-MPC were characterized by various analytical techniques. The N-MPC presents many advantages for supercapacitor applications, including higher surface area (801 m2 g−1), microporous structure, and uniform pore size. The supercapacitor performance of N-MPC was evaluated in a 6 M KOH electrolyte and exhibited a high specific capacitance of 505 F g−1 at a current density of 0.5 A g−1. The electrode showed excellent cycling stability with 89% capacitance retention after 10,000 cycles at a current density of 3.0 A g−1.

Nanopore confined anthraquinone in MOF-derived N-doped microporous carbon as stable organic cathode for lithium-ion battery

Anthraquinone (AQ), as organic cathode material, has provided an excellent opportunity to update the preexisting energy storage technologies owing to its facile and desirable fabrication at molecular level, higher theoretical gravimetric capacities and remarkable sustainability. However, some of its pristine properties like insulation and dissolution into electrolyte of organic active materials during cycling, have been inevitable obstacles to boost its electrochemical performance. Herein, we report a rational strategy to improve lithium ion storage performance of AQ by confining nanosized amorphous AQ into zeolitic imidazolate framework-8 (ZIF-8)-derived nitrogen-doped microporous carbon scaffold (AQ@N-ZIF-8). The AQ@N-ZIF-8 cathode delivers a high reversible specific capacity of 240 mAh g−1 at current rate of 0.1 C and retains ~216 mAh g−1 after 300 cycles (remarkably low capacity fading rate of 0.08% per cycle) with coulombic efficiency up to 99%. The exceptional lithium ion storage capacity of AQ@N-ZIF-8 is mainly ascribed to the synergistic effect of high loading capacity of AQ encapsulation and nanopore confinement of AQ dissolution in carbon scaffolds, and the enhanced conductivity of the encapsulated AQ by higher contents of nitrogen dopant. Moreover, the N-ZIF-8 with micropores facilitates the fast diffusion of organic electrolyte ions.

Triazine-functionalized covalent benzoxazine framework for direct synthesis of N-doped microporous carbon

A covalent benzoxazine framework was synthesized and underwent thermal curing, carbonization and KOH activation providing the nitrogen-doped microporous carbon.

Nitrogen-doped microporous carbon with high CO2 sorption by KOH activation of black gram

Nitrogen-doped microporous carbon materials were synthesized by KOH activation of char produced by heating powdered black gram at 300 °C in an inert atmosphere. The carbohydrate and protein present in the black gram were converted to nitrogen-enriched carbon structures during the charring as evidenced by elemental analysis and Raman spectrum. The black gram char derived activated carbon materials (BGC) were characterized by elemental analysis, XRD, Raman spectroscopy, SEM, TEM, XPS and N2 gas adsorption-desorption studies. The nitrogen content, textural properties and CO2 adsorption capacities of the black gram derived activated carbon (BGC-x-y) depend on the KOH to black gram char ratio (x) and activation temperature (y). The highest surface area (2305 m2 g−1) and total pore volume (1.23 cm3 g−1) were exhibited by BGC-3-800 whereas the highest micropore volume (0.397 cm3 g−1) was obtained for BGC-1-700. The nitrogen (1.78 to 5.34 wt%) in the amorphous BGC-x-y materials was present in the pyrolic, pyridinic, quaternary and N-oxide forms. The highest CO2 adsorption capacity of 3.46 and 5.3 mmol g−1 at 25 and 0 °C, respectively, at 1 atmosphere was achieved for BGC-1-700. The physical adsorption (heat of adsorption: −39 to −35 kJ mol−1) of CO2 is mainly due to micropore filling as the adsorption capacity increases with micropore volume. The CO2 adsorption on BGC-1-700 showed very good selectivity over nitrogen adsorption and excellent recyclability over five adsorption-desorption cycles.

Electrochemical hydrogen storage in a nitrogen-doped uniformed microporous carbon

A nitrogen-doped carbon material with uniformed micro-porosity structure was synthesized by carbonized a copolymer made with a molecular-scale template, octa(aminophenyl)silsesquioxane，and phenolic resol and the silica domain removing. High nitrogen content as well as unimodal micropore with narrow size distribution were achieved. This nitrogen doped well-defined microporous carbon exhibited high electrochemical hydrogen storage and superior stability over those in regular active carbon material.

Nitrogen-Doped Microporous Carbon Derived from Polyaniline Nanofiber for Removal of 2,4-Dichlorophenol

Abstract Nitrogen-doped microporous carbon is successfully fabricated through carbonization and KOH activation of polyaniline nanofiber, which is synthesized by dilute polymerization, and could directly provide the nitrogen doping source. Characterization shows that as-prepared sample is successfully doped with nitrogen with a content of 5.9%, and presence of a large amount of micropores render a high specific surface area of 977.9 m2/g to the sample. Capability of removing 2,4-dichlorophenol (2,4-DCP) from aqueous solution is explored through the bath adsorption experiments by utilizing the nitrogen-doped microporous carbon. The adsorbent manifesting a highest adsorption capacity of 378.8 mg/g is effective in a broad pH range (2.0–10.0) for removal of 2,4-DCP. Besides, the removal ratio of 2,4-DCP can be rapidly achieved to 90% within 10 min. Adsorption isotherm and kinetics data are fitted well with the Freundlich isotherm and the pseudo-second-order kinetic model, respectively. Moreover, nitrogen-doped...

Efficient Encapsulation of Small S2-4 Molecules in MOF-Derived Flowerlike Nitrogen-Doped Microporous Carbon Nanosheets for High-Performance Li-S Batteries.

Lithium-sulfur (Li-S) battery is regarded as one of the most promising next-generation efficient energy storage systems because of its ultrahigh theoretical capacity of 1675 mAh/g and energy density of 2600 Wh/kg accompanied by the environmental benignity and abundance from natural sulfur. However, the insulating nature of sulfur and the dissolution of the polysulfides Li2S n (4 ≤ n ≤ 8) seriously restrict its practical application. The metastable small sulfur molecules (S2-4) stored in microporous carbon (pore size of <0.6 nm) as the active materials can avoid the production of the soluble polysulfide and solve the shuttle effect thoroughly. In addition, the conductivity of sulfur can be also improved. However, the preparation of microporous carbon materials with reasonable pore size and unique morphology for efficiently encapsulating S2-4 is still challenging. Herein, three flowerlike microporous nitrogen-doped carbon nanosheets with the pore size of <0.6 nm (namely, FMNCN-800, -900, and -1000) as the cathode materials in Li-S batteries were obtained from temperature-dependent carbonization of the metal-organic framework (MOF), Zn-TDPAT, which was from the simply reflux reaction of N-rich ligand H6TDPAT with Zn(II) salt. Our study showed that the FMNCN-900 from carbonization of Zn-TDPAT at 900 °C has suitable pore volume and nitrogen content, accommodating small S2-4 molecules in its micropores with the mass uptake of about 45%. Meanwhile, the appropriate amount of the nitrogen doping and the unique nanostructure of the flowerlike carbon nanosheet in the FMNCN-900 can effectively support its fast electronic transmission and lithium-ion conduction. The resulting S@FMNCN-900 composite cathode material presents the excellent electrochemical property in the Li-S battery (here the carbonate as electrolytes) with a reversible capacity of about 1220 mAh/g at 0.1C after 200 cycles and even 727 mAh/g at 2C after the long-term cycle of 1000 with only around 0.02% capacity loss per cycle. Obviously, the results indicate that the delicate construction of MOF-derived nitrogen-doped microporous carbon nanosheet is a promising strategy to develop novel electrode material for high-performing Li-S batteries.

RETRACTED: Carbonization-dependent nitrogen-doped hollow porous carbon nanospheres synthesis and electrochemical study for supercapacitors

Abstract In this paper, a nitrogen-doped hollow microporous carbon nanospheres was synthesized via the combination of hyper-crosslinking mediated self-assembly and further pyrolysis using polylactide-b-polystyrene (PLA-b-PS) copolymers and aniline monomers as precursor. The pore structure and the correlative electrochemical performance of nitrogen-doped hollow microporous carbon nanospheres were affected by the molar mass ratio of aniline and PS in block copolymers and the carbonization conditions. The electrochemical measurements results showed that the obtained PLA 150 -PS 250 -N 4 -900-10H sample with nitrogen content of 3.57% and the BET surface area of 945 m 2 g −1 displays the best capacitance performance. At a current density of 1.0 Ag −1 , the resultant specific capacitance is 250 Fg −1 . In addition, it also exhibits high capacitance retention of ~98% after charging−discharging 1500 times at 25 Ag −1 . The results demonstrate the nitrogen-doped hollow microporous carbon nanospheres can be used as promising supercapacitor electrode materials for high performance energy storage devices.