Nitrogen-doped Porous Carbon Monoliths Research Articles

Dual synergistic effects assisting Cu-SeS2 electrochemistry for energy storage

Selenium sulfide (SeS2) features higher electronic conductivity than sulfur and higher theoretical capacity and lower cost than selenium, attracting considerable interest in energy storage field. Although nonaqueous Li/Na/K-SeS2 batteries are attractive for their high energy density, the notorious shuttle effect of polysulfides/polyselenides and the intrinsic limitations of organic electrolyte have hindered the deployment of this technology. To circumvent these issues, here we design an aqueous Cu-SeS2 battery by encapsulating SeS2 in a defect-enriched nitrogen-doped porous carbon monolith. Except the intrinsic synergistic effect between Se and S in SeS2, the porous structure of carbon matrix has sufficient internal voids to buffer the volume change of SeS2 and provides abundant pathways for both electrons and ions. In addition, the synergistic effect of nitrogen doping and topological defect not only enhances the chemical affinity between reactants and carbon matrix but also offers catalytic active sites for electrochemical reactions. Benefiting from these merits, the Cu-SeS2 battery delivers superior initial reversible capacity of 1,905.1 mAh g-1 at 0.2 A g-1 and outstanding long-span cycling performance over 1,000 cycles at 5 A g-1. This work applies variable valence charge carriers to aqueous metal-SeS2 batteries, providing valuable inspiration for the construction of metal-chalcogen batteries.

Nature‐inspired porous multichannel carbon monolith: Molecular cooperative enables sustainable production and high‐performance capacitive energy storage

AbstractThe advancement of supercapacitors (SCs) is closely bound up with the breakthrough of rational design of energy materials. Freestanding and thick carbon (FTC) materials with well‐organized porous structure is promising SC electrode delivering high areal capacitive performance. However, controllable and sustainable fabrication of such FTC electrode is still of great challenges. Inspired by natural honeycombs with cross‐linked multichannel structure, herein, an innovative molecular‐cooperative‐interaction strategy is elaborately provided to realize honeycomb‐like FTC electrodes. The nitrogen‐doped porous carbon monolith (N‐PCM) is obtained with advantages of interconnect pore structure and abundant nitrogen doping. Such strategy is based on naturally abundant molecular precursors, and free of pore‐templates, expensive polymerization catalyst, and dangerous reaction solvent, rendering it a sustainable and cost‐effective process. Systematic control experiments reveal that strong interactions among molecular precursors promise the structural stability of N‐PCM during carbonization, and rational selection of molecular precursors with chemical blowing features is key step for well‐developed honeycomb‐like pore structure. Interestingly, the optimized sample exhibits hierarchical pore structure with specific surface area of 626.4 m2 g−1 and rational N‐doping of 7.01 wt%. The derived SC electrode with high mass loading of 40.1 mg cm−2 shows an excellent areal capacitance of 3621 mF cm−2 at 1 mA cm−2 and good rate performance with 2920 mF cm−2 at 25 mA cm−2. Moreover, the constructed aqueous symmetric SC and quasi‐solid‐state SC produce high energy densities of 0.32 and 0.27 mWh cm−2, respectively. We believe that such a composition/microstructure controllable method can promote the fabrication and development of other thick electrodes for energy storage devices.image

Ultrahigh-CO2 Adsorption Capacity and CO2/N2 Selectivity by Nitrogen-Doped Porous Activated Carbon Monolith

Abstract Among microporous adsorbents, N-doped activated carbon monolith has been developed to achieve functionalized nanoporous carbon via cross-linked polymer precursors, which are used in Friedel-Craft alkylation and pyrolysis. Nitrogen-doping is establish an efficient method for boosting the CO2 adsorption capacity of carbon-based adsorbents, and research in this area is still full of challenges to reach a fit doping level of nitrogen (N) and intrinsic microporosity. Herein is an easy method that enables the preparation of microporous nitrogen-doped porous carbon monolith with proportion of 4.6 wt% N, which employs poly (H-BINAM) as primary material. By virtue of chemical activation, high microporosity is generated and gives a monolithic structured porous nitrogen-doped activated carbon (MPC-700). The resulting material showed a remarkable CO2 adsorption capacity (6.74 mmol g−1 at 273 K and 5.18 mmol g−1 at 298 K under 1 bar), and an excellent CO2 over N2 selectivity (153), which is measured from single-component adsorption isotherms according to Henry’s Law. This value exceeds the CO2 over N2 selectivity of reported carbon-based adsorbents including diverse nitrogen doped examples, the features of which are largely associated with remarkably high N-content and furthermore partial graphitic framework.

Nitrogen-doped porous carbon monoliths from molecular-level dispersion of carbon nanotubes into polyacrylonitrile (PAN) and the effect of carbonization process for supercapacitors

Nitrogen-doped porous carbon monoliths (NDP-CMs) have long been pursued as the desirable supercapacitor electrode materials. However, the currently effective template methods and Lewis acid/base activation strategy suffer from the drawbacks of either high costs or tedious steps. We report on a simple and practicable novel method to the production of CNTs constructed NDP-CMs. Polyacrylonitrile (PAN) contained carbon nanotubes (CNTs), being dispersed into tubular level of dispersions (mono-dispersions), were used as the starting material and NDP-CMs were obtained through a direct carbonization process. First, PAN/CNT based mesostructured polymeric monoliths with interconnected networks were formed using a template-free temperature-induced phase separation (TTPS) method and the mono-dispersed CNTs networks act as the backbones of PAN molecules. Then, NDP-CMs with a surface area of 840 m2/g and a pore diameter 2.48 nm were obtained through heat treatment. Thus, the NDP-CMs based supercapacitor demonstrated a reversible specific capacitance of 246 F/g. Furthermore, pyridinic nitrogen and quaternary nitrogen species contribute significantly to the advantageous electrochemical activities of NDP-CMs.

Synthesis of Nitrogen‐Doped Porous Carbon Monolith for Binder‐Free All‐Carbon Supercapacitors

AbstractA nitrogen‐doped porous carbon monolith (N‐PCM) was synthesized following a simple self‐assembly method in a one‐pot hydrothermal process. A solution of hexamethylenetetramine (HMT) in formaldehyde and ammonia was used as partial carbon precursor and nitrogen source, respectively. The monolithic polymer was formed through self‐assembly of formaldehyde and resorcinol catalyzed by ammonia. After the annealing process, the N‐PCM was prepared. The N‐PCM with tailorable macrostructure possessed a high specific surface area (1124 m2 g−1), rich porous structure and reasonable N content (up to 2.1 %). Used as binder‐free all‐carbon supercapacitor electrode, the N‐PCM allowed efficient migration of electrolyte ions and electrons, showing a high specific capacitance up to 202 F g−1 at a current density of 1 A g−1, and favorable capacitance retention (93.5 % capacitive retention after 5000 cycles) in a 6 M KOH solution. This advanced monolith carbon material with high surface area and controllable morphology produced in a simple and efficient method could be used as a promising electrode material for high‐performance supercapacitors.

Nitrogen-doped porous carbon monoliths from polyacrylonitrile (PAN) and carbon nanotubes as electrodes for supercapacitors

Nitrogen-doped porous activated carbon monoliths (NDP-ACMs) have long been the most desirable materials for supercapacitors. Unique to the conventional template based Lewis acid/base activation methods, herein, we report on a simple yet practicable novel approach to production of the three-dimensional NDP-ACMs (3D-NDP-ACMs). Polyacrylonitrile (PAN) contained carbon nanotubes (CNTs), being pre-dispersed into a tubular level of dispersions, were used as the starting material and the 3D-NDP-ACMs were obtained via a template-free process. First, a continuous mesoporous PAN/CNT based 3D monolith was established by using a template-free temperature-induced phase separation (TTPS). Second, a nitrogen-doped 3D-ACM with a surface area of 613.8 m2/g and a pore volume 0.366 cm3/g was obtained. A typical supercapacitor with our 3D-NDP-ACMs as the functioning electrodes gave a specific capacitance stabilized at 216 F/g even after 3000 cycles, demonstrating the advantageous performance of the PAN/CNT based 3D-NDP-ACMs.

Enhanced selective adsorption of CO2 on nitrogen-doped porous carbon monoliths derived from IRMOF-3.

The N-doped porous carbon monoliths prepared by direct carbonization of IRMOF-3, through an in situ activation and self-templating process, were found to exhibit significantly enhanced performance for the selective adsorption of CO2 compared to pristine IRMOF-3. The transformation from the microporous structure to the meso-macroporous structure opens the pathway for CO2 to more easily access the nitrogen anchors.

A facile nanocasting strategy to nitrogen-doped porous carbon monolith by treatment with ammonia for efficient oxygen reduction

A series of three-dimensional N-doped hierarchical macro- and meso-porous carbon monoliths (NCMs), which were prepared successfully using a facile nanocasting strategy in combination with pyrolysis in NH3, showed comparable catalytic activity but superior durability and methanol tolerance to Pt/C for the oxygen reduction reaction.

Nitrogen-doped porous carbon monolith as a highly efficient catalyst for CO2conversion

In this work, we report an N-doped porous carbon monolith used for the first time as a catalyst for the cycloaddition of CO2 to cyclic carbonates. It acts as an efficient, single-component, metal-, solvent- and halogen-free catalyst for the formation of chloropropene carbonate from CO2 and epichlorohydrin. The N-doped carbon monolith AA-950 significantly exhibited a high CO2 capture capacity of 16.20 mmol g−1 (298 K and 20 bar) and high conversion of epoxides. A catalytic mechanism has also been proposed based on the basis of DFT calculations. Our findings may trigger interest in the studies of carbon materials for CO2 capture and conversion performance.

Synthesis of a nitrogen-doped porous carbon monolith and its use for CO2 capture

Monolithic nitrogen-doped porous carbon was synthesized by the copolymerization of resorcinol and formaldehyde in the presence of l-lysine as the catalyst at the ambient conditions. The carbon is designated RFL. In order to increase the active nitrogen content, nitrogen-rich melamine was added, and the resulting material (RFLM) has more nitrogen-containing functional groups, and a higher specific surface area and pore volume than the original RFL. Glutamic acid was used to control the rate of polymerization, resulting in a porous carbon (RFLMG) with optimized texture properties. However, samples of RFLM and RFLMG show lower CO2 adsorption capacities than do the RFL series, indicating that there is no explicit linear relationship between the nitrogen content and CO2 adsorption capacity. This may be directly caused by the different form of the nitrogen-containing functional groups. [New Carbon Materials 2013, 28(4): 267–272]

Nitrogen‐Doped Carbon Monolith for Alkaline Supercapacitors and Understanding Nitrogen‐Induced Redox Transitions

A nitrogen-doped porous carbon monolith was synthesized as a pseudo-capacitive electrode for use in alkaline supercapacitors. Ammonia-assisted carbonization was used to dope the surface with nitrogen heteroatoms in a way that replaced carbon atoms but kept the oxygen content constant. Ammonia treatment expanded the micropore size-distributions and increased the specific surface area from 383 m(2) g(-1) to 679 m(2) g(-1). The nitrogen-containing porous carbon material showed a higher capacitance (246 F g(-1)) in comparison with the nitrogen-free one (186 F g(-1)). Ex situ electrochemical spectroscopy was used to investigate the evolution of the nitrogen-containing functional groups on the surface of the N-doped carbon electrodes in a three-electrode cell. In addition, first-principles calculations were explored regarding the electronic structures of different nitrogen groups to determine their relative redox potentials. We proposed possible redox reaction pathways based on the calculated redox affinity of different groups and surface analysis, which involved the reversible attachment/detachment of hydroxy groups between pyridone and pyridine. The oxidation of nitrogen atoms in pyridine was also suggested as a possible reaction pathway.

Rapid Synthesis of Nitrogen‐Doped Porous Carbon Monolith for CO2 Capture (Adv. Mater. 7/2010)

The inside cover shows a background SEM image of hierarchical carbon monolith, a swirl of CO2 molecular models, and two split hemispheres representing the building unit of the carbon framework with abundant porous channels. An-Hui Lu and co-workers report on p. 853 a nitrogen-doped porous carbon monolith with hierarchical pore structures (macroporous and microporous), which show high performance for CO2 adsorption, making them excellent CO2 capture materials.