A sustainable synthesis of nitrogen-doped carbon aerogels
One-step hydrothermal synthesis of nitrogen-doped nanocarbons: Albumine directing the carbonization of glucose.
synthesize nitrogen-doped carbon aerogels ..
H.*, Macroscopic-scale synthesis of nitrogen-doped carbon nanofiber aerogels by template-directed hydrothermal carbonization of nitrogen-containing carbohydrates. Nano Energy 2016, 19, 117-127.
Activated carbons (ACs) have been attracting a lot of investigation in previous decades. The reason for this attention is due to it is cheap, abundant, environmentally safe, commercially available and a sustainable biological resource. Generally, ACs are usually prepared by a two-step process, in which carbon precursors are pyrolyzed at temperatures in the range of 600~900°C in an inert atmosphere such as Ar or N2, followed by physical activation at elevated temperature in the presence of suitable oxidizing atmosphere chemical activation process using chemical agents such as KOH, NaOH, H3PO4, and ZnCl2,,,. It has been demonstrated that the incorporation of heteroatoms, such as sulfur, boron, nitrogen, and oxygen, into the carbon lattice can significantly enhance mechanical, semi-conducting, field-emission, and electrical properties of carbon materials. For example, nitrogen doping is considered to be the most promising method for enhancing surface polarity, electric conductivity and electron-donor tendency of the ACs, thereby improving their performances in CO2 capture, electric double-layer capacitors, fuel cells, and catalysis. To prepare these materials, one approach is to use nitrogen-containing original precursors or ionic liquids for pyrolysis, and another approach is to post-treat carbon with N-containing dopants such as ammonia, amine, or urea. Biomass is an attractive original precursor, which is cheap, environment friendly and readily available in high quality and quantity. In addition to its carbon and water content, biomass is rich in elements such as sulfur, nitrogen, and phosphorus, as well as metals such as Fe, Cu, and others. Up to now, however, only a small portion of biomass materials such as pig bones, egg white protein, amaranth, hemp, bean dregs,, seaweeds or seaweed biopolymers,, etc., are used as carbon precursors for supercapacitor electrodes and CO2 capture. Therefore, the search for new precursors, which are cheap, accessible and with potential to create significant economic valorisation, is highly desired. Herein we employ stem bark with complex multilayered structure from broussonetia papyrifera (BP) as the carbon precursor to develop a simple and facile method for the large-scale production of nitrogen doped ACs.
Original design of nitrogen-doped carbon aerogels from sustainable ..
Elemental analysis (EA, ) of the CNSMC shows a substantial presence of both the nitrogen and sulfur content, which is 5.0wt% and 4.6wt%, respectively. The nature of nitrogen and sulfur species at the surface of CNSMC was investigated by X-ray photoelectron spectroscopy (XPS). The XPS survey spectrum of the CNSMC () shows peaks for C1s (284.6eV), N1s (400.5eV), O1s (531.5eV) and S2p (164.5eV), confirming the existence of elements detected by EA. The nitrogen concentration on the surface of the CNSMC is determined to be 5.3wt% by XPS (), which is quite close to the EA result. The N1s peak of CNSMC can be resolved into three components centered at 398.6, 400.7 and 402.4eV (), corresponding to pyridinic-N, pyrrolic-N, and graphitic-N doped in the carbon matrix. More than 81.3 at.% of N species in CNSMC are planar, including 48.9 at.% pyrrolic-N and 32.4 at.% pyridinic-N, which are believed to promote the chemical adsorption of sulfur atoms to oxygen functional groups,. As for sulfur, its surface concentration obtained from XPS is 4.1wt%, which is also close to the value obtained by EA. Analysis of the surface chemistry of CNSMC shows that sulfur is mainly in thiophenic (R–S, 163.6eV, 47.1 at.%) and sulfonic acid (R-SO3, 167.8eV, 29.4 at.%) configuration (),,. The thiophenic-S (sulfur atom bonded with carbon directly by a C–S bond) is believed to make the carbon matrix positively charged, thereby increasing its affinity to adsorb polysulfides,. Above all, the XPS results confirm that we have successfully produced N, S co-doped carbon material by the simple in-situ synthesis method.
Herein, in order to take advantage of the synergistic effect of heteroatoms co-doping and a 3D porous structure, we apply a coral-like, nitrogen and sulfur co-doped mesoporous carbon (labelled as CNSMC) with convenient conductive framework as a promising sulfur container for high-performance Li-S batteries. By the facile synthesis method, a three-dimensionally continuous and spatially interconnected carbon branch network was formed in our CNSMC, and ordered mesopores were homogenously embedded with a nitrogen content of 5.3wt% and a sulfur content of 4.1wt%. Benefitting from the strong chemical adsorption ability, convenient transport pathway for ions and electrons, and high electronic conductivity of the carbon framework, the as-fabricated CNSMC/S composites have exhibited excellent rate performance with superior cycling stability.
A sustainable synthesis of nitrogen-doped carbon aerogels.
Rybarczyk MK, Gontarek E, Lieder M and Titirici MM (2018). Salt melt synthesis of curved nitrogen-doped carbon nanostructures: ORR kinetics boost. vol. 435, 543-551.
H.*, Sustainable Hydrothermal Carbonization Synthesis of Iron/Nitrogen-Doped Carbon Nanofiber Aerogels as Electrocatalysts for Oxygen Reduction. Small 2016, 12 (46), 6398-6406.
One-pot synthesis of nitrogen-sulfur-co-doped carbons with tunable ..
Synthesis of Nitrogen-Doped Porous Carbon Nanofibers as an ..
synthesis of nitrogen-doped porous carbon monolith ..
capacity at first discharge of nitrogen-doped carbon aerogels.
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Wohlgemuth SA, White RJ, Willinger MG, Titirici MM and Antonietti M (2012). A one-pot hydrothermal synthesis of sulfur and nitrogen doped carbon aerogels with enhanced electrocatalytic activity in the oxygen reduction reaction. vol. 14, (5) 1515-1523.
Organic polymers can be used to create aerogels
H.*, Synthesis of Nitrogen-Doped Porous Carbon Nanofibers as an Efficient Electrode Material for Supercapacitors. ACS Nano 2012, 6 (8), 7092-7102.
Cellulose from plants can be used to create a flexible aerogel
In conclusion, a novel nitrogen and sulfur co-doped and 3D structured mesoporous carbon material has been synthesized through an in-situ constructing strategy for sulfur encapsulation. The as-fabricated composite electrodes exhibit excellent cycle stability at very high current rate. The excellent electrochemical performance can be attributed to the following: (1) the main doped species (pyridinic-N, pyrrolic-N, thiophenic-S and sulfonic-S) increase the affinity of carbon surface to polysulfides and therefore suppress their diffusion; (2) the coral-like framework of CNSMC provides a convenient conductive pathway to ensure the effective and rapid utilization of sulfur; (3) the CNSMC with structural stability acts as a robust supporting matrix to ensure the integrality of the electrode configuration during high C-rate cycling. Further experiments are on-going to understand the overall mechanisms of the co-doped system and to increase the loading and adsorption abilities by tailing the pore size distribution and element doping content of the carbon matrix. The promising electrochemical performance we have observed so far provides clear evidence of the success of our strategy to optimize the mesoporous conductive framework and enhance the surface chemistry by heteroatoms co-doping. Considering the outstanding features discussed above, we believe that our synthetic strategy can be applied not only in advanced Li-S batteries, but also for other promising energy-storage devices.
International Journal of Engineering Research and …
A one-pot hydrothermal synthesis of sulfur and nitrogen doped carbon aerogels with enhanced electrocatalytic activity in the oxygen reduction reaction.
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