Chemical Blowing Approach for Ultramicroporous Carbon Nitride Frameworks and Their Applications in Gas and Energy Storage

Abstract

A scalable, template-free synthetic strategy is presented for the preparation of ultramicroporous carbon nitride frameworks (CNFs) through a chemical blowing approach by using ammonium chloride as blowing agent and hexamethylene tetraamine as the C and N precursor and a subsequent potassium hydroxide chemical activation is employed to obtain CNFs with surface areas up to 1730 m 2 g −1 along with a high nitrogen content of 13.3 wt%. CNFs showed CO 2 uptake capacities up to 5.74 mmol g −1 at 1 bar and 1.67 mmol g −1 at 0.15 bar, 273 K along with a very high CO 2 /N 2 selectivity. In addition, H 2 uptake capacity of 1.9 wt% and the isosteric heats of adsorption (Q st ) value of 9.0 kJ mol −1 at zero coverage have been also observed. Moreover, the presence of nitrogendoped graphene walls in CNFs also facilitated their application as supercapacitors, with capacitance values up to ≈114 F g −1 at 0.5 A g −1 , along with a good cyclability and capacitance retention. This approach effectively extends unique surface properties of carbon nitrides into the micropore regime for effective capture of small gases and energy storage applications. Importantly, textural properties of CNFs can be simply tuned by judicious choice of organic precursors and the blowing agent.

Nitrogen‐Doped Carbons with Hierarchical Porosity via Chemical Blowing Towards Long‐Lived Metal‐Free Catalysts for Acetylene Hydrochlorination

“…treatment in HF‐solution). Recently, chemical blowing, which generates micropores during the carbonization process through gas evolution by decomposing ammonium chloride (NH 4 Cl) into HCl and NH 3 , was introduced as an alternative strategy to yield highly microporous NCs . The possible combination of this approach with thermally decomposable templates, such as magnesium acetate (Mg(OAc) 2 ) or calcium carbonate (CaCO 3 ), could boost the chemical blowing effect and further introduce auxiliary mesopores.…”

“…Recently, chemical blowing, which generates micropores during the carbonization process through gas evolution by decomposing ammonium chloride (NH 4 Cl) into HCl and NH 3 , was introduced as an alternative strategy to yield highly microporous NCs. [9] The possible combination of this approach with thermally decomposable templates, such as magnesium acetate (Mg(OAc) 2 ) or calcium carbonate (CaCO 3 ), could boost the chemical blowing effect and further introduce auxiliary mesopores. This would enable the synthesis of NCs with hierarchical porosity, which can ultimately lead to more robust systems for acetylene hydrochlorination.Herein, we develop a salt template-assisted chemical blowing approach, [9] employing NH 4 Cl as a blowing agent, hexamethylene tetraamine (HMT) as the C/N-precursor, and Mg (OAc) 2 or CaCO 3 as thermally decomposable templates (Fig-[a] S.…”

Energy Efficient Synthesis of Ordered Mesoporous Carbon Nitrides with a High Nitrogen Content and Enhanced CO2 Capture Capacity

“…The surface of the MCN is composed of different functional groups including ‐NH and ‐NH 2 groups which are the key anchoring points for the adsorption of acidic CO 2 molecule. The density and the position of these functional groups can be controlled by varying the synthesis strategy with different nitrogen containing molecular precursors …”

“…The densitya nd the position of these functional groups can be controlled by varying the synthesis strategy with different nitrogen containing molecular precursors. [9][10][11] The introduction of high nitrogenc ontents into the wall structure or -NH and -NH 2 groupsintot he surfaceedges of the MCN materials may alter their physicochemical properties, thus enhancing their CO 2 adsorption capacity.T he contento fi nbuilt primary,s econdary,a nd quaternary ammonium functional groups inside MCN framework has been typically attributed to the presence of structural defects whicha re affected by the molecular structure of CN precursors, reaction conditions, degreeo fp olymerization, structuralo rdering, and pore diameters. By realising this potential, Vinu and his co-workersd esignedaseries of MCN with different nitrogen contents and framework structures using various nitrogen precursors including aminotriazine, aminoguanidine, ethylene diamine, polyaniline, and gelatin, through nano-hard templating approach whereinc alcined mesoporouss ilicas were used as templates for CO 2 adsorption and sensing applications.…”

Improved porosity and ionic sorption capacity of carbon particles prepared by spray pyrolysis from an aqueous sucrose/NaHCO3/TEOS solution

“…Porous carbon materials (PCMs) have gained much attention in the research areas of energy storage devices, [13][14][15] catalysts, [16][17][18] and adsorptive separation [19][20][21][22] due to their unique properties including excellent electrical conductivity, large specic surface area and chemical stability. The required properties of PCMs are different depending on their application area.…”