Nitrogen-enriched Mesoporous Carbon Research Articles

Facile and fast fabrication of CuCo alloy and N-codoped hierarchical porous carbon catalyst for efficient oxygen reduction reaction in microbial fuel cells

Designing a low-cost, high-performance oxygen reduction reaction (ORR) catalyst to replace the precious metal catalyst remains a huge challenge for microbial fuel cells (MFCs). Herein, a facile and rapid approach to fabricate highly active N-doped hierarchical porous carbon (NHPC) supported bimetal CuCo/NHPC composites with densely accessible active sites is developed by pyrolysis of Cu-doped ZIF-67 (CuCo-ZIF) precursor. In which, CuCo-ZIF precursor is synthesized through a one-pot hydrothermal method. Results showed that in addition to create additional Cu-Nx sites and increase N content, the Cu doping induces a hierarchical porous structure CuCo/NHPC composite with pores centered around 2.4, 4.2 nm and 10–60 nm, which can significantly accelerate the mass/electron transfer and improve efficient utilization of the active sites. The resulting CuCo/NHPC composite provides abundant active sites, high content of pyridinic-N and graphitic-N, which significantly boosts ORR performances. The CuCo/NHPC-T with pyrolysis temperature of 800 °C achieves remarkable ORR activity with low charge transfer resistances, high half-wave potential. The MFC assembled with CuCo/NHPC-800 (774.2 mW·m−2 and 0.713 V) significantly outperforms MFC assembled with Co-NC-800 (541.9 mW·m−2 and 0.583 V) in terms of maximum power density and open-circuit voltage. Moreover, the output voltage of MFC assembled with CuCo/NHPC-800 exhibited no significant downward trend within 30 days, which was better than that of Pt/C catalyst. This work provides a feasible time-saving route to develop promising nitrogen-enriched mesoporous carbon bimetallic ORR catalysts.

MOF-derived porous carbon supported iron-based catalysts with optimized active sites towards oxygen reduction reaction

Development of earth-abundant materials as novel substitutes for platinum group metal catalysts towards the oxygen reduction reaction (ORR) remains a great challenge to drive the commercialization of fuel cell. Iron-based catalysts were synthesized by using a metal-organic framework (MOF) as the precursor. FeNC-650, which is obtained by pyrolyzed at 650°C, is composed of Fe and Fe3O4 nanoparticles encapsulated in the nitrogen-enriched mesoporous carbon. It exhibits higher electrocatalytic activity and stability, compared with other FeNC catalysts and commercial Pt/C for ORR. The effect of pyrolysis temperature on active sites and unique structures is investigated. The excellent electrocatalytic performance and superior stability make it a promising non-precious metal catalyst for practical fuel cell application.

Facile Synthesis of Crystalline Nanoporous GaN Templated by Nitrogen Enriched Mesoporous Carbon Nitride for Friedel‐Crafts Reaction

AbstractHighly crystalline nanoporous GaN (NP‐GaN) materials have been synthesized for the first time by the transformation of novel diamino tetrazine based mesoporous carbon nitride (MCN‐4) having very high nitrogen content (N/C ratio of 1.8) and GaCl3 through the unique reactive hard templating approach. Powder XRD and HRTEM analysis show that the prepared NP‐GaN is highly pure and possesses excellent crystallinity. N2 adsorption analysis confirm that the samples exhibit mesoporosity with excellent textural parameters including high specific surface areas. It is also demonstrated that NP‐GaN materials show excellent catalytic activity in the Friedel‐Crafts hexanoylation of benzene by using hexanoyl chloride (HC) with excellent conversion of HC. The activity of the NP‐GaN is also compared with MCN‐4, bulk Ga2O3 and GaN. Among the materials studied, NP‐GaN shows the highest catalytic performance in the above mentioned reaction with excellent conversion of HC and product selectivity to hexanophenone.

Macroscopically shaped monolith of nanodiamonds @ nitrogen-enriched mesoporous carbon decorated SiC as a superior metal-free catalyst for the styrene production

Nanodiamonds (NDs) are recognized as a class of robust metal-free catalysts for the steam-free, direct dehydrogenation (DDH) of ethylbenzene (EB) to styrene (ST). In spite of that, some main drawbacks, such as their powdery form along with their tendency to form aggregates, limit their full exploitation at the industrial level. In this work, we describe the preparation of macroscopically shaped monoliths consisting of silicon carbide-based foams coated with a nitrogen-rich mesoporous carbon matrix (NMC) as a non-innocent glue for highly dispersed ND fillers. The NMC phase is prepared from cheap and non-toxic food-grade components and it prevents the undesired NDs agglomeration thus maximizing the reagents exposure throughout the catalytic DDH tests. Moreover, the NMC phase represents a key source of surface basicity capable of inhibiting the occurrence of EB cracking side reactions during the catalytic runs. As a result, the ND@NMC/SiC composite shows excellent dehydrogenation performance already at low ND loading if compared with the powdery NDs and/or the SiC-supported NDs of the state-of-the-art. Noteworthy, the ND@NMC/SiC composite presents its best catalytic performance under DDH conditions close to those used in industrial plants (reaction temperture up to 600°C and EB concentrations up to 10 vol.%) with high ST rates (λcatal. of 9.9mmolSTgcat−1h−1), ST selectivity over 96% and long term stability on stream.

Nitrogen-enriched carbon with extremely high mesoporosity and tunable mesopore size for high-performance supercapacitors

As one of the most potential electrode materials for supercapacitors, nitrogen-enriched nanocarbons are still facing challenge of constructing developed mesoporosity for rapid mass transportation and tailoring their pore size for performance optimization and expanding their application scopes. Herein we develop a series of nitrogen-enriched mesoporous carbon (NMC) with extremely high mesoporosity and tunable mesopore size by a two-step method using silica gel as template. In our approach, mesopore size can be easily tailored from 4.7 to 35 nm by increasing the HF/TEOS volume ratio from 1/100 to 1/4. The NMC with mesopores of 6.2 nm presents the largest mesopore volume, surface area and mesopore ratio of 2.56 cm3 g−1, 1003 m2 g−1 and 97.7%, respectively. As a result, the highest specific capacitance of 325 F g−1 can be obtained at the current density of 0.1 A g−1, which can stay over 88% (286 F g−1) as the current density increases by 100 times (10 A g−1). This approach may open the doors for preparation of nitrogen-enriched nanocarbons with desired nanostructure for numerous applications.

Ultrahigh-rate and high-density lithium-ion capacitors through hybriding nitrogen-enriched hierarchical porous carbon cathode with prelithiated microcrystalline graphite anode

Lithium-ion capacitors (LICs) are novel advanced electrochemical energy storage (EES) systems integrating both battery and capacitor functions. Most efforts for developing high-power LICs are currently dedicated to nanostructure design of battery-type anodes, which in general results in low packing densities and cannot fundamentally improve the slow Faradaic reaction. Up to now, little attention has been focused on the effects of porous carbon cathodes and the reasonable matching of cathode/anode on the power performance of LICs. Herein, a novel nitrogen-enriched mesoporous carbon nanospheres/graphene (N-GMCS) nanocomposite is demonstrated, which shows simultaneously hierarchical porous structure, 3D conductive network, as well as very high mass density. When such N-GMCS cathode is coupled with prelithiated microcrystalline graphite (PLMG) anode, the integrated device shows quite high packing density which is highly desirable in EES systems. In particular, the PLMG anode in N-GMCS//PLMG system breaks the limitation of slow Faradaic reaction and lithium-ion bulk diffusion, providing an ultrafast capacitor-like electrochemical response. Quite attractive maximum energy density (80Whkg−1, 68.6WhL−1) and state-of-the-art maximum power density (352kWkg−1, 292kWL−1) can be achieved in N-GMCS//PLMG, which are 5 and 2.8 times as large as those of the supercapacitor counterpart, respectively.

Electrocatalytic activity of a nitrogen-enriched mesoporous carbon framework and its hybrids with metal nanoparticles fabricated through the pyrolysis of block copolymers

Small metal NPs at NEMCF exhibit a four-electron transfer pathway, a large kinetic current density and a small onset potential.

Facile synthesis of nitrogen-enriched mesoporous carbon for carbon dioxide capture

Abstract To investigate carbon dioxide adsorption behaviors, we prepared mesoporous carbon (MC) materials that incorporated framework nitrogen functional groups via a facile polymerization-induced colloid aggregation (PICA) procedure, where the nitrogen content varied as a function of carbonization temperature. The prepared MCs had high specific surface areas (e.g., 974 m2/g) with well-developed mesopores. The highest carbon dioxide adsorption capacity of 106 mg/g at 25 °C was achieved with the MCs-800 sample (carbonization temperature of 800 °C). We found that the materials prepared in this study were highly effective for carbon dioxide capture, because the nitrogenous functional groups in the MCs enhanced their affinities for acidic carbon dioxide.

Nitrogen Enriched Mesoporous Carbon As High Capacity Cathode in Li-O2 Batteries

not Available.

Bottom-Up Catalytic Approach towards Nitrogen-Enriched Mesoporous Carbons/Sulfur Composites for Superior Li-S Cathodes

We demonstrate a sustainable and efficient approach to produce high performance sulfur/carbon composite cathodes via a bottom-up catalytic approach. The selective oxidation of H2S by a nitrogen-enriched mesoporous carbon catalyst can produce elemental sulfur as a by-product which in-situ deposit onto the carbon framework. Due to the metal-free catalytic characteristic and high catalytic selectivity, the resulting sulfur/carbon composites have almost no impurities that thus can be used as cathode materials with compromising battery performance. The layer-by-layer sulfur deposition allows atomic sulfur binding strongly with carbon framework, providing efficient immobilization of sulfur. The nitrogen atoms doped on the carbon framework can increase the surface interactions with polysulfides, leading to the improvement in the trapping of polysulfides. Thus, the composites exhibit a reversible capacity of 939 mAh g−1 after 100 cycles at 0.2 C and an excellent rate capability of 527 mAh g−1 at 5 C after 70 cycles.

Nitrogen enriched mesoporous carbon as a high capacity cathode in lithium–oxygen batteries

Nitrogen enriched mesoporous carbon (N-MCS) with extremely high mesopore volume and nitrogen content is prepared through a one-step hard template method. The N-MCS cathode shows excellent discharge performance in lithium-oxygen batteries. The pore space is better utilized due to its optimized pore structure and uniformly incorporated N.

Facile synthesis of mesoporous carbon nitrides using the incipient wetness method and the application as hydrogen adsorbent

Highly nitrogen-enriched mesoporous carbon nitride materials with 2-dimensional (2-D) (2D-meso-CN) and 3-dimensional (3-D) mesostructures (3D-meso-CN) were synthesized using mesoporous silica as a hard template and cyanamide as a precursor via the incipient wetness process without using any solvent. The materials were characterized by small-angle X-ray scattering (SAXS), X-ray diffraction (XRD), and transmission electron microscopy (TEM) for the mesostructure analysis, N2 adsorption–desorption isotherms for surface area and pore size distribution, and X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared (FT-IR) spectroscopy for the composition analysis of frameworks. The mesoporous carbon nitride replicas have graphitic-like stacking of carbon nitride sheets in mesopore walls. The N/C ratio of the mesoporous carbon nitride replicas is 1.13 after the carbonization at 550 °C for 3 h. 2D-meso-CN and 3D-meso-CN have the BET surface area of 361 and 343 m2 g−1, large pore volume of 0.50 and 0.67 cm3 g−1, and pore diameter of 27.8 Å (for 2D-meso-CN), 24.5 and 80.3 Å (for 3D-meso-CN), respectively. It was found that the 3D-meso-CN has higher capacity of hydrogen uptake of 0.25 wt% than the pure mesoporous carbon FDU-15 (0.16 wt%) at 50 bar under room temperature (298 K).

Nitrogen enriched mesoporous carbon spheres obtained by a facile method and its application for electrochemical capacitor

A kind of mesoporous carbon spheres (MCS) containing in-frame incorporated nitrogen has been prepared by a facile polymerization-induced colloid aggregation method. As the electrode material for electric double layer capacitor (EDLC) in 5 mol/L H 2SO 4, the MCS products present excellent specific capacitance as 211 F/g much larger than that of the most popularly applied activated carbon at a high discharge current density of 1 A/g. Its specific capacitance can still remain 200 F/g at 20 A/g. The superior electrochemical performance of MCS is associated with the following characteristics: high specific surface area (∼1330 m 2/g) contributed mainly by the mesopores, uniform pore size as large as 29 nm and moderate content of nitrogen (10 wt%), which are the requirements for ideal supercapacitors.