N-rich Carbon Research Articles

Synthesis of N-rich microporous carbon materials from chitosan by alkali activation using Na2CO3

Abstract The paper presents the first systematic study on the synthesis of nitrogen-rich nanoporous activated carbons by chitosan carbonization in the presence of a hard template (activator), i.e. Na2CO3. Carbonization process was carried out in the range of 600–900 °C under a flow of nitrogen. The effect of the addition of different volumes of activator and the temperature of carbonization on the development of specific surface area and pore structure (pore volume and median pore diameter) of the activated carbons was investigated. Additionally, the nitrogen content and nitrogen-containing surface species were determined by means of XPS and combustion elemental analysis. The nitrogen content was placed in the range of 2.4–13.1 wt.%. On the grounds of the low-temperature adsorption of nitrogen, it was found that obtained adsorption isotherms were of type-I, based on the IUPAC classification, which is typical for microporous materials.

Nitrogen-doped porous carbon derived from citric acid and urea with outstanding supercapacitance performance

In this work, we presented a novel approach to synthesize nitrogen-doped porous carbon materials via a three-step fabrication process using citric acid as the carbon source and urea as the nitrogen source. Firstly, hydrochar was synthesized by a microwave-assisted hydrothermal method using citric acid and urea and as the reactants. The hydrochar was then subjected to high-temperature carbonization in Ar atmosphere followed by KOH activation, giving nitrogen-doped porous carbon materials. The morphology, structure, and textural properties of the carbons were investigated by SEM, TEM, N2 sorption isotherms, and XPS. The as-prepared porous carbon possesses a high BET surface area of 2397m2g−1 and an average pore size of 1.8nm. Such N-rich porous carbon shows outstanding capacitive performance (365Fg−1 at 0.5Ag−1), good rate capacitive behavior, and excellent cycling stability, indicating a great potential for supercapacitors.

Facile Synthesis of Ultrasmall CoS2 Nanoparticles within Thin N-Doped Porous Carbon Shell for High Performance Lithium-Ion Batteries.

Cobalt sulfide (CoS2) is considered one of the most promising alternative anode materials for high-performance lithium-ion batteries (LIBs) by virtue of its remarkable electrical conductivity, high theoretical capacity, and low cost. However, it suffers from a poor cycling stability and low rate capability because of its volume expansion and dissolution of the polysulfide intermediates in the organic electrolytes during the battery charge/discharge process. In this study, a novel porous carbon/CoS2 composite is prepared by using nano metal-organic framework (MOF) templates for high-preformance LIBs. The as-made ultrasmall CoS2 (15 nm) nanoparticles in N-rich carbon exhibit promising lithium storage properties with negligible loss of capacity at high charge/discharge rate. At a current density of 100 mA g(-1), a capacity of 560 mA h g(-1) is maintained after 50 cycles. Even at a current density as high as 2500 mA g(-1), a reversible capacity of 410 mA h g(-1) is obtained. The excellent and highly stable battery performance should be attributed to the synergism of the ultrasmall CoS2 particles and the thin N-rich porous carbon shells derieved from nanosized MOF precusors.

Simple and sensitive fluorescent and electrochemical trinitrotoluene sensors based on aqueous carbon dots.

Aqueous N-rich carbon dots (CDs), prepared by the microwave-assisted pyrolysis method, are applied as a dual sensing platform for both the fluorescent and electrochemical detection of 2,4,6-trinitrotoluene (TNT). The fluorescent sensing platform is established on the strong TNT-amino interaction which can quench the photoluminescence of amino functionalized CDs through charge transfer. The resultant linear detection ranges from 10 nM to 1.5 μM with a fast response time of 30 s. Glassy carbon electrode modified with CDs exhibits a fine capability for TNT reduction with the linear range from 5 nM to 30 μM, better than that obtained by the fluorescent method. Moreover, the minimum distinguishable response concentration with respect to these two methods is down to the nanomolar level with a high specificity and sensitivity.

Achieving battery-level energy density by constructing aqueous carbonaceous supercapacitors with hierarchical porous N-rich carbon materials

3D hierarchical porous N-rich graphitic carbon materials were prepared and further used for symmetric aqueous supercapacitors with battery-level energy density while retaining capacitor-type power density and cycling stability.

Amorphous titanate-crosslinking N-rich carbon hybrid with 3D channels for fast lithium storage

A novel amorphous titanate-crosslinking N-rich carbon hybrid is successfully prepared for the first time and exhibits superior high-rate performance.

Sb nanoparticles decorated N-rich carbon nanosheets as anode materials for sodium ion batteries with superior rate capability and long cycling stability

Antimony nanoparticle decorated N-rich porous carbon nanosheets were prepared through a sol-gel route. The composite displayed high reversible capacity, superior rate performance and long cycling stability as an anode material for room temperature Na-ion batteries. Even at an ultrahigh charge-discharge rate of 2 A g(-1), a large specific capacity of 220 mA h g(-1) was still achieved after 180 cycles.

Ultrasmall MnO@N-rich carbon nanosheets for high-power asymmetric supercapacitors

Manganese monoxide (MnO) holds great potential for high-performance supercapacitors; however, it is highly desirable to establish a feasible structure to address common concerns of MnO materials. Herein, we have inserted ultrasmall MnO nanoparticles into N-rich carbon nanosheets (MnO@NCs) via a facile and scalable method. By integrating copious nitrogen species (over 13 wt%), flexible but robust carbon nanosheets offer powerful support for dispersing large amounts of MnO nanoparticles, creatively avoiding the inherent deficiencies of MnO such as poor electrical conductivity, low mechanical stability and severe electrochemical dissolution. Consequently, the MnO@NC electrode exhibited a striking capacitance of 570 F g−1 at 2 A g−1 within a wide operation voltage of 1 V, which spurs the low capacitance of MnO materials (generally 200–350 F g−1) to a higher level. Furthermore, initial attempts at fabricating asymmetric supercapacitors based on MnO@NCs demonstrated an energy density superior to its well-studied MnO2 counterpart. The introduction of N-rich species is of great significance for releasing restricted properties and fully exerting positive effects on the supercapacitors. Particularly, the impressive capacitance retention of ∼99% over 6000 cycles also propels a new direction for transition metal oxide/NC composites towards high-performance energy storage devices.

Rational Design of Ni Nanoparticles on N‐Rich Ultrathin Carbon Nanosheets for High‐Performance Supercapacitor Materials: Embedded‐ Versus Anchored‐Type Dispersion

Highly dispersed Ni nanoparticles (NPs) and abundant functional N-species were integrated into ultrathin carbon nanosheets by using a facile and economical sol-gel route. Embedded- and anchored-type configurations were achieved for the dispersion of Ni NPs in/on N-rich carbon nanosheets. The anchored-type composite exhibited outstanding pseudocapacitance of 2200 F g(-1) at 5 A g(-1) with unusual rate capability and extraordinary cyclic stability over 20 000 cycles with little capacitance decay. Aqueous asymmetric supercapacitors fabricated with this composite cathode demonstrated a high energy density of 51.3 Wh kg(-1) at a relatively large power density of 421.6 W kg(-1) , along with outstanding cyclic stability. This approach opens an attractive direction for enhancing the electrochemical performances of metal-based supercapacitors and can be generalized to design high-performance energy-storage devices.

Sn-contained N-rich carbon nanowires for high-capacity and long-life lithium storage

We report here for the first time Sn-contained N-rich carbon nanowires, which are prepared via a facile and scalable procedure using poly-pyrrole as the carbon source. As-obtained nanowires with a diameter of about 50nm crosslink with each other with enough void space, beneficial to accommodating lithiation-induced volumetric change and mechanical stress. In particular, this product contains abundant nitrogen (9.8wt.%), favorable for Li+ diffusion and storage. It therefore exhibits excellent cycling stability of 682.6 and 760.1mAhg−1 at 500mAg−1 after 200 and 600 cycles, respectively. It also delivers great high rate performance even at 10Ag−1.

A composite of Co nanoparticles highly dispersed on N-rich carbon substrates: an efficient electrocatalyst for Li–O2battery cathodes

In this work, we present a facile sol-gel method to prepare a composite of Co nanoparticles highly dispersed on N-rich carbon substrates (Co-C composite). The assembled Li-O2 batteries with the composite as a cathode catalyst showed lower overpotential and better cyclability, and the improved performance may be attributed to the superior electrocatalytic activity of the Co-C composite.

Novel ordered nanoporous graphitic C3N4as a support for Pt–Ru anode catalyst in direct methanol fuel cell

The fabrication of graphitic carbon nitride with 3-dimensionally extended highly ordered pore arrays is described, and the N-rich porous carbon was utilized for the first time as a support for Pt50–Ru50 alloy catalyst to study the support effect on the anodic performance in direct methanol fuel cells; it displays promising results as a catalyst support in the fuel cell.

95/06543 An integrated framework to address climate change (ESCAPE) and further developments of the global and regional climate modules (MAGICC)

Deciphering the structural and volume changes occurring during electrode reactions in lithium-ion batteries is perhaps a boon for high energy density batteries. Here, we report the synthesis of 3D network of dichalcogenide molybdenum disulfide (MoS2) encapsulated over nitrogen rich graphitic carbon nitride nanosphere (g-C3N4) forming an interconnected and uniform g-C3N4/MoS2 scaffolds. The crystallinity, phase purity, morphological features and elemental composition were evaluated through XRD, FESEM, TEM, HRTEM, BET and XPS analyses. The electrochemical properties of N-rich g-C3N4/MoS2 scaffolds were investigated as potential anode materials for lithium-ion batteries. Electrochemical testing of the g-C3N4/MoS2 constructured electrode delivered reversible capacity of 857 mAh g−1at 0.1 C rate after fifty cycles and exhibited a high rate performance with reversible capacity of 383 mAh g−1 at 10 C rate (higher than theoretical capacity of graphite, 372 mAh g−1). The superior electrochemical property of g-C3N4/MoS2 is attributed to N-rich carbon support which favors better electronic conductivity, and affords more sites for Li+ ions. The nitrogen rich carbon nitride accommodates volume changes caused during repeated charge/discharges and maintains high structural integrity and specific capacity.