N-doped Mesoporous Carbon Material Research Articles

Cobalt nanoparticles inlayed N-doped mesoporous carbon microspheres for high performance Lithium-Selenium battery

To solve the volume expansion and the dissolution of high-order polyselenide of selenium cathode during discharge process, herein, a cobalt nanoparticles inlayed N-doped mesoporous carbon material (NMC-Co) consisting of carbon nanosheets was synthesized to apply as a selenium host for high performance Lithium-Selenium (Li-Se) battery. The obtained material with high specific surface area and high porosity has an excellent structure combining mesopores and inlayed cobalt nanoparticles, which provides favorable conditions for electrolyte infiltration and alleviation of cathode volume expansion, and also effectively restricts the generation and dissolution of polyselenide. As expected, when using NMC-Co as a host for the selenium cathode, Se50@NMC-Co loading with 50% of Se can deliver a high reversible capacity of 419.1 mA h g−1 at a current rate of 0.2C after 100 cycles (1C = 675 mA h g−1) and an excellent cycling stability of only 0.024% capacity decay per cycle after 200 cycles at 1C is demonstrated.

Enhanced electrochemical hydrogen storage performance upon the Pt-Co nanoparticles decorated N-doped mesoporous carbon

Carbonaceous materials are proved to be the promising materials for storing hydrogen electrochemically. To enhance the performance, decorated Pt-Co bi-metallic nanoparticles onto the N-doped mesoporous carbon material were developed while Co enriched the capacity, and Pt was used to enhance the kinetic performance. Results showed that the hydrogen storage capacity of 2% Pt-Co@NMC material was over 360 mAh g−1 under a current density of 100 mA g−1, and the capacity retention was 53.6% under the 2000 mA g−1 rate over that at 100 mA g−1. Furthermore, it also carries low self-discharge and good cycling performance. First-principles calculations revealed that the adsorption of the H atom on the Pt (110) crystal plane is the most stable, which is mainly due to the hydrogen spillover effect to improve the kinetic performance of hydrogen intercalation.

Promotional effect of embedded Ni NPs in alginate-based carbon toward Pd NPs efficiency for high-concentration p-nitrophenol reduction

Noble metal-based catalytic material with maximum utilization is of prime attraction for conserving rare metal resources. Herein, highly dispersion Ni nanoparticles (NPs)-modified N-doped mesoporous carbon material (Ni-N@C) was fabricated by pyrolysis of Ni2+/Histidine cross-linked alginate hydrogels. In a step forward, the obtained Ni-N@C nanocatalyst was treated by the solution of Pd2+, and tiny amount of Pd NPs were deposited on the surface of Ni via the reducibility of Ni to achieve the high dispersion of precious metals material. In the degradation of highly-concentration p-nitrophenol, the catalyst presents excellent performance which could completely degrade pollutants within a very short period. It was demonstrated that pre-embedded Ni NPs could not only increase the efficiency of Pd NPs but also endow the facile separation characteristic to the catalyst. Besides, the catalyst maintained favorable catalytic capacity even after five reaction cycles. In brief, this work may provide novel guidance for the maximum utilization of noble metal-modified mesoporous N-doped carbon-supported catalysts in practical applications of industrial and the treatment highly-concentration p-nitrophenol.

UIO-66-NH2-derived mesoporous carbon used as a high-performance anode for the potassium-ion battery.

As potassium is abundant and has an electronic potential similar to lithium's, potassium-ion batteries (KIBs) are considered as prospective alternatives to lithium-ion batteries (LIBs). However, the much larger radius of the K ion poses challenges for the potassiation and depotassiation processes when the typical graphite-based anode is used, resulting in poor electrochemical performance. Thus, there is an urgent need to develop novel anode materials that are suitable for K ions. Herein, we develop a porous carbon material with high surface area derived from UIO-66-NH2 metal–organic frameworks as an anode material instead of a graphite-based anode. The material is prepared using a double-solvent diffusion-pyrolysis method, which increased mesopore volume and average pore size, and to a certain extent, slightly improved the nitrogen content of the production. The material exhibits a high capacity as well as excellent rate performance and cycling stability. A potassium battery with our porous carbon as the anode delivers a high reversible capacity of 346 mA h g−1 at 100 mA g−1 (compared to 279 mA h g−1 with a graphite-based anode), and 214 mA h g−1 at a discharge rate of up to 2 A g−1. After 800 cycles, the capacity is still 187 mA h g−1 at 0.1 A g−1. Qualitative and quantitative kinetics analyses demonstrated that the battery's high K storage performance was principally dominated by a surface-driven capacitive mechanism, and the potassiation and depotassiation processes may have occurred on the surface of the porous carbon instead of in the interlayer space, as is the case with a graphite anode. This work may provide a basis for developing other carbonaceous materials to use in KIBs.

Highly N-doped, H-containing mesoporous carbon with modulated physicochemical properties as high-performance anode materials for Li-ion and Na-ion batteries

A series of N-doped mesoporous carbon (NMC) materials are synthesized by the co-pyrolysis of an N-containing compound and carbon sources using a modified nanocasting method. The physicochemical properties are manipulated by changing the amount of resol precursors to permit the usage of these materials in the desired applications. As anodes for Li-ion batteries, the prepared NMC2, which has the highest number of hydrogenated N functional groups, delivers a high discharge capacity of 900, 700, and 600 mAh g−1 at current densities of 0.5, 1, and 2 A g−1, respectively, after 200 cycles of discharging and charging. Even at an extremely high current density of 10 A g−1, the NMC2 electrode delivers a discharge capacity of 300 mA g−1. In addition, in Na-ion batteries, NMC3, which has the highest pyridinic N content and average pore diameters, exhibits a discharge capacity of 163 mAh g−1 at 1 A g−1 over 500 cycles. Hence, an intimate relationship between the key physicochemical parameters and electrochemical properties of NMC materials are established for use of these materials in specific applications. The obtained results demonstrate that the fabricated NMC materials possess superior characteristics in comparison to those of most state-of-the-art porous carbon materials.

Preparation of benzoxazine-based N-doped mesoporous carbon material and its electrochemical behaviour as supercapacitor

The N-doped mesoporous carbon materials (CNM) had been synthesized with hard template method. Benzoxazine (BOZ) was adopted as a precursor and SBA-15 as template. The electrochemical performance of carbon materials prepared by different ultrasonic time, different benzoxazine concentration and different carbonization temperature were conducted by a three-electrode system. In order to further explain electrochemical behaviour of the obtained carbon materials, the corresponding characterizations were also done. CNM-800 had a highest specific capacitance value, 428.8 F g−1 (0.25 A/g) in the three-electrode system. After 20,000 cycles of CNM-800 at the current density of 5 A g−1, CNM-800 still had 98.5% of the original capacitance, which showed that CNM-800 had a good cycling stability. In order to investigate the application value of supercapacitors, a two-electrode system was also adopted, a maximum energy density was 11.2 Wh kg−1. The prepared carbon material (CNM-800) have the higher specific capacitance than the related literatures. This kind of N-doped mesoporous carbon material would have a potential application value as supercapacitor.

Single Au Atoms on the Surface of N-Free and N-Doped Carbon: Interaction with Formic Acid and Methanol Molecules

Formic acid and methanol are considered as liquid organic hydrogen carriers and could be produced sustainably from biomass or by CO2 hydrogenation using catalysts. The choice of a catalyst for decomposition of these substances is a challenge. We prepared N-free and N-doped mesoporous carbon materials containing less than 2 wt% of gold not stabilized by chlorine anions. High-angle annular dark field scanning transmission electron microscopy (STEM) data showed that the supported gold was present in the state of single Au atoms and Au nanoparticles after reduction. The use of the N-doped carbon support allowed reaching high dispersion of the Au nanoparticles with a mean size of ~ 2 nm, as compared to ~ 10 nm for the N-free support. Density functional theory studies indicated that a single Au atom may attach strongly (> 3.6 eV) to carbon atoms on the graphene edge or even more strongly to carbon atoms in a double vacancy; however, it may attach only weakly to N species of the N-doped carbon. Formic acid and methanol molecules interact relatively strongly (~ 0.75 eV and ~ 1.0 eV, respectively) via their oxygen atoms with the Au atom on the graphene edge, while they interact only weakly with the graphene fragments containing the Au atoms in double vacancies (~ 0.4 eV and ~ 0.3 eV, respectively). This demonstrates importance of coordinative unsaturation of Au atoms for adsorption and may influence further reactivity of the adsorbed species. The obtained results can be used for development of catalysts and electrocatalysts containing single Au atoms for hydrogen production from liquid organic hydrogen carriers.

Two-dimensional covalent organic frameworks as self-template derived nitrogen-doped carbon nanosheets for eco-friendly metal-free catalysis

Heteroatom-doped carbon materials with superior physico-chemical properties and high stability are potential candidates for environmentally friendly metal-free catalysis. In this study, mesoporous carbon materials with high N content and lattice defects were successfully fabricated via self-templated carbonization of a two-dimensional covalent organic framework (2D COF). The ordered structure and clear composition of intrinsic COF precursors aid the understanding of the specific role of dopants in the as-prepared N-doped mesoporous carbon materials. Based on the obtained experimental results and characterizations, graphitic N and its related defects were found to be closely associated with catalytic activity, indicating they are probably the main active sites. In addition, the obtained catalyst showed remarkable catalytic performance in both hydrogenation of nitroarenes and Knoevenagel condensation of aromatic aldehyde derivatives in aqueous solution. This study is expected to provide a new inspiration for the synthesis of heteroatom-doped carbon materials from cost-effective COFs via self-templated carbonization for eco-friendly metal-free catalysis.

Cost-Effective and Facile Preparation of Fe2O3 Nanoparticles Decorated N-Doped Mesoporous Carbon Materials: Transforming Mulberry Leaf into a Highly Active Electrocatalyst for Oxygen Reduction Reactions

Herein, a promising method to prepare efficient N-doped porous carbon-supported Fe2O3 nanoparticles (Fe2O3/N-PCs) ORR electrocatalysts is presented. The porous carbon was derived from a biomass i.e., mulberry leaf through a cost-effective approach. The existence of diverse compounds containing carbon, oxygen, nitrogen and sulfur in mulberry leaf benefit the formation and uniform dispersion of Fe2O3 nanoparticles (NPs) in the porous carbon. In evaluating the effects of the carbon support on the Fe2O3 NPs towards the ORR, we found that the sample of Fe2O3/N-PCs-850 (Fe2O3/N-PCs obtained at 850 °C) with high surface area of 313.8 m2·g−1 exhibits remarkably superior ORR activity than that of materials acquired under other temperatures. To be specific, the onset potential and reduction peak potential of Fe2O3/N-PCs-850 towards ORR are 0.936 V and 0.776 V (vs. RHE), respectively. The calculated number of electron transfer n for the ORR is 3.9, demonstrating a near four-electron-transfer process. Furthermore, it demonstrates excellent longtime stability and resistance to methanol deactivation compared with Pt/C catalyst. This study provides a novel design of highly active ORR electrocatalysts from low-cost abundant plant products.

Preparation of ordered N-doped mesoporous carbon materials via a polymer-ionic liquid assembly.

Here we report a facile and effective strategy for the preparation of ordered mesoporous carbon materials with a high-nitrogen-content (8.1 at%) coating layer through a polymer-ionic liquid assembly strategy. The prepared N-doped mesoporous carbon materials demonstrated enhanced CO2 adsorption capacity (2.29 mmol g-1) compared with non-doped carbon (1.84 mmol g-1).

One-step assembly of N-doped partially graphitic mesoporous carbon for nitrobenzene reduction

N-doped mesoporous carbon material has been synthesized by a novel one-step assembling strategy using ionic liquid (IL) as the carbon source and structure-directing agent. The obtained mesoporous carbon material has bimodal mesopores (about 3.8 and 9.0nm) and partially graphitic structure with a BET surface area of 372m2/g and mesopore volume of 0.61cm3/g. The nitrogen in the IL precursor can be incorporated into the framework of mesoporous carbon with a content of 3.2wt%. The obtained carbon material shows excellent catalytic performance for nitrobenzene (NB) reduction reaction with an 88.6% yield to aniline (AN).