Nitrogen-doped Porous Carbon Matrix Research Articles

Synergistic Al-Al Dual-Atomic Site for Efficient Artificial Nitrogen Fixation.

Synthesis of ammonia by electrochemical nitrogen reduction reaction (NRR) is a promising alternative to the Haber-Bosch process. However, it is commonly obstructed by the high activation energy. Here, we report the design and synthesis of an Al-Al bonded dual atomic catalyst stabilized within an amorphous nitrogen-doped porous carbon matrix (Al2NC) with high NRR performance. The dual atomic Al2-sites act synergistically to catalyze the complex multiple steps of NRR through adsorption and activation, enhancing the proton-coupled electron transfer. This Al2NC catalyst exhibits a high Faradaic efficiency of 16.56±0.3 % with a yield rate of 29.22±1.2 μg h-1 mgcat -1. The dual atomic Al2NC catalyst shows long-term repeatable, and stable NRR performance. This work presents an insight into the identification of synergistic dual atomic catalytic site and mechanistic pathway for the electrochemical conversion of N2 to NH3.

Energy- and cost-efficient salt-assisted synthesis of nitrogen-doped porous carbon matrix decorated with nickel nanoparticles for superior electromagnetic wave absorption

Energy- and cost-efficient salt-assisted synthesis of nitrogen-doped porous carbon matrix decorated with nickel nanoparticles for superior electromagnetic wave absorption

CoZn-ZIF and melamine co-derived double carbon layer matrix supported highly dispersed and exposed Co nanoparticles for efficient degradation of sulfamethoxazole

Metal-organic framework (MOF)-derived carbon materials have drawn tremendous attention as activators of peroxymonosulfate (PMS) for the degradation of antibiotics. However, it is still challenging to construct MOF-derived materials with well-dispersed and highly-exposed metal active sites. Herein, the bimetallic Cobalt-Zinc-zeolite imidazolate framework and melamine co-derived double layer nitrogen-doped porous carbon matrix supported highly dispersed cobalt nanoparticles (Co NPs) (denoted as Co-NC-C) with the exposure of more Co NPs sites was developed by one-step pyrolysis method. The transmission electron microscopy results demonstrate that double layer carbon matrix as a dispersant can effectively inhibit the agglomeration of Co NPs, and Co-NC-C possessed more exposure of Co active sites compared with Co-NC without melamine. Co-NC-C efficiently activated PMS to remove over 96.67% of sulfamethoxazole (SMX) at a widespread range of pH within 120 min due to its the highly-exposed Co active sites and high graphitization degree. Additionally, the degradation mechanism dominated by the singlet oxygen was demonstrated. Finally, four products and two probable degradation pathways of SMX were confirmed. Half of the products were less toxic than SMX based on the ecological structure activity relationships analysis results. The study provides valuable insights for the development of MOF-derived catalysts with well-dispersed and highly-exposed metal active sites.

Template-assisted formation of atomically dispersed iron anchoring on nitrogen-doped porous carbon matrix for efficient oxygen reduction

Template-assisted formation of atomically dispersed iron anchoring on nitrogen-doped porous carbon matrix for efficient oxygen reduction

FeCoNi Ternary Nano-Alloys Embedded in a Nitrogen-Doped Porous Carbon Matrix with Enhanced Electrocatalysis for Stable Lithium-Sulfur Batteries.

The application of composite materials that combine the advantages of carbonaceous material and metal alloy proves to be a valid method for improving the performance of lithium-sulfur batteries (LSBs). Herein iron-cobalt-nickel (FeCoNi) ternary alloy nanoparticles (FNC) that spread on nitrogen-doped carbon (NC) are obtained by a strategy of low-temperature sol-gel followed by annealing at 800 °C under an argon/hydrogen atmosphere. Benefiting from the synergistic effect of different components of FNC and the conductive network provided by the NC, not only can the "shuttle effect" of lithium polysulfides (LiPS) be suppressed, but also the conversion of LiPS, the diffusion of Li+, and the deposition of Li2S can be accelerated. Taking advantage of those merits, the batteries assembled with an FNC@NC-modified polypropylene (PP) separator (FNC@NC//PP) can deliver a high reversible specific capacity of 1325 mAh g-1 at 0.2 C and maintain 950 mAh g-1 after 200 cycles, and they can also achieve a low capacity fading rate of 0.06% per cycle over 500 cycles at 1 C. More impressively, even under harsh test conditions (the ratio of electrolyte to sulfur (E/S) = 6 μL mg-1 and sulfur loading = 4.7 mg cm-2 and E/S = 10 μL mg-1 and sulfur loading = 5.9 mg cm-2), the area capacity of batteries is still much higher than 4 mAh cm-2.

Tailoring single-atom FeN4 moieties as a robust heterogeneous catalyst for high-performance electro-Fenton treatment of organic pollutants

An iron single-atom catalyst, composed of robust FeN4 moieties anchored on a nitrogen-doped porous carbon matrix (Fe-SAC/NC), has been developed via a surfactant-coordinated metal-organic framework (MOF) approach for application in heterogeneous electro-Fenton (HEF) process. The cohesive interaction between the surfactant and MOF precursor enabled the formation of abundant and stable FeN4 moieties. The Fe-SAC/NC-catalyzed HEF allowed the complete degradation of 2,4-dichlorophenol with low iron leaching (1.2 mg L-1), being superior to nanoparticle catalyst synthesized without surfactant. The experiments and density functional theory (DFT) calculations demonstrated the dominant role of single-atom FeN4 sites to activate the electrogenerated H2O2 yielding •OH. The dense FeN4 moieties allowed harnessing the modulated electronic structure of the SAC to facilitate the electron transfer, whereas the adjacent pyrrolic N enhanced the adsorption of target organic pollutants. Moreover, the excellent catalysis, recyclability and viability of the Fe-SAC/NC were verified by successfully treating several organic pollutants even in urban wastewater.

Mn-N-C Nanostructure Derived from MnO2-x/PANI as Highly Performing Cathode Additive in Li-S Battery

Highly dispersed Mn metallic nanoparticles (15.87 nm on average) on a nitrogen-doped porous carbon matrix were prepared by thermal treatment of MnO2-x/polyaniline (PANI), which was derived from the in situ polymerization of aniline monomers initiated by γ-MnO2 nanosheets. Owing to the large surface area (1287 m2/g), abundant active sites, nitrogen dopants and highly dispersed Mn sites on graphitic carbon, an impressive specific capacity of 1319.4 mAh g−1 with an admirable rate performance was delivered in a Li-S battery. After 220 cycles at 1 C, 80.6% of the original capacity was retained, exhibiting a good cycling stability.

NiO nanocrystals encapsulated into a nitrogen-doped porous carbon matrix as highly stable Li-ion battery anodes

Though the carbon matrix is extensively investigated to enhance the electrochemical performances of metal oxides for lithium-ion batteries (LIBs), it is still difficult to expose the whole active sites in the electrode material to participate in electrochemical reactions. Herein, we report a facile MOF-derived strategy for the controlled synthesis of a hybrid structure with NiO nanocrystals uniformly distributed into nitrogen-doped porous carbon matrix (NiO@N–C). In this strategy, the simultaneously generated nitrogen-doped porous carbon matrix can confine the further growth of the resulting NiO nanocrystals during the carbonization process, in which the ultrafine particle sizes of NiO can shorten ion diffusion length and provide abundant exposed active sites for lithium-storage, while the carbon matrix can function as a buffer layer to alleviate the volume expansion. Benefiting from the advantages of the structural features and porous carbon matrix, NiO@N–C delivers a large reversible capacity of 1373 mAh g−1 at 100 mA g−1 after 200 cycles and a remarkable cycling stability up to 1000 cycles at 1 A g−1 with a capacity of 877 mAh g−1, suggesting its potential as an anode material for lithium-ion batteries.

Synthesis of polypyrrole/nitrogen-doped porous carbon matrix composite as the electrode material for supercapacitors

Polypyrrole complex nitrogen-doped porous carbon matrix (PPy/N-PCM) was synthesized by a simple two-step method. Firstly, graphene oxide was prepared by the modified Hummers method. Secondly, Polypyrrole was compounded on the graphene oxide substrate, and the carbon matrix with a high specific surface area was obtained through high-temperature carbonization and KOH activation, and polypyrrole was used as a nitrogen source for the final nitrogen-doped composite material. The structure characterization of the carbon matrix and the final composite material shows that the carbon matrix surface has obvious porous structure, and the polypyrrole nanospheres grow uniformly on the porous carbon matrix surface. The electrochemical evaluation show that the prepared PPy/N-PCM has excellent supercapacitor performance, and its specific capacitance can reach 237.5 F g−1. When the current density reaches 10 A g−1, it has good cycle stability (the capacitance retention after 1000 charge and discharge is 88.53% of the initial capacitance value, which is better than pure PPy-60.76% and PPy/rGO-C-71.84%). The excellent capacitance performance, good-looking micro-morphology and simple synthesis method of the PPy/N-PCM provide the possibility for its commercialization.

Ultrafine iron-cobalt nanoparticles embedded in nitrogen-doped porous carbon matrix for oxygen reduction reaction and zinc-air batteries

Oxygen reduction reaction (ORR) is a key process in renewable energy conversion and storage technologies, including fuel cells and metal-air batteries. Pt is a highly efficient ORR electrocatalyst, but its large-scale application is severely prohibited by the high cost. In the pursuit of cost-effective electrocatalysts, it is urgent to develop non-noble metal ORR catalysts. Herein, we report a facile strategy for synthesizing an ORR electrocatalyst based on ultrafine bimetallic FeCo nanoparticles (NPs) anchoring on N-doped porous carbon matrix (FeCo-NC). By optimizing the ratio of Fe and Co, the FeCo-NC-1 catalyst exhibits excellent performance for ORR with the half-wave potential of 0.84 V and limiting current density of −5.3 mA cm−2, which is comparable to the commercial Pt/C catalyst. When applied to Zn-air batteries, FeCo-NC-1 catalyst possesses a high open-circuit potential (1.50 V) and large specific capacity (726.2 mA h g−1) with a good long-term stability and methanol-tolerant capability, which are even superior to the commercial Pt/C catalyst. The first-principle calculations indicate the bimetallic FeCo-NC has stronger O2 adsorption than the single metal nitrogen-doped carbon catalysts (Fe-NC and Co-NC), which is the primary reason for the better ORR performance. We believe this work can be helpful for the development of inexpensive and high-efficient ORR electrocatalysts.

Synthesis of ultrafine Co3O4 nanoparticles encapsulated in nitrogen-doped porous carbon matrix as anodes for stable and long-life lithium ion battery

Hybrid nanostructures with ultrafine metal oxides in porous nitrogen-doped carbon matrix have received great attention for the enhancing performance of lithium-ion batteries because of their advantages in effectively solving the problems during the discharge/charge processes, such as low conductivity, large volume expansion, and long diffusion path for the fast transfer of Li+ ion. Herein, we report a facile strategy for the synthesis of ultrafine Co3O4 nanoparticles uniformly encapsulated into nitrogen-doped porous carbon matrix (Co3O4@NC) through pyrolysis of metal-organic frameworks (MOFs) followed by a hydrothermal oxidation method. Moreover, Co3O4@NC inherited the advantage of MOFs with porous structure, and the as-synthesized Co3O4 nanoparticles uniformly distributed into the simultaneously generated nitrogen-doped carbon matrix. Benefiting from its unique structural features, Co3O4@NC exhibits a large discharge capacity of 1017 mAh g−1 after 100 cycles at 100 mA g−1, and the long reversible capacity of 731 mAh g−1 can be retained after 1000 cycles at 1000 mA g−1, indicating that Co3O4@NC has potential application in lithium-ion batteries with long cycling life and high power density.

FeP nanoparticles derived from metal-organic frameworks/GO as high-performance anode material for lithium ion batteries

Double carbon coated FeP composite (FeP@NC@rGO) was in situ fabricated via the phosphorization process of the as-prepared Prussian blue@graphene oxide (PB@GO) precursor. The FeP nanocrystals were successfully embedded in the nitrogen-doped porous carbon matrix. When used as the anode for lithium ion batteries (LIBs), the FeP@NC@rGO anode shows superior lithium storage properties, delivering a high specific capacity of 830 mA h g−1 after 100 cycles at 100 mA g−1 and excellent rate capability of 359 mA h g−1 at 5 A g−1. The outstanding performance mainly ascribes to the synergistic effect of the double carbon coating and porous structure design. The introduction of porous carbon and graphene coating on FeP nanoparticles greatly enhance the electronic conductivity of the active material and well accommodates the large volume variation of FeP during the cycling process.

Fabrication of 3D lawn-shaped N-doped porous carbon matrix/polyaniline nanocomposite as the electrode material for supercapacitors

Abstract A facile approach to acquire electrode materials with prominent electrochemical property is pivotal to the progress of supercapacitors. 3D nitrogen-doped porous carbon matrix (PCM), with high specific surface area (SSA) up to 2720 m 2 g −1 , was obtained from the carbonization and activation of the nitrogen-enriched composite precursor (graphene/polyaniline). Then 3D lawn-shaped PCM/PANI composite was obtained by the simple in-situ polymerization. The morphology and structure of these resulting composites were characterized by combining SEM and TEM measurements, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) spectroscopy analyses and Raman spectroscope. The element content of all samples was evaluated using CHN analysis. The results of electrochemical testing indicated that the PCM/PANI composite displays a higher capacitance value of 527 F g −1 at 1 A g −1 compared to 338 F g −1 for pure PANI, and exhibits appreciable rate capability with a retention of 76% at 20 A g −1 as well as fine long-term cycling performance (with 88% retention of specific capacitance after 1000 cycles at 10 A g −1 ). Simultaneously, the excellent capacitance performance coupled with the facile synthesis of PCM/PANI indicates it is a promising electrode material for supercapacitors.

Ultrasmall Tin Nanodots Embedded in Nitrogen-Doped Mesoporous Carbon: Metal-Organic-Framework Derivation and Electrochemical Application as Highly Stable Anode for Lithium Ion Batteries

This work reports a facile metal-organic-framework based approach to synthesize Sn/C composite, in which ultrasmall Sn nanodots with typical size of 2–3nm are uniformly embedded in the nitrogen-doped porous carbon matrix (denoted as Sn@NPC). The effect of thermal treatment and nitrogen doping are also explored. Owing to the delicate size control and confined volume change within carbon matrix, the Sn@NPC composite can exhibit reversible capacities of 575mAhg−1 (Sn contribution: 1091mAhg−1) after 500 cycles at 0.2Ag−1 and 507mAhg−1 (Sn contribution: 1077mAhg−1) after 1500 cycles at 1Ag−1. The excellent long-life electrochemical stability of the Sn@NPC anode has been mainly attributed to the uniform distribution of ultrasmall Sn nanodots and the highly-conductive and flexible N-doped carbon matrix, which can effectively facilitate lithium ion/electron diffusion, buffer the large volume change and improve the structure stability of the electrode during repetitive cycling with lithium ions.

Self-wrapped Sb/C nanocomposite as anode material for High-performance sodium-ion batteries

Self-wrapping is a facile and highly efficient way to realize evenly coating and homogeneous distribution. Ultrasmall antimony (Sb) nanoparticles embedded in three-dimensional (3D) nitrogen-doped porous carbon matrix are fabricated by self-wrapping and controlled growth process with chitosan (CHI) as a self-wrapping precursor. As anode material for sodium-ion battery, the as-obtained Sb/CCHI nanocomposite shows an initial discharge capacity of 403mAhg−1 with Coulombic efficiency of 69.4%, and retains the capacity up to 372mAhg−1 after 100 cycles at a current of 500mAg−1. A reversible capacity of 138mAhg−1 is attained even at a very high current density of 32Ag−1. This unique Sb/CCHI nanocomposite is a potential anode material for high-performance sodium-ion batteries.