Nitrogen-doped Carbon Spheres Research Articles

Strengthening Co[sbnd]Co bond by copper doping in Co9S8 coupled with nitrogen-doped carbon sphere for enhancing the catalytic activity of oxygen reaction

Oxygen reaction plays a vital role in energy storage such as zinc-air battery and microbial fuel cell (MFC). Thus, it is necessary to search and develop non-precious metal electrocatalysts with remarkable activity. In this work, copper is cleverly doped into the octahedral sites of Co9S8 to strengthen the CoCo bond and then combined with nitrogen-doped hollow carbon spheres to achieve high catalytic activity and durability for oxygen reduction reactions (ORR) and oxygen evolution reactions (OER). The prepared Cu-Co9S8-NHCS-1 exhibits the potential gap of 0.788 V between Ej=10 of OER and E1/2 of ORR. Moreover, the zinc-air battery with Cu-Co9S8-NHCS-1 cathode possesses a power density of 91.0 mW cm-2 and long-term stability over 120 h. The MFC using Cu-Co9S8-NHCS-1 cathode exhibits a power density of 924 ± 18 mW m-2, higher than that of 862 ± 20 mW m-2 with Pt/C. These results indicate that the Cu-Co9S8-NHCS-1 is an excellent bifunctional electrocatalyst for ORR and OER, and has promising applications in energy conversion.

Transforming radical to non-radical pathway in peroxymonosulfate activation on nitrogen doped carbon sphere for enhanced removal of organic pollutants: Combined effect of nitrogen species and carbon structure

Carbon induced non-radical based peroxymonosulfate (PMS) activation has exhibited several advantages over radical process for eliminating organic pollutants in complicated water matrices. However, the relationship between configuration and composition of carbon and non-radical mechanism, which is important for designing high-efficiency carbon catalysts, remains elusive. In this work, the nitrogen doped carbon spheres (NCSs) with superior PMS activation ability were prepared from low-cost chitosan via two-step hydrothermal carbonization-pyrolysis method for organic pollutants removal. The carbon structure and nitrogen species of NCSs were tuned via changing hydrothermal temperature to explore their correlation with their PMS catalytic mechanism. Results showed hydrothermal carbonization boosted the content of pyridinic N, graphitic N and sp2-hybrided carbon (CC) in NCS, which significantly enhanced its catalytic performance and collaboratively promoted the catalytic mechanism switch from radical-dominant (SO4•− and •OH) to non-radical-dominant (surface-mediated electron transfer (SMET) and 1O2) process. The NCS with most pyridinic N and CC performed best, whose catalytic activity was 10.4 times higher than that without hydrothermal carbonization. The pyridinic N and CC enhanced the SMET process through strengthening PMS adsorption capacity and facilitating the electron migration from pollutant to PMS, respectively, while graphitic N triggered PMS oxidation on its neighboring electron-deficient C to produce 1O2.

Nitrogen-doped carbon spheres with precisely-constructed pyridinic-N active sites for efficient oxygen reduction

The intelligent design of non-metallic catalysts with high-performance and long-term stability towards oxygen reduction reaction (ORR) is essentially required for green and sustainable energy conversion systems. Optimizing carbon nanomaterials with abundant and uniformly distributed nitrogen (N)-type active sites provide more advantages for boosting the ORR. However, designing catalysts with well-defined N-doping active sites is extremely challenging using the current methods/techniques. Herein, we report a rational solvothermal strategy to synthesize covalent triazine polymers (CTPs), which act as ideal “all in one” precursors to fabricate N-doped non-metallic catalyst via subsequent pyrolysis. Due to abundant and precisely-constructed pyridinic-N active sites, the newly-realized N-doped carbon spheres (N/N-CS) catalyst exhibits superb catalytic activity for the ORR with a high half-wave potential (E1/2 = 0.865 V vs. RHE), excellent tolerance to methanol and great long-term performance. Impressively, while being utilized as cathode material in primary Zn-air batteries, the N/N-CS electrode performs a superior peak power density (∼148 mW cm−2) to that of commercial Pt/C electrocatalyst (∼123 mW cm−2). This work expands an innovative and high-efficiency method for synthesizing non-metallic electrocatalysts with precisely-controlled active sites offering remarkable catalytic ability towards various energy conversion reactions.

Nitrogen-doped carbon hollow spheres packed with multiple nano Sn particles for enhanced lithium storage

Metallic tin has been considered as one of the promising anode candidates for next-generation lithium-ion batteries. However, its poor cycling stability due to the severe volume expansion upon lithiation hinders its further application. Here we propose a shell-to-yolks evolution strategy to synthesize a novel structured Sn-based composite that can well address this issue. The as-prepared composite with multiple Sn cores embedded in one hollow nitrogen-doped carbon sphere is called multiple-yolks-shelled Sn@nitrogen doped carbon (MYS-Sn@NxC). The appropriate voids between Sn particles inside the sphere can well accommodate the volume change during cycles. The robust NxC shell maintains a stable structure of the electrode. As a result, the MYS-Sn@NxC electrode demonstrates excellent electrochemical performance, achieving a long stable reversible capacity of 820 mAh g−1 after 1000 cycles at 2C and nearly 530 mAh g−1 at a high rate of 5C. (1C = 1000 mA g−1).

Atomic modulation of Fe-Co pentlandite coupled with nitrogen-doped carbon sphere for boosting oxygen catalysis

Reversible oxygen reaction plays a crucial role in rechargeable battery systems, but it is limited by the slow reaction kinetics. Herein, the ionic modulation of cobalt pentlandite coupled with nitrogen-doped bowl-like hollow carbon sphere is well designed on octahedral and tetrahedral sites. The robust FexCo9–xS8-NHCS-V with iron replacing at the octahedron possesses prolonged metal sulfur bond and exhibits excellent bifunctional electrocatalytic performance towards oxygen reduction reaction (ORR, E1/2 = 0.80 V vs. RHE) and excellent oxygen evolution reaction (OER, Ej= 10 = 1.53 V vs. RHE) in 0.1 mol/L KOH. Accordingly, a rechargeable Zn-air battery of FexCo9–xS8-NHCS-V cathode endows high energy efficiency (102 mW cm−2), and a microbial fuel cell achieves a high-power density (791 ± 42 mW m−2), outperforming the benchmark Pt/C catalyst.

π-π conjugation driving degradation of aromatic compounds with in-situ hydrogen peroxide generation over Zn2In2S5 grown on nitrogen-doped carbon spheres

The water contaminant control with the simultaneous production of clean energy has been considered an ideal and sustainable strategy. Herein, a self-assembled Zn2In2S5 with N-doped hollow carbon spheres (NHCS) was first synthesized via in-situ hydrothermal method to achieve excellent performance for aromatic pollutant removal with high amounts of H2O2 formed. Such a composite harvested phenol degradation efficiency of 97.6% with high H2O2 yield of 1.31 mmol L−1, and bisphenol A (BPA) degradation efficiency of 79.7% with high H2O2 yield of 2.31 mmol L−1. In addition, in-situ produced H2O2 solution of composites achieved high-efficiency bacterial inactivation. Based on the characterization results, NHCS contained abundant aromatic frameworks of π conjugates with CC and N-hybrid rings. Meanwhile, phenol or BPA with rich π bonds was tightly adsorbed to the photocatalyst surface through π-π interactions, which resulted in decreased activation energy with surface-adsorbed phenol * /BPA * . The obtained electrons were quickly transferred to the dispersed dissolved oxygen accompanied by promoting the reduction of O2 into H2O2. This synergetic process was expected to develop novel photocatalysts towards water disinfection achieved the reuse of wastewater.

Developing a novel nitrogen-doped hollow porous carbon sphere (N-HPCS) blended nanofiltration membrane with superior water permeance characteristic for high saline and colored wastewaters treatment

• A porous shell of nitrogen-doped hollow carbon sphere (N-HPCS) is synthesized. • The N-HPCS is incorporated in the NF membrane as a novel nanofiller. • Loading 0.25 wt% of N-HPCS manifested an excellent flux, antifouling, and long-term stability. • A novel fabricated membrane is desired for dye rejection with high salt recovery. This study developed a novel mixed matrix polyethersulfone (PES) nanofiltration membrane by blending nitrogen-doped hollow carbon sphere with a mesoporous shell (N-HPCS). By loading only 0.25 wt% of N-HPCS into membrane matrix (M2), hydrophilicity (28.9°), pure water flux (105.6 L/m 2 h), mean pore diameter (1.59 nm), and fouling resistance extensively increased. Compared to the unmodified membrane (M0), the rejection of four studied salts at 3 bar enhanced averagely by 2.4-times using the M2 membrane. M2 showed 97.0%, 98.7%, and 99.2% of dye retention for methylene blue, rhodamine B, and reactive red 195, respectively. In addition, its removal percentage for Pb(II) and Cd(II) was above 98%. The results showed that the Na 2 SO 4 concentration adversely affected its rejection due to the reduction in Debye length at higher ionic strength. While the reactive red 195 retention and Pb(II) removal almost remained constant by increasing their concentration. For studying the potential ability of M2 for high saline textile wastewater treatment, reactive red 195 retention was studied as a function of Na 2 SO 4 concentrations from 100 to 5000 mg/L. At the highest salt concentration of 5000 mg/L, outstanding dye retention of > 97.9% with water permeate > 104.1 L/m 2 was observed. Furthermore, 58 h successful continuous filtration of high concentration of Na 2 SO, reactive red 195, and Pb(II) demonstrated long-term stability of M2. Overall, our study provides a promising new approach for fabricating a high-performance modified membrane by N-HPCS for application in the practical context of wastewater treatment, especially in dye and textile industries.

Nitrogen-Doped Carbon Spheres with Precisely-Constructed Pyridinic-N Active Sites for Efficient Oxygen Reduction

Nitrogen-Doped Carbon Spheres with Precisely-Constructed Pyridinic-N Active Sites for Efficient Oxygen Reduction

Facile Synthesis of High Content Nitrogen-Doped Hierarchical Porous Carbon Spheres for High-Capacity Lithium-Sulfur Batteries

Facile Synthesis of High Content Nitrogen-Doped Hierarchical Porous Carbon Spheres for High-Capacity Lithium-Sulfur Batteries

Green self-activation engineering of metal–organic framework derived hollow nitrogen-doped carbon spheres towards supercapacitors

Hollow nitrogen-doped carbon microspheres are fabricated via a green self-activation strategy, and exhibit attractive electrochemical properties for aqueous supercapacitors.

Nitrogen-doped carbon hollow trunk-like structure as a portable electrochemical sensor for noradrenaline detection in neuronal cells

To date, the production and development of portable analytical devices for environmental and healthcare applications are rapidly growing. Herein, a portable electrochemical sensor for monitoring of noradrenaline (NA) secreted from living cells using mesoporous carbon-based materials was fabricated. The modification of the interdigitated electrode array (IDA) by nitrogen-doped mesoporous carbon spheres (N-doped MCS) and nitrogen-doped carbon hollow trunk-like structure (N-doped CHT) was used to fabricate the NA sensor. The N-doped CHT surface shows multiple holes distributed with micrometer-sized open holes (1–2 μm) and nanometer-sized thin walls (∼98 nm). The N-doped CHT surface heterogeneity of wrinkled and twisted hollow trunk structures improve the diffusion pathway and the NA molecules loading. The N-doped CHT/IDA showed a highly selective assay for monitoring of NA with high sensitivity (1770 μA/μM × cm2), a low detection limit (0.005 μM), and a wide linear range (0.01–0.3 μM). The N-doped CHT/IDA monitored the NA secreted from PC12 cells under various concentrations of simulation agents (KCl). The designed N-doped CHT/IDA provides a portable NA-sensor assay with facile signaling, good stability, high biocompatibility, in-vitro assay compatibility, and good reproducibility. Therefore, the designed sensor can be used as a portable sensor for NA detection in live cells and can be matched with portable smartphones after further developments.

Nitrogen doped carbon spheres from Tamarindus indica shell decorated with vanadium pentoxide; photoelectrochemical water splitting, photochemical hydrogen evolution & degradation of Bisphenol A

At present energy and environmental remediation are of highest priority for the well defined sustainability. Multifunctional materials that solve both the issues are on high demand. In the present work, a simple method has been followed to extract carbon spheres fromTamarindus indica(commonly known astamarind fruit) shelland doped with nitrogen (N-CS). Vanadium pentoxide nanoflakes were decorated aroundN-CS and the resultant is labeled as V2O5/N-CS nanocomposite. The spectroscopic, microscopic, elemental mapping and x-ray photoelectron spectroscopic characterization confirm the nitrogen doping and formation of hybrid material. N-CS, V2O5, and V2O5/N-CS nanocompositehave been evaluated for their efficiency to evolve hydrogen and for degradation of Bisphenol A (BPA) under visible light. In addition, electrocatalytic hydrogen evolution in presence of light has also been evaluated. The DRS spectrum proves the decrease in the bandgap of V2O5 upon its decoration around N-CS material. In a photochemical experiment, the V2O5/N-CS nanocomposite evolved 18,600 μmolg−1 of H2.Electrochemical hydrogen evolution has also been evaluated in presence of light and obtained the onset potential of −60mV with 52 mV dec−1 Tafel slope value. Scavenger studies indicate superoxide radicals and hydroxyl radicals are the active species responsible for the degradation of BPA. BPA degradation pathway has been predicted with the support of LC-MS results of the intermediates. All these results indicate the synthesized nanocomposite could be an efficient, stable multifunctional material for photocatalytic applications.

DSPE-PEG-Coated Uniform Nitrogen-Doped Carbon Capsules for NIR-Mediated Synergistic Chemophototherapy of Skin Cancer.

Uniform monodispersed nitrogen-doped carbon spheres have been emerging as an exciting platform for multipurpose medical applications like photothermal therapy and photoacoustic imaging and as carriers for aromatic anticancer drugs. However, synthesis of uniform N-doped mesoporous carbon of size less than 100 nm with reasonable photothermal and photodynamic activities is a challenging task. In this connection, the present paper reports synthesis of nitrogen-doped mesoporous carbon spheres (NMCSs) from five different copolymers of pyrrole and substituted aniline (-H, o-NH2, m-NH2, p-NH2, and m-NO2) using a soft template approach. It has been found that NMCSs synthesized from poly(pyrrole-co-m-nitroaniline) show uniform mesoporous particles of size 80 nm, a photothermal conversion efficiency η of 52.7%, and an average 1O2 quantum yield of 20% under exposure of a 980 nm NIR laser. With a high η of 52%, a multifunctional nanodrug has been formulated by loading 5-Fu in NMCS. The overall drug-loaded NMC was encapsulated by thermosensitive DSPE-PEG to improve translocation of the particle in the cell and thermosensitive drug release. A reliable release of anticancer drug 5-Fu (78%) has been achieved in 50 h in lysosomal conditions under 980 nm laser exposure. This NMC-5-Fu-DSPE-PEG nanodrug produces reactive oxygen species and enhances the therapeutic effect in comparison with free drug under an NIR laser as verified in B16F0 melanoma cells.

Nitrogen-doped biomass-derived porous carbon spheres for supercapacitors with ultrafast charge/discharge rate up to 2.5 V s−1

Nitrogen-doped biomass-derived porous carbon spheres for supercapacitors with ultrafast charge/discharge rate up to 2.5 V s−1

High Capacity and Fast Kinetics of Potassium-Ion Batteries Boosted by Nitrogen-Doped Mesoporous Carbon Spheres

HighlightsNitrogen-doped mesoporous carbon spheres (MCS) are prepared as anode materials of potassium-ion batteries by a facile method.The MCS have larger interlayer spacing, high specific surface area, abundant mesoporous structures and nitrogen-doped active sites, achieving high-rate and long-cycle performances as anodes.The capacitive-controlled effects play dominant role in total storage mechanism and the MCS anodes are successfully applied to K-ion full-cells achieving high rate capacities.

Incorporating Cobalt Nanoparticles in Nitrogen-Doped Mesoporous Carbon Spheres through Composite Micelle Assembly for High-Performance Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries have exhibited tremendous potential among the various secondary batteries benefitting from their large energy density, low expense, and enhanced security. However, the commercial use for Li-S batteries is immensely limited by the insulation of S, noticeable volume expansion from S to Li2S2/Li2S, and the undesired shuttle effect of lithium polysulfides (LiPs). Herein, a composite sulfur host has been prepared by in situ incorporations of cobalt nanoparticles (NPs) into nitrogen-doped mesoporous carbon spheres (Co/N-PCSs) through the composite micelle assembly strategy. The resultant functional Co/N-PCSs not only possess uniform spherical morphology with large open mesopores, high surface area, and pore volume but also have small Co NPs homogeneously inlaid into the pore walls of carbon frameworks. Both the experimental and theoretical calculation results demonstrate that the formed cobalt NPs can efficiently accelerate the lithium-ion diffusion reaction and greatly entrap the soluble intermediate LiPs. Benefiting from the well-designed structure, the Co/N-PCSs@S cathode with a S loading of 73.82 wt % delivers superior electrochemical performance, including long cycling stability (60% for the residual capacity at 1 A g-1 within 300 cycles) and excellent rate performance (∼512 mAh g-1 at 6 A g-1). This design strategy of implanting metal NPs in mesoporous carbon can be inspiring in energy storage applications.

Solvothermal synthesis of carbon incorporated MnS2 Spheres; high sensing performance towards the detection of furazolidone in bio-fluids

Herein, we designed and synthesis a composite material consisting of manganese disulfide anchored on nitrogen-doped carbon spheres (MnS2@N-CS) as an electrode modifier, and their application to the detection of furazolidone (FUZ) was investigated. The integration of MnS2 and N-CS by solvothermal assisted synthesis route using inexpensive glucose as a carbon source as well as served as a nucleation center for the formation of MnS2. The morphology and crystalline structure of the MnS2@N-CS were well characterized by XRD, XPS, FESEM, HR-TEM, and EDX analysis. The electrochemical test of the MnS2@N-CS modified electrode shows an interesting electrochemical performance for the sensitive and selective detection of FUZ with a broad concentration range of 0.001–1590 µM and a lower detection limit (LOD) of 0.0041 µM. The enhancement in the catalytic activity of MnS2@N-CS can be attributed to the synergistic effect of MnS2 and N-CS, high electron transportation, and the unique spherical structure of MnS2@N-CS. The newly developed MnS2@N-CS sensor also displayed excellent sensitivity, repeatability, and reproducibility with a relative standard deviation (RSD) of 3.2%. Furthermore, the strong interaction between MnS2 and N-CS could help to succeed in the long-term stability of the sensor. Finally, this MnS2@N-CS sensor was successfully applied for the detection of FUZ in the biological sample and food samples such as human serum, urine, and milk with excellent recoveries.

Catalytic Activity Analysis of Uniform Palladium Nanoparticles Anchored on Nitrogen-Doped Mesoporous Carbon Spheres for Oxygen Reduction Reaction

Palladium (Pd)-based catalysts, as an ideal alternative to platinum (Pt) for oxygen reduction reaction (ORR), have been the focus of recent research because of their comparable catalytic activities, low cost, and abundant resource. Unfortunately, Pd is easy to suffer from agglomeration because of the decrease of their excessive metal surface free energy at elevated temperature, dramatically reducing their catalytic activities for ORR. Herein, we report a facile in-situ self-assembly strategy coupled with the annealing method to synthesize the well-dispersed Pd nanoparticles on nitrogen-doped mesoporous carbon spheres (Pd-NMCS) catalysts, and analyze the catalytic activities for ORR. More importantly, the nitrogen atoms in the NMCS can expose more basic/catalytic sites that can coordinate with Pd nanoparticles to form the strong Pd-N interactions, which can not only tightly anchor Pd nanoparticles but also be advantageous to show outstanding stability and good resistance to methanol crossover. As expected, the obtained Pd-NMCS exhibit good ORR catalytic activities, desirable reaction kinetics, excellent stability, as well as better methanol tolerance, which may offer potential for the practical application of fuel cells. The existence of strong Pd-N interaction enables the Pd nanoparticles to uniformly disperse on the NMCS (Pd-NMCS), thus achieving good ORR catalytic activities, desirable reaction kinetics, outstanding stability as well as better tolerance to methanol crossover of the Pd-NMCS catalyst in the alkaline condition.

Efficient oxygen reduction reaction by a highly porous, nitrogen-doped carbon sphere electrocatalyst through space confinement effect in nanopores

A highly porous nitrogen-doped carbon sphere (NPC) electrocatalyst was prepared through the carbonization of biomass carbon spheres mixed with urea and zinc chloride in N2 atmosphere. The sample carbonized at 1000 °C demonstrates a superior oxygen reduction reaction (ORR) performance over the Pt/C electrocatalyst, while its contents of pyridinic nitrogen and graphitic nitrogen are the lowest among samples synthesized at the same or lower carbonization temperatures. This unusual result is explained by a space confinement effect from the microporous and mesoporous structures in the microflakes, which induces the further reduction of peroxide ions or other oxygen species produced in the first step reduction to water to have the preferred overall four electron reduction ORR process. This work demonstrates that in addition to the amount or species of its active sites, the space confinement can be a new approach to enhance the ORR performance of precious-metal-free, nitrogen-doped carbon electrocatalysts.

Molecular Level Design of Nitrogen-Doped Well-Defined Microporous Carbon Spheres for Selective Adsorption and Electrocatalysis.

Nitrogen-doped porous carbon spheres have attracted great interest in diversified fields owing to their unique physical and chemical properties. However, the synthesis of nitrogen-doped porous carbon spheres with hierarchical superstructures and refined micropore structures is still a challenge. Herein, we develop a molecular-scale silica templating strategy to prepare nitrogen-doped microporous carbon spheres (MCSSs) with high porosity and a well-defined micropore structure. Octa(aminophenyl) polyhedral oligomeric silsesquioxane is used as a building block in MCSS precursors to provide precise molecular-scale templating and nitrogen doping. The morphology of MCSSs can be easily tuned by choosing the proper solvent. The as-synthesized MCSS with a large surface area (2036 m2 g-1), narrow micropore size distribution, nitrogen doping, and hierarchical geometry can serve as an efficient selective adsorbent for CO2 and organic pollutants. Furthermore, the MCSS decorated with Fe-N-C active sites (MCSS-Fe) shows enhanced electrocatalytic ORR activity in alkaline solution. This novel approach may open a new avenue for controllable fabrication of porous carbon spheres with desired geometry and well-designed pore structure and show potential applications in selective adsorption and catalysis.