Synergistic Effect Of Nitrogen Doping Research Articles

Fluorine-doped carbon quantum dots with deep-red emission for hypochlorite determination and cancer cell imaging

As a type of new carbon-based nanomaterials, carbon dots (CDs) possess exceptional optical properties, making them highly desirable for use in fluorescent sensors. However, the CDs with deep-red (DR) or near-infrared (NIR) emission have rarely been reported. In this work, we prepared deep-red emissive fluorine-doped carbon quantum dots (F-CDs) by introducing a precursor simultaneously containing fluorine and amidogen. The synergistic effect of nitrogen doping and D-π-A pattern production contributed to the maximum emission of F-CDs at 636 nm with an absolute quantum yield of 36.00% ± 0.68%. Moreover, we designed an F-CDs-based fluorescence assay to determine the content of hypochlorite (ClO−), with a limit of detection (LOD) as low as 15.4 nmol/L, indicating the high sensitivity of F-CDs to ClO−. In real samples, the F-CDs-based fluorescent sensor exhibited excellent sensitivity and selectivity in the detection of ClO−, with an error below 2%, suggesting their great potential in daily life. In cancer cell imaging, the F-CDs not only demonstrated high sensitivity to ClO− but also exhibited excellent mitochondria targeting, as evidenced by the high Pearson's correlation coefficient (PCC) of 0.93 in colocalization analysis. The work presented here suggests the great potential of replacing commercial dyes with F-CDs for highly specific mitochondria labeling and cell imaging.

Fe-Decorated Nitrogen-Doped Carbon Nanospheres as an Electrochemical Sensing Platform for the Detection of Acetaminophen.

In this work, Fe-decorated nitrogen-doped carbon nanospheres are prepared for electrochemical monitoring of acetaminophen. Via a direct pyrolysis of the melamine-formaldehyde resin spheres, the well-distributed Fe-NC spheres were obtained. The as-prepared Fe-NC possesses enhanced catalysis towards the redox of acetaminophen for abundant active sites and high-speed charge transfer. The effect of loading Fe species on the electrochemical sensing of acetaminophen is investigated in detail. The synergistic effect of nitrogen doping along with the above-mentioned properties is taken advantage of in the fabrication of electrochemical sensors for the acetaminophen determination. Based on the calibration plot, the limits of detection (LOD) were calculated to be 0.026 μM with a linear range from 0-100 μM. Additionally satisfactory repeatability, stability, and selectivity are obtained.

Dual synergistic effects assisting Cu-SeS2 electrochemistry for energy storage

Selenium sulfide (SeS2) features higher electronic conductivity than sulfur and higher theoretical capacity and lower cost than selenium, attracting considerable interest in energy storage field. Although nonaqueous Li/Na/K-SeS2 batteries are attractive for their high energy density, the notorious shuttle effect of polysulfides/polyselenides and the intrinsic limitations of organic electrolyte have hindered the deployment of this technology. To circumvent these issues, here we design an aqueous Cu-SeS2 battery by encapsulating SeS2 in a defect-enriched nitrogen-doped porous carbon monolith. Except the intrinsic synergistic effect between Se and S in SeS2, the porous structure of carbon matrix has sufficient internal voids to buffer the volume change of SeS2 and provides abundant pathways for both electrons and ions. In addition, the synergistic effect of nitrogen doping and topological defect not only enhances the chemical affinity between reactants and carbon matrix but also offers catalytic active sites for electrochemical reactions. Benefiting from these merits, the Cu-SeS2 battery delivers superior initial reversible capacity of 1,905.1 mAh g-1 at 0.2 A g-1 and outstanding long-span cycling performance over 1,000 cycles at 5 A g-1. This work applies variable valence charge carriers to aqueous metal-SeS2 batteries, providing valuable inspiration for the construction of metal-chalcogen batteries.

Molten salt synthesis of nitrogen-doped hierarchical porous carbon from plantain peels for high-performance supercapacitor

• A green and scalable molten salt method is employed to synthesize hierarchical porous carbon from plantain peels. • A high SSA of 959 m 2 /g, interconnected pore structure and highly defective and graphitized framework obtained. • The N -doped porous carbon exhibited high specific capacitance of 550 F/g at a current density of 1 A/g in a three-electrode setup. • Capacitance retention of 99% after 1000 cycles at 4 A/g This work employs a non-corrosive and non-toxic molten salt combination of NaCl and KCl as an activation agent in an air environment to synthesize nitrogen-doped hierarchical porous carbon from plantain peels at 800 °C for supercapacitor application. Due to the synergistic effect of nitrogen doping, the synthesized nitrogen-doped activated unripe porous carbon (AUPN) has a hierarchical (micro-meso-macropores) porous structure and a high surface area of 959 m 2 /g, providing sufficient active sites for charge storage, rapid electrolyte and ionic mobility. X-ray diffraction and Raman spectroscopy analysis revealed the formation of a carbon product with a limited degree of graphitization and the crystallite size (L a ), which is valuable for evaluating the defects caused by nitrogen doping. In a three-electrode cell with a 6 M KOH electrolyte, AUPN recorded a specific capacitance of 550 F/g at 1 A/g. After 1000 cycles, capacitance retention was 99% at 4 A/g. Compared to other reported porous carbon materials, the overall electrochemical performance of AUPN is superior. This is due to the abundant nitrogen-doping, which introduces pseudocapacitance and increases the surface wettability of the porous carbon, resulting in a decrease in ionic-transport resistance. These findings indicate that this green and scalable technique is a potential synthesis method for producing porous carbon materials for energy storage applications.

Unveiling the cooperative roles of pyrrolic-N and carboxyl groups in biomass-derived hierarchical porous carbon nanosheets for high energy-power Zn-ion hybrid supercapacitors

The low energy density of Zn-ion hybrid supercapacitors (ZHSCs) remains to be one of the key challenges against its commercialization due to the lack of cathode materials with high capacity, particularly at high current density. Herein, biomass-derived hierarchical porous carbon nanosheets functionalized with oxygen groups and nitrogen dopants used as the cathode for ZHSCs are synthesized via a consecutive two-step pyrolysis-activation strategy, which manifest a high capacity of 220.1 mAh g−1 at 0.2 A g−1, and maintain 118.2 mAh g−1 when the current density increases 100 times to 20 A g−1. Benefitting from the promising performance of the as-obtained cathode materials, the ZHSC finally demonstrates an ultra-high energy density of 181.6 Wh kg−1 at the power density of 165.0 W kg−1, which surpasses the vast majority of state-of-the-art reported ZHSCs. Accordingly, the experimental results and theoretical calculations reveal that the hierarchically porous ultrathin nanosheet architecture with macro-, meso- and micropores is favorable for boosting the physical adsorption of Zn2+, while the introduction of surface pyrrolic-N and carboxyl (–COOH) groups synergistically boosts the chemical adsorption of Zn2+. The present work provides insights into the synergistic effect of nitrogen doping and oxygen functional groups modification hierarchical porous carbon for Zn-ion storage.

Synthesis of ultra-high specific surface area aerogels with nitrogen-enriched Ti3C2Tx nanosheets as high-performance supercapacitor electrodes

A novel combination method for nitrogen doping and 3D structure construction is explored to prepare nitrogen-doped Ti3C2Tx aerogels. The synergistic effects of nitrogen doping and 3D structure construction on Ti3C2Tx are analyzed.

3D nitrogen and sulfur equilibrium co-doping hollow carbon nanosheets as Na-ion battery anode with ultralong cycle life and superior rate capability

In sodium ion batteries, heteroatom doping is deemed to be an important way to enhance the electrochemical activity of carbon-based anode materials. In this work, we report 3D nitrogen and sulfur equilibrium co-doping hollow carbon nanosheets for sodium ion battery anode, which can deliver a maximum capacity of 497 mA h g−1 under 0.2 A g−1, good rate capability (260 mA h g−1 under 50 A g−1 and 245 mA h g−1 under 60 A g−1), and good cycling stability (339 mA h g−1 under 5 A g−1 over 5000 cycling and 249 mA h g−1 under 10 A g−1 over 5000 cycling), suggesting wonderful electrochemical performance. To the best of our knowledge, the excellent performance of the long-term cyclability at such high rates is rarely reported for carbon-based sodium ion battery anodes. Meanwhile, the storage mechanism of sodium was studied by in-situ Raman spectroscopy, cyclic/linear sweep voltammetry and electrochemical impedance spectroscopy. Its superior properties can be attributed to the special three-dimensional hollow nanosheets with high specific surface, doping regulation of N and S elements to carbon structure and synergistic effect of nitrogen doping enhancing pseudocapacitive contributions.

Synergistic Effect of Nitrogen Doping and Ultra-Microporosity on the Performance of Biomass and Microalgae-Derived Activated Carbons for CO2 Capture.

We report a unique naturally derived activated carbon with optimally incorporated nitrogen functional groups and ultra-microporous structure to enable high CO2 adsorption capacity. The coprocessing of biomass (Citrus aurantium waste leaves) and microalgae (Spirulina) as the N-doping agent was investigated by probing the parameter space (biomass/microalgae weight ratio, reaction temperature, and reaction time) of hydrothermal carbonization and activation process (via the ZnCl2/CO2 activation) to generate hydrochars and activated carbons, respectively, with tunable nitrogen content and pore sizes. The central composite-based design of the experiment was applied to optimize the parameters of the prehydrothermal carbonization procedure resulting in the fabrication of N-enriched carbonaceous products with the highest possible mass yield and nitrogen content. The resulting hydrochars and activated carbon samples were characterized using elemental analysis, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, and Brunauer-Emmett-Teller surface area analysis. We observe that while N-doping and the activation process can individually enhance the CO2 adsorption capacity to some extent, it is the combined effect of the two processes that synergistically work to greatly increase the adsorption capacity of the N-doped activated carbon by an amount which is more than the sum of individual contributions. We analyze the origins of this synergy with both physical and chemical characterization techniques. The resulting naturally derived activated carbon demonstrates one of the highest CO2 adsorption capacities (8.43 mmol/g) with rapid adsorption kinetics and good selectivity and reusability.

Excess Se-doped MoSe2 and nitrogen-doped reduced graphene oxide composite as electrocatalyst for hydrogen evolution and oxygen reduction reaction

Noble metal catalysts (e.g., Pt, Ru, and Ir) are expensive and scarce and cannot be synthesized at a large scale. The cheap and stable chalcogenides seem to be an attractive alternative and are most likely to replace the precious metal catalysts. However, the poor conductivity, limited number of active sites, and other properties of the chalcogenides limit their applications. In this work, we synthesized defect-rich MoSe2 with nitrogen-doped reduced graphene oxide (MoSe2/NG) in a simple hydrothermal process by introducing excess Se precursor. The catalyst with optimal performance (MoSe2/NG-4) exhibits good bifunctional properties in the oxygen reduction reaction and hydrogen evolution reaction (HER). It exhibits a small overpotential of 120 mV at a current density of 10 mA cm −2 in the HER, with a smaller Tafel slope of 69 mV dec−1, which is much lower than the values of most reported most reported Mo-based catalysts. Besides, it behaves as an effective catalyst in the ORR and adopts a four-electron reaction pathway. This excellent bifunctional catalytic property is mainly due to the rich heterostructure of MoSe2/NG-4 and synergistic effect of nitrogen doping, excellent conductivity of graphene, and the rich active sites. This work provides a new approach for the synthesis and application of chalcogenides and their complexes in the field of catalysis.

Synergistic Effects of Nitrogen Doping on MXene for Enhancement of Hydrogen Evolution Reaction

Earth-abundant, nonprecious, and efficient electrocatalysts for effective hydrogen evolution reaction (HER) are crucial for future large-scale green energy production. Low-cost two-dimensional MXen...

Fe3C/Fe2O3 heterostructure embedded in N-doped graphene as a bifunctional catalyst for quasi-solid-state zinc–air batteries

The development of nonprecious metal catalysts with highly efficient and durable activities is of great importance for high performances of zinc–air batteries. Herein, the N-doped graphene wrapped Fe3C/Fe2O3 heterostructure has been designed as a bifunctional oxygen catalyst for zinc–air batteries. In the synthesis process of the catalyst, graphene oxide (GO) can assemble with graphitic carbon nitride (g-C3N4) and FeOOH nanorods by the π−π stacking and hydrogen bonds, respectively. The assembly of GO, g-C3N4 and FeOOH nanorods results in nanostructure of carbon layers coated iron species and leads to outstanding durability in both alkaline and acidic media. The synergistic effect of nitrogen doping and Fe3C/Fe2O3 heterostructure allows the catalyst (Fe3C/Fe2O3@NGNs) to display high oxygen reduction and evolution reaction activities. The liquid zinc–air battery assembled with the catalyst presented a remarkable peak power density (139.8 mW cm−2), large specific capacity (722 mAh g−1) and excellent charging–discharging cycling performance. The quasi-solid-state zinc–air battery with the catalyst exhibited an impressive open-circuit voltage and a peak power density. Therefore, the Fe3C/Fe2O3@NGNs catalyst is expected to have a bright future for practical applications in energy conversion devices.

Magnetic Ni-Co alloy encapsulated N-doped carbon nanotubes for catalytic membrane degradation of emerging contaminants

Nitrogen-doped carbon nanotubes encapsulated with Ni-Co alloy nanoparticles (NiCo@NCNTs) were readily synthesized by annealing Ni/Co salts with dicyandiamide. The magnetic nanocarbons were assembled as a flat membrane for heterogeneous degradation of organic toxins. The synergistic effect of nitrogen doping and metal alloy encapsulation significantly enhanced the catalytic activity and stability of NCNTs in catalytic activation of peroxymonosulfate (PMS) for purification of an emerging pollutant, ibuprofen. The hybrid catalyst yielded a fast reaction rate of 0.31 min−1, which was 23.4 and 5.8 times higher than that of pristine CNTs and monometallic (Ni or Co) encased CNTs, respectively. The robust membrane catalysis was further confirmed by degrading other organic aqueous pollutants, such as naproxen, sulfachloropyridazine, phenol, methylene blue, and methyl orange. Mechanistic investigation was performed using electron paramagnetic resonance and competitive radical screening tests, which indicated that radical (OH and SO4−) oxidation and nonradical pathway co-existed and played critical roles for catalytic degradation. The study provides a novel advanced oxidation system with catalytic membrane for wastewater remediation.

Ultra-small Mo2C nanodots encapsulated in nitrogen-doped porous carbon for pH-universal hydrogen evolution: insights into the synergistic enhancement of HER activity by nitrogen doping and structural defects

A facile one-pot synthesis method was used. The synergistic effect of nitrogen doping and structure defects on the carbon layer leaded to the high HER activity.

Synergistic Effect of Nitrogen Doping and MWCNT Intercalation for the Graphene Hybrid Support for Pt Nanoparticles with Exemplary Oxygen Reduction Reaction Performance.

The potential of graphene–multi-walled-carbon nanotube (G-M) hybrids prepared by the one-pot modified Hummers method followed by thermal annealing has been demonstrated by employing one as an electrocatalyst support for oxygen reduction reaction (ORR). N doping effectively modified the electronic structure of the G-M hybrid support, which was beneficial for the uniform distribution of Pt nanoparticles, and ORR activities were further improved. The newly prepared Pt/N-G-M catalyst demonstrated higher electrochemical activity than Pt/G-M and Pt/G catalysts. Even compared with commercial 20 wt % Pt/C (JM20), Pt/N-G-M delivered a better half-wave potential and mass activity. In terms of the durability test, Pt/N-G-M maintained 72.7% of its initial electrochemical active surface area (ECSA) after 2000 repeated potential cycles between 0 and 1.2 V in acidic media in relation to the 44.4% retention for JM20. Moreover, the half-wave potential for Pt/N-G-M showed only a minimal change, significantly superior to the 139 mV of loss for JM20. It is expected that Pt/N-G-M can be the potential candidate as a highly efficient and durable catalyst if utilized in proton exchange membrane fuel cells (PEMFCs).

In situ growth of Ni/NiO on N-doped carbon spheres with excellent electrocatalytic performance for non-enzymatic glucose detection

A non-enzymatic potentiometric glucose sensor was developed by modifying a glass carbon electrode (GCD) with Ni/NiO decorated nitrogen doped carbon spheres (Ni/NiO/NCSs). The Ni/NiO/NCSs were prepared with in situ growth of Ni/NiO on the nitrogen doped carbon spheres. The morphology and composition of the materials were characterized by SEM, TEM, XRD and XPS, respectively. The Ni/NiO/NCSs modified GCD electrode exhibited higher current response than that of nitrogen free counterpart and NiO/nitrogen carbon spheres for non-enzymatic oxidation of glucose in alkaline media. The amperometric measurement revealed that the sensor had wide linear regions of 2 μM–600 μM and 800 μM-2500 μM with a sensitivity of 219.19 μA mM−1cm−2 and 87.88 μAmM−1cm−2 respectively. Moreover, the Ni/NiO/NCS composites also exhibited good selectivity by adding certain amount of urea, NaCl, l-proline, l-valine, l-Leucine and ascorbic acid into 0.1 M NaOH solution. The excellent electrocatalytic performance may be attributed to the synergistic effect of nitrogen doping and Ni loading, which may result in the increase of electron density and the enhancement of surface conductivity of the composite electrode materials.

Cooperation of nitrogen-doping and catalysis to improve the Li-ion storage performance of lignin-based hard carbon

Hard carbon draws great interests as anode material in lithium ion batteries (LIBs) due to its high theoretical capacity, high rate capability and abundance of its precursors. Herein we firstly synthesize the lignin-melamine resins by grafting melamine onto lignin. Afterwards, nitrogen doped hard carbon is prepared by the pyrolysis of lignin-melamine resins with the aid of catalyst (Ni(NO3)2·6H2O) at 1000 °C. Compared with the samples without nitrogen-doping and catalysis, as-prepared nitrogen doped hard carbon exhibits higher reversible capacity (345 mAh g–1 at 0.1 A g−1), higher rate capability (145 mAh g−1 at 5 A g–1) and excellent cycling stability. The superior electrochemical performance is ascribed to the synergistic effect of nitrogen doping, graphitic structure and amorphous structure. Among them, nitrogen doping could create the vacancies around the nitrogen sites, which enhance the reactivity and the electronic conductivity of materials. Additionally, graphitic structure also enhances the electronic conductivity of materials, thus improving the electrochemical performance of hard carbon. It is worthwhile that lignin, renewable and abundant biopolymer, is converted to hard carbon with good electrochemical performance, which realizes the high value utilization of lignin.

Low-Temperature Sol-Gel Synthesis of Nitrogen-Doped Anatase/Brookite Biphasic Nanoparticles with High Surface Area and Visible-Light Performance

Nitrogen doping in combination with the brookite phase or a mixture of TiO2 polymorphs nanomaterials can enhance photocatalytic activity under visible light. Generally, nitrogen-dopedanatase/brookite mixed phases TiO2 nanoparticles obtained by hydrothermal or solvothermal method need to be at high temperature and with long time heating treatment. Furthermore, the surface areas of them are low (<125 m2/g). There is hardly a report on the simple and direct preparation of N-doped anatase/brookite mixed phase TiO2 nanostructures using sol-gel method at low heating temperature. In this paper, the nitrogen-doped anatase/brookite biphasic nanoparticles with large surface area (240 m2/g) were successfully prepared using sol-gel method at low temperature (165 °C), and with short heating time (4 h) under autogenous pressure. The obtained sample without subsequent annealing at elevated temperatures showed enhanced photocatalytic efficiency for the degradation of methyl orange (MO) with 4.2-, 9.6-, and 7.5-fold visible light activities compared to P25 and the amorphous samples heated in muffle furnace with air or in tube furnace with a flow of nitrogen at 165 °C, respectively. This result was attributed to the synergistic effects of nitrogen doping, mixed crystalline phases, and high surface area.

Few layer nitrogen-doped graphene with highly reversible potassium storage

Few-layer nitrogen-doped graphene (FLNG) have been successfully prepared by a simple bottom-up synthesis of technique using Dicyandiamide and Coal tar pitch as raw materials. The as-synthesized FLNG with the thickness of about 2–10nm, high surface area (479.21m2g−1) and high nitrogen content (14.68 at%) exhibits excellent K-ion storage performances. The FLNG delivers competitive reversible capacity (320mAhg−1 at 50mAg−1 after 60 cycles), superior rate capability as well as long-term cycling life at large current density (150mAhg−1 at 500mAg−1 after 500 cycles). The multiple synergistic effects of nitrogen doping, high specific surface area, interconnected mesopores with large pore volume not only facilitate the ions transportation throughout the electrode matrix, but also provide substantial active sites for K-ion storage. Furthermore, Electrochemical Impedance Spectroscopy (EIS) of the FLNG electrode during the initial K-ion intercalation process were measured to thoroughly understand the electrochemical reaction process. These results will be beneficial for designing novel anode materials for alkaline-ion batteries in the future.

The synergistic effect of nitrogen doping and para-phenylenediamine functionalization on the physicochemical properties of reduced graphene oxide for electric double layer supercapacitors in organic electrolytes

This work studied the synergistic effect of N-doping and p-PDA functionalization on the properties of RGO for supercapacitors.

Adsorption of CO2 by Petroleum Coke Nitrogen-Doped Porous Carbons Synthesized by Combining Ammoxidation with KOH Activation

The goal of our research is developing an efficient and cost-effective carbonaceous CO2 sorbent. Using petroleum coke as the precursor, porous nitrogen-doped carbons were prepared by combining ammoxidation with KOH activation. The as-synthesized samples possess highly developed microporosities and large nitrogen loadings. High CO2 adsorption capacities of 3.76–4.57 mmol/g at 25 °C and 5.80–6.62 mmol/g at 0 °C under atmospheric pressure were achieved. Specifically, the sample prepared under mild temperature (650 °C) and low KOH/precursor ratio (KOH/precursor = 2) shows a CO2 uptake of 4.57 mmol/g at 25 °C, among the highest achieved for nitrogen-doped porous carbons. This high CO2 capture capacity can be attributed to the synergistic effect of nitrogen doping and high narrow microporosity of the sorbent. However, experimental evidence suggests that nitrogen doping contributes less than narrow microporosity. Additionally, the CO2/N2 selectivity and CO2 heats of adsorption of the sorbent are as high as 22 an...