Nitrogen Co-doping Research Articles

Unraveling the Ion Uptake Capacitive Deionization of Sea- and Highly Saline-Water by Sulfur and Nitrogen Co-Doped Porous Carbon Modified with Molybdenum Sulfide.

In parallel to the depletion of potable water reservoirs, novel technologies have been developed for seawater softening, as it is the most abundant source for generating deionized water. Although salt removal at subosmotic pressures and ambient temperatures by applying low-operating potentials with high energy efficiency made capacitive deionization (CDI) an advantageous water-softening process, its practical application is limited by insufficient ion removal capacity and low concentration influent. The performance of a CDI system is in progress with engineering the electrode active materials, also facilitating the advance design in highly saline- and seawater study. Herein, an innovative strategy was developed to provide high-performance CDI systems based on efficient and electrochemical ion-uptake active materials with a simple initial preparation. Nitrogen-doped porous carbons (N-pCs) received benefits from a high specific surface area and good surface wettability. The N-pCs were modified with molybdenum oxide/sulfide intercalative array and developed as CDI electrode active materials for desalination of both low/medium saline- and seawater. The MoS2/S,N-pC electrode materials exhibited perfect optimized salt adsorption capacity (SACs) of 47.9 mg g-1 when compared to N-pC (37.9 mg g-1) and MoO3/N-pC (39.6 mg g-1) counterparts at 1.4 V in a 750 ppm NaCl solution. In addition, the assembled CDI cells exhibited reasonable cycle stability and retained 96.7% of their initial SAC in continuous CDI cycles for 128,000 s. The fabricated CDI cell rendered an excellent salt removal efficiency (SRE, %) of 13.34% from the real seawater sample at 1.2 V. In detail, the SRE % of the NaCl, KCl, MgCl2, and CaCl2 soluble salts with respect to seawater sample exhibited a remarkable SRE % of 30.8%, 36%, 32.6%, and 19.3%, respectively. These SRE % values (>13.34%) provide convincing evidence on the reasonable ion uptake capability of the fabricated CDI cells for removing Na+, K+, Mg2+, and Ca2+ ions compared to other soluble component. The advanced cell design parallel to the promising outcomes provided herein makes these CDI systems immensely propitious for efficient water softening.

Synergistic effect of nitrogen and sulfur co-doped holey graphene for sensitive fenitrothion detection supported by DFT study

The rational design and fabrication of high-performance electrochemical sensors for the determination of environmentally hazardous substances, such as fenitrothion, is of great significance and remains a great challenge. Understanding the interaction between fenitrothion and substrates is critical to inform the design of electrochemical sensors. Herein, we have developed an electrochemical sensor based on nitrogen and sulfur co-doped holey graphene (NS-HG) for fenitrothion. NS-HG with high levels of nitrogen and sulfur leaded to excellent conductivity and a fast electron transfer rate. NS-HG modified electrode showed high electrochemical activity towards fenitrothion. The results were supported by density functional theory (DFT) calculations. The adsorption energy calculations and density of states analysis (DOS) showed that NS-HG exhibited strengthened fenitrothion adsorption and fast electron transfer rate by nitrogen and sulfur co-doping. The fenitrothion sensor based on NS-HG showed an excellent analytical response with high sensitivity, low LOD (0.062 ng·ml−1), excellent selectivity, stability, and satisfactory recoveries for real samples. This research provides new insights into understanding the synergetic effect of co-dopant, and new opportunities for the rational design of electrochemical sensors.

Investigating the synergistic effect of sulfur and nitrogen co-doping in graphene for enhanced CO2 reduction to CO: A computational study

Recently, N and S co-doped graphene showed excellent activity and selectivity for electrochemical CO2 reduction (CO2RR) to CO, much better than that of singly N doped counterpart, but the underlying mechanism of S promotional effect is still elusive. Here, by using density functional theory (DFT) calculation, N or S singly doped graphene and co-doped graphene for CO2RR to CO and competitive hydrogen evolution reaction (HER) are compared to reveal the synergy effect. The results show that singly S doped graphene exhibits negligible activity for CO production because of high formation energy of COOH intermediate, whereas graphene doped with pyridinic N and pyrrolic N show moderate energy barrier for CO2RR, but N atom would be easily passivated due to strong binding with H atom. In N and S co-doped graphene, N and S pair prefer to replace CC bond, but they are not bonded. In this configuration, the S atom can serve as active site, having even lower energy barrier for CO2RR than that of pyridinic N, meanwhile the S atom is not passivated by hydrogen atom. The electronic origin of enhanced activity for S atom is also presented.

Nitrogen and Sulfur Co-Doped Carbon Quantum Dot-Engineered TiO2 Graphene on Carbon Fabric for Photocatalysis Applications

Nitrogen and Sulfur Co-Doped Carbon Quantum Dot-Engineered TiO₂ Graphene on Carbon Fabric for Photocatalysis Applications

Phosphorus and Nitrogen Codoped Carbon Nanoparticles as Both Anode and Cathode Materials with Enhanced Li+/PF6– Storage for High Energy Density Lithium-Ion Capacitors

Phosphorus and Nitrogen Codoped Carbon Nanoparticles as Both Anode and Cathode Materials with Enhanced Li⁺/PF₆^– Storage for High Energy Density Lithium-Ion Capacitors

Highly efficient electrosynthesis of H2O2 in acidic electrolyte on metal-free heteroatoms co-doped carbon nanosheets and simultaneously promoting Fenton process

Recently electrochemical synthesis of H2O2 through oxygen reduction reaction (ORR) via 2e− pathway is considered as a green and on-site route. However, it still remains a big challenge for fabricating novel metal-free catalysts under acidic solutions, since it suffers from high overpotential due to the intrinsically week *OOH adsorption. Herein, a co-doped carbon nanosheet (O/NC) catalyst toward regulating O and N content was synthesized for improving the selectivity and activity of H2O2 electrosynthesis process. The O/NC exhibits outstanding 2e− ORR performance with low onset potential of 0.4 V (vs. RHE) and a selectivity of 92.4% in 0.1 mol/L HClO4 solutions. The in situ electrochemical impedance spectroscopy (EIS) tests reveals that the N incorporation contributes to the fast ORR kinetics. The density functional theory (DFT) calculations demonstrate that the binding strength of *OOH was optimized by the co-doping of oxygen and nitrogen at certain content, and the O/NCCOOH site exhibits a lower theoretical overpotential for H2O2 formation than OCCOOH site. Furthermore, the promoted kinetics for typical organic dye degradation in simultaneous electron-Fenton process on O/NC catalyst was demonstrated particularly for broadening its environmental application.

Synthesis and characterization of nitrogen and phosphorus co-doped TiO2 nanoparticle anchored graphitic carbon nitride nanosheets: Photocatalytic application on dye removal

In this study, nitrogen and phosphorus co-doped titanium dioxide (NP-TiO2) nanoparticles are anchored onto graphitic carbon nitride nanosheets (GCN) by the simple sonochemical method. The synthesized NP-TiO2/GCN nanocomposites are characterized by UV–Visible absorbance spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, Photoluminescence spectroscopy, Scanning electron microscopy and Transmission electron microscopy. We find that the co-doping of nitrogen and phosphor to TiO2 nanoparticles of size (10–25) nm as well as simultaneous anchoring onto GCN nanosheets. The optimised 2.5 wt% GCN in NP-TiO2/GCN showed complete degradation of MB dye and MO dye at 105 min and 60 min respectively. The photocatalytic degradation performance is 5 times superior to that of individual NP-TiO2 and GCN under visible light. The degradation rate constants of NP-TiO2/GCN is found to be 0.01491 min−1 for MB dye and 0.02153 min−1 for MO dye. The improved photocatalytic performance of NP-TiO2/GCN nanocomposite is due to the synergistic effects of both NP-TiO2 and GCN, which decrease the bandgap as well as charge recombination.

Boron–Nitrogen Codoped Carbon Nanosheets as Oil-Based Lubricant Additives for Antioxidation, Antiwear, and Friction Reduction

Boron–Nitrogen Codoped Carbon Nanosheets as Oil-Based Lubricant Additives for Antioxidation, Antiwear, and Friction Reduction

Boosting supercapacitor performance through the facile synthesis of boron and nitrogen co-doped resin-derived carbon electrode material

In this study, we present the synthesis of porous carbon materials designated as B, N co-doped porous carbon materials (PRNB), co-doped with boron and nitrogen through a two-step carbonization process of self-made phenolic resin. Among them, urea, boric acid, and potassium oxalate were used as the heteroatom dopants and activator, respectively. The co-doping of boron and nitrogen induced a unique electronic structure, resulting in improved capacitance performance compared to single-doped materials. Moreover, the addition of potassium oxalate as an activator facilitated the etching of the carbon framework during pyrolysis. Owing to the co-doping effect of boron and nitrogen and the abundant micropores, the PRNB material exhibited a remarkably high specific capacitance of 330 F g−1 at 1 A g−1. It also displayed excellent rate performance (70 %) and stability, with only a 6 % loss after 10,000 cycles compared to other materials. The symmetric electrode based on PRNB achieved an energy density of up to 29.7 Wh kg−1 in a neutral electrolyte, which provides a novel approach for resin-derived carbon to improve electrochemical performance.

Effects of oxygen/nitrogen co-incorporation on regulation of growth and properties of boron-doped diamond films

Regulation with nitrogen and oxygen co-doping on growth and properties of boron doped diamond films is studied by using laughing gas as dopant. As the concentration of laughing gas (N2O/C) increases from 0 to 10%, the growth rate of diamond film decreases gradually, and the nitrogen-vacancy (NV) center luminescence intensity increases first and then weakens. The results show that oxygen in laughing gas has a strong inhibitory effect on formation of NV centers, and the inhibitory effect would be stronger as the concentration of laughing gas increases. As a result, the film growth rate and nitrogen-related compensation donor decrease, beneficial to increase the acceptor concentration (∼3.2 × 1019 cm−3) in the film. Moreover, it is found that the optimal regulation with the quality and electrical properties of boron doped diamond films could be realized by adding appropriate laughing gas, especially the hole mobility (∼700 cm2/V⋅s), which is beneficial to the realization of high-quality boron doped diamond films and high-level optoelectronic device applications in the future.

Design of a Synthetic Strategy to Achieve Enhanced Fluorescent Carbon Dots with Sulfur and Nitrogen Codoping and Its Multifunctional Applications.

Here, a rational strategy to achieve multifunctional N, S codoped carbon dots (N, S-CDs) is reported, aiming to improve the photoluminescence quantum yields (PLQYs) of the CDs. The synthesized N, S-CDs have excellent stability and emission properties independent of excitation wavelength. Through the introduction of S element doping, the fluorescence emission of CDs is red-shifted from 430to 545nm, and the corresponding PLQYs can be greatly enhanced from 11.2% to 65.1%. It is found that the doping of S elements causes an increase in the size of CDs and an elevated graphite N content, which may be the key factors to cause the redshift of fluorescence emission. Furthermore, the introduction of S element also serves to suppress the nonradiative transitions, which may be responsible for the elevated PLQYs. Besides, the synthesized N, S-CDs have certain solvent effect and can be applied to detect water content in organic solvents, and have strong sensitivity to alkaline environment. More importantly, the N, S-CDs can be used to achieve an "on-off-on" dual detection mode between Zr4+ and NO2 - . In addition, N, S-CDs combinedwith polyvinylpyrrolidone (PVP) can also be utilized as fluorescent inks for anti-counterfeiting applications.

Evaluating the Activity of Neuraminidase in Bacterial Vaginosis Microflora and Imaging Sialic Acid on the Cell Membrane by Boron and Nitrogen Codoped Fluorescent Carbon Dots.

Sialic acids (SAs) are commonly located on the cell surface as terminal ends of glycoproteins and glycolipids. Neuraminidase (NEU) is a class of glycoside hydrolase enzymes that can cleave SAs from receptors. Both SA and NEU play important roles in human physiological and pathological processes of cell-cell interaction, communication, and signaling. Additionally, bacterial vaginosis (BV), a form of gynecological inflammation caused by dysbiosis of the vaginal microbiome, results in the abnormal activity of NEU in vaginal fluid. Here, we developed a novel probe for rapidly and selectively sensing SA and NEU based on a one-step prepared boron and nitrogen codoped fluorescent carbon dots (BN-CDs). The selective recognition reaction between SA and the phenylboronic acid groups on the surface of BN-CDs inhibits fluorescence emission from BN-CDs, while the NEU-catalyzed hydrolysis of SA bound on BN-CDs leads to fluorescence recovery. The probe was applied in diagnosing BV and showed consistent results to Amsel criteria. Moreover, the low cytotoxicity of BN-CDs facilitates its application in fluorescence imaging of SA on the membrane of red blood cells (RBCs) and leukemia cell lines (U937, KAS-1). The excellent sensitivity, accuracy, and applicability of the developed probe support its broad potential applications in future clinical diagnosis and treatment.

Nitrogen and Sulfur Codoped Hierarchical Porous Carbon Derived from Lignin for High-Performance Zinc Ion Capacitors

As electrode materials for zinc ion capacitors (ZICs), porous carbons are an important factor affecting the electrochemical behavior of ZICs. Heteroatom doping is an efficient approach to adjust the pore structure, regulate the electronic structure, increase the surface wettability, and provide pseudo capacitance. In this work, hierarchical porous N/S codoped activated carbon (N/S-AC) materials were prepared from lignin using urea and thiourea as the dopants. The preparation process consisted of first step charring and second step activation with codoping to yield N/S-AC, which exhibited hierarchical pore structure, suitable for providing abundant active sites. The use of N/S-AC as cathode materials for ZIC delivered an outstanding specific capacitance of 307 F g–1 at 1 A g–1 and a remarkable capacity retention of 99.72% after 20,000 cycles at 10 A g–1. The device also exhibited a high energy density of 108.8 Wh kg–1 at 2880 W kg–1 and 65.8 Wh kg–1 at 115200 W kg–1. The excellent electrochemical properties were attributed to the synergistic effect of nitrogen and sulfur elements, and hierarchical porous structure. In sum, these findings are promising for development of ZIC electrode materials with high energy density.

Nitrogen doped bimetallic sludge biochar composite for synergistic persulfate activation: Reactivity, stability and mechanisms

As a recycling use of waste activated sludge (WAS), we used high-temperature pyrolysis of WAS to support bimetallic Fe–Mn with nitrogen (N) co-doping (FeMn@N–S), a customized composite catalyst that activates peroxysulphate (PS) for the breakdown of tetracycline (TC). First, the performance of TC degradation was evaluated and optimized under different N doping, pH, catalyst dosages, PS dosages, and contaminant concentrations. Activating PS with FeMn@N–S caused the degradation of 91% of the TC in 120 min. Next, characterization of FeMn@N–S by XRD, XPS and FT-IR analysis highlights N doping is beneficial to take shape more active sites and reduces the loss of Fe and Mn during the degradation reaction. As expected, the presence of Fe–Mn bimetallic on the catalyst surface increases the rate of electron transfer, promoting the redox cycle of the catalyst. Other functional groups on the catalyst surface, such as oxygen-containing groups, accelerated the electron transfer during PS activation. Free radical quenching and ESR analysis suggest that the main contributor to TC degradation is surface-bound SO4•−, along with the presence of single linear oxygen (1O2) oxidation pathway. Finally, the FeMn@N–S composite catalyst exhibits excellent pH suitability and reusability, indicating a solid practicality of this catalyst in PS-based removal of antibiotics from wastewater.

One-step synthesis of nitrogen and sulfur co-doped hierarchical porous carbon derived from acesulfame potassium as a dual-function agent for supercapacitors and lithium‑sulfur batteries

Acesulfame potassium (AK) is an artificial sweetener that contains N and S functional groups in its organic moiety and is suitable as porous carbon precursor. In this study, AK derived carbon (AKC) was obtained via direct carbonization and in situ doping without additives under the dual conditions of inert gas protection and high temperatures. The obtained AKCs exhibited high porosity structure with a specific surface area of 2043 m2 g−1 and 3.22 wt% N and 8.61 wt% S dual heteroatom doping. When applied to the supercapacitor electrode, the AKC ensured a high capacitance of 264 F g−1 at 0.5 A g−1, which maintained 86.1 % of the initial capacitance after 5000 cycles at 5 A g−1, and an ultra-high energy density of 16.3 Wh kg−1 in a full cell device. By analyzing its application in the lithium‑sulfur battery cathode, the S-loaded AKC exhibited a high capacity of 1075 mAh g−1 at 0.1C, and 490.5 mAh g−1 after 150 cycles with 66.5 % of capacity retention. The excellent performance of AKC can be attributed to its high specific surface area, pore structure, and sulfur and nitrogen co-doping combine effect. Overall, AKCs exhibited excellent electrochemical performances, thereby proposing a new synthetic strategy of preparing dual heteroatom doped porous carbon for high-performance electrode materials through a single precursor and low-cost perspective.

CO2 Adsorption on N-Doped Porous Biocarbon Synthesized from Biomass Corncobs in Simulated Flue Gas

This study was to develop a low-cost N-doped porous biocarbon adsorbent that can directly adsorb CO2 in high-temperature flue gas from fossil fuel combustion. The porous biocarbon was prepared by nitrogen doping and nitrogen-oxygen codoping through K2CO3 activation. Results showed that these samples exhibited a high specific surface area of 1209-2307 m2/g with a pore volume of 0.492-0.868 cm3/g and a nitrogen content of 0.41-3.3 wt %. The optimized sample CNNK-1 exhibited a high adsorption capacity of 1.30 and 0.27 mmol/g in the simulated flue gas (14.4 vol % CO2 + 85.6 vol % N2) and a high CO2/N2 selectivity of 80 and 20 at 25 and 100 °C and 1 bar, respectively. Studies revealed that too many microporous pores could hinder CO2 diffusion and adsorption due to the decrease of CO2 partial pressure and thermodynamic driving force in the simulated flue gas. The CO2 adsorption of the samples was mainly chemical adsorption at 100 °C, which depended on the surface nitrogen functional groups. Nitrogen functional groups (pyridinic-N and primary and secondary amines) reacted chemically with CO2 to produce graphitic-N, pyrrolic-like structures, and carboxyl functional groups (-N-COOH). Nitrogen and oxygen codoping increased the amount of nitrogen doping content in the sample, but acidic oxygen functional groups (carboxyl groups, lactones, and phenols) were introduced, which weakened the acid-base interactions between the sample and CO2 molecules. It was demonstrated that SO2 and water vapor had inhibition effects on CO2 adsorption, while NO nearly has no effect on the complex flue gas. Cyclic regenerative adsorption showed that CNNK-1 possessed excellent regeneration and stabilization ability in complex flue gases, indicating that corncob-derived biocarbon had excellent CO2 adsorption in high-temperature flue gas.

WITHDRAWN: The high-efficiency supercapacitor electrodes influencing laser-induced nanomaterials with Co-doped Nitrogen and Phosphorous

In this research, a double laser pyrolysis method was used to create nitrogen and phosphorus co-doped laser-stimulated graphene. This method has proven to be both versatile and cost-effective. There was a significant impact on the Graphene – Laser Induced Nitrogen(N) and Phosphorous(P) Graphene performance, dopant absorption, and laser power. In the N and P -Laser Induced Graphene (LIG) optimized with 3 wt% Si (OH)4 and laser power of 3.6 W (Nitrogen and Phosphorous – Laser induced graphene-3.6), a specific areal capacitance (CA) of 165.8 mF/cm2 was achieved in the next pyrolysis process, while 1 M H2SO4 is employed as dissolved electrolyte. LIG-NP demonstrated a capacitance of 70.1 mF/cm2 at a density of 0.6 mA/cm2, which is four times and 16 times more than that of N-doped LIG and single pyrolyzed LIG NPs, respectively, using a gel electrolyte. Cycling stability was good (capacitance retention of 84%), Coulombic efficiency was around 100%, and area energy density was 9.67 N/cm2 with 10,000 cycles. Flexible and wearable electronics could benefit from a simple fabrication method for heteroatom-coated LIG electrodes.

Hydrothermal Synthesis of Nitrogen and Phosphorus Codoped Carbon Dot Interfacial Modification Layer for Efficient Charge Transfer between ZnO Electron Transport Layer and PTB7:PC70BM Active Layer

The interface between the active layer and the charge-transporting layer is critical for performance improvement in polymer solar cells (PSCs). The use of zinc oxide (ZnO) as an electron transport layer (ETL) in PSCs was limited due to inherent defects in the surface of ZnO prepared by the sol-gel method, mismatched energy bands with the photoactive layer, and incompatibility between the photoactive layer and ZnO ETL. In this study, nitrogen and phosphorus codoped carbon dots (N & P-CDs) were prepared from Ensete ventricosum (false banana) and used as an interfacial modification layer for ZnO ETL. The inverted devices with structures ITO/ZnO/N & P-CD/PTB7:PC70BM/Al were fabricated to investigate the charge transfer dynamic between the active layer and ETL interface modification with N & P-CDs. We have observed that the interfacial modification between the ZnO ETL and the active layer, using N & P-CDs, improves the charge transfer between ZnO ETL and PTB7:PC70BM active layer. The obtained result shows that the ETL/BHJ interface resistance of the devices with ZnO:undoped CDs, ZnO:N-CDs, ZnO:P-CDs, and ZnO:N & P-CD ETLs decreases dramatically from 103.4 to 84.04, 78.16, 37.88, and 28.9 Ω, respectively. This is due to the improvement of charge extraction efficiency by smoothing ZnO surface defects and minimizing the band mismatch between the active layer and ZnO using N & P-CDs. The results indicate that the water-soluble N & P-CDs developed in this study have the potential to be used for efficient free charge carrier extraction for PSCs.

Amorphous FeOOH Anchored on Boron and Nitrogen Codoped Carbon Nanotubes for Fenton-like Oxidation of Sulfamethoxazole

Amorphous iron oxide/hydroxides with structural disorder can be a potential alternative to typical crystalline structures when applied in environmental nanotechnology. In this work, novel amorphous FeOOH quantum dots (QDs) anchored on boron and nitrogen codoped graphene nanotubes (FeOOH@BNG) with different Fe loadings were synthesized and applied in the degradation of common antibiotic pollutant sulfamethoxazole (SMX). The as-fabricated catalysts were characterized by a series of physicochemical and thermal techniques, revealing the highly dispersive FeOOH QDs on the BNG surface. The as-prepared catalyst shows excellent catalytic ability toward SMX degradation via a Fenton-like approach. The excellent activity of the as-prepared FeOOH@BNG catalysts was ascribed to the enhanced textural properties and better exposure of active sites, thanks to the highly dispersive Fe sites on the BNG supports. The optimal catalyst, FeOOH-5@BNG, was further employed for the optimization of key reaction parameters such as catalyst loading, H2O2 dosage, pH, and reaction temperature. Moreover, electron paramagnetic resonance (EPR) and reactive species quenching tests were employed to reveal the responsive reactive oxygen species and the mechanism in the FeOOH@BNG/H2O2 system for SMX degradation. The current study not only opens new insights into the fabrication of amorphous but metallic nanomaterials but also leads to their potential application in environmental remediation.

Carbon and nitrogen co-doped In2O3 porous nanosheets with oxygen vacancies for remarkable photocatalytic CO2 conversion

Photocatalytic CO2 reduction to sustainable products by utilizing solar energy has great prospects for development. However, most of the conventional catalysts have the disadvantages of inefficient, low visible light absorption, and poor product selectivity. For this reason, in this study, carbon and nitrogen co-doped In2O3 (C,N-In2O3) porous nanosheets with oxygen vacancies have been successfully prepared by pyrolyzing the as-prepared carbon-rich InOOH (C-InOOH) nanosheets precursor in an ammonia-helium mixture gas. The derived C,N-In2O3 photocatalyst possesses a mesoporous structure, large surface area, accelerated charge transfer and separation, and high visible-light absorption ability. The carbon and nitrogen co-doping produced proper surface defects (oxygen vacancies), which can facilitate CO2 adsorption and inhibit photogenerated charge recombination. As expected, an efficient CO2 photoreduction is achieved over the C,N-In2O3 sample with a CO production rate of 152 μmol h−1 g−1 and 80% selectivity together with an excellent stability. This study provided an efficient C,N co-doping strategy for fabricating high-active and stable photocatalysts, which could be applied to the conversion and utilization of solar energy in the future.