Nitrogen Co-doping Research Articles

Photodegradation of Phenol under Visible Light Irradiation Using Cu-N-codoped ZrTiO<sub>4</sub> Composite as a High-Performance Photocatalyst

Codoping of nitrogen and copper into zirconium titanate composite (Cu-N-codoped ZrTiO4) was carried out through a sol-gel process. This study aimed to investigate the effect of copper and nitrogen dopants on the photocatalytic activity of ZrTiO4 composite in degrading phenol. To prepare the composite, an aqueous suspension of zirconia (ZrO2) alongside a fixed amount of urea and various amount of copper sulfate was added dropwise into diluted titanium(IV) tetraisopropoxide (TTIP) in ethanol. The composites were calcined at temperatures of 500, 700, and 900 °C. Fourier-transform infrared spectrophotometry (FTIR), X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray (SEM-EDX) mapping, and specular reflectance UV-visible spectrophotometry (SR UV-vis) were used for their characterization of composite. The photocatalytic activity was evaluated by adding the composite into a 10 mg L−1 phenol solution for various irradiation time spans. The remaining concentration of phenol solution was determined by absorption at 269 nm. Cu-N-codoped ZrTiO4 composite containing 5% Cu calcined at 500 °C demonstrated the highest observed rate constant and a significant band gap decrease from 3.13 to 2.68 eV.

One-pot Microwave Synthesis of Cobalt, Nitrogen, and Sulfur Co-Doped Carbon Quantum Dots for Efficient Monosodium Glutamate Determination in Food Samples

The synthesis of cobalt, nitrogen and sulfur co doped carbon quantum dots (Co-NS-CQDs) has become a subject of significant research interest. These CQDs were produced using a single-step microwave method, which is considered environmentally friendly, and the entire process was completed in just 90 seconds. In this synthesis, citric acid was utilized as the carbon source, methionine served as the source for both nitrogen and sulfur, and cobaltous acetate was used to introduce cobalt ions into the CQDs structure. The synthesized carbon quantum dots (CQDs) exhibit a narrow size distribution and a high quantum yield of 51.5%, which is notably superior to non-metal-doped CQDs with a yield of 38%. Characterization of these CQDs was performed using different techniques such as transmission electron microscopy (TEM), high-resolution TEM (HRTEM), Fourier transformation infrared spectroscopy (FTIR), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The developed CQDs have blue luminescence at emission wavelength 438 nm after excitation at 350 nm. Different factors affecting the CQDs synthesis including dialysis duration, reaction time and reaction temperature. These CQDs were utilized as a probe for the detection of monosodium glutamate (MSG) in various food products. The intensity of the fluorescence of the CQDs showed a direct and linear increase with the concentration of MSG within the range of 25–250 µg/mL. The detection and quantitation limits for MSG were 2.78 µg/mL and 8.44 µg/mL, respectively. Additionally, the developed method is environmentally friendly, as confirmed by assessments using the analytical Eco scale, Green Analytical Procedure Index (GAPI), and Analytical Greenness calculator (Agree). The proposed method presents several advantages over other reported methods in terms of convenience, rapid response, and attainment of accurate and precise results.

Optimization, Kinetics, and Thermodynamics Study on the Degradation of RhB by ZnO Modified with Nitrogen and Sulfur Co-Doped Carbon Quantum Dots

Optimization, Kinetics, and Thermodynamics Study on the Degradation of RhB by ZnO Modified with Nitrogen and Sulfur Co-Doped Carbon Quantum Dots

Phosphorus and Nitrogen Codoped Porous Carbon Nanosheets for Energy Storage and Gas Adsorption

Phosphorus and Nitrogen Codoped Porous Carbon Nanosheets for Energy Storage and Gas Adsorption

Effective CO2 photoreduction to methane over Bi2MoO6/ Ni, N co-doped TiO2 nano-photocatalyst

Bi2MoO6/Ni–N co-doped TiO2 (BM/Ni–N-T) composite was prepared by a hydrothermal, and subsequently a solvothermal method and used for CO2 photocatalytic conversion under visible light irradiation. The effect of nickel concentration in TiO2 on the photocatalytic properties and the effect of nitrogen-nickel co-doping in TiO2 structure on methane production were investigated. Furthermore, the effect of constructing a heterojunction structure between modified TiO2 and Bi2MoO6 semiconductors on the photocatalytic performance was investigated. The morphological and structural properties of the samples were characterized by X-ray diffraction, nitrogen adsorption, field emission scanning electron microscopy, Raman spectroscopy, and photoluminescence spectroscopy. Doping nickel with different concentrations in TiO2 structure could result in a narrowing of the bandgap and increase the light absorption capacity in comparison to an undoped TiO2 sample. The results reveal that modification of TiO2 with both of nickel and nitrogen elements leads to higher surface area and narrower bandgap than pure TiO2. Incorporation of nickel and, or nitrogen into TiO2 structure suppresses the CO2 absorption on the catalyst surface and results in enhanced electron-hole separation efficiency compared to pure TiO2. The 3Ni-T sample with 3 wt% nickel shows the optimum methane production among single-doped TiO2 samples. The Ni–N co-doped TiO2 sample exhibits a good response in CO2 conversion, which was nine times higher than that of undoped TiO2. The BM/Ni–N-T photocatalyst exhibits excellent photocatalytic performance for CO2 conversion (67.9 μmol/g), which is several times higher than that of pure TiO2 (3.2 μmol/g). The enhanced composite photocatalytic performance is mainly attributed to nitrogen and nickel co-doping in TiO2 and heterojunction structure, which improves light absorption capacity and charge carrier separation efficiency.

Transition metal (Mn, Fe, Co, Ni) and nitrogen co-doping for improving the photocatalytic activity of monolayer MoS2

Exploring efficient photocatalyst is important for environmental protection. In this work, we systematically investigate the doping configuration, formation energy, band structures, density of state, recombination rate, catalytic active site, work function, redox potential, and optical absorption properties of transition metal and nitrogen co-doped monolayer MoS2. In transition doped MoS2, transition metal atoms replace Mo. Transition metal and nitrogen atoms substitute Mo and S atoms in transition metal and nitrogen co-doped MoS2, respectively. Compared with undoped MoS2, transition metal and nitrogen co-doped MoS2 have low photogenerated carrier recombination rate, abundant catalytic active sites, small work function, suitable redox potentials, and strong light absorption, especially Mn-N and Ni-N co-doped MoS2.

Boron and nitrogen co-doped carbon supported cobalt nanoparticle in neutral aluminum-air battery

Abstract A boron and nitrogen co-doped carbon supported cobalt nanoparticle catalyst (CoBNC-phen) is successfully prepared. The co-doping method led to the formation of a Co–N bond, inhibiting the accumulation of Co nanoparticles. This also changes the electronic state, hence promoting oxygen reduction reaction performance. CoBNC-phen exhibits a half-wave potential of 23 mV higher than the commercial Pt/C. The power-density of the aluminum-air battery is 20% higher when CoBNC-phen is applied as the air cathode. Meanwhile, the voltage remained stable after 15 h of discharge.

Biomass carbon aerogels by polyatomic synergistic modification and synchronous activation for supercapacitors

The regulation and modification of carbon aerogel are essential for the construction of supercapacitors electrode with high energy density. Heteroatom doping has also been used in the modification of carbon aerogels to further improve the properties of materials. In this work, nitrogen and sulfur co-doped porous biomass carbon aerogels (NSPCs) for high-performance supercapacitors were innovatively synthesized by a straightforward and highly efficient one-step gel and synchronous activation strategy. Such a covalently interconnected hierarchical porous structure with co-doped nitrogen and sulfur greatly improves the pore structure and wettability of the materials and forms functional groups to provide additional pseudocapacitance. Owing to these structural advantages and the component synergy, the NSPCs exhibit high electrolyte ion storage ability, unhindered ion channels, and excellent electrochemical performance, and display a specific capacitance of 344.3 F g−1, and a capacitance retention rate of 91.5 % after 10,000 cycles. Additionally, the NSPCs-based symmetric supercapacitor showed a high energy density of 12.82 Wh kg−1.

B and N substitutional co-doping in 7AGNRs

On-surface synthesis of graphene nanoribbons enables engineering their electronic and magnetic properties, which sensitively depend on their precise bonding structure, morphology and chemical composition. Here, we investigate nitrogen and boron co-doping in order to better understand the effects of simultaneous chemical substitution in sites along the backbone of 7AGNRs. In a comparative analysis with the pristine system, the origin of the impurity bands that nitro-borylated systems exhibit was addressed. In addition to this, we studied the appearance of an electric dipolar moment, the charge transfer mechanism behind it and its dependence on the distance between BN centres. The high defect concentration limit and the dilute limit were investigated, along with various doping schemes with four substitutional doping sites and the possible emergence of magnetism in these systems.

Anchoring polypyrrole on nitrogen and sulfur codoped graphene fibers to construct flexible supercapacitors

Graphene fiber-based flexible supercapacitors could function as flexible energy storage and supply equipment for wearable electronic devices. However, the future applications are restricted because of the low energy density for flexible supercapacitors. In this paper, the polypyrrole is anchored on nitrogen/sulfur co-doped graphene fibers (PPy/NSGF) by a hydrothermal self-assembly method and in situ polymerization process. The as-fabricated PPy/NSGF possess a high specific areal capacitance of 424.8 mF cm−2 and an excellent energy density of 43.3 μW h cm−2. The fiber-shaped supercapacitor assembled by PPy/NSGF can be utilized to power light. The improved properties of PPy/NSGF are mostly attributed to the increased electroactive sites from heteroatom nitrogen and sulfur codoping and in situ polymerization of polypyrrole. The produced graphene-based composite fibers are expected to become potential flexible electrode materials for fiber-shaped supercapacitors in future smart clothes and miniaturized flexible wearable electronics.

A Nanograss Boron and Nitrogen Co-Doped Diamond Sensor Produced via High-Temperature Annealing for the Detection of Cadmium Ions.

The high-performance determination of heavy metal ions (Cd2+) in water sources is significant for the protection of public health and safety. We have developed a novel sensor of nanograss boron and nitrogen co-doped diamond (NGBND) to detect Cd2+ using a simple method without any masks or reactive ion etching. The NGBND electrode is constructed based on the co-doped diamond growth mode and the removal of the non-diamond carbon (NDC) from the NGBND/NDC composite. Both the enlarged surface area and enhanced electrochemical performance of the NGBND film are achievable. Scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, cyclic voltammetry, electrochemical impedance spectroscopy, and differential pulse anodic stripping voltammetry (DPASV) were used to characterize the NGBND electrodes. Furthermore, we used a finite element numerical method to research the current density near the tip of NGBND. The NGBND sensor exhibits significant advantages for detecting trace Cd2+ via DPASV. A broad linear range of 1 to 100 μg L-1 with a low detection limit of 0.28 μg L-1 was achieved. The successful application of this Cd2+ sensor indicates considerable promise for the sensitive detection of heavy metal ions.

Nitrogen and oxygen co-doped porous biocarbon@sulfur/carbon nanotubes as cathodes for high-performance lithium-sulfur batteries

Practical applications of lithium-sulfur batteries (LSBs) are limited due to the shuttle effect and the low conductivity of sulfur (S) and lithium polysulfide (LiPS). Currently, porous carbon materials doped with heteroatoms show extraordinary potential in this regard. Therefore, using KOH activation, we successfully prepared porous London Plane seed stems biochar (LPSC) with nitrogen and oxygen co-doping as the S carrier. We used carbon nanotubes (CNTs) as electrode coatings to improve the conductivity and suppress the shuttle effect. The results showed that the LPSC@S/CNTs composite electrode had an initial discharge capacity of 1090.4 mAh g−1 at 0.05 C. Furthermore, the capacity remained at 86.0 % after 300 cycles. This study provides a promising and sustainable approach to high-performance energy storage solutions.

Carbon quantum dot with co-doped nitrogen and phosphorus for tazettine ratiometric fluorescent sensing

An overdose of tazettine (TZ) has toxic side effects, which makes it extremely important to rapidly and subtly determine the TZ. In this study, double-emitting, nitrogen–phosphorus co-doped carbon quantum dots (N,P-CQDs) were prepared using cis-butenedioic acid, phosphoric acid, and p-phenylenediamine. An effective inner filter effect (IFE) can occur between TZ and N,P-CQDs, resulting in their fluorescence quench. Therefore, a ratio fluorescent probe was constructed for detecting the TZ was constructed. After optimizing the experimental conditions, the quenching efficiency showed a strong linear connection with the TZ concentration in the range of 0.01–30 µmol/L, with the detection limit of 0.002 µmol/L. This method could be satisfactorily applied to detect TZ in mouse plasma samples.

O, N co-doped CuCrO2 as efficient hole transport layer for high-performance ultraviolet photodetectors

The optoelectronic properties and film-formation characteristics of CuCrO2 are optimized through oxygen (O) and nitrogen (N) co-doping using the space-limited domain annealing method in ambient air. After O, N co-doping at 100 °C, the conductivity of CuCrO2 is enhanced due to a decrease in trap-state density and an increase in hole concentration, thereby facilitating carrier transport. With a work function (WF) of 5.24 eV and an electron affinity (χ) of 2.29 eV, the CuCrO2 films serves as both a hole transport layer (HTL) and an electron-blocking layer, playing a pivotal role in enhancing photogenerated holes extraction while suppressing nonradiative charge recombination at the heterojunction interface. Consequently, the responsivity and detectivity of the device with FTO/TiO2 NRs/O, N co-doped CuCrO2/Au structure reach 188 mA W−1 and 3.14 × 1013 cm Hz1/2 W−1 in self-powered mode, respectively. Simultaneously, the rise/decay time is reduced to just 31.2/32.1 ns. Furthermore, after applying a bias of − 2 V, the photodetector demonstrates significantly improved performance with a responsivity of up to 5 × 105 mA/W (365 nm, 0.97 mW cm−2) and an apparent quantum efficiency of ∼30,000%. These results highlight the promising potential of utilizing O, N co-doped CuCrO2 HTL for constructing high-performance optoelectronic devices.

Lead and Nitrogen Co-Doped Multi-Walled Carbon Nanotube Electrocatalyst for Oxygen Reduction Reaction

The electrocatalysis of oxygen reduction reaction (ORR) on lead and nitrogen co-doped multi-walled carbon nanotube (Pb/N/MWCNT) composite catalyst has been investigated in the neutral, acidic and alkaline media. The mixture of lead phthalocyanine (PbPc) and MWCNTs was pyrolysed in nitrogen atmosphere to achieve co-doping of lead and nitrogen. The successful co-doping as well as formation of Pb nanoparticles were confirmed with the use of various physical and surface characterisation methods such as scanning and transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction analysis. This work brings forth the electrocatalytic effect of Pb and nitrogen co-doping of carbon by a detailed electrochemical analysis using rotating disk electrode (RDE) method. The Pb and nitrogen co-doped MWCNT material demonstrate a reasonable electrocatalytic ORR activity in acidic, neutral and alkaline media. The results indicate great potential of Pb to be employed in electrocatalyst design as co-doping agent to achieve superior cathode catalysts for microbial, proton and anion exchange membrane fuel cells.

Effect of nitrogen and transition-metal co-doping on quantum capacitance enhancement of graphene as supercapacitor electrodes: A density functional theory study

Quantum capacitance plays a crucial role in determining the energy density of graphene-based supercapacitors. In this study, density functional theory calculations were conducted to investigate the enhancement of quantum capacitance and surface storage charge density through the co-doping of transition metals (TM) such as Mn, Fe, Co, Ni, Cu, Zn, Cr, V, Ti, and N atoms in graphene (TMN3-G). At a doping concentration of 2 at% (atomic percentage), all types of metal doped graphene exhibited an increase in quantum capacitance compared to pristine graphene. The highest increase was observed in CrN3-G, where the maximum quantum capacitance increased from 19.2 μF/cm2 for pristine graphene to 122.8 μF/cm2, due to the increased density of states around the Fermi level. The maximum surface storage charge density also increased from 6.4 μC/cm2 for pristine graphene to 44.4 μC/cm2 for CrN3-G. Moreover, the study investigated the effect of different doping concentrations on quantum capacitance performance by changing the doping concentration for VN3-G. It was found that the quantum capacitance for VN3-G increased with higher doping concentration, reaching up to 282 μF/cm2 when the doping concentration was increased to 12.5 at% from 2 at%. Based on our calculation results, ZnN3-G, NiN3-G, CrN3-G, and TiN3-G are suitable for the anode of supercapacitors, while CuN3-G and CoN3-G are suitable for the cathode. FeN3-G, MnN3-G, and VN3-G are suitable for both electrodes. These findings provide valuable insights for designing high-capacity graphene-based supercapacitors.

Functional separator with 1 T/2H-MoSe2 nanosheets decorated nitrogen and sulfur co-doped mesoporous hollow carbon spheres for high-performance Li-S batteries

Due to the dissolution, shuttling, and tardy kinetics conversion of lithium polysulfides (LiPSs) during cycling, there are serious defects in the utilization of active material and capacity retention ability for lithium-sulfur batteries (LSBs). To inhibit effectively the shuttling effect of LiPSs, herein, we propose the dual design strategies, using 1 T/2H mixed phase MoSe2 (1 T/2H-MoSe2) nanosheets uniformly growing on the external surface and inner wall of nitrogen and sulfur co-doped mesoporous hollow carbon spheres (MoSe2-NSHC) as both sulfur host and modified material of conventional polypropylene (PP) separator. The hollow structure of MoSe2-NSHC has a large specific surface area and internal space, which not only loads a large amount of sulfur, but also buffers severe volume expansion of sulfur during charge/discharge process. Meanwhile, 1 T/2H-MoSe2 and co-doped nitrogen and sulfur in the carbon skeleton effectively anchor LiPSs and accelerate the kinetics conversion of LiPSs by forming chemical bond. Density-functional theory calculations indicate the corresponding mechanisms. Based on these advantages, lithium-sulfur battery assembled with a MoSe2-NSHC/S cathode and a MoSe2-NSHC-PP separator delivers an initial discharge capacity of 1402 mAh/g at 0.2C, and also exhibits the first discharge capacity of 1155 mAh/g at 0.5C with a capacity retention rate of 79 % after 100 cycles. And after 800 cycles at 1C, the outstanding long-term cyclability with a low capacity decay per cycle of 0.039 % is also obtained. Notably, even in case of sulfur loading of 3.2 mg cm−2 and electrolyte/sulfur ratio of 6 μL mg−1, lithium-sulfur battery still exhibits a good electrochemical performance. Importantly, this work provides a feasible approach for commercial application of LSBs.

Metal-Free Light-Driven 1,4-NADH Regeneration System from Nitrogen and Sulfur Codoped Carbon Dots

Metal-Free Light-Driven 1,4-NADH Regeneration System from Nitrogen and Sulfur Codoped Carbon Dots

One-Pot, Optimized Microwave-Assisted Synthesis of Difunctionalized and B-N Co-Doped Carbon Dots: Structural Characterization.

In this work, we employed a novel microwave-assisted synthesis method to produce nitrogen and boron co-doped carbon dots (B-N co-doped CDs). To achieve optimal synthesis, we conducted a comprehensive parameter modulation approach, combining various synthesis temperatures, times, and precursor concentrations, while keeping the power constant at 150 W and pH 5. Using maximum fluorescence emission as our response variable, the best conditions were identified as 120 °C, 3 min, and a precursor concentration of 1 mg/mL. Characterization using field emission scanning electron microscopy revealed these CDs to have a spherical morphology with an average size of 10.9 ± 3.38 nm. Further high-resolution transmission electron microscopy showed an interplanar distance of 0.23 nm, which is in line with prior findings of CDs that present a 0.21 nm distance corresponding to the (100) plane of graphite. Optical properties were ascertained through UV-vis absorption, identifying distinct π-π* and n-π* transitions. Fluorescence spectroscopy highlighted an emission peak at 375 nm when excited at 295 nm, achieving a quantum yield of 56.7%. Fourier-transform infrared spectroscopy and Raman spectroscopy analyses confirmed the boronic acid and amine groups' presence, underscoring the graphitic nature of the core and the co-doping of boron and nitrogen. These empirical observations were compared with theoretical investigations through simulated Raman spectra, proposing a potential structure for the CDs. X-ray photoelectron spectroscopy further endorsed the co-doping of nitrogen and boron, along with the detection of the specified functional groups. All these characteristics could lend this nanomaterial to different types of applications such as fluorescent probes for a broad range of analytes and for fluorescent cell imaging.

Effect of the N,S-Codoped Carbon Layer on the Rate Performance of Air-Stable Lithium Iron Oxide Prelithiation Additives.

Lithium iron oxide (Li5FeO4, LFO) holds great promise in cathode prelithiation additives for lithium-ion batteries. However, it is hard to make full use of the power under high current rates due to its poor air stability and electronic conductivity. The carbon protective layer is an effective approach, and introducing heteroatoms would be beneficial to further improving Li+ kinetics. However, the interplay between the dopants and Li+ is always ignored. Herein, we aim to reveal the interaction among Li+ ions and the defects of carbon layers from nitrogen/sulfur dopants and the corresponding influence on delithiation performances of LFO. It is found that the codoping of nitrogen and sulfur on carbon layers contributes to the boosted capacity and rate capability. The modified SNC@LFO presents a large irreversible capacity (779.3 mAh g-1 at 0.1 C) and excellent rate performance (537.1 mAh g-1 at 1 C), which is up to 16.6 and 64.0%, respectively, compared to LFO.