Nitrogen-doped Carbon Nanosheets Research Articles

2D metal–organic framework derived ultra-thin nitrogen-doped oxygen rich porous carbon nanosheets for zinc-ion hybrid supercapacitors

2D MOF derived ultra-thin carbon nanosheets with high reactivity, super-hydrophilicity and hierarchical porosity are prepared. The corresponding Zn-ion hybrid supercapacitor delivers exceptional energy storage capability with long cycling stability.

Three-dimensional N-doped carbon nanosheets loaded with heterostructured Ni/Ni3ZnC0.7 nanoparticles for selective and efficient CO2 reduction.

Electrocatalytic CO2 reduction (CO2RR) has emerged as a promising approach for converting CO2 into valuable chemicals and fuels to achieve a sustainable carbon cycle. However, the development of efficient electrocatalysts with high current densities and superior product selectivity remains a significant challenge. In this study, we present the synthesis of a porous nitrogen-doped carbon nanosheet loaded with heterostructured Ni/Ni3ZnC0.7 nanoparticles through a facile hydrothermal-calcination method (Ni/Ni3ZnC0.7-NC). Remarkably, the Ni/Ni3ZnC0.7-NC catalyst exhibits outstanding performance towards CO2RR in an H-cell, demonstrating a high CO faradaic efficiency of 92.47% and a current density (jCO) of 15.77 mA cm-2 at 0.87 V vs. RHE. To further explore its potential industrial applications, we constructed a flow cell and a rechargeable Zn-CO2 flow cell utilizing the Ni/Ni3ZnC0.7-NC catalyst as the cathode. Impressively, not only does the Ni/Ni3ZnC0.7-NC catalyst achieve an industrial high current density of 254 mA cm-2 at a voltage of -1.19 V vs. RHE in the flow cell, but it also exhibits a maximum power density of 4.2 mW cm-2 at 22 mA cm-2 in the Zn-CO2 flow cell, while maintaining excellent rechargeability. Density functional theory (DFT) calculations indicate that Ni/Ni3ZnC0.7-NC possesses more spontaneous reaction pathways for CO2 reduction to CO, owing to its heterogeneous structure in contrast to Ni3ZnC0.7-NC and Ni-NC. Consequently, Ni/Ni3ZnC0.7-NC demonstrates accelerated CO2RR reaction kinetics, resulting in improved catalytic activity and selectivity for CO2RR.

2D crumpled nitrogen-doped carbon nanosheets anode with capacitive-dominated behavior for ultrafast-charging and high-energy-density Li-ion capacitors

The synergistic effect of abundant mesopore distribution and nitrogen doping enables 2D crumpled nitrogen-doped carbon nanosheets as anode materials for Li-ion capacitors with large capacitive-capacities and ultrahigh rate performance.

Conductive nitrogen-doped carbon nanosheet-encapsulates bismuth nanoparticles for simultaneous high-performance detection of Cd(II) and Pb(II)

Cadmium (Cd) and lead (Pb) are two of the most toxic heavy metals, which cause serious pollution to the environment. It is of great significance to develop electrochemical sensing platforms that can be used for the efficient and simultaneous detection of Cd(II) and Pb(II). Herein, bismuth nanoparticles encapsulated in nitrogen-doped carbon nanosheets (Bi@NC) were successfully synthesized. An electrochemical sensor based on Bi@NC was proposed for the high-performance determination of trace Cd(II) and Pb(II). Encapsulated and uniformly distributed Bi nanoparticles with abundant active sites form alloys with Cd(II) and Pb(II), and the conductive nitrogen-doped carbon nanosheet accelerates the electron transport rate, thus the electrochemical signals of Cd(II) and Pb(II) are significantly amplified. Under optimized conditions, Cd(II) and Pb(II) can be simultaneously detected in concentrations ranging from 1 to 150 μg L−1, with sensitivity of 0.48 μA μg−1 L and 0.36 μA μg−1 L, respectively. Meanwhile, the sensor possesses the outstanding advantages of ultra-high sensitivity, excellent selectivity, and storage stability, being able to serve as an electrochemical platform for Cd(II) and Pb(II) sensing in fruit and river water.

High nitrogen-doped carbon nanosheets for electrochemical sensing of malachite green

The facile fabrication of doped carbon materials with multiple functions has been a challenging issue in materials science. Herein, nitrogen-doped carbon nanosheets with high doping level (32.05 wt%) were obtained by one-step calcination with urea and polyaniline as precursors. The presence of abundant edges and crimp, and the increase of the proportion of pyrrolic and graphitic nitrogen promote the exposure of the active site of the doped nanosheets. These structural advantages result in a favourable electrochemical response to organic pollutant malachite green. The linear range of detection of malachite green is 1 ∼ 10 μmol/L and the limit of detection is 13.2 nmol/L by differential pulse voltammetry electrochemical sensor constructed with high nitrogen- doped carbon nanosheets. The electrochemical sensor showed a satisfactory recovery rate for malachite green detection in actual tap water sample. This work offers a constructive solution for the facile fabrication and chemical sensor application of doped two-dimensional carbon-based materials.

Developing Single-Atomic Manganese Nanozymes for Synergistic Mild Photothermal/Multienzymatic Therapy.

Synergistic mild photothermal/nanozyme therapy with outstanding hyperthermia performance and excellent multienzyme properties is highly needed for osteosarcoma treatment. Herein, we have developed efficient single-atom nanozymes (SANs) consisting of Mn sites atomically dispersed on nitrogen-doped carbon nanosheets (denoted as Mn-SANs) for synergistic mild photothermal/multienzymatic therapy against osteosarcoma. Benefiting from their black N-doped carbon nanosheet matrices, Mn-SANs showed an excellent NIR-II-triggered photothermal effect. On the other hand, Mn-SANs with atomically dispersed Mn sites have outstanding multienzyme activities. Mn-SANs can catalyze endogenous H2O2 in osteosarcoma into O2 by catalase (CAT)-like activity, which can effectively ease osteosarcoma hypoxia and trigger the oxidase (OXD)-like catalysis that converts O2 to the cytotoxic superoxide anion radical (•O2-). At the same time, Mn-SANs can also mimic glutathione oxidase (GSHOx) to effectively consume the antioxidant glutathione (GSH) in osteosarcoma and inhibit intracellular glutathione peroxidase 4 (GPX4) expression. Such intratumoral •O2- production, GSH depletion, and GPX4 inactivation mediated by Mn-SANs can create a large accumulation of lipid peroxides (LPO) and •O2-, leading to oxidative stress and disrupting the redox homeostasis in osteosarcoma cells, which can ultimately induce osteosarcoma cell death. More importantly, heat shock proteins (HSPs) can be significantly destroyed via Mn-SAN-mediated plentiful LPO and •O2- generation, thus effectively impairing osteosarcoma cells resistant to mild photothermal therapy. Overall, through the cooperative effect of chemical processes (boosting •O2-, consuming GSH, and enhancing LPO) and biological processes (inactivating GPX4 and hindering HSPs), collaborative mild photothermal/multienzymatic therapy mediated by Mn-SANs is a promising strategy for efficient osteosarcoma treatment.

Carbon Nanosheets Infused with Gold Nanoparticles as an Ultrasensitive Nose for Electrochemical Arsenic Sensing.

Herein, we introduce an eco-friendly electrochemical sensor based on melamine-enriched nitrogen-doped carbon nanosheets decorated with gold nanoparticles (Au-CNSm) for arsenic sensing. An extremely facile, low-toxicity, biocompatible, and affordable hydrothermal technique was adopted for the synthesis of the Au-CNSm nanocomposite. The Au-CNSm-integrated sensing platform was optimized for electrode composition by cyclic voltammetry (CV). Owing to the synergistic effects of melamine-enriched carbon nanosheets (CNSm) and gold nanoparticles (AuNPs), the anodic peak current increased in the Au-CNSm-modified sensing electrode as compared to the CNSm-decorated platform. A wide linear range of 0.0001-100 μM and a low detection limit of 0.0001 μM were obtained. The visual signals can be measured at a very minute concentration of 0.0001 μM (0.1 ppb) on a screen-printed carbon electrode (SPCE) modified with Au-CNSm. Hence, this electrode system clearly outperformed the previously reported studies in terms of linear range, limit of detection (LOD), and electrocatalytic activity for arsenic sensing. Interestingly, the fabricated biosensor can be developed as a point-of-care device for real-time environmental monitoring for public safety. Henceforth, owing to exceptional attributes such as portability, selectivity, and sensitivity, this device offers great promise in modeling a revolutionary new class of electrochemical sensing platforms for an ultrasensitive and reliable detection strategy for arsenite (As(III)).

AlN nanoparticles anchored on cross-linked N-doped carbon nanosheets as sulfur hosts for lithium-sulfur battery

Lithium–sulfur (Li–S) battery has attracted extensive attention owing to its high theoretical energy density, low cost, and environmental friendliness. On the other hand, there are also some scientific problems, such as volume expansion and the shuttle effect of polysulfides. Here, three-dimensional cross-linked N-doped carbon nanosheets (NCNs) loaded with aluminum nitride (AlN) nanoparticles were synthesized and used as sulfur hosts for Li–S battery. The AlN@NCNs nanocomposites greatly improved the cycling and rate performance of Li–S battery. The AlN@NCNs/S nanocomposites provided a stable discharge capacity of 507.4 mAh/g after 400 cycles at 0.5 A/g, with a Coulombic efficiency of up to 99 %. After 500 cycles at 1.0 A/g, the capacity kept at 435.2 mAh/g. The polar AlN nanoparticles have strong adsorption on polysulfides, which obviously relieve the shuttle effect of polysulfides. Therefore, combining nitrogen-doped carbon nanosheets with metal nitride nanoparticles enhanced the electrochemical performance of Li–S batteries.

Nickel single-atom catalysts on porous carbon nanosheets for high-performance lithium-selenium batteries

Lithium-selenium (Li–Se) batteries have attracted intensive attention due to the high theoretical volumetric capacity (3253 mA h cm−3) and high electrical conductivity (1 × 10−3 S m−1) of selenium. However, the shuttle effect, rapid capacity fading and sluggish electrochemical process of the lithium selenides limit its further application. Herein, a catalyst of nickel single atoms (SA)/nitrogen-doped porous carbon nanosheets (Ni-NC) has been constructed and applied as an ideal host for selenium cathode. Such a material allows the adsorption of lithium selenides while the Ni SA serves as efficient catalytic site for the conversion of these selenides during charge/discharge process, as the theoretical calculation results suggest that the Ni SA could enhance the binding energy of the carbon host towards the intermediates and improve the electron transfer. As expected, the Ni-NC/Se cathode exhibits a capacity of 495 mAh g−1 at 0.2 C and 311 mAh g−1 at 4 C and good cycling stability of 225 mAh g−1 after 1000 cycles at 4 C with a Coulombic efficiency of ∼100 %, significantly better than the pure carbon host without Ni SA sites.

Ultrasensitive rutin electrochemical sensor based on in-situ salt template growth two-bimetallic ZIF-derived zinc/cobalt@nitrogen doped ultra-thin carbon nanosheets (Zn/Co@N[sbnd]CNSs)

Rutin (RU) is a common flavonoid compound that has attracted widespread attention. Accurately and quickly detecting RU is crucial. Herein, a novel electrochemical RU sensor based on in-situ salt template two-dimension ZIF-derived ultra-thin zinc/cobalt@ nitrogen doped carbon nanosheets composites modified glassy carbon electrode (Zn/Co@NCNSs/GCE) was constructed. Zn/Co-ZIF was synthesized by in-situ salt template method and the ultra-thin sheet structure Zn/Co@NCNSs were obtained by directly pyrolysis Zn/Co-ZIF and template removal showing good electrochemical performance for rutin detection, which benefited from the sheet structure with larger surface. For the detection of rutin, the Zn/Co@NCNSs/GCE showed wider linear range (10 nM - 1000 nM) and lower detection limit (LOD, 2.7 nM). In addition, the sensor achieved good recovery and accuracy in detecting RU in actual samples (RU tablets and orange juice).

Nitrogen-doped cross-linked carbon nanosheets-loaded CdB2O4 nanoparticles as efficient sulfur host for lithium–sulfur battery

Three-dimensional interconnected nitrogen-doped carbon nanosheet-(NCNs) loaded cadmium borate (CdB2O4) nanoparticles were prepared using a soak-dry-calcine process. CdB2O4 nanoparticles were well dispersed and anchored on the carbon nanosheets. Applied in sulfur cathode of lithium–sulfur battery, the CdB2O4–based composite delivered a stable capacity of 666.8 mAh g−1 over 400 cycles at 0.5 A g−1 with a high coulombic efficiency of 99%. It maintained 449.9 mAh g−1 at 1.0 A g−1 after 500 cycles, with a decay rate of 0.065% per cycle. The superior electrochemical performance of the nanocomposite was due to the abundant mesopores, which could encapsulate more active sulfur and alleviate the volume expansion caused by discharge procedure. Furthermore, the CdB2O4 nanoparticles anchored on the nanosheets effectively confined the lithium polysulfides and exhibited a high electrocatalysis effect toward the conversion of polysulfides in the charge–discharge process.

Co-Ru alloy nanoparticles decorated onto two-dimensional nitrogen doped carbon nanosheets towards hydrogen/oxygen evolution reaction and oxygen reduction reaction

Constructing highly-efficient electrocatalysts toward hydrogen evolution reaction (HER)/oxygen evolution reaction (OER)/oxygen reduction reaction (ORR) with excellent stability is quite important for the development of renewable energy-related applications. Herein, Co-Ru based compounds supported on nitrogen doped two-dimensional (2D) carbon nanosheets (NCN) are developed via one step pyrolysis procedure (Co-Ru/NCN) for HER/ORR and following low-temperature oxidation process (Co-Ru@RuOx/NCN) for OER. The specific 2D morphology guarantees abundant active sites exposure. Furthermore, the synergistic effects arising from the interaction between Co and Ru are crucial in enhancing the catalytic performance. Thus, the resulting Co-Ru/NCN shows remarkable electrocatalytic performance for HER (70 mV at 10 mA cm−2) in 1 M KOH and ORR (half-wave potential E1/2 = 0.81 V) in 0.1 M KOH. Especially, the Co-Ru@RuOx/NCN obtained by oxidation exhibits splendid OER performance in both acid (230 mV at 10 mA cm−2) and alkaline media (270 mV at 10 mA cm−2) coupled with excellent stability. Consequently, the fabricated two-electrode water-splitting device exhibits excellent performance in both acidic and alkaline environments. This research provides a promising avenue for the advancement of multifunctional nanomaterials.

Fe-Single-Atom Catalysts on Nitrogen-Doped Carbon Nanosheets for Electrochemical Conversion of Nitrogen to Ammonia

Fe-Single-Atom Catalysts on Nitrogen-Doped Carbon Nanosheets for Electrochemical Conversion of Nitrogen to Ammonia

Fabrication of N-doped graphitic carbon nanosheets via reaction between CaC2 and g-C3N4 as promising Li-ions battery anode

Nitrogen-doped carbon materials have attracted much attention for energy storage. Herein, we synthesize nitrogen-doped graphitic carbon nanosheets (NGCN) via a simple reaction between g-C3N4 and CaC2. The NGCN product integrates various features including high nitrogen content (3.98 at.%), large surface area (72.96 m2 g−1) and high graphitization degree (interplanar spacing, 0.335 nm). When served as anode material in Li-ions batteries, the NGCN exhibits a quite encouraging reversible capacity of 475 mAh g−1 at a current density of 500 mA g−1, with a capacity retention of 98.5 % after 1000 cycles. It also has an acceptable rate capability (238 mAh g−1 at 5000 mA g−1). This work promises an efficient route to convert sustainable carbon sources into nitrogen-doped graphitic carbon nanosheets with excellent electrochemical performances for energy storage.

Directional manipulation of electron transfer in copper/nitrogen doped carbon by Schottky barrier for efficient anodic hydrazine oxidation and cathodic oxygen reduction

Development of bifunctional hydrazine oxidation and oxygen reduction electrocatalysts with high activity and stability is of great significance for the implementation of direct hydrazine fuel cells. Combining zero-dimensional metal nanoparticles with three-dimensional nitrogen-doped carbon nanosheets is an attractive strategy for balancing performance and cost. However, the precise construction of these composites remains a significant challenge, and thorough study of their interaction mechanisms is lacking. Herein, the CuNPs/CuSA-NPCF catalyst was constructed by anchoring copper nanoparticles on a three-dimensional nitrogen-doped porous carbon nanosheet framework through coordination of polyvinyl pyrrolidone and copper ions. The Schottky barrier of metal–semiconductor matched the Fermi level of the rectifying contact, thus enabling directional electron transfer. The resulting electron-deficient Cu nanoparticles surface exhibited Lewis acidity, which was beneficial to adsorption of hydrazine molecule. While the electron-enriched Cu–N4/carbon surface improved the adsorption of oxygen molecule, and accelerated electron supply from Cu-N4 active sites to various oxygen intermediates. The CuNPs/CuSA-NPCF Mott-Schottky catalyst exhibited excellent catalytic activity for hydrazine oxidation reaction and oxygen reduction reaction in an alkaline media. The directional manipulation of electron transfer in heterogeneous materials was an attractive universal synthesis method, providing new approach for the preparation of efficient and stable hydrazine fuel cell catalysts.

Synthesis of metal-free nitrogen-doped mesoporous carbon nanosheets with reference to molecular self-assembly for efficient peroxymonosulfate activation

The application of metal-free carbon materials in Sulfate radical-based advanced oxidation processes (SR-AOPs) has attracted great attention. In SR-AOPs, porosity and active sites are the keys for nitrogen-doped carbon materials to exhibit high catalytic activity. In this paper, melamine and gallic acid were selected as raw materials, preparing metal-free nitrogen-doped carbon materials by using the molecular self-assembly synthesis method. The catalysts with different structural morphology and surface chemistry were obtained by controlling the pyrolysis temperature. It proposed the formation mechanism of nitrogen-doped mesoporous carbon nanosheets (NMC). The pyrolysis temperature was critical for the regulation of surface properties as well as the structure of carbon materials. It was found that NMC-800 exhibited fluffy and porous microstructure, and various active sites on the surface of the catalyst, including graphite N, pyridine N and CO. In the NMC-800/PMS system, the SMX degradation efficiency and corresponding rate constant could achieve 90.3 % and 0.1705 min−1, respectively. Besides, the degradation pathways and intermediate products of SMX were discussed by the analysis of quenching experiments, electron spin resonance (ESR) and liquid chromatography-mass spectrometry (LC-MS).

Design of nanosheet/nanotube composites of Fe, N-doped carbon for enhanced oxygen reduction in zinc-air batteries

Low-density active sites, low-mass transfer rate, and poor stability of carbon-based catalytic materials from the pyrolysis of conventional metal-nitrogen complexes can hamper the oxygen reduction reaction (ORR). Herein, a composite structure of nitrogen-doped carbon nanosheets grafted with carbon nanotubes are synthesized by Zn-ZIF-L breaking and co-functionalized by coupling Fe2O3 nanoparticles with active Fe-Nx species to form an active ORR catalyst (D-FeNC/MOF). Under the synergetic effect of high-density active sites and multi-size pore distribution, the diffusion resistance of oxygen in the pores can be decreased to facilitate the transfer of reactants and products, and the improvement of ORR efficiency. Comparing to the commercial Pt/C catalyst, the d-FeNC/MOF has exhibited a more positive half-wave potential of 0.875 V (vs. RHE) and a higher catalytic stability. Besides, the zinc-air battery assembled with d-FeNC/MOF as a cathode catalyst can also offer a maximum power density of 170 mW cm−2 and a specific energy density of 842 Wh kg−1. This work can provide a new way for designing non-Pt catalysts for various electrochemical energy devices.

Ultrasmall RuM (Mo, W, Cr) Decorated on Nitrogen-doped Carbon Nanosheet with Strong Metal-support Interactions for Electrocatalytic Hydrogen Generation in Wide pH Range

Developing efficient electrocatalysts for hydrogen evolution reaction (HER) in full pH range can promote the practical applications of hydrogen energy. In this work, nitrogen doped carbon nanosheets supported RuM (Mo, W, Cr) (RuM/NCN) are prepared through an ultrafast microwave approach. The carbon nanosheet structure coupled with the ultrasmall RuM nanoparticles can expose rich active sites to optimize the catalytic activity. Moreover, the strong metal-support interactions also favor to accelerate the reactions kinetics and improve stability. Thus, the developed RuMo/NCN (RuW/NCN) show excellent HER catalytic activities with overpotentials of 72 (75) mV, 82 (82) mV and 124 (119) mV to reach current density of 10 mA cm -2 in 1 M KOH, 0.5 M H2SO4 and alkaline seawater, respectively, and also achieve excellent performance in 1 M PBS. This work provides a valid and novel avenue to design efficient electrocatalysts in renewable energy-related fields.

Turning the coordination environment of atomic Fe-N4 center by peripheral nitrogen species for boosted catalytic performance

Atomically dispersed metal-nitrogen-carbon (M-N-C) catalysts show great potential for heterogeneous catalysis. However, recognizing and engineering the microenvironment of M-Nx sites to achieve satisfactory catalytic performance remains challenging. Herein, we propose a facile g-C3N4-assisted template strategy to anchor atomic Fe-N4 sites on highly nitrogen-doped carbon nanosheets. Through regulating the ratio and type of peripheral nitrogen species by carbonization temperature, the optimal Fe-N-C-800 catalyst showed significantly boosted catalytic activities (overall turnover frequency of 13.43 min−1 and activation energy of 19.44 kJ mol−1) for nitroarene reduction with extremely low reductant dosage, exceeding most reported metal catalysts. Experimental and theoretical results reveal appropriate graphitic- and pyrrolic-N dopants surrounding the Fe-N4 center can tailor the local electronic structure and contribute to obvious upshift of the d-band center, which dramatically promotes the adsorption and conversion of reactant substrates, eventually delivering the unprecedented catalytic performance. This work provides a guide for rational coordination environment regulation of single-atom catalysts for efficient chemical transformations.

N-doped carbon nanoflakes coordinate with amorphous Fe to activate ozone for degradation of p-nitrophenol

Due to their high catalytic performance, metal nitrogen-doped carbon materials are widely used in the field of environmental restoration of polluted water but there is limited research on metal nitrogen doped carbon composite materials as ozone catalysts. Herein, we report the preparation of amorphous iron-coordinated nitrogen-doped carbon nanosheets as a catalyst for ozone by the coordination of Fe-metal ions at the end of phenol chain in the lignin network. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy (Raman), powder X-ray diffraction (XRD) and element mapping were used to characterize the Fe/D-NC composite material and investigate its morphology and composition. Highly uniform distribution of iron species was found through characterization. By exploring the degradation performance of composite materials of Fe/D-NC-T (700，800，900 ℃) prepared at different temperatures, it was found that the optimal Fe/D-NC-800 could effectively degrade p-nitrophenol (PNP) within 30 min. Quenching experiments and ESR analysis showed that both free and non-free radicals (•OH, O2•− and 1O2) and intrinsic Lewis acid sites (LAS) of the composite material Fe/D-NC-800 were involved and responsible for the degradation of PNP. This work not only offers new platforms for catalytic ozonation and may drive the development of metal-lignin-based catalytic ozonation for effective water treatment but also opens new avenues toward lignin valorization and biomass economy.