N-doped Carbon Research Articles

Highly efficient and durable water electrolysis via ligand modulated interfacial assembly

Herein, we report a robust ligand-modulated interfacial assembly strategy for controllable metal doping to yield high-efficiency and durable bifunctional electrocatalysts of FeCoS-embedded hollow N-doped carbon (denoted H-FeCoS/NC) for electrocatalytic overall water splitting (EOWS). Specifically, the hollow Co-based layered double hydroxide (Co-LDH) is employed to render interfacial assembly of CoFe-PBA with tunable composition, morphology, and interface on Co-LDH, regulated by inorganic ligand. Subsequent sulfidation produces H-FeCoS/NC, manifesting outstanding OER/HER activities owing to favourable ligand-modulated Fe-doping, large specific surface area, well-dispersed FeCoS nanoparticles. DFT calculation reveals that ligand-modulated Fe-doping effectively promotes charge transfer, optimizes the intermediates/electrocatalyst interaction, and reduces OER/HER energy barriers, thus boosting the EOWS performance. The H-FeCoS/NC-assembled electrolyzer delivers a low cell voltage of 1.52 V and stably operates for 1000 h in alkaline medium, surpassing most non-noble-metal-based electrocatalysts. This work highlights a facile interfacial assembly route to engineer highly active electrocatalysts for high-performance and durable energy conversion and storage.

MoC nanoparticles embedded in superior thin g-C3N4 nanosheets for efficient photocatalytic activity

Photogenerated charge carrier transfer efficiency in graphitic carbon nitride (g-C3N4) based heterostructures depended strongly on the interface nature. In this paper, MoC nanoparticles less than 5 nm were implanted in superior thin g-C3N4 nanosheets to create high charge carrier separation and transfer efficiency. Cubic MoC in N-doped graphitic carbon was first fabricated using dicyandiamide and ammonium molybdate tetrahydrate at 800 °C. The MoC nanoparticles were homogeneously implanted in g-C3N4 nanosheets by further thermal polymerization of bulk g-C3N4 prepared using melamine and MoC/C composites to create a Schottky junction which was confirmed by band gap analysis and free radical capture test. Melamine and dicyandiamide also play important role to create highly efficient catalysts. The MoC nanoparticles revealed fine crystallinity. A well-developed interface between MoC and g-C3N4 was observed. Because of high conductivity of MoC, well-developed interface, and co-catalyst role of MoC, the MoC/g-C3N4 junction exhibited ideal photocatalytic activity for dye degradation and water splitting. The kinetic constant rate of Rhodamine B degradation using a MoC/g-C3N4 sample created by optimized conditions was 0.061 min−1 which was 8.7 times of that of pristine g-C3N4 nanosheets. In the case of without co-catalyst addition, the photocatalytic hydrogen generation rate using this composite sample was 233.0 μmol g−1 h−1 which was 15.2 times of that of initial g-C3N4 nanosheets. These results supply an efficient approach for the first time to homogeneously distribute small cubic MoC nanoparticles in superior thin g-C3N4 nanosheets to construct heterostructures and greatly reduce photogenerated charge carrier recombination.

Size-Controllable N-Doped Porous Carbon Synthesized from a Metal–Organic Framework Enables High-Performance Lithium/Sodium-Ion Batteries

Size-Controllable N-Doped Porous Carbon Synthesized from a Metal–Organic Framework Enables High-Performance Lithium/Sodium-Ion Batteries

Synthesis and multifunctional application of two novel carbon quantum dots as corrosion inhibitors

N, S- and N-doped carbon quantum dots (CDs) were synthesized by calcination in the presence of L-cysteine and 2-aminobutyric acid by using P-phenylenediamine as the raw material. The CDs were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, and fluorescence spectroscopy. Results show that both kinds of CDs have spherical structures and particle sizes. The CDs were dispersed in 3.5 wt% NaCl solution and doped into the epoxy coating to prepare the composite coating. The two kinds of CDs have good corrosion inhibition effects in both applications.

Theoretical Study on the Electrocatalytic CO2 Reduction Mechanism of Single-Atom Co Complexed Carbon-Based (Co-Nχ@C) Catalysts Supported on Carbon Nanotubes.

Electrocatalytic CO2 reduction serves as an effective strategy to tackle energy crises and mitigate greenhouse gas effects. The development of efficient and cost-effective electrocatalysts has been a research hotspot in the field. In this study, we designed four Co-doped single-atom catalysts (Co-Nχ@C) using carbon nanotubes as carriers, these catalysts included tri- and dicoordinated N-doped carbon nanoribbons, as well as tri- and dicoordinated N-doped graphene, respectively denoted as H3(H2)-Co/CNT and 3(2)-Co/CNT. The stable configurations of these Co-Nχ@C catalysts were optimized using the PBE+D3 method. Additionally, we explored the reaction mechanisms of these catalysts for the electrocatalytic reduction of CO2 into four C1 products, including CO, HCOOH, CH3OH and CH4, in detail. Upon comparing the limiting potentials (UL) across the Co-Nχ@C catalysts, the activity sequence for the electrocatalytic reduction of CO2 was H2-Co/CNT > 3-Co/CNT > H3-Co/CNT > 2-Co/CNT. Meanwhile, our investigation of the hydrogen evolution reaction (HER) with four catalysts elucidated the influence of acidic conditions on the electrocatalytic CO2 reduction process. Specifically, controlling the acidity of the solution was crucial when using the H3-Co/CNT and H2-Co/CNT catalysts, while the 3-Co/CNT and 2-Co/CNT catalysts were almost unaffected by the solution's acidity. We hope that our research will provide a theoretical foundation for designing more effective CO2 reduction electrocatalysts.

Tuning the shell thickness of N-doped interconnected hollow carbon sphere for the electrochemical sensing of antibiotic drug chloramphenicol.

N-doped hollow carbon spheres (NHCSs) with different shell thicknesses are constructed using various amounts of SiO2 precursor. An interconnected framework with diminished wall thickness ensures an efficient and continuous electron transport which helps to enhance theperformance of NHCS. Improvement of the electrocatalytic performance was shown in the determination of antibiotic drug chloramphenicol (CAP) due to theunique hollow thin shell morphology, ample defect sites, accessible surface area, higher surface-to-volume ratio and ansynergistic effect. Boosted electrocatalytic activity of 1.5 N-doped HCS (1.5 NHCS) was applied to detect CAP with a linear range and detection limit of 1-1150µM and 0.098µM (n = 3), respectively, with superior storage stability and considerable sensitivity. These results suggest that the proposed work can besuccessfully applied to the determination of CAP in milk and water samples.

Homogeneous Deposition of Zinc on N-Doped Carbon Fibers Interconnected with Sn Nanoparticles for Advanced Aqueous Zinc Batteries.

Currently, inhomogeneous distribution of Zn2+ on the surface of the Zn anode is still the essential reason for dendrite formation and unsatisfactory stability of zinc ion batteries. Given the merits of strong interaction between Sn and Zn, as well as a low nucleation barrier during Zn deposition, the combination of metallic Sn with carbon material is expected to improve the deposition of zinc ions and inhibit the growth of zinc dendrites by guiding the homogeneous plating/stripping of zinc on the electrode surface. In this article, zincophilic Sn nanoparticles with low nucleation barriers and strong interaction with Zn2+ were embedded into 3D N-doped carbon nanofibers using a simple electrostatic spinning technique. Accordingly, when serving as an artificial coating layer for the zinc metal anode, an ultrastable Sn@NCNFs@Zn||Sn@NCNFs@Zn symmetric cell can be achieved for over 3500 h with a low nucleation overpotential of 29.1 mV. Significantly, the full cell device assembled with the as-prepared anode and MnO2 cathode exhibits desirable electrochemical behaviors. Moreover, this simple method could be extended to other metal-carbon composites, and to ensure ease in scaling up as required. Such significant approach can provide an effective strategy for the design of high-performance zinc anodes.

Fast diffusion kinetics improves electron transfer regime selectivity to boost peroxymonosulfate activation

Electron transfer process (ETP) is barely influenced by half-life and migration distance in peroxymonosulfate (PMS) activation because it directly extracts electrons from pollutants for oxidation. However, the enhanced ETP selectivity is still challenging due to the poor mass transfer of PMS and pollutant. In this work, 2D porous N-doped carbon (PNC) with high reactant diffusion kinetics and multiple diffusion modes was designed to induce the interlayer confinement for efficient PMS activation with elevated ETP selectivity. Taking tetrabromobisphenol A as target pollutant, the confined PNC/PMS system achieved significantly enhanced PMS activation performance with the selectivity of ETP up to 97.8%. The vertical mass transfer of reactants into the inner interlayer space of the catalysts was proved to be promoted by the construction of molecule tunnels according to a diffusion model. Density functional theory calculations indicated that the subsequently triggered interlayer confinement facilitated the co-adsorption of PMS/pollutant on the interlayer surface and narrowed the energy gap of charge migration, resulting in enhanced PMS activation performance and ETP selectivity. Benefiting from the almost 100 % ETP selectivity, the confined PNC/PMS system exhibited substantially increased PMS utilization efficiency, admirable anti-interference ability towards various water matrices as well as long-term stability in a continuous-flow reactor. This work provides a new protocol for efficient and selective PMS activation by interlayer confinement in water remediation.

Rational design of mangosteen-like bismuth nanospheres coated by N-doped carbon shell as superb composite anode for high-performance sodium-ion batteries

Metallic bismuth (Bi) anode materials are promising candidates for alkali-ion batteries due to its high theoretical gravimetric/volumetric capacity. However, the pronounced volume change from Bi to full sodiation phase Na3Bi, inducing the structural collapse, and ionic conduction interruption upon cycling, hinders their implementation in sodium-ion batteries (SIBs). Herein, a mangosteen-like bismuth nanosphere coated by N-doped carbon shell (Bi@NC) was designed and synthesized to address these limitations. Due to the nanosize of Bi core and in situ, generated N-doped carbon shell, this Bi@NC anode can not only effectively accommodate the volume change during the alloying/dealloying process but also provide high-speed channels for electron/ion transport to the highly active bismuth nanospheres. The Bi@NC electrode exhibits outstanding cycling stability (1000 cycles at 5 A g−1 with an impressive capacity retention of 96.5 %) and rapid sodium storage performance (392.8 mAh g−1 at 20 A g−1). Importantly, ex-situ techniques and kinetic analysis have revealed the distinctively sharp multiphase transitions and the “battery-capacitor dual-mode” sodium-storage mechanism. This research introduces a new approach to enhance the performance of bismuth-based anodes in advanced SIBs and demonstrates potential for practical applications.

Nonradical peroxymonosulfate activation via high-level pyrrolic-nitrogen and electron-deficient carbon at 2D ultrathin carbonaceous nanosheets for efficient BPA removal

Activation of persulfate by N-doped carbon is an emerging advanced oxidation process (AOP) for removing organic pollutants from water via singlet oxygen (1O2)-dominated non-radical way, however, the efficient generation of 1O2 is a hot topic worth deep exploration. In this study, glucose was used as an additional carbon and oxygen of prefabricated supramolecular melamine-cyanuric acid precursor, the final co-thermal polymerization products completely changed from conventional graphitic carbon nitride to ultrathin carbonaceous materials when the mass of glucose up to 0.72 g. The simple one-pot strategy can easily generate active electron-deficient carbon sites due to nitrogen and oxygen doping by modulating the electronic structure of the carbon framework, which is critical for the activation of peroxymonosulfate (PMS) to produce 1O2. The glucose content can adjust the degree of disorder of the amorphous carbonaceous nanosheet, and significantly improve the exposure of active pyrrolic nitrogen sites (27.47 %) and doped oxygen through the defective structure, which is another essential factor for the generation of 1O2 in the activation of PMS. The MCAG-0.72/ PMS exhibited excellent performance in BPA degradation, 95 % BPA (20 mg L−1) can be removed in 60 min with 1.0 mM PMS with reaction constant k=0.0209 min−1. Furthermore, MCAG-0.72 also demonstrated excellent BPA degradation in different actual water metrics and performance well in the four consecutive cycles. This study provides a novel convenient strategy to synthesize cost-effective N/O co-doped carbonaceous material for efficient activating PMS to remove refractory organics in water and wastewater, it sheds light on practical large-scale industrial applications in PMS-based AOPs.

Tubular-like Nanocomposites with Embedded Cu9S5-MoSx Crystalline-Amorphous Heterostructure in N-Doped Carbon as Li-Ion Batteries Anode toward Ultralong Cycling Stability.

Transition metal sulfides (TMSs) show the potential to be competitive candidates as next-generation anode materials for Li-ion batteries (LIBs) due to their high theoretical specific capacity. However, sluggish ionic/electronic transportation and huge volume change upon lithiation/delithiation remain major challenges in developing practical TMS anodes. We rationally combine structural design and interface engineering to fabricate a tubular-like nanocomposite with embedded crystalline Cu9S5 nanoparticles and amorphous MoSx in a carbon matrix (C/Cu9S5-MoSx NTs). On the one hand, the hybrid integrated the advantages of 1D hollow nanostructures and carbonaceous materials, whose high surface-to-volume ratios, inner void, flexibility, and high electronic conductivity not only enhance ion/electron transfer kinetics but also effectively buffer the volume changes of metal sulfides during charge/discharge. On the other hand, the formation of crystalline-amorphous heterostructures between Cu9S5 and MoSx could further boost charge transfer due to an induced built-in electric field at the interface and the presence of a long-range disorder phase. In addition, amorphous MoSx offers an extra elastic buffer layer to release the fracture risk of Cu9S5 crystalline nanoparticles during repetitive electrochemical reactions. Benefiting from the above synergistic effect, the C/Cu9S5-MoSx electrode as an LIB anode in an ether-based electrolyte achieves a high-rate capability (445 mAh g-1 at 6 A g-1) and superior ultralong-term cycling stability, which delivers an initial discharge capacity of 561 mAh g-1 at 2 A g-1 and its retention capacity after 3600 cycles (376 mAh g-1) remains higher than that of commercial graphite (372 mAh g-1).

Fabrication of self-N-doped porous biochar by synergistic pyrolysis activation for efficient tetracycline and CO2 adsorption

The development of green and economical adsorption materials with high pollutant adsorption performance is of great significance to meet environmental challenges. Herein, self N-doped porous carbon materials with excellent tetracycline and CO2 adsorption properties are successfully prepared by synergistic pyrolysis activation of corn stalk and Chlorella mixture. The addition of N-riched Chlorella significantly affects the nanopore and surface chemical structure of biochar, forming rich micro-mesopores, changing the intrinsic N doping form and surface oxygen-containing functional groups. An ultra-high tetracycline adsorption capacity of 1159.7 mg/g can be achieved by using the prepared KBC-3:1 as an adsorbent. A series of kinetic isothermal adsorption models, thermodynamic calculations, as well as comparative characterization analysis show that multiple adsorption mechanisms coexist. The pore filling of micro-mesopores (1.5–3 nm), π-π interactions of CC bonds, H bonding interactions of CO and the strong electrophilicity of pyrrolic N contribute to the excellent tetracycline adsorption performance of KBC-3:1. Furthermore, the material shows great resistance to cationic (K+, Mg2+, Cu2+) interference and excellent cycling performance. In addition, KBC-3:1 also exhibits excellent adsorption capacity for CO2, and the adsorption capacity of 5.21 mmol/g can be achieved at 273 K and 1 bar, which could be attributed to the synergistic activation effect leading to KBC-3:1 having the most abundant pyrrolic and pyridinic N species as well as the rich microporous structure. This work can provide guidance for the development of green and economical high performance carbon materials based on the intrinsic characteristics of biomass.

Direct recycling of spent lithium-ion battery cathodes inspired by the polymerization of dopamine

The direct recycling process shows excellent flexibility and potential for the regeneration of spent lithium-ion battery cathodes. However, conventional direct recycling methods involve high temperatures or potential secondary pollution. Herein, the green restoration of spent LiFePO4 (LFP) cathodes is achieved via a polymerization of dopamine (POD)-assisted process in water at room temperature. A unique mechanism is proposed based on DFT calculations: Some intermediates, rather than dopamine or polydopamine, restore the crystal structure of spent LFP. Furthermore, a short annealing treatment could not only increase the structural stability, but also avoid the potential secondary pollution caused by the reductants by converting the Polydopamine (PDA) layer to an N-doped carbon layer and improve the electrochemical performance of the regenerated LFP. A subsequent techno-economic analysis suggests that the present strategy promises great potential in practical application. Environmental implicationSpent lithium-ion batteries (LIBs) contain a large number of toxic and hazardous substances, which would affect ecological balance and human activities, so recycling and reuse of spent LIBs play a vital role in environmental protection. The POD-assisted recycling strategy can maximize the recycling value of the LiFePO4 cathode material, and avoid the secondary pollution caused by the reducing agent. Compared with the traditional pyrometallurgy and hydrometallurgy, the POD-assisted recycling strategy has less negative impact on the environment, higher economic value, and has a broad application prospect.

N-Doped Carbon Dots for Selective Detection of Fe3+ and Degradation of Fe3+/Basic Red 9 Complexes in Water Samples.

In this work, the eco-friendly N-doped carbon dots KF-CDs and A-CDs were derived from kiwifruit by a simple one-step hydrothermal strategy at 180°C for 6h. KF-CDs have a high fluorescence quantum yield (27.85%), it is obviously rapid quenched by Fe3+, and have a good linear relationship from 1 to 8.26 µM (the detection limit was 0.077 µM). Basic red 9 is extensively used in biological, environmental and industry. Although it makes a great contribution to the economy, its toxicity should be taken seriously, especially with harmful metal ions. Within 2h, A-CDs could degrade basic red 9 with degradation efficiency 89.6%, even though there was a stable compound formed with Fe3+ that the degradation efficiency was up to 88.3%. The results complement the research blank of carbon dots in catalytic degradation of basic red 9.

Pd Nanoclusters Supported on N-Doped Carbon Spheres for Hydrogenation of Phenols and Benzoic Acids

Pd Nanoclusters Supported on N-Doped Carbon Spheres for Hydrogenation of Phenols and Benzoic Acids

Fluorine and sulfur atoms induced N-doped 3D porous carbon catalyzing oxygen reduction in the zinc-air battery

Introducing other heteroatom is considered to be a highly effective approach to improve the limited catalytic activity from single nitrogen element doping in nitrogen-doped porous carbon materials. In this work, F and S-modified nitrogen-doped porous carbon (F-S-N-C) is prepared by annealing the assembly material of poly3-fluoro aniline, hydroxyethyl sulfonic acid and g-C3N4, in which the g-C3N4 is employed as template agent and pore-forming agent. A series of characterization techniques indicate that simultaneous doping of F and the S atoms enhance the electron transfer and construct more defects for N-doped 3D porous carbon, resulting in improved electrocatalytic performance. The prepared F and S-cooperated nitrogen-doped porous carbon (F-S-N-C) exhibits significantly improved oxygen reduction reaction electrocatalytic activity in alkaline media with a half-wave potential of 0.808 V. The zinc-air battery (ZAB) with F-S-N-C as the air cathode catalyst demonstrates a peak power density of 167 mW cm−2, which is higher than that of commercial Pt/C (158 mW cm−2). Moreover, the specific capacity of the F-S-N-C-based ZAB reaches to 817 mAh·g−1.

Unraveling a High-Performance Self-Supported Flexible Zinc-Ion Battery Cathode with Tailored Electrospun MnOx/N-Doped Carbon Nanofibers

Unraveling a High-Performance Self-Supported Flexible Zinc-Ion Battery Cathode with Tailored Electrospun MnO_<i>x</i>/N-Doped Carbon Nanofibers

Encapsulating Si nanoparticles in ZIF-8-derived carbon through surface amination for stable lithium storage

The application of silicon in lithium-ion batteries has been impaired by the low conductivity and large volume expansion. Herein, we develop a facile “surface amination” strategy to successfully encapsulate Si nanoparticles within the ZIF-8-derived N-doped carbon matrix. The amino group-containing organosilica serves as the linking agent between Si nanoparticles and Zn2+ and facilitates the coating of the ZIF-8 layer on the Si nanoparticles. This in turn induces the construction of N-doped carbon matrix encapsulated Si nanoparticles (NH2-Si@C) during the subsequent carbonization. With buffered volume change and increased conductivity, the rationally designed NH2-Si@C demonstrates a high reversible capacity (1494 mAh g–1 at 1 A g–1) and satisfactory rate performance (1062 mAh g–1 at 5 A g–1).

Chitosan-derived N-doped porous carbon with fiber network structure for advanced lithium‑sulfur batteries

The flexible design and construction of advanced carbon-based sulfur hosts contribute to the rapid redox and reaction kinetics of lithium polysulfides (LiPSs) in lithium‑sulfur batteries (LSBs), laying the foundation for the next generation of high-energy density energy storage devices. Herein, chitosan (CS)-derived porous N-doped carbon with fiber network structure was prepared by a simple freeze-drying method combined with sintering process. The effect of inorganic salt additives on the morphology of CS-derived carbon was investigated by SEM. The types and contents of N-doping were investigated through XPS analysis. The influence of morphology and N content on the performance of LSBs has been explored in detail through cycling and CV testing. In addition, the true active sites in the CS-derived carbon were determined by XPS and first principles calculations. As an active species, pyrrolic N exhibits superior adsorption energy and the most suitable degradation energy barrier for LiPSs. As the optimal electrode, the performance of LSBs under different electrolyte to sulfur (E/S) conditions was further investigated to explore the potential application of CS-KOH electrodes in high-energy density batteries. The results unveil that the influence of E/S on Li2S deposition is quite significant, with a limit of 5 μL mg−1. This work provides a new strategy for the preparation of high-performance advanced carbon-based materials with fiber network structures from polysaccharide biomass, and also promotes the application of CS in energy storage.

Facile synthesis of inherently nitrogen-doped PAN-derived microporous carbons activated with NaNH2 for selective CO2 adsorption and separation

N-doped porous carbons (PCs) are extensively researched for CO2 capture and separation under flue gas conditions, but their complex and expensive preparation methods hinder widespread industrial use. Herein, we present a direct approach for synthesizing N-doped PCs by utilizing polyacrylonitrile (PAN) and NaNH2 as precursors, without the need for any solvents. The utilization of NaNH2 as both a porogen and nitrogen supply during carbonization is primarily responsible for the formation of the well-developed pore structure and high specific surface area of N-doped PCs. The optimized sample “PN-3” demonstrated excellent textural features with an excellent specific surface area (SSA) of 2490 m2/g, a pore volume of 2.0559 cm3/g, a well-defined pore size distribution (PSD), and abundant micropores (<1 nm). In addition, PN-3 has the highest pyrrolic nitrogen content (∼40.1 at.%), resulting in a significant capacity for CO2 adsorption (7.15 mmol/g at 273 K/1bar, 4.56 mmol/g at 298 K/1 bar, 26.2 mmol/g at 298 K/ 40 bar). Furthermore, it exhibits an outstanding CO2/N2 selectivity (∼102) based on the ideal adsorbed solution theory (IAST) at 273 K, surpassing the performance of most of previously reported biomass and polymer-derived N-doped carbons in terms of CO2 adsorption and separation. In addition, the adsorption process is characterized by a modest heat of adsorption (39.10 kJ/mol) and a steady cyclic pattern of CO2 adsorption–desorption under flue gas settings (15 % CO2 and 85 % N2). This indicates that the adsorption is mostly governed by physisorption, which allows for an energy-efficient regeneration process. In summary, this study showcases the successful production of highly PCs that can effectively adsorb CO2, enlightening the way toward establishment of a cost-effective and facile synthetic protocol for achieving CO2 capture/separation at the commercial scale.