N-doped Porous Carbon Nanosheets Research Articles

Self-assembly formation of Co quantum dot loaded N-doped porous carbon cathode for quinoline degradation in the electro-Fenton system

Quinoline is high toxicity and difficult biodegradation in oil washing wastewater. Therefore, efficient removal of quinoline contaminant from water bodies poses a major challenge. Hence, Co quantum dot loaded N-doped porous carbon (CoNC) nanosheets grown in situ on carbon cloth were fabricated as cathode for the degradation of quinoline in electro-Fenton system. Under optimal conditions (c(Fe2+) = 0.5 mM, U = -0.3 V, pH = 3), quinoline was completely degraded within 15 min with superior apparent rate constant of 0.385 min−1, which was 19.6 times higher than that of the ZIF-L precursor, due to the abundance of Co QDs active sites and hydrophilicity and electrical conductivity of N-doped porous carbon. In addition, three reaction pathways for quinoline were deduced by combining Density Functional Theory (DFT) calculation and Liquid Chromatography-Mass Spectrometry (LC-MS). More importantly, in situ FTIR and free energy calculations were analyzed to reveal that pathway Ⅰ as spontaneous reaction was the main reaction pathway. Finally, the toxicity of the intermediates was assessed with ECOSAR software and E. coli experiments, and the overall toxicity decreased during the degradation reactions. This work provides novel perspectives on environmental protection by designing in-situ grown cathodes through self-assembly method, thereby effectively purifying pollutants from wastewater.

Shuttle-free zinc–iodine batteries enabled by a cobalt single atom anchored on N-doped porous carbon host with ultra-high specific surface area

Aqueous zinc‑iodine batteries are favorable solutions for grid-level energy storage owing to their cost-effective components and intrinsic safety. Nevertheless, the sluggish conversion kinetics and polyiodide shuttle effect have significantly hindered their practical applications. Herein, a Co single atom anchored on N-doped porous carbon nanosheets (Co-SAs@NPC) was produced through an efficient molten-salt engaged pyrolysis process and further utilized as the iodine host for aqueous zinc-iodine batteries. The large specific surface area (1741 m2 g−1) combined with abundant heteroatom-containing functional groups can afford a tight physical and chemical confinement towards iodine species. Meanwhile, the presence of Co single atoms exhibits high electrocatalytic activity towards I2 reduction reactions. According to the experimental results and DFT theoretical calculations, the resulting Co-SAs@NPC can simultaneously offer generous electrochemical active sites and electrocatalytic activity, which displays a high adsorption ability towards iodide species and boost the reversible redox reactions between iodine and iodides. Consequently, the as-assembled zinc-iodine batteries with Co-SAs@NPC/I2 cathodes can deliver a high specific capacity (295 mA h g−1 at 0.3 A g−1), good rate performance (199 mAh g−1 at 20 A g−1), and long cyclic stability over 10,000 cycles. Additionally, the absence of polyiodide shuttle was analyzed by a series of ex-situ spectrum analyses.

Ru embedded into N-Doped Porous Carbon Nanosheets as a Robust Catalyst for Efficient Hydrogenation of Levulinic Acid to γ-Valerolactone

Ru embedded into N-Doped Porous Carbon Nanosheets as a Robust Catalyst for Efficient Hydrogenation of Levulinic Acid to γ-Valerolactone

2D ZIF-8 derived N-doped porous carbon nanosheets for high-performance Li-Se batteries

Lithium-selenium (Li-Se) batteries have attracted increasing attention because of excellent carbonate electrolyte compatibility, comparable theoretical volumetric specific capacity and high electrical conductivity. However, there are still unavoidable issues such as large volume expansion, rapid capacity decay and slow electrochemical reaction kinetics for practical applications. In this work, we report 2D ZIF-8 derived N-doped porous carbon nanosheets (NPC-NS) as Se host for high-performance Li-Se batteries. The unique 2D structure of Se@NPC-NS facilitates Li+ diffusion and charge transfer, thus the Se@NPC-NS cathode exhibits fast electrochemical reaction kinetics. In addition, the N doping enhances electronic conductivity and porous structure mitigates the volume expansion. As a result, the Se@NPC-NS cathode delivers a high reversible capacity of 585 mAh/g with a capacity retention of 99.1 % at 0.5C (1C = 675 mA g−1) after 225 cycles. Especially after 500 cycles at a high current density of 10C, the Se@NPC-NS cathode still displays a reversible specific capacity of 307 mAh/g with only 0.03 % capacity decay per cycle. This work would shed some light on the 2D carbon host as Se-based cathode for high-rate and long-life performance Li-Se batteries.

Enhancing the NO2 detection ability of surface acoustic wave sensors with ZnO-decorated N-doped porous carbon nanosheets

The ZnO provides abundant adsorption sites of NO2 to the N-PCNs, optimizing the sensing mechanism of N-PCNs for NO2, and significantly reinforcing the NO2 detection ability of sensing layers for SAW sensors.

In situ preparation of cobalt@N-doped porous carbon bifunctional electrocatalyst for efficient overall water splitting

Developing highly efficient noble-metal-free bifunctional nanocatalysts for electrocatalytic water splitting is attractive but challenging. Notably, the rational structure engineering could effectively promote electronic transfer and improve the active area. Herein, a free-standing N-doped porous carbon nanosheet arrays encapsulated with metallic Co nanoparticles electrocatalyst (Co@NC-A) for overall water splitting was designed via pyrolysis process followed with acid treatment. The N-doped carbon matrix not only enhances electron mobility and protects the metallic Co nanoparticles from electrolyte corrosion, but also improves the electrochemically active area and facilitates mass transfer. Consequently, the Co@NC-A exhibits superior electrocatalytic performance toward OER (η10 = 270 mV) and HER (η10 = 162 mV) in 1 M KOH. Moreover, the Co@NC-A as a bifunctional catalyst in overall water splitting could approach 10 mA cm−2 at a cell voltage of 1.66 V and operate stably for 50 h. Combined with the density functional theory (DFT) calculations, the improvement of the HER and OER activities is also attributed to the modified electronic structure with N-doped carbon and the optimized free energy toward the adsorption/desorption of intermediates. This work provides a novel and facile non-precious metal catalyst for water splitting and should be instructive for designing more carbon-based nanocatalysts.

N-doped defect-rich porous carbon nanosheets framework from renewable biomass as efficient metal-free bifunctional electrocatalysts for HER and OER application

In response to the demand for clean, renewable energy sources and storage technologies, innovative materials and combinations have been developed at reasonable prices as effective electrode materials. Current research and development of carbon-based metal-free catalysts have opened up new research areas for bifunctional electrocatalysts for overall water splitting. Herein, we developed N-self-doped defect-rich porous carbon nanosheets derived from platycladus orientalis tree-cone biomass for overall water splitting. The developed N-self-doped defect-rich porous carbon nanosheets have large surface areas (3369 m2/g), high pore volumes (2.1 cm3 g−1), and high electrical conductivities (12.69 S/cm). N-self-doped defect-rich porous carbon nanosheet framework was employed in water splitting as a dual function in hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Electrodes fabricated from the KOH-II ABC nanosheets show excellent OER and HER performances in the 0.5 M H2SO4 solution. The current density of 10 mA cm−2 is reached at a low overpotential of 90 mV for OER and 188 mV for HER. In addition, KOH-II ABC nanosheets also show a remarkable performance on overall water splitting, which only required a cell voltage of 1.49 V to reach current densities of 10 mA cm−2 in 0.5 M H2SO4 solution. The presence of defects in the carbon nanosheets, higher specific surface area, excellent electrochemical active surface area and N doping effectively enhance the reaction kinetics for attaining efficient OER and HER performances. This facile approach to preparing biomass-derived N-doped defect-rich porous carbon materials empowers next-generation green fuel conversion technologies for carbon neutrality.

Atomic Edge Fe-N4 Active Sites on N-Doped Porous Carbon Nanosheets Derived from Zeolitic-Imidazolate Frameworks for High-Efficiency Oxygen Reduction

Atomic Edge Fe-N₄ Active Sites on N-Doped Porous Carbon Nanosheets Derived from Zeolitic-Imidazolate Frameworks for High-Efficiency Oxygen Reduction

Interfacial Coupling Engineering Boosting Electrocatalytic Performance of CoFe Layered Double Hydroxide Assembled on N-Doped Porous Carbon Nanosheets for Water Splitting and Flexible Zinc-Air Batteries.

The disadvantages of layered double hydroxides (LDHs) such as easy stacking, poor inherent conductivity, and limited versatility hinder their application in splitting water and zinc-air batteries (ZABs). Interface engineering to regulate the electron distribution of LDHs by introducing another component is a way to compensate for the poor electron transport capacity of LDHs during catalysis. Herein, a hierarchical structure is synthesized by assembling CoFe-LDH nanosheets onto the surface of layered N-doped porous carbon (NPC), CoFe-LDH@NPC, by using an interface engineering strategy. CoFe-LDH@NPC has high catalytic activity for the oxygen/hydrogen evolution reaction (OER/HER) with overpotentials of 280/100 mV, respectively. The two-electrode water splitting catalyzed by CoFe-LDH@NPC only needs 1.61 V to drive a current density of 10 mA cm-2 for 60 h. The theoretical results show that there is an electron-deficient/electron-rich interface between the NPC substrate and the CoFe-LDH in CoFe-LDH@NPC. The electrons on the coupling interface are easily transferred, which results in a change of the adsorption behavior of the reaction intermediates and improves the catalytic activity for the OER and HER. In addition, CoFe-LDH@NPC-catalyzed rechargeable flexible ZABs have excellent performance with low charge-discharge polarization (0.87 V) and a long-term stability of 65 h.

Graphite-N modified single Fe atom sites embedded in hollow leaf-like nanosheets as air electrodes for liquid and flexible solid-state Zn-air batteries

The oxygen reduction procedure requires the development of an extremely effective, easily fabricated, and non-noble metal electrocatalyst. In this paper, we offer an unique method for manufacturing a defect-rich Fe single-atom catalyst loaded on the N-doped porous carbon nanosheets carrier (Fe-N4@NC-PCSs) by in-situ pyrolysis of a double-layered leaf-like compound (ZIF-L@PDA-FePhen) using dopamine hydrochloride aided precursor ZIF-L. The Fe-N4@NC-PCSs catalyst exhibits exceptional oxygen reduction reaction (ORR) activity across the pH-universal range, particularly in alkaline electrolytes, with a prominent half-wave potential of 0.938 V, outperforming practically previously described non-noble electrocatalysts as well as the commercial Pt/C catalyst (0.84 V). At pH-universal, the Fe-N4@NC-PCSs catalyst exhibits exceptional half-wave potential and an impressive electron/proton transfer ability resulting from its rich iron nitrogen active sites and a significant number of metal defects. Furthermore, the liquid zinc-air battery, as well as the flexible solid-state battery based on Fe-N4@NC-PCSs work excellently, with open circuit voltage of 1.465 V, maximum peak power density of 207 mV cm−2, and good charge–discharge endurance and mechanical flexibility. Calculations using density functional theory show that graphitic nitrogen can improve the local electronic redistribution for active sites and give them a lower free-energy barrier to ORR. This work serves as motivation for the creation of nitrogen moiety regulation extremely reactive atomic metal catalysts.

One-Step Synergistic Effect to Produce Two-Dimensional N-Doped Porous Carbon Nanosheets with Ultrahigh Porosity from Biomass for High-Performance Supercapacitors

One-Step Synergistic Effect to Produce Two-Dimensional N-Doped Porous Carbon Nanosheets with Ultrahigh Porosity from Biomass for High-Performance Supercapacitors

Graphene/metal-organic framework nano-sandwiches derived N, P-codoped porous carbon nanosheets as robust material for electrochemical analysis

Construction of novel two-dimensional porous carbon nanosheets with superior electrochemical activity is of great challenge. Here, graphene/ZIF-8 nano-sandwiches derived N, P-codoped porous carbon nanosheets (N, P-codoped PCN) was easily obtained by sequential room temperature self-assembly and high-temperature carbonization method. Relative to the widely used physically exfoliated graphene nanosheets (GN) and graphene/ZIF-8 derived N-doped porous carbon nanosheets (N-doped PCN), N, P-codoped PCN displayed larger active surface, faster electron transport ability and stronger physical adsorption ability, which can be ascribed to the dual doping effect of heteroatoms N and P. As a result, N, P-codoped PCN exhibited remarkable oxidation signal enhancement for tumor marker (8-hydroxy-2′-deoxyguanosine), analgesic and antipyretic drug (acetaminophen) and organic pesticide (benomyl). Besides, the limits of detection were measured as low as 1.58 nM, 7.50 nM and 2.10 nM with sensitivity of 270.00 μA μM−1 cm−2, 757.14 μA μM−1 cm−2 and 272.86 μA μM−1 cm−2 for 8-hydroxy-2′-deoxyguanosine, acetaminophen and benomyl, respectively. Basing on this, a novel and highly sensitive electrochemical sensing platform was developed. It is believed that the reported two-dimensional N, P-codoped PCN with unique structure and composition is highly valuable for the development of carbon-based electrochemical sensors.

Green and facile synthesis of carbon encapsulated Fe3N nanospheres grown on N-doped porous carbon nanosheet as an excellent anode material

The development of iron nitride anode materials is greatly impeded by their traditional synthetic methods. In this work, carbon encapsulated Fe3N nanospheres grown on N-doped porous carbon nanosheet is successfully prepared by a green, facile and controllable approach. Only a small nitrogen source is needed in the synthetic process by in-situ nitrogenization. The Fe3N nanospheres are coated by carbon and uniformly adhered to N-doped porous carbon nanosheet, which prominently mitigates the variation of volume and elevates the electrochemical reaction kinetics. The feature is conducive to realizing a long life and brilliant rate performance. As an anode for lithium-ion batteries, a high discharge capacity of 484 mA h g−1 is delivered after 600 cycles at 2 A g−1. Extensive impact is brought by this study for the preparation and application of metal nitride materials.

RuCo alloy nanoparticles embedded within N-doped porous two-dimensional carbon nanosheets: a high-performance hydrogen evolution reaction catalyst

RuCo alloy nanoparticles embedded within N-doped porous two-dimensional carbon nanosheets: a high-performance hydrogen evolution reaction catalyst

A One-Step Self-Flowering Method toward Programmable Ultrathin Porous Carbon-Based Materials for Microwave Absorption and Hydrogen Evolution.

Ultrathin 2D porous carbon-based materials offer numerous fascinating electrical, catalytic, and mechanical properties, which hold great promise in various applications. However, it remains a formidable challenge to fabricate these materials with tunable morphology and composition by a simple synthesis strategy. Here, a facile one-step self-flowering method without purification and harsh conditions is reported for large-scale fabrication of high-quality ultrathin (≈1.5nm) N-doped porous carbon nanosheets (NPC) and their composites. It is demonstrated that the layered tannic/oxamide (TA/oxamide) hybrid is spontaneously blown, exfoliated, bloomed, in situ pore-formed, and aromatized during pyrolysis to form flower-like aggregated NPC. This universal one-step self-flowering system is compatible with various precursors to construct multiscale NPC-based composites (Ru@NPC, ZnO@NPC, MoS2 @NPC, Co@NPC, rGO@NPC, etc.). Notably, the programmable architecture enables NPC-based materials with excellent multifunctional performances, such as microwave absorption and hydrogen evolution. This work provides a facile, universal, scalable, and eco-friendly avenue to fabricate functional ultrathin porous carbon-based materials with programmability.

Palladium nanoparticles anchored on MXene-based N-doped porous carbon nanosheets as an advanced electrocatalyst for ethanol oxidation

Pd-based electrocatalysts with advanced activity and durability can greatly accelerate the commercial process of direct ethanol fuel cells (DEFCs). However, Pd nanoparticles (NPs) are easily aggregated and deactivated during the ethanol oxidation reaction (EOR), which will restrict their electrocatalytic efficiency during the long-term running. To solve these problems, we develop new sandwich-like MXene-based N-doped porous carbon (NPCM) through carbonizing and acid etching of ZIF/MXene composite nanosheets. The derived NPCM nanosheets possess a highly ordered nano-porous and N-doped structure, which can be used as competitive catalyst supports to highly disperse Pd NPs and effectively avoid the aggregation and deactivation of Pd NPs. Meanwhile, the as-synthesized Pd/NPCM can offer more activity sites and more space for electrocatalysis reaction, leading to excellent CO tolerance. Thanks to the combination of MXene and ZIF, the designed Pd/NPCM electrocatalyst can offer connected channels for the fast diffusion of reactants and products. Impressively, the Pd/NPCM electrocatalyst exhibits a mass activity of 2237 mA·mgPd−1, which is 1.90 and 6.37 folds that of Pd/ZIF (1179 mA mgPd−1) and Pd/C (351 mA mgPd−1) electrocatalyst, respectively. This work not only explores a novel strategy for preparing advanced electrocatalyst support materials but also opens up their wide applications in DEFCs.

Cu nanoclusters activating ultrafine Fe3N nanoparticles via the Mott-Schottky effect for rechargeable zinc-air batteries

The rational design and synthesis of cost-effective bifunctional oxygen electrocatalysts is crucial for the large-scale commercial applications of rechargeable zinc-air batteries. In this work, the CuNCs/Fe3N-NPCF catalyst was constructed by anchoring the metallic Cu/Fe3N ensembles with different sizes onto N-doped porous carbon nanosheets. The Mott-Schottky heterostructure formed by Fe3N nanoparticles and its surrounding Cu clusters enabled spontaneous electron transfer, which speeded up the electron supply from active sites to various oxygen intermediates. The electrophilic region on Cu side and the nucleophilic region on Fe3N side improved the adsorption of O2 and OH-, respectively. The CuNCs/Fe3N-NPCF exhibited onset potential of 0.98 V and low Tafel slope of 59.30 mV dec−1 in ORR, and overpotential of 282 mV at 10 mA cm−2 current density in OER. The CuNCs/Fe3N-NPCF-based zinc-air battery displayed the excellent catalytic activity and durability. These findings provided the guides in developing the efficient and stable Mott-Schottky bifunctional oxygen electrocatalysts.

Molten salt synthesis of ZIF derived CoFe alloy embedded in 2D ultrathin N-doped porous carbon nanosheets for efficient alkaline media oxygen electrocatalysis

Developing advanced electrocatalysts for cooperative oxygen electrocatalysis is significant to metal-air batteries. Herein, we report a novel and simple molten salt approach for constructing CoFe alloy embedded in 2D ultrathin N-doped porous carbon nanosheets (CoFe/NPC). Furthermore, the pyrolysis temperature and Co/Fe molar ratio were optimized for high activity. As expected, the optimal Co0.5Fe0.5/NPC-900 manifests outstanding catalytic activity and durability for bifunctional oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). It only needs a positive half-wave potential of 0.89 V to drive ORR and a low overpotential of 318 mV to afford 10 mA·cm−2 for OER, outperforming that of commercial Pt/C and RuO2. More impressively, excellent durability with continuous operation is also achieved. The numerous exposed catalytic sites, the accelerated mass and charge transfer, and the interplay between CoFe alloy and the 2D ultrathin N-doped carbon species account for the enhanced catalytic performance of CoFe/NPC. Similarly, the architecture of porous substrate anchoring CoFe alloy enables long-term durability due to strong metal-support interaction.

Fluorine and phosphorus atoms cooperated on an N-doped 3D porous carbon network for enhanced ORR performance toward the zinc–air batteries

A three-dimensional N-doped porous carbon nanosheet catalyst cooperated by fluorine and phosphorus atoms was prepared in this work, which showed high oxygen reduction performance in 0.1 M KOH and a power density of 138 mW cm−2 in zinc–air battery.

Generation of covalent organic framework-derived porous N-doped carbon nanosheets for highly efficient electrocatalytic hydrogen evolution

N-doped carbon nanosheets derived from triazine-containing polyimide-based covalent organic framework (TP-COF) exhibit outstanding electrocatalytic hydrogen evolution.