Nitrogen-doped Carbon Composites Research Articles

Magnetic Nitrogen-Doped Fe<sub>3</sub>C@ c Catalysts for Efficient Activation of Peroxymonosulfate for Degradation of Organic Pollutants

Recoverable and stable nanocatalysts are essential for peroxymonosulfate - based advanced oxidation processes (AOPs) in wastewater purification treatment. In this paper, Fe3C nanorods @ nitrogen-doped carbon composites (N-Fe3C@C) with core-shell architecture were fabricated by the co-precipitation and calcination methods, and characterized and analyzed in terms of their crystal structure, microscopic morphology, and surface chemical elements. In addition, N-Fe3C@C-4 degraded 85.36% of tetracycline in 10 min under PMS, which was much higher than the catalytic ability of Fe3O4 (42.03% in 10 min). Both the active radical trapping and EPR experiments verified that 1O2 played a key role for degradation of organic dyes in PMS system. The investigation on the degradation mechanism revealed that the presence of the carbon layer facilitated to adsorb TC, accelerate free radical generation and promote the redox cycle of Fe2+/Fe3+ in the nanocatalyst. This study offers novel ideas for multifunctional catalysts for advanced wastewater purification treatment.

Efficient CO2 reduction under visible light: Synergistic effects of Cu nanoparticles and Ni single atoms

Photocatalytic reduction of CO2 is a considerable method to alleviate global warming and energy shortage. In this work, CoAl-LDH/Ni1CuNP nitrogen-doped carbon composites (CA/Ni1CuNP N-C) can efficiently reduce CO2 into CO, CH4, and C2H6 under visible light. In situ characterization techniques and theoretical calculations were employed to investigate the CO2 evolution pathway and photocatalytic mechanism. The synergistic interaction of Cu nanoparticles and Ni single-atom sites accelerated the photogenerated charge separation and facilitated the adsorption properties of key intermediates. As a result, the yields of CH4 and C2H6 on CA/Ni1CuNP N-C were achieved up to 35.245 and 25.328 μmol g−1 h−1 with electron selectivity of 40.24% and 50.61%, respectively. This work is instructive for using metal nanoparticles to optimize single-atom catalysts to promote their catalytic activity.

Facile synthesis of ammonium trivanadate(V)/nitrogen doped carbon composites with high catalytic activity for the selective oxidation of 5-hydroxymethylfurfural

2,5-Diformylfuran (DFF), arising as an oxidation product of 5-hydroxymethylfurfural (HMF), has garnered significant interest owing to its versatile range of applications. In this study, the desired catalyst of NH4V3O8/N-C was successfully prepared and investigated by various characterization methods. A systematic effect of reaction conditions was conducted, revealing that under 5 bar of oxygen pressure, DFF was synthesized from HMF selective oxidation using the NH4V3O8/N-C catalyst. This transformation was achieved within 2 h at 120 °C, exhibiting an impressive DFF selectivity of 97.8%. During the recycling experiment, the catalytic efficiency remained consistently high even after being employed for eight cycles.

Magnetic Nitrogen-Doped Carbon Composites Decorated with Carbon Nanotubes for Adsorption of Malachite Green

Magnetic Nitrogen-Doped Carbon Composites Decorated with Carbon Nanotubes for Adsorption of Malachite Green

A three-dimensional porous Si/SiOx decorated by nitrogen-doped carbon as anode materials for lithium-ion batteries

Nano-sized Si-based materials have been proposed as one of the most promising anodes of lithium-ion batteries (LIBs) due to their advantageous capacity. However, the widespread use of nano-sized Si-based material is still limited by their high cost, large volume expansion, and intrinsically low conductivity. Here, we demonstrate the decoration of three-dimensional porous Si/SiOx with nitrogen-doped carbon composites via a hydrothermal and megnesiothermic reduction. The as-prepared composites deliver a high reversible capacity of 1082 mAh g−1 after 200 cycles at a current density of 200 mA g−1. The rate performance of the composites was evaluated from 100 to 1000 mA g−1, even at a high current density of 1000 mA g−1, the reversible specific capacity remained at 510 mAh g−1. The good electrochemical performance of the composites may be ascribed to the three-dimensional porous structure, which relieves the volume changes of Si/SiOx during lithiation/delithiation processes. In addition, the introduced nitrogen-doped carbon can offer additional active sites for storage capacity and increase the electrical conductivity. Therefore, this work provides a promising anode for high-energy-density LIBs.

Binary metal oxide (MnO2/SnO2) nanostructures supported triazine framework-derived nitrogen-doped carbon composite for symmetric supercapacitor

A high-performance supercapacitor was fabricated using binary metal oxide (manganese oxide and tin oxide) decorated triazine framework-derived nitrogen-doped carbon (MnO2@SnO2/T-NC) composites. Morphological analysis showed that the SnO2/T-NC composite surface was densely decorated with MnO2 nanorods (<20 nm). The MnO2@SnO2/T-NC (5:1) composite delivered a capacitance of 676 F g−1 at 1 A g−1current density. The symmetric system displayed a capacitance of 91.1 F g−1 at 1 A g−1 with good cycling stability. After 7000 cycles, the device withheld 92.3 % of its total capacitance at 3 A g−1. The electrode's high performance may be ascribed to the redox reaction of metal oxides and fast electrolyte transport through porous carbon. After charging the symmetric supercapacitor device for 23 s at 4.4 V, green (2.0 V) and blue (3.3 V) light-emitting diodes were powered for 21 and 10 min, respectively.

Boosting Ferroptosis Therapy with Iridium Single-Atom Nanocatalyst in Ultralow Metal Content.

Nanocatalysts are promising tumor therapeutics due to their ability to induce reactive oxygen species in the tumor microenvironment. Although increasing metal loading can improve catalytic activity, the quandary of high metal content versus potential systemic biotoxicity remains challenging. Here, a fully exposed active site strategy by site-specific anchoring of single iridium (Ir) atoms on the outer surface of a nitrogen-doped carbon composite (Ir single-atom catalyst (SAC)) is reported to achieve remarkable catalytic performance at ultralow metal content (≈0.11%). The Ir SAC exhibits prominent dual enzymatic activities to mimic peroxidase and glutathione peroxidase, which catalyzes the conversion of endogenous H2 O2 into •OH in the acidic TME and depletes glutathione (GSH) simultaneously. With an advanced support of GSH-trapping platinum(IV) and encapsulation with a red-blood-cell membrane, this nanocatalytic agent (Pt@IrSAC/RBC) causes intense lipid peroxidation that boosts tumor cell ferroptosis. The Pt@IrSAC/RBC demonstrates superior therapeutic efficacy in a mouse triple-negative mammary carcinoma model, resulting in complete tumor ablation in a single treatment session with negligible side effects. These outcomes may provide valuable insights into the design of nanocatalysts with high performance and biosafety for biomedical applications.

Highly active and stable catalysts for Baeyer–Villiger oxidation – Traditional postloading vs in situ synthesis of Fe/N/C nanoparticles

Nitrogen-doped carbon composites are prepared using simple precursors, such as glucose or urea and used as supports for Fe nanoparticles. The present work investigated two approaches for incorporating metal nanoparticles into the composite: traditional metal postloading and in situ formation of a metal/N-doped carbon catalyst. The impacts of the preparation technique on (i) the characteristics of the resulting iron oxides (Fe2O3 and Fe3O4) and (ii) the nanoparticle distribution on the support were determined. Microscopic surface characterization revealed that the postloading method promoted a uniform distribution of Fe nanoparticles (5–10 nm), which enhanced the activity and long-term stability of the catalytic system for the Baeyer–Villiger oxidation of cyclic ketones. The product yield reached 97% (5 h, 60 °C), and after the third reaction cycle, the yield remained at 96%. The proposed synthetic approach for preparing active and stable catalysts provides a new perspective for the inexpensive and sustainable synthesis of lactones.

Nickel-doped Co3O4 spinel nanospheres embedded in nitrogen-doped carbon composites derived from bimetallic NiCo metal–organic framework as a high-performance asymmetric supercapacitor

Nitrogen-doped porous carbon spheres (NCS) with NixCo3O4 composite were derived from a metal–organic framework through a heat treatment.

Agarose-gel-based self-limiting synthesis of a bimetal (Fe and Co)-doped composite as a bifunctional catalyst for a zinc-air battery

Exploring efficient noble-metal-free electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is crucial for the development of rechargeable Zn-air batteries. Herein, a self-limiting method using an agarose gel was proposed to prepare bimetallic (iron and cobalt) nitrogen-doped carbon composites (FeCo-NC). The resulting FeCo-NC catalyst has a high surface area and a hierarchical porous structure. The optimized FeCo-NC electrocatalyst exhibits a small potential difference (ΔE) = 0.72 V between the ORR half-wave potential and the OER potential at a current density of 10 mA cm−2 in alkaline media. Impressively, the FeCo-NC Zn-air battery exhibits a high open-circuit voltage, large power density, and outstanding charge–discharge cycling stability. This study provides an effective means of designing electrocatalysts and energy conversion systems.

Nano-Si/graphite/N-doped biocarbon hybrid anode material for high-performance lithium-ion batteries

Improving the cycle life of silicon-based anodes is extremely important to the development of Li-ion batteries. Nano-silicon / graphite / Nitrogen-doped carbon composites are prepared as hybrid anode material in this work. The nano-silicon particles are distributed in the graphite framework, which improves the electrical conductivity of the composite. The amorphous nitrogen-doped carbon layer of the composite could be a buffer structure for the volume change of Si while providing a fast transport channel for lithium ions and further enhancing the electrical conductivity of the composites. The specific capacity of the composite electrode is 656.5 mAh g-1 at 500 mA g-1. The capacity retention rate is 91% after 100 cycles. The composite electrode could deliver a specific capacity of 497.3 mAh g-1 after 200 cycles even at a large current density of 1A g-1.

Front Cover: Dealloying Synthesis of Silicon Nanotubes for High‐Performance Lithium Ion Batteries (ChemPhysChem 9/2022)

The Front Cover shows one-dimensional silicon nanotube–nitrogen-doped carbon composites fabricated through a dealloying process. The nanotube engineered silicon coupled with conductive carbon coating synergistically boosts the electrochemical performance. More information can be found in the Research Article by Limin Chang, Ping Nie and co-workers.

Ultrasmall metal (Fe, Co, Ni) nanoparticles strengthen silicon oxide embedded nitrogen-doped carbon superstructures for long-cycle-life Li-ion-battery anodes

A universal electrospray-carbonization approach to prepare ternary metal/SiO x /nitrogen-doped carbon (NC) superstructures is proposed, where metal (Fe, Co, Ni, CoNi, FeNi, FeCo and FeCoNi) and small SiO x nanoparticles (NPs) are homogeneously distributed in NC matrix. Metal greatly promotes the electrochemical activity and stability of the SiO x system, which can be considered as high-performance Li-ion-battery anodes. • Metal/SiO x /nitrogen-doped carbon superstructures are designed as LIB anodes. • Nitrogen-doped carbon inhibits the gathering of SiO x and relieves its strain. • Ultrasmall Ni nanoparticles and nitrogen-doped carbon improve the kinetics of SiO x . • The strategy to prepare multiple SiO x - or metal-based composites is universal. For silicon oxides (SiO x ) as a prospective Li-ion-battery anode material, the low inherent conductivity and huge volume fluctuation during cycling immensely limit their electrochemical performance. Herein, a universal electrospray-carbonization approach to prepare ternary metal/SiO x /nitrogen-doped carbon (NC) superstructures is proposed. Accordingly, metal (Fe, Co, Ni, CoNi, FeNi, FeCo and FeCoNi) nanoparticles (NPs) and small SiO x NPs derived from rice husks (RHs) are homogeneously distributed in the NC matrix. Metal (Fe, Co, Ni) NP-embedded NC frameworks avoid the accumulation, increase the conductivity and accommodate adequent volume expansion of SiO x NPs. This results in an enhanced rate capability and excellent cycle stability upon cycling. Besides, Ni/SiO x /NC (NSC) superstructures with ultra-small Ni NPs can exhibit better electrochemical kinetics for fast diffusion of ions and charge transfer and cyclability than Co/SiO x /NC (CSC) and Fe/SiO x /NC (FSC) composites. When NSC superstructures are employed as lithium-ion battery (LIB) anodes, superior specific capacities of 757.5 mA h g −1 at the 200th cycle, as well as superb long cyclability with discharge capacities of 665.0 mA h g −1 for 500 cycles at 500 mA g −1 and 116.3 mA h g −1 at the 5000th cycle, even at 10 A g −1 , are achieved. Furthermore, the easy and general approach for preparing multiple SiO x -, metal- or alloy-based superstructures paves the way for designing high-performance rechargeable batteries and electrocatalysts.

Co–N Active Sites between Co Nanoparticles and N-Doped Carbon toward Remarkably Enhanced Electrocatalytic Oxygen Evolution and Hydrogen Evolution Reactions

The rational design and synthesis of a non-noble-metal electrocatalyst for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) with good conductivity, high efficiency, and excellent stability are major challenges in the field of renewable energy. Therefore, we developed a simple and effective method to grow ZIF-67 in situ on graphitic carbon nitride (GCN) and then annealed it to generate nitrogen-doped carbon (NC) loaded with Co@C nanoparticles (Co@C/NC). Benefiting from this in situ growth method, after annealing, a large number of N atoms on the surface of NC nanosheets anchor more metal Co to form more catalytic Co–N active sites. At the same time, the Co@C/NC composites use NC nanosheets as the matrix, which can improve the electrochemical double-layer capacitance and conductivity of the composites. As demonstrated in electrochemical measurements, the OER and HER overpotentials of Co@C/NC composites at a current density of 10 mA cm–2 were only 300 and 175.4 mV in 1.0 M KOH, respectively. The preparation method is suitable for synthesizing various metal and carbon composite electrocatalysts. It provides ideas for designing and manufacturing high-performance non-noble-metal dual-function OER/HER catalysts.

Mono- and Bimetallic Silver-Containing Nitrogen-Doped Carbon Composites and Their Electrocatalytic Activity

The N-doped metal-carbon composites based on the carbonized melamine-formaldehyde polymer (MFP) with silver, silver-copper, and silver-cobalt particles were synthesized. Mono- and bimetallic silver-containing composites were prepared by the reduction of metal nitrates with hydrazine hydrate in an aqueous ethanol medium in the presence of carbon black particles obtained by the heat treatment of MF-polymer at 500 °C. The structural-phase changes before and after the use of metal-carbon composites as electrocatalysts in the electrohydrogenation of p-nitroaniline (p-NA) were studied by X-ray diffraction analysis. The morpho-logical features of the created MFBC + Ag, MFBC + (Ag+Cu) and MFBC + (Ag+Co) composites were stud-ied by electron microscopy. It was established that the synthesized composites mainly contain crystalline phases of the corresponding reduced metals or their alloys. The monometallic MFBC(1) + Ag(1) composite contains reduced silver crystallites of various shapes and localization on porous MF carbon black particles. Higher electrocatalytic activity of the synthesized Ag-containing composites in the p-NA electrohydro-genation was shown in comparison not only with the electrochemical reduction of p-NA but also with MFBC + (Ag+Cu) composites with electrocatalytic hydrogenation of p-NA on Ag + Cu particles (without MFBC). It was found that the use of the studied MFBC-composites increases the selectivity of the formation of the main hydrogenation product (p-phenylenediamine) and decreases the yields of by-products.

Synthesis of CoSe2 reinforced nitrogen-doped carbon composites as advanced anodes for potassium-ion batteries

Owing to the synergistic effect of CoSe2 and N-doped carbon matrix, a composite of CoSe2 nanoparticles dispersed in polydopamine-derived N-doped carbon matrix exhibits high specific capacity and excellent cyclability as potassium-ion battery anode.

Cu/NC@Co/NC composites derived from core-shell Cu-MOF@Co-MOF and their electromagnetic wave absorption properties

Metal-organic-frameworks (MOFs) derived carbon or nitrogen-doped carbon (NC) materials are usually used as electromagnetic wave (EMW) absorbers. However, the effective control of the composition and structure of composites is still a major challenge for the development of high-performance EMW absorbing materials. In this work, core–shell structure and bimetallic composition Cu/nitrogen doped carbon @Co/ nitrogen doped carbon (Cu/NC@Co/NC) composites were designed and synthesized through the thermal decomposition of Cu-MOF@Co-MOF precursor. Cu/NC@Co/NC composites with different compositions were obtained by changing the ratio of Co-MOF and Cu-MOF. The composite (Cu/NC@Co/NC-3.75) prepared using 3.75 mmol of Co(NO3)2·6H2O exhibits outstanding EMW absorption properties due to the optimized impedance matching and strong attenuation ability, which is caused by enhanced interfacial and dipolar polarization as well as multiple reflection and scattering. With the filler loading in paraffin of 35 wt%, the minimum reflection loss (RLmin) is up to −54.13 dB at 9.84 GHz with a thin thickness of 3 mm, and the effective absorption bandwidth (EAB, RL≤ − 10 dB) reaches 5.19 GHz (10.18–15.37 GHz) with the corresponding thickness of 2.5 mm. Compared with the Cu/NC and Co/NC, the Cu/NC@Co/NC-3.75 composite exhibits much better EMW absorbing performances caused by the bimetallic composition and the unique core–shell structure. This work provides a rational design for MOF-derived lightweight and broadband EMW absorbing materials.

Nickel/nickel oxide nanocrystal nitrogen-doped carbon composites as efficient electrocatalysts for urea oxidation

Abstract The key problem to be solved for the large-scale commercial application of direct urea fuel cells (DUFCs) is to develop a highly efficient catalyst for urea oxidation reaction (UOR). Some drawbacks such as scarcity and poor catalytic performance limit the application of noble metal-based catalysts in the oxidation of urea, it is particularly necessary to design and synthesize non-noble metal-based catalysts with good catalytic performance. In this work, we have fabricated Ni-based composites (Ni/NiO-N-C) through the pyrolysis of the precursor Ni(OH)2@PPH (polyaniline-polyvinyl alcohol hydrogels). The optimal Ni/NiO-N-C-500 catalyst displays an excellent activity of 182 mA cm−2 at 0.6 V vs SCE for UOR in alkaline media. Meanwhile, Ni/NiO-N-C-500 also indicates excellent stability after 1000 cycling CV tests (81% capacitance retention), which is attributed to the synergy between Ni/NiO nanocrystalline active centers and nitrogen-doped carbon substrate, that is, N-doped carbon layers improve the surface electron density and the electrical conductivity of the composite catalyst, thus leading to the improvement of the catalytic activity of catalyst. On account of its easy synthesis, high activity and good durability, the Ni/NiO-N-C-500 catalyst has the potential to act as a good alternative material for precious metal-based catalysts in DUFCs.

Copper embedded in nitrogen-doped carbon matrix derived from metal-organic frameworks for boosting peroxide production and electro-Fenton catalysis

In this work, we demonstrated that metal-organic frameworks (MOFs) derived copper embedded in nitrogen-doped carbon composite (Cu/NC) could be applied as a high-efficient catalyst for simultaneously producing hydrogen peroxide (H2O2) and hydroxyl radical (·OH) via two-electron oxygen reduction reaction (ORR) and Fenton-like reaction, respectively. Based on the systematically physical characterization and electrochemical analysis, the copper species was encapsulated by the nitrogen-doped carbon layer to form a MOFs-derived Cu/NC catalyst, which presents superior two-electron ORR performance and long-term durability. In particular, the presence of nitrogen-doped carbon and the unique structure of the Cu/NC catalyst could provide active sites and accelerate the electron transfer during the ORR process. The boosting two-electron ORR properties of Cu/NC owning to the synergetic effect between dispersed copper and nitrogen groups. The oxidative degradation and electron paramagnetic resonance (EPR) spectra demonstrated that ·OH is the main reactive oxygen species (ROS) during the Bisphenol A (BPA) removal. The results presented herein suggest that MOFs-derived metal-carbon composite, as an all-in-one catalyst, can activate two-electron ORR for H2O2 production and Fenton-like for ·OH generation to achieve efficient pollutant degradation, rather than a single Cu-induced Fenton-like pathway.

ZIF-8 derived nitrogen-doped carbon composites boost the rate performance of organic cathodes for sodium ion batteries

Biomass derived organic materials have gained a worthy potential for electrode materials of sodium-ion batteries (SIBs) due to their high specific capacity, renewability, lower cost, and structural diversity. However, high solubility and poor electronic conductivity are the key obstacles in development of traditional organic electrodes. Herein, the composite material PI@NC is prepared using 3,4,9,10-perylenetetracarboxylic dianhydride ethylene diamine and nitrogen-doped carbon matrix through in-situ polymerization. The formation of NC conductive scaffolds establishes the efficient pathways in electrodes for electronic conduction. As per expectations, PI@NC as a cathode material boosts the rate performance of SIBs. Specifically, the as-prepared composites offer outstanding redox behavior with superior rate capacities of 91 mAh g−1 at a higher current density of 10 A g−1 for sodium storage. Moreover, in order to show the potential application values of electrode materials, a full battery is successfully fabricated based on our PI@NC cathode and commercial disodium terephthalate (NaTP) anode.