N-doped Carbon Materials Research Articles

Novel highly utilized PdNi bimetallic-loaded N-doped carbon catalysts prepared from MOF for Suzuki coupling reaction and hydro reduction of nitroaromatics

The usage of palladium-based catalysts in numerous chemical reactions has been increased significantly; in particular, the synthesis of heterogeneous catalysts by attaching palladium atoms to carriers has expanded rapidly. Therefore, the selection of nitrogen-doped carbon materials for carriers has become a popular research subject. In this study, Ni-Ni PMOF was first created, then Ni nanoparticles (NPs) modified nitrogen-doped mesoporous carbon materials were synthesized through pyrolysis. Subsequently, Pd atoms were successfully deposited onto the surface of Ni NPs as Pd2+ is capable of being reduced by metal Ni. The structure of the prepared carriers was verified by FT-IR, XRD, SEM, TEM, XPS and other characterizations, and was found to have a fluffy and porous structure that increases the number of active sites of PdNi NPs. This material was found to be effective in catalyzing the Suzuki coupling reaction (TOF = 1019 h) and the reduction reaction of p-nitrophenol (Kapp = 4.34 × 10−2 s−1), and its catalytic activity remained stable even after 10 uses, showing good recoverability and recyclability. This study thus provides a novel approach for the preparation of N-doped porous carbon materials, which can enable green chemistry by making efficient and full use of precious metals.

Auto-reduction of Au(III) on Fe-Doped, Pyrrolic-N-Modified nanoporous carbon derived from ZIF-8 for the electrochemical immunosensing of CA-125

Ovarian cancer (OC) is associated with high late mortality owing to hidden symptoms in the early stages and limited screening measurements. Therefore, it is urgent to develop a highly efficient label-free immunosensor for targeting cancer antigens. In this study, we developed a gold-loaded iron-doped nanoporous carbon (denoted as Au@Fe-NC) as an ideal substrate for cancer antigen detection with high specificity and sensitivity. First, an Fe, N-doped nanoporous carbon (Fe-NC) material was synthesized by carbonizing a Fe-doped metal-organic framework at 900 °C under continuous nitrogen flow. The resultant Fe-NC contains pyrrolic-N, which facilitates the auto-reduction of Au3+ to Au⁰ without requiring an external reducing agent. Thus, the Au@Fe-NC was spontaneously formed by mixing an aqueous HAuCl₄ solution with Fe-NC. The immunosensor developed using Au@Fe-NC exhibits outstanding stability as well as high sensitivity to carbohydrate antigen 125 (CA-125), a tumor marker, presenting a linear dynamic range of 0.1 pg mL−1 to 1 µg mL−1 and a detection limit of 0.1 pg mL−1. The proposed Au@Fe-NC-based immunosensor has the ability to detect CA-125 in human serum samples and is a promising material for OC diagnosis.

N-DOPED POROUS CARBON DERIVED FROM A DEEP EUTECTIC SOLVENT AND ITS APPLICATION IN SOLID-PHASE EXTRACTION OF PROFENOFOS FROM FRUITS

Porous N-doped carbon materials with glucose and urea derived from a deep eutectic solvent, and their performance in determining pesticides were investigated. The carbon materials were characterized with nitrogen absorption, transmission electron microscopy, X-ray photoelectron spectroscopy, and the results showed that they had high specific surface areas, pore volumes and rich functional groups. Under optimized conditions, this method showed a good linearity (0.2–2.0 µg/mL) and high sensitivity (detection limit of 0.023 µg/mL, S/N = 3). The proposed method was successfully applied in an analysis of a fruit sample with recoveries ranging from 97.2 % to 103.3 %, and good reproducibility was achieved. This work revealed great potentials of a porous N-doped carbon material used as an excellent sorbent material in analyzing organophosphorus pesticides.

Controllable introduction of edged nitrogen sites in CVD-derived carbon materials for enhanced fenton-like reactions

Nitrogen doped carbon materials have great potential in the peroxymonosulfate based advanced oxidation processes due to their high efficiency. However, because of the limitation of prepared method, the doped N species are usually uncontrollable. In this work, a series of metal-free N-doped carbon materials are synthesized by chemical vapor deposition (CVD) with a CaO template and through regulating the deposition temperature we achieve the gradient control of the edged-N species. Taken phenol as the pollutant probe, the catalytic performances of N-doped carbon material are investigated, and 700 °C is determined to be the optimal deposition temperature for carbon material with a reaction rate constant of 0.335 min−1. After the analysis of kinetics and the N species, we demonstrate that the content of pyrrolic N has an exponential relationship with the activity. Radicals quenching experiments, electron paramagnetic resonance and electrochemical test are also employed to verify that O2•–, 1O2, and direct electron transfer are the dominated reactive oxidation species rather than typic hydroxyl and sulfate radicals. Overall，this doped strategy through CVD give a new insight of controlling doped species in carbon materials preparation.

Preparation of N-doped carbon-modified Na3V2(PO4)2F3 based on ZIF-8 as a template and its electrochemical properties

N-doped porous carbon material (N-PC) was generated through high-temperature cracking, using ZIF-8 as a template, and preparation of Na3V2(PO4)2F3/N-PC composites were designed and prepared as cathode materials for sodium-ion batteries, and the electrochemical sodium storage performance was systematically investigated. The physical characterization results showed that the addition of N-PC played a role in increasing the electrical conductivity of Na3V2(PO4)2F3 material and improving the specific surface area. The electrochemical test results showed that the discharge specific capacity of Na3V2(PO4)2F3/N-PC composite was 109.56 mAh/g at 0.1C, and the capacity retention rate was 85.10 % after 100 cycles, and the RSEI of Na3V2(PO4)2F3/N-PC composite (81.55 Ω) is better than that of Na3V2(PO4)2F3 pure-phase material (142.5 Ω), which indicates that the ion transfer impedance of the modified material has been effectively reduced, and the ion de-embedding is more fluent.

In-situ synthesis of encapsulated N-doped carbon metal oxide nanostructures for Zn-air battery applications

La, Mn and Co-based materials with diverse compositions encapsulated in N-doped carbon materials were synthesized by an in-situ sol-gel method. The as-prepared materials were physically activated with CO2 giving as a result composites with excellent performance for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The composites were characterized by different physicochemical techniques revealing the importance of porosity created by CO2 activation. This crucial step increases the number of accessible active sites such as Co-Nx-C sites, Co/MnO heterointerfaces and graphitic N groups. Moreover, the formation of La2O2CO3 was detected to enhance electrical conductivity and electrochemical performance and it is active for ORR. Although the composite containing La, Mn and Co has less concentration of the highly active sites, its small particle size favour a better distribution of these sites. The Co-containing composites were tested as air-electrodes in a Zn-air battery and compared to commercial electrocatalysts. All composites showed a better operation in terms of higher cyclability and higher energy density which is a consequence of metal nanostructures encapsulation in N-doped porous carbon shells. Interestingly, the pure Co-based composite showed an outstanding performance related to the high concentration of the Co-Nx-C active sites that provide high activity and stability.

Bagasse derived N-doped graphitic carbon encapsulated cobalt nanoparticles as an efficient bifunctional catalyst for water splitting reactions

The utilization of non-precious metal-based electrodes to unlock cost-effective and scalable processes for the production of clean energy is highly desirable. Herein, we reported a straightforward hydrothermal carbonization method for the synthesize of nitrogen-doped graphitic carbons integrated with cobalt (Co@NGC-600, Co@NGC-700, and Co@NGC-800) from sugarcane bagasse and their electrocatalytic applications in oxygen and hydrogen evolution reactions. The graphitic nature of the Co integrated N-doped carbon materials was confirmed by Raman and XPS analysis. FESEM and HRTEM analysis confirms the dispersion of Co on N-doped carbon nanosheets. The Co@NGC-800 catalyst shows low overpotential and Tafel slope, requiring only 304 mV (84.1 mV dec−1) for oxygen electrode and 234 mV (118 mV dec−1) for HER at a current density of 10 mA cm−2. Moreover, Co@NGC-800 materials showed better activity than Co@NGC-700, Co Co@NGC-600, and Co@NC. The active Co@NGC-800 bifunctional electrocatalysts pair contributes to the fabrication of a water electrolyser with a 10 mA/cm2 current density at 1.68 V. The Co@NGC-800 // Co@NGC-800 electrocatalyst exhibits good stability over a period of 24 h with negligible potential aberration during the process of water splitting. The electrocatalytic performance of the prepared catalyst in a 1.0 M KOH solution exhibits admirable bifunctional activity and remarkable stability. In fact, it outperforms cobalt-based and carbon-supported electrocatalysts, including highly valued commercial catalysts like IrO2 and Pt@C. The solar cell configuration, utilizing the energetic bifunctional Co@NGC-800 electrocatalyst, can continuously generate hydrogen and oxygen. The overall water-splitting process of Co@NGC-800 catalyst delivered at a cell voltage of 1.68 V, enabling sustained and efficient oxygen and hydrogen evolution at a large scale.

Single-Mg-Atom Catalyst with a Dual Active Center as an Emerging Promising Sensing Platform.

Bisphenol compounds [bisphenol A (BPA), etc.] are one class of the most important and widespread pollutants in food and environment, which pose severe endocrine disrupting effect, reproductive toxicity, immunotoxicity, and metabolic toxicity on humans and animals. Simultaneous rapid determination of BPA and its analogues (bisphenol S, bisphenol AF, etc.) with extraordinary potential resolution and sensitivity is of great significance but still extremely challenging. Herein, a series of single-atom catalysts (SACs) were synthesized by anchoring different metal atoms (Mg, Co, Ni, and Cu) on N-doped carbon materials and used as sensing materials for simultaneous detection of bisphenols with similar chemical structures. The Mg-based SAC enables the potential discrimination and simultaneous rapid detection of multiple bisphenols, showing outstanding analytical performances, outperforming all other SACs and traditional electrode materials. Our experiments and density functional theory calculations show that pyrrolic N serves as the adsorption site for the adsorption of bisphenols and the Mg atom serves as the active site for the electrocatalytic oxidation of bisphenols, which play a synergistic role as dual active centers in improving the sensing performance. The results of this work may pave the way for the rational design of SACs as advanced sensing and catalytic materials.

The electrocatalytic activity of pomelo peel-derived nitrogen-doped carbon material for oxygen reduction reaction

Exploring the non-precious metal catalysts of oxygen reduction reaction (ORR) becomes the key to promote the industrialization of new energy devices such as fuel cells and metal-air batteries because of the sluggish kinetics of ORR. Three-dimensional N-doped carbon (NC-900) material was obtained using the high-temperature pyrolysis of pomelo peel waste. The prepared NC-900 catalyst possesses an ultra-high specific surface area of 1631.3 m2·g−1, high content of 57.7 ± 0.9% pyrrolic-N, and three-dimensional porous structure. As the ORR catalyst, NC-900 has a onset potential of 0.992 V and half-wave potential of 0.859 V, comparable to 0.988 and 0.872 V of Pt/C. The typical 4-electron pathway of ORR process is occupied by the surface of NC-900. The ORR catalytic activity of NC-900 was almost unaffected by methanol. After 8 h of continuous operation, the reduction current on the surface of NC-900 was decreased only 2.7% of the initial current. Based on these outstanding ORR performances, the pomelo peel-derived NC-900 can serve as a strong competitor for the substitute of Pt/C to promote the potential industrialization of new energy devices.

CoP nanoparticles embedded in N-doped carbon for highly efficient oxygen evolution reaction electrocatalysis

Development of high-activity and low-cost electrocatalysts is significant to enhance the low-kinetic process of oxygen evolution reaction (OER). In this paper, we utilized the self-assembly between melamine, phytic acid and cobalt ions to obtain two-dimensional Co-MPA. Subsequently, in situ phosphating of cobalt ions to obtain CoP/N-CNT was achieved by the pyrolytic of Co-MPA. The small size of CoP (∼18 nm) and the N-doped carbon material endowed CoP/N-CNT with excellent OER electrocatalytic activity, which delivered an overpotential of 330 mV to drive a current density of 10 mA cm−2. Moreover, the TOF value of CoP/N-CNT catalyst is 4.6 times higher than the commercial RuO2 catalyst (at the overpotential of 480 mV), providing it as a promising electrocatalyst for OER.

Utilizing Carbonaceous Materials Derived from [BMIM][TCM] Ionic Liquid Precursor: Dual Role as Catalysts for Oxygen Reduction Reaction and Adsorbents for Aromatics and CO2.

This work presents the synthesis of N-doped nanoporous carbon materials using the Ionic Liquid (IL) 1-butyl-3-methylimidazolium tricyanomethanide [BMIM][TCM] as a fluidic carbon precursor, employing two carbonization pathways: templated precursor and pyrolysis/activation. Operando monitoring of mass loss during pyrolytic and activation treatments provides insights into chemical processes, including IL decomposition, polycondensation reactions and pore formation. Comparatively low mass reduction rates were observed at all stages. Heat treatments indicated stable pore size and increasing volume/surface area over time. The resulting N-doped carbon structures were evaluated as electrocatalysts for the oxygen reduction reaction (ORR) and adsorbents for gases and organic vapors. Materials from the templated precursor pathway exhibited high electrocatalytic performance in ORR, analyzed using Rotating Ring-Disk electrode (RRDE). Enhanced adsorption of m-xylene was attributed to wide micropores, while satisfactory CO2 adsorption efficiency was linked to specific morphological features and a relatively high content of N-sites within the C-networks. This research contributes valuable insights into the synthesis and applications of N-doped nanoporous carbon materials, highlighting their potential in electrocatalysis and adsorption processes.

MnCo/N-C composite nanomaterials derived from MOFs as peroxymonosulfate activators for highly efficient removal of dyes

Fenton-like technology is an eco-friendly and efficient method to degrade organic contaminants. Herein, a bimetallic catalyst with high catalytic activity was obtained by anchoring Co and Mn on N-doped carbon materials (MnCo/N-C) through a one-step pyrolysis process. Peroxymonosulfate (PMS) was activated by cobalt nanoparticles, nitrogen-coordinated metal atoms, and defect sites in MnCo/N-C to produce several reactive species, including SO4•–, 1O2, O2•–, and •OH. The catalyst showed high activity and excellent stability during the catalytic processes. The degradation of 50 mL of rhodamine B solution with a concentration of 0.03 g/L was almost completed in only five minutes by using 0.1 g/L of the catalyst and 0.2 g/L of PMS. Furthermore, the catalyst could be used over a wide pH range of 3–11. Overall, this work provides a simple approach to preparing a more effective and long-lasting Fenton-like catalyst for the degradation of organic contaminants.

Heteroatom doping-induced Pt dispersion and electronic effect for boosting the catalytic performance in the hydrogenation of nitrobenzene to p-aminophenol

N-doped carbon materials were synthesized using a straightforward salt template method for Pt metal modification, resulting in a reduction in particle size from 4.8 nm to 2.1 nm due to the interaction between Pt and the carrier. The hydrogenation activity of nitrobenzene increased by 4.5 times compared to undoped catalysts. Additionally, the electronic effects of N and Pt enhanced the selectivity of p-aminophenol by up to 20.4 %. The anchoring of Pt by N improved the stability of active metal centers in a strong acidic system, thereby retarding Pt loss. Theoretical calculations and characterization revealed that the enhancement of activity relied on the high dispersion of Pt, while the improvement in product selectivity was associated with changes in the adsorption strength of the phenylhydroxylamine intermediate. N anchoring of Pt, inducing an electron effect, disentangled the activity and selectivity of nitrobenzene hydrogenation for the preparation of p-aminophenol.

Fe[sbnd]N doped carbon materials from oily sludge as electrocatalysts for alkaline oxygen reduction reaction

Alkaline oxygen reduction reaction (ORR) presents an important role for energy conversion technologies and requires the development of an efficient electrocatalyst. Pt-based catalysts provide suitable activity; however, Pt production accessibility and high costs create hurdles to their commercial implementation. Fe coordinated within N-doped carbon materials (FeNC) are a promising alternative due to their high ORR catalytic activity, although the currently commercially available FeNC materials rely on harsh synthetic protocols which can lead to increased environmental impacts. In this work we target this issue by taking advantage of an oily sludge waste currently generated in refineries to synthesize FeNC materials, thus, avoiding the environmental impact caused by the management of this waste. The solid particles within oily sludge, which present a high concentration of C and Fe, were combined by different nitrogen sources and pyrolyzed at high temperatures.The prepared materials present a hierarchical pore structure with surface areas up to 547 m2 g−1. X-ray photoelectron spectroscopy analysis found that the impregnation of N using phenanthroline promotes the formation of pyridinic-N structures, which enhances the ORR performance compared to melamine doping. Additional doping of Fe with phenanthroline results in an ORR mass activity of 1.23 ± 0.04 A gFeNC−1 at 0.9 VRHE, iR-free in a rotating disc electrode (0.1 M KOH). This catalyst also shows a lower relative loss in activity at 0.9 VRHE after 8000 cycles in O2-saturated conditions compared to a commercial FeNC catalyst, PMF D14401, (−63.5 vs −69 %, respectively), demonstrating promise as a cheap and simple route to FeNC catalysts for alkaline ORR.

Dual-Atom Nanozyme Eye Drops Attenuate Inflammation and Break the Vicious Cycle in Dry Eye Disease

HighlightsA dual-atom nanozyme (DAN) was successfully prepared based on Fe and Mn bimetallic single-atom embedded in N-doped carbon material and modified with hydrophilic polymer.The DAN possess excellent enzyme catalytic activity and attenuate dramatically inflammation by inhibiting the reactive oxygen species (ROS)/NLRP3 signal axis.The DAN break the vicious cycle in dry eye disease and is a potential strategy for treating dry eye disease.

Tuning the Pyridine Units in Vinylene-Linked Covalent Organic Frameworks Boosting 2e- Oxygen Reduction Reaction.

The N-doped carbon materials are supposed to be the efficient oxygen reduction reaction (ORR) catalysts with the undefined N-doped carbon ring groups. It is essential to well define the role of the nitrogen atoms of these carbon structures in active behavior. Even though, the covalent organic frameworks (COFs) with precise structures are well developed, but unable to exclude the polar linkages influence. This study presents a series of pyridine-containing COFs linked via nonpolar carbon-carbon double bonds (C = C). Their catalytic activity and selectivity for 2e- ORR are successfully modulated by locating the embedded pyridine nitrogen in the backbones through the linking modes of pyridine moieties within the frameworks. Such phenomena can be attributed to their different binding abilities toward O2, leading to the different binding strength of the intermediate OH* to the catalytic sites, also verified by the theoretical calculation. This work provides us a new insight to design high-efficiency ORR catalysts through the exact location of pyridine nitrogen.

Preparation of porous carbon electrode materials from potassium hydroxide extract of lignite doped with nitrogen

Lignite is cheap, easy to obtain and rich in pores, so it was used as an electrode material for supercapacitors early. In this paper, Yimin lignite (YM) was used as raw material, and KOH was used to extract organic components. Melamine was adulterated into the extracted material for thorough mixing. The reaction mechanism and structural changes in it were explored. Experimental results and density functional theory (DFT) calculations showed that introducing nitrogen atoms into the coal-based activated carbon leads to a rearrangement of the carbon skeleton structure and changes the surface chemical environment. In this process, we adjust the porosity, specific surface area and discharge specific capacity of the produced carbon materials by changing nitrogen doping ratio, activation time and activation temperature. The excellent N-doped porous carbon material At-120 (activation time:120 min) was prepared with a high specific surface area (SBET: 3020 m2/g), abundant micropores (Vmic: 1.242 cm3/g), proper mesopores (Vmes: 0.182 cm3/g, Vmes ratio: 12.6 %), low impurity content, and high amount of N doping (6.43 wt%). These characteristics of At-120 enabled it to have a high specific capacitance value of 433.5 F/g at a current density of 1 A/g. The enhanced At-120 has 42.18 % higher specific capacitance than the undoped lignite alkali extract(LC).

Zinc sulfide quantum dots modified 3D Nitrogen-Doped framework carbon enhances the ion transport rate of potassium ion hybrid capacitors

The potassium-ion hybrid capacitor (PIHC) has garnered considerable attention due to its ability to leverage the advantages of both battery-type anodes and capacitor-type cathodes simultaneously. Nevertheless, the slow K+ transfer rate between the PIHC battery-type anode and capacitor-type cathode significantly impedes the overall performance. Herein, we have employed quantum-sized zinc sulfide (ZnS) immobilized within a three-dimensional N-doped porous carbon framework (ZnSQDS@3DNC) as a standalone anode. The corresponding three-dimensional N-doped porous carbon (3DNC) serves as the cathode, thereby constructing a PIHC device. The strong coupling between ZnS quantum dots and N-doped three-dimensional porous carbon material effectively enhances ion/electron transport, facilitating intercalation-conversion-exfoliation reactions and improving K+ transfer rates. The numerous active sites within the 3DNC significantly enhance the capacitance performance of the cathode, facilitating the reversible adsorption and desorption of FSI-. The values of DK+ have all been calculated to be within the range of 10-10 to 10-9 cm2 s−1, indicating the rapid diffusion capability of this ZnSQDs@3DNC structure. More impressively, the assembled PIHC device can achieve high energy densities of 179.9 Wh kg−1 at power densities of 200 W kg−1, with an ultralong cycling life over 10,000 cycles. This study serves to advance the development of metal-ion hybrid capacitors and provides direction for improving ion transport kinetics.

Leveraging Curvature on N-Doped Carbon Materials for Hydrogen Storage.

Carbon sorbent materials have shown great promise for solid-state hydrogen (H2) storage. Modification of these materials with nitrogen (N) dopants has been undertaken to develop materials that can store H2 at ambient temperatures. In this work density functional theory (DFT) calculations are used to systematically probe the influence of curvature on the stability and activity of undoped and N-doped carbon materials toward H binding. Specifically, four models of carbon materials are used: graphene, [5,5] carbon nanotube, [5,5] D5d-C120, and C60, to extract and correlate the thermodynamic properties of active sites with varying degrees of sp2 hybridization (curvature). From the calculations and analysis, it is found that graphitic N-doping is thermodynamically favored on more pyramidal sites with increased curvature. In contrast, it is found that the hydrogen binding energy is weakly affected by curvature and is dominated by electronic effects induced by N-doping. These findings highlight the importance ofmodulating the heteroatom doping configuration and the lattice topology when developing materials for H2 storage.

Synergistic electronic structure modulation in single-atomic Ni sites dispersed on Ni nanoparticles encapsulated in N-rich carbon nanotubes synthesized at low temperature for efficient CO2 electrolysis

Ni, N-doped carbon materials (Ni–N–C) are prosperous candidates for the electrochemical CO2 reduction reaction (CO2RR) due to their outstanding activity and selectivity. However, the role of the coexisting uncoordinated N-doped sites and Ni nanoparticles (Ni-NPs) in overall CO2RR has been overlooked in prior studies. To address this gap, a low temperature synthesis method developed for Ni-NP-encapsulated Ni–N–C nanotube (Ni-NCNT) catalysts with atomically dispersed Ni–N4 and abundant uncoordinated N-doped sites, where Ni-NPs increase the electron density on Ni–N–C nanotube through carbon network and synergistically enhances the CO2RR activity. The systematic analysis reveals the cooperative role of Ni-NPs and uncoordinated N-doped sites in altering the electronic structure of Ni–N4 sites. The results of control experimental studies confirm the synergistic interaction of uncoordinated N-doped sites boost the CO2RR activity of Ni–N4 sites. Additionally, density functional theory calculations show that the strong interaction between the Ni-NPs and Ni–N–C did not affect the electronic structures of the Ni–N4 centers, but rather alter the electronic structure of uncoordinated pyridinic-N sites. This variation led to decreased the energy barriers of rate-limiting steps of COOH* formation on Ni–N4 and N-doped sites, resulting in excellent CO2RR performance.