N-doped Carbon Spheres Research Articles

Cu/N-doped carbon spheres derived from soybean flour as an active green nanocomposite for the synthesis of 1,4-disubstituted 1H-1,2,3-triazole derivatives

Cu immobilized onto N-doped carbon spheres (Cu/N-doped CS) derived from soybean flour was synthesized via the hydrothermal method and certified as a green high-efficiency catalyst for the regioselective synthesis of 1,4-disubstituted 1H-1,2,3-triazoles. The obtained N-doped carbon spheres from a combination of glucose and soy flour have a larger size and suitable affinity for load copper species. The morphology and structure of the as-prepared catalyst have been confirmed based on FT-IR, XRD, FE-SEM, EDX, BET, and ICP-OES characterizations. The catalytic performance of the Cu/N-doped carbon spheroids was investigated experimentally. It was found that the Cu/N-doped CS nanocomposite has a high efficiency and recyclability for 5 cycles without any appreciable loss in its catalytic activity in the synthesis of 1,4-disubstituted 1H-1,2,3-triazoles via the three-component condensation reaction of various epoxide/alkyl or aryl halides, sodium azide, and phenylacetylene in a water medium. Furthermore, significant advantages such as stability, ease of preparation, low cost of the carbon resource, high regioselectivity, and good product yield have been achieved in the heterogeneous catalyst system attractive for large-scale in many industrial products.

Improved Energy Storage Performance of N-Doped Hollow Mesoporous Carbon Spheres as Substrate for MoS2

Improved Energy Storage Performance of N-Doped Hollow Mesoporous Carbon Spheres as Substrate for MoS2

Mesoporous carbon spheres modified with atomically dispersed iron sites for efficient electromagnetic wave absorption

Carbon materials have obtained some achievements in electromagnetic wave (EMW) absorption owing to their excellent electrical conductivity and low density. However, poor impedance matching and high electrical conductivity limit their EMW absorption properties. Metal single atoms absorbers have garnered considerable attention in EMW absorption, largely due to the high metal availability and special coordination structure, but the modulation of the EMW absorption properties still needs to be improved. Herein, atomically dispersed Fe sites embedded into the N-doped mesoporous carbon spheres (Fe–SAs/NC) were synthesized through a facile coordination-assisted polymerization assembly strategy without acid leaching treatment. Benefitting from abundant mesoporous structure, the Fe–SAs/NC displays large specific surface area (339 m2 g−1) and optimized impedance matching, which results in an effective reduction of the absorber density. The homogeneously dispersed Fe single atoms (Fe–SAs) on the carbon skeleton lead to the improvement in conduction and dipole polarization losses of Fe–SAs/NC, which endows Fe–SAs/NC with exceptional EMW absorption properties. Experimental results indicate that Fe–SAs/NC displays desirable EMW absorption properties with the minimal reflection loss of −52.5 dB at 2.8 mm and the effective absorption bandwidth of 4.8 GHz. The study provides valuable insights for the development of carbon materials modified with atomically dispersed metal sites to achieve high-efficient EMW absorbers.

Core-shell cobalt-iron@N-doped carbon: A high-performance cathode material for lithium-sulfur batteries.

Lithium-sulfur batteries hold great promise as energy storage systems, but the shuttle effect of lithium polysulfides (LiPS) and large volume variation limit their capacity and cycle life. We have developed CoFe alloy wrapped in N-doped porous carbon spheres (e-CF@NC) with a core-shell structure through simple copolymerization and pyrolysis. The nitrogen-doped porous carbon shell provides electron and ion transport channels and more active sites for electrolyte ion adsorption. The high chemically stable carbon can limit the segregation of polysulfides, further improving the battery cycling stability. Besides, the inside CoFe alloy particles catalyze the conversion between LiPS and Li2S, speeding up reaction kinetics and reducing solvation of active sites. Consequently, lithium-sulfur batteries with e-CF@NC-2 as the cathode display a high initial specific capacity of 1146 mA h g-1 at 0.1 C, excellent rate performance (891 mA h g-1 at 1 C, 741 mA h g-1 at 2 C), and satisfied cycle stability (average capacity decay rate of 0.033% per cycle at 1 C for 300 cycles), demonstrating significant application potential.

Promoting Electrocatalytic Reduction of CO2 and Nitrate to Urea on N-Doped Porous Hollow Carbon Spheres.

The electrocatalytic coreduction of CO2 and nitrate is a green method for urea synthesis, mitigating CO2 emission and nitrate contamination. However, its slow kinetics and high energy barrier result in a poor urea production performance. Herein, we reported N-doped porous hollow carbon spheres (N-PHCS) for promoting CO2 and nitrate conversion to urea via nanoconfinement and N-doping from both reaction kinetics and thermodynamics. A high urea yield of 12.0 mmol h-1 gcat-1 with Faradaic efficiency of 19.1% was achieved on N-PHCS at -1.0 V (vs Ag/AgCl), which was comparable to or even higher than those of metal-based electrocatalysts reported. The experimental and theoretical calculation results revealed that carbon spheres with an appropriate interior void and pore size were favorable for confining reactants and intermediates to accelerate urea production, while N-doping can reduce the energy barrier for urea synthesis. By regulating the microstructure and N doping of N-PHCS, it showed a superior performance for urea electrosynthesis. The energy favorable pathway for urea synthesis was through the C-N coupling reaction of *NO and *CO, and pyridinic N can reduce the reaction energy barrier.

Enhanced stability in Co0.8Ni0.2/NDMCS catalysts: Carbon nitride encapsulation for robust hydrogen generation

Catalytic hydrolysis of NaBH4 is a promising method for "on-demand" hydrogen generation, with cobalt catalysts playing a key role due to their high hydrogen generation rates. However, rapid cobalt dissolution and poor recycling hinder stable hydrogen production. This study presents a dual-mode stabilization technique using carbon nitride encapsulation to address these challenges. Co0.8Ni0.2 alloy nanoparticles (NPs) are confined within N-doped mesoporous carbon spheres (NDMCS) and encapsulated with a carbon nitride shell (∼ 5 nm thick). XPS results reveal strong non-classical metal-support interaction, increasing activation energy from 38.82 to 44.6 kJ mol−1, which controls cobalt's reactivity, leading to excellent recycling efficiency (90 % retention of initial rate, no change in particle size) in high-concentration reactants (2 %NaBH4 + 2 %NaOH). The retention rate drops to 26.8 % without this stabilization due to rapid metal dissolution. This stability of Co0.8Ni0.2 alloy in alkaline conditions has significant practical implications for hydrogen generation and other electrochemical applications.

Modification of polypropylene separator with multifunctional layers to achieve highly stable sodium metal anode

Separator modification is an effective approach to suppress dendrite growth to realize high-energy sodium metal batteries (SMBs) in practical applications, however, its success is mainly subject to surface modification. Herein, a separator with multifunctional layers composed of N-doped mesoporous hollow carbon spheres (HCS) as the inner layer and sodium fluoride (NaF) as the outer layer on commercial polypropylene separator (PP) is proposed (PP@HCS-NaF) to achieve stable cycling in SMB. At the molecular level, the inner HCS layer with a high content of pyrrolic-N induces the uniform Na+ flux as a potential Na+ redistributor for homogenous deposition, whereas its hollow mesoporous structure offers nano-porous buffers and ion channels to regulate Na+ ion distribution and uniform deposition. The outer layer (NaF) constructs the NaF-enriched robust solid electrolyte interphase layer, significantly lowering the Na+ ions diffusion barrier. Benefiting from these merits, higher electrochemical performances are achieved with multifunctional double-layered PP@HCS-NaF separators compared with single-layered separators (i.e. PP@HCS or PP@NaF) in SMBs. The Na||Cu half-cell with PP@HCS-NaF offers stable cycling (280 cycles) with a high CE (99.6%), and Na||Na symmetric cells demonstrate extended lifespans for over 6000 h at 1 mA cm−2 with a progressively stable overpotential of 9 mV. Remarkably, in Na||NVP full-cells, the PP@HCS-NaF separator grants a stable capacity of ∼81 mA h g−1 after 3500 cycles at 1C and an impressive rate capability performance (∼70 mA h g−1 at 15C).

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.

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

D-band center engineering of single Cu atom and atomic Ni clusters for enhancing electrochemical CO2 reduction to CO

The rational design of catalysts with atomic dispersion and a deep understanding of the catalytic mechanism is crucial for achieving high performance in CO2 reduction reaction (CO2RR). Herein, we present an atomically dispersed electrocatalyst with single Cu atom and atomic Ni clusters supported on N-doped mesoporous hollow carbon sphere (CuSANiAC/NMHCS) for highly efficient CO2RR. CuSANiAC/NMHCS demonstrates a remarkable CO Faradaic efficiency (FECO) exceeding 90% across a potential range of −0.6 to −1.2 V vs. reversible hydrogen electrode (RHE) and achieves its peak FECO of 98% at −0.9 V vs. RHE. Theoretical studies reveal that the electron redistribution and modulated electronic structure—notably the positive shift in d-band center of Ni 3d orbital—resulting from the combination of single Cu atom and atomic Ni clusters markedly enhance the CO2 adsorption, facilitate the formation of *COOH intermediate, and thus promote the CO production activity. This study offers fresh perspectives on fabricating atomically dispersed catalysts with superior CO2RR performance.

Synergistically promoting the catalytic conversion of polysulfides via in-situ construction of Ni-MnO2 heterostructure on N-doped hollow carbon spheres towards high-performance sodium-sulfur batteries

The room-temperature sodium-sulfur (RT Na-S) battery is considered to be a highly promising electrochemical energy storage device, attributed to its high energy density, rich sulfur reserve, and nontoxicity. However, it is constrained by the polysulfide shuttling and the low intrinsic conductivity of active sulfur. A sacrificial template method has been used to develop hetero-structured Ni-MnO2 embedded in micro/mesoporous hollow carbon spheres (HCS@Ni-MnO2) to overcome these challenges. As evidenced by electrochemical properties and computational results, the construction of hetero-structured Ni-MnO2 provides a strong affinity to polysulfides. Meanwhile, the highly conductive in-situ constructing Ni-MnO2 structure has strong adsorption to soluble sodium polysulfides and effectively improves the catalytic conversion. The micro- and mesoporous hollow carbon sphere improves the reactivity of the sulfur cathodes and physically suppresses polysulfides shuttling. Befitting from the physical and chemical confinement and the fast redox reaction of polysulfides, the as-prepared S/HCS@Ni-MnO2 cathode exhibits a high capacity of 1031.7 mAh g−1 at 0.2 A g−1 after 100 cycles, surpassing the capacities of S/HCS@Ni (820.3 mAh g−1), S/HCS@MnO2 (942.4 mAh g−1) and S/HCS (866.7 mAh g−1). Moreover, the battery with S/HCS@Ni-MnO2 cathode also exhibits excellent cycle life (586.8 mAh g−1 at 5 A g−1 after 1000 cycles) and a high rate performance (553.8 mAh g−1 at 10 A g−1). This study provides an efficient strategy for synthesizing multiple compound hetero-structured materials to facilitate the development of energy storage applications.

Amino-Induced CO2 Spillover to Boost the Electrochemical Reduction Activity of CdS for CO Production.

A considerable challenge in CO2 reduction reaction (CO2RR) to produce high-value-added chemicals comes from the adsorption and activation of CO2 to form intermediates. Herein, an amino-induced spillover strategy aimed at significantly enhancing the CO2 adsorption and activation capabilities of CdS supported on N-doped mesoporous hollow carbon sphere (NH2-CdS/NMHCS) for highly efficient CO2RR is presented. The prepared NH2-CdS/NMHCS exhibits a high CO Faradaic efficiency (FECO) exceeding 90% from -0.8 to -1.1V versus reversible hydrogen electrode (RHE) with the highest FECO of 95% at -0.9V versus RHE in H cell. Additional experimental and theoretical investigations demonstrate that the alkaline -NH2 group functions as a potent trapping site, effectively adsorbing the acidic CO2, and subsequently triggering CO2 spillover to CdS. The amino modification-induced CO2 spillover, combined with electron redistribution between CdS and NMHCS, not only readily achieves the spontaneous activation of CO2 to *COOH but also greatly reduces the energy required for the conversion of *COOH to *CO intermediate, thus endowing NH2-CdS/NMHCS with significantly improved reaction kinetics and reduced overpotential for CO2-to-CO conversion. It is believed that this research can provide valuable insights into the development of electrocatalysts with superior CO2 adsorption and activation capabilities for CO2RR application.

Cu Single Atoms Embedded in N-Doped Hollow Carbon Spheres for Simultaneous Electrochemical Detection of Hydroquinone and Catechol

Cu Single Atoms Embedded in N-Doped Hollow Carbon Spheres for Simultaneous Electrochemical Detection of Hydroquinone and Catechol

Exploring nitrogen doped mesoporous carbon spheres for superior microwave absorption

Mesoporous carbon materials hold significant promise for usage in microwave absorption due to their wide and unique advantages stemming from their mesoporous structure. This study synthesizes N-doped mesoporous carbon spheres (NMCs) by carbonizing mesoporous silica nanospheres (MSN). By controlling the annealing temperature, the resulting NMCs exhibit a significant increase in pore size. The exceptional microwave absorption capability of multifunctional carbon with a mesoporous structure result from its appropriate composition. The minimum reflection loss (RL) can reach −58.04 dB with a thickness of 3.3 mm, and the corresponding effective absorption bandwidth (EAB) reaches up to 8.19 GHz, outperforming the many previously documented microwave absorbing materials. The material's practical application potential was evaluated using computer simulation technology (CST), resulting in a simulated RCS value of 32.88 dBm2.The microwave absorption process of this material has been extensively studied and thoroughly described. Our study offers valuable guidance for developing and producing efficient microwave absorbers doped with nitrogen and possessing a unique mesoporous structure.

Revealing electrostatic-manipulated self-assembly mechanism helps to readily design enhanced MOF-derived microwave absorbers

The controllable self-assembly of Metal Organic Frameworks (MOFs) crystals plays a vital role in modulating the performance for microwave absorbers. However, most current strategies require colloidal or intricate chemical modifications of nanoparticles, thereby increasing the complexity of structural construction and impeding the broader application of microwave absorbers. To resolve this tough issue, we herein innovatively propose a more easily achievable electrostatic-manipulated self-assembly strategy. By readily manipulating the electrostatic adsorption and repulsion between particles, the aggregation and growth sites of initial MOF crystals are anchored, hence facilitating to the construction of solid-core/shell and hollow porous microstructures for absorbers. The substantial improvement depending on electrostatic effects is clearly observed in experimental results. It demonstrates that the Co@hollow N-doped carbon spheres (Co@HNCSs) absorber, induced by electrostatic repulsion, shows the best overall absorption performance, with a strong absorption of −65.4 dB at a thickness of 1.9 mm and an effective absorption bandwidth (EAB) of 5.4 GHz at a thickness of 1.6 mm, covering almost the entire Ku band. The influence of these strategies on the electromagnetic response mechanisms is further comprehensively discussed. Accordingly, we believe this strategy offers new insights for the MOFs’ structural absorbers via electrostatic-manipulated self-assembly strategy.

Zinc-ion hybrid supercapacitors with hierarchically N-doped porous carbon electrodes and ZnSO4/ZnI2 redox electrolyte exhibit boosted energy density

Zinc-ion hybrid capacitors (ZIHCs) with high energy density is commercial need as energy storing devices, but facile preparation is still a challenge. Herein, we proposed a combined strategy for preparation of ZIHCs with high performance. For this purpose, a nanoemulsion assembly approach with Pluronic F127 as structure-directing agent, 1, 3, 5-trimethylbenzene as pore-expanding agent, polydopamine as carbon and nitrogen source, was used to synthesize hierarchically N-doped porous carbon spheres (N-HNCSs). The optimized sample of N-HNCS-1 exhibited uniform size of 150 nm, hierarchically porous structure, large surface area (705.46 m2 g−1), and N-doping amount of 6.51 %. These properties were beneficial for the transportation of the electrolyte ions resulted in that the N-HNCS-1 electrode displayed superior electrochemical performance with specific capacity of 142 mAh g−1. Furthermore, the Zn//ZnSO4 + ZnI2//N-HNCS-1 ZIHCs achieves an exceptionally high energy density of 347.7 Wh kg−1, which is 3-fold higher than that of Zn//ZnSO4//N-HNCS-1 ZIHCs. To elucidate this outstanding performance, we investigate the mechanisms involved, including Zn2+ deposition/stripping, SO42-/I- adsorption/desorption, Zn4SO4(OH)6⋅0.5 H2O precipitation/dissolution, and redox reactions relating to iodine ions. The incorporation of ZnI2 redox-electrolyte significantly enhanced the energy density by providing prominent pseudocapacitance via the faradaic reaction. Therefore, the high performance of Zn//ZnSO4 + ZnI2//N-HNCS-1 ZIHCs is attributed to the introduction of nitrogen (N) species, advantageous 3D carbonaceous framework, and redox reactions triggered by adding zinc iodide (ZnI2) into the aqueous zinc sulfate (ZnSO4) electrolyte. This groundbreaking research opens up possibilities for the development of high-energy ZIHCs, and advancements in energy storage technology.

FeCo alloy nanoparticles supported on N-doped mesoporous carbon spheres for effective degradation of antibiotics and industrial dyes

Iron (Fe) is widely recognized for its effectiveness in the Fenton reaction and is commonly used in wastewater treatment. However, exploring other metals in similar Fenton-like reactions has been relatively limited. FeCo alloy nanoparticles (NPs), anchored on nitrogen-doped mesoporous carbon spheres (FeCo/NMCS), have been effectively synthesized and used as a Fenton-like catalyst in wastewater treatment under alkaline conditions. The NMCS exhibited spherical with an average diameter of 488.1 nm, while the FeCo alloy NPs, uniformly distributed over the NMCS, had an average diameter of 8.2 nm. The mesopores served as anchoring points for the NiCo alloy NPs, effectively preventing their possible agglomeration. The NMCS was composed of 3.91 wt% nitrogen. With 30 mg of FeCo/NMCS and 25 mM H2O2, more than 92% of tetracycline hydrochloride (TC) was degraded within 35 min at pH levels 7, 9, and 11. The remarkable degradation rate was attributed to the dual active sites present in the FeCo alloys. The rapid degradation of TC, even at pH 11, indicates the potential of FeCo/NMCS as a valuable solution for wastewater treatment under alkaline conditions. Industrial reactive (Y145, R195, B222A) and disperse dyes (O30, R167, B79) with a concentration of 10 ppm were degraded within 20 min when using 10 mg of the FeCo/NMCS catalyst and 25 mM H2O2 at pH 9. After five consecutive TC degradation cycles at pH 7 and 9, the FeCo/NMCS demonstrated consistent performance, emphasizing its reusability. FeCo/NMCS provides a promising solution to pollution control and wastewater treatment with stability, superior catalytic activity, magnetic separability, and recyclability.

Hydrogenation of cinnamaldehyde over palladium nanoparticles supported on functionalized N-doped solid carbon spheres

Hydrogenation of cinnamaldehyde over palladium nanoparticles supported on functionalized N-doped solid carbon spheres

Highly active CeO2-CuCo nanoparticles supported on hollow N-doped carbon spheres for boosting ammonia borane hydrolysis and tandem 4-nitrophenol reduction reactions

It’s a safe method to use high hydrogen density ammonia borane (AB) to facilitate the tandem hydrogenation of aromatic nitro compounds. While a major problem for tandem hydrogenation, the development of non-noble metal catalysts with high activity and stability is encouraging. This work involved the synthesis of highly active CeO2/CuCo nanoparticles support on hollow N-doped carbon spheres and its investigation for AB hydrolysis, taking into account the impacts of the HNCSs and CeO2 supports. Because CuCo alloy, CeO2, and HNCSs supports worked in concert, HNCSs@CeO2/CuCo was found to be the best catalyst. The activation energy achieved was comparable to the reported Pd- and Pt-based catalysts, with a value as low as 21.8 kJ/mol. Using AB as the in-situ H2 source, HNCSs@CeO2/CuCo exhibited a significant degree of activity in the one-pot tandem reduction of 4-NP with the turnover frequency of 2830.2 h−1, even surpassing over ten times of some noble metal catalysts. Following five consecutive cycles of reaction condition tuning, the HNCSs@CeO2/CuCo catalyst demonstrated a constant conversion efficiency. Also, the catalyst's uses for one-pot tandem reduction of other highly active aromatic nitro compounds were expanded.

Self-nitrogen-doped hierarchical porous carbon spheres as metal-free catalyst for efficient photocatalytic CO2 reduction

It is rather important to develop an efficient, stable and economical photocatalyst for solar-driven CO2 reduction. Herein, N-doped hierarchical porous carbon spheres (NPCS-F6) with metal-like activity is synthesized using acrylamide and F127 as nitrogen source and soft template, and the effective synergy between nitrogen-containing species and hierarchical pore structure makes the samples exhibit excellent CO2 reduction properties. XPS characterization illustrates that the introduced pyridine nitrogen and pyrrole nitrogen groups contribute to the increase of CO2 reduction sites on the surface of the material. N2 adsorption analysis verifies the existence of hierarchical pore structures in which micropores facilitate the exposure of more adsorption active sites, while mesopores and macropores can be used as transfer channels to connect the internal micropores and reduce the molecular diffusion resistance to improve CO2 adsorption performance. In addition, the pore structure of the samples prepared with P123 and CTAB as templates is mainly microporous, whereas carbon spheres with hierarchical pores coexisting are obtained with F127 as template. The evaluation of photocatalytic CO2 reduction activity shows that the CO yield of NPCS-F6 could reach 17.56 μmol·g−1 for 8 h, which is 1.17 times, 1.08 times and 1.07 times of the original NCS-8 (15.05 μmol·g−1), NPCS-P6 (P123 as soft template, 16.25 μmol·g−1) and NPCS-C1 (CATB as soft template, 16.39 μmol·g−1), respectively. Comprehensive characterization results are analyzed to propose a possible mechanism for photocatalytic CO2 reduction, in which photogenerated electron-hole pairs are generated inside the material under light conditions, and the photogenerated electrons are transferred to the N-6/N-5 active sites through the electron transfer channel N-Q to react with CO2 molecules adsorbed on the surface to be reduced to CO. Finally, our results provide a favorable and feasible strategy to synthesize metal-free photocatalysts for high-efficiency CO2 adsorption and targeted reduction of CO2 to CO.