Carbon Spheres Research Articles

Crosslinking assembly of Propenyl-Calix[4]-Crown-6 interpenetrating functional mesoporous carbon Spheres: High selectivity and stability to Remove Cs(I) from high acid solution

The calix[4]-crown-6 ligand shows high selectivity for Cs(I) over other alkali and alkaline earth metal cations, making it a promising candidate for radiocesium separation. However, its high viscosity and poor adhesion limit its practical use and stability. In this study, an alkenyl-functionalized calix[4]-crown-6 (p-C[4]C6) was developed. Using a mesoporous structure and post-assembly techniques, a composite (p-C[4]C6/MMCs) was created via crosslinking within mesoporous matrix channels. The p-C[4]C6/MMCs exhibited high stability and practicality. The p-C[4]C6/MMCs demonstrated high selectivity, good reusability, and significant adsorption capacity (47.76 mg/g) for Cs(I) in 3.0 M HNO3. Kinetic, isotherm, and thermodynamic studies suggest a spontaneous chemical adsorption mechanism. This research provides insights into the design of calix[4]-crown-6 based materials and offers a viable approach for Cs(I) separation from high-level liquid waste (HLW).

Attaining superior performance in an aqueous hybrid supercapacitor based on N-Doped highly porous carbon spheres and N-S dual doped Co3O4

Cobalt oxide (Co3O4) has seen a significant interest for its application as an electrode for supercapacitors, due to its cost-effectiveness, high theoretical capacitance and outstanding redox activity. However, Co3O4 exhibits poor electrical conductivity and cycle life restricting its high-power energy storage applications. High porosity carbons are materials of choice for applications in electric double layer charge storage but suffer from poor energy densities due to limited charge storage capabilities. Here we propose a hierarchical functionalization strategy to develop N, S co-doped Co3O4 and N doped high porosity carbon micro-spheres for efficient and durable hybrid supercapacitor. Benefiting from the structural eminence, improved electrical conductivity and high quantity of N content, the heteroatom enriched N, S co-doped Co3O4 and N doped porous carbon spheres demonstrates superior electrochemical performance. Moreover, hybrid supercapacitor cell with N, S co-doped Co3O4 as a cathode and N doped porous carbon spheres as anode deliver a high specific energy of 52 Wh kg-1 at power density of 1462 W kg-1 coupled with the capacity retention of 95 % after 5,000 charge-discharge cycles.Therefore, by improving both anode and cathode simultaneously can be considered an effective approach to enhance energy storage capabilities of hybrid supercapacitors while maintain exceptionally high-power densities.

Effects of Acid Sites on Thin MCM‐22 Zeolite Catalysts and Their Catalytic Applications for Acetylene Aromatization

AbstractTwo types of thin zeolite MCM‐22 catalysts were prepared by using a carbon sphere template. By applying different calcination methods, a hollow sphere‐type MCM‐22 catalyst (HS‐MCM‐22) and a nanosheet‐type MCM‐22 catalyst (NS‐MCM‐22) were synthesized. Those catalysts were tested and evaluated for acetylene aromatization to see the effects of thin structures. The two types of thin catalysts were found to have higher amounts of acid sites than those of the conventional MCM‐22 catalyst. It was found that the extremely short diffusion length not only enhanced the aromatic yield, but also suppressed the formation of graphitic coke. Notably, the diffusion length of NS‐MCM‐22 was found to be at least 15 times shorter than that of conventional MCM‐22, leading to an 11% and 18% increase in benzene yield, respectively. The thin structure seemed to help the produced aromatics efficiently desorb before they were further converted into carbon precursors and coke. According to the thermogravimetric analysis, the carbon species in the spent thin catalysts were found less graphitic than that of the conventional MCM‐22 catalyst. Because of this, the thin MCM‐22 catalysts were believed to show higher coke removal capability. Especially, the coke removal rate of NS‐MCM‐22 was estimated over 90% despite the severe carbon deposition during the reaction.

FeCo Alloy Nanoparticles Supported on N-doped Mesoporous Carbon Spheres for Hydrogen Evolution and Reduction of Organic Dyes

FeCo Alloy Nanoparticles Supported on N-doped Mesoporous Carbon Spheres for Hydrogen Evolution and Reduction of Organic Dyes

Construction of atom-scale Co/Fe/Ni M-N-C active sites within nitrogen-doped carbon spheres for high-performance bifunctional oxygen catalysts in rechargeable zinc-air batteries

Developing carbon-based catalysts with metal‑nitrogen‑carbon (M-N-C) active sites as efficient and low-cost bifunctional catalysts to replace precious metal catalysts for rechargeable zinc-air batteries devices has garnered significant attention. Herein, nitrogen-doped submicron carbon-based spherical bifunctional electrocatalysts (CNPD-CoFeNi) with abundant atom-scale Co/Fe/Ni M-N-C active sites and defects were synthesized. The introduction of massive amounts of Zn species increases the spatial distance of Co/Fe/Ni metal sites to prevent aggregation during pyrolysis, and the evaporation of Zn at high temperatures creates defects synergizing with M-N-C. Consequently, CNPD-CoFeNi possesses a stable carbon-based spherical structure, high electrical conductivity, rich nitrogen content, abundant atom-scale Co/Fe/Ni M-N-C active sites, and defects, displaying outstanding durability, oxygen reduction reaction (ORR) activity with a half-wave potential of 0.87 V, and satisfactory OER performance, surpassing or comparable with the state-of-art Pt/C and RuO2, respectively. Notably, liquid Zn-air batteries with CNPD-CoFeNi catalyst exhibit an exceptional high peak power density of 146.5 mW cm−2 and stable charge-discharge cycling over 270 h, outperforming Pt/C-RuO2 based devices. Additionally, the all-solid-state Zn-air battery also displays satisfactory practicability and stability. The synthesis strategy and its remarkable results provide valuable guidance and inspiration for the future advancement of precious metal substitutes in ORR/OER and rechargeable zinc-air batteries.

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.

Minimizing liquid/solid interfacial energy boosts Fe−N doping inside hollow carbon sphere for oxygen reduction in membrane-less direct formate fuel cell

Porous hollow carbon sphere (HCS) is an attractive catalyst support for oxygen reduction reaction (ORR) due to its large specific surface area for active site anchoring, porous and hollow structure for active site exposure and mass transfer. However, due to the high transfer resistance for exogenous heteroatoms into HCS, most of active sites are usually loaded on the outer surface of HCS, leading to the decrease of active site density and the aggregation of heteroatomic particles. In this work, we proposed that accompanied with the decrease of liquid/solid interfacial energy by changing solvent composition during impregnation, penetration of exogenous heteroatoms-containing solution was facilitated in HCS, resulting in increased density of uniformly-dispersed Fe−Nx active site by 58 %. Taking advantage of high-content and well-dispersed active site, structure-derived porosity for ion transfer and active site exposure, this HCS-derived catalyst (Fe-HCS@C2H5OH) exhibited positive onset and half-wave potentials of 0.953 V and 0.901 V (vs. RHE), as well as high power density of 20.17 ± 0.31 mW cm−2 when applied in membrane-less direct formate fuel cell cathode, surpassing those of commercial Pt/C and the state-of-the-art carbonaceous catalysts. This strategy of interfacial energy control provides a new stepping-stone for the synthesis of high-performance electrocatalysts.

An Engineering Porous Spherical Carbon Cathode for High-Energy Sodium-Ion Capacitor.

Sodium-ion hybrid capacitors (SICs) are emerging as promising devices that can balance energy and power output. However, the lack of a high-capacity cathode that can match the anode has limited its further application. In this work, we develop an efficient method to prepare spherical porous carbons (SPCs) with great specific surface area and narrow pore size distribution from coal-based humic acid via spray drying and a subsequent chemical activation process. Thanks to this unique porous structure, the SPC cathode has a superb capacity of 223 F g-1 at 0.05 A g-1, as well as splendid rate performance and cycling stability. SICs constructed by an SPC cathode and hard carbon anode can exhibit a high energy density of 179.8 Wh kg-1 at 155 W kg-1 and achieved 89.4% capacity retention after 10 000 cycles at 0.5 A g-1. This outcome presents a viable approach to attaining high-capacity cathodes for constructing outstanding performance hybrid capacitors.

Extremely Durable K-Ion Batteries Enabled by Heteroatom Co-Doped Highly-Ordered Porous Carbon Spheres with Nearly 100% Capacity Retention up to 11,000 Cycles.

Currently, one major target for exploring K-ion batteries (KIBs) is enhancing their cycle stability due to the intrinsically sluggish kinetics of large-radius K+ ions. Herein, we report a rationally designed electrode, the S/O co-doped hard carbon spheres with highly ordered porous characteristics (SPC), for extremely durable KIBs. Experimental results and theory calculations confirm that this structure offers exceptional advantages for high-performance KIBs, facilitating rapid K+ diffusion and (de)-intercalation, efficient electrolyte penetration and transport, improved K+ storage sites, and enhanced redox reaction kinetics, thus ensuring the long-term cycle stability. As a result, the as-constructed SPC anode delivers a high reversible capacity of ca. 200 mAh g-1 at a high current density of 2.0 A g-1 and robust stability with ∼100% capacity retention up to 11,000 cycles, outperforming most carbon-based KIB anodes. This work offers insight into developing advanced KIBs with durable stability toward practical applications.

Curvature-Induced Electron Spin Catalysis with Carbon Spheres.

Here, we report curvature-induced electron spin catalysis by using solid carbon spheres as catalysts, which were synthesized using positive curvature molecular hexabromocyclopentadiene as a precursor molecule, following a radical coupling mechanism. The curvature spin of carbon is regarded as an overlapping state of σ- and π-radical, which is identified by the inverse Laplace transform of pulse-electron paramagnetic resonance. The growth mechanism of carbon spheres abiding by Kroto's model, is supported by the density functional theory study of thermodynamics and kinetics calculations. The solid carbon spheres present excellent catalytic behaviour of oxidation coupling of amines to form corresponding imines with the conversion of >99%, selectivity of 98.7%, and yield of 97.7%, which is attributed to the predominantly curvature-induced electron spin catalysis of carbon, supported by the calculation of oxygen adsorption energy. This work proposes a view of curvature-induced spin catalysis of carbon, which opens up a research direction for curvature-induced electron spin catalysis.

Curvature‐Induced Electron Spin Catalysis with Carbon Spheres

Here, we report curvature‐induced electron spin catalysis by using solid carbon spheres as catalysts, which were synthesized using positive curvature molecular hexabromocyclopentadiene as a precursor molecule, following a radical coupling mechanism. The curvature spin of carbon is regarded as an overlapping state of σ‐ and π‐radical, which is identified by the inverse Laplace transform of pulse‐electron paramagnetic resonance. The growth mechanism of carbon spheres abiding by Kroto’s model, is supported by the density functional theory study of thermodynamics and kinetics calculations. The solid carbon spheres present excellent catalytic behaviour of oxidation coupling of amines to form corresponding imines with the conversion of >99%, selectivity of 98.7%, and yield of 97.7%, which is attributed to the predominantly curvature‐induced electron spin catalysis of carbon, supported by the calculation of oxygen adsorption energy. This work proposes a view of curvature‐induced spin catalysis of carbon, which opens up a research direction for curvature‐induced electron spin catalysis.

Novel C/MoS2 hollow nanocomposites enhance lithium storage in battery anodes

With society's rapid progress, there is an increasing need for electricity among individuals, but the prevailing source of electricity is still mainly obtained through the burning of nonrenewable fossil fuels, which are not renewable and pose serious environmental hazards. Lithium-ion batteries are used widely for excellent rechargeable capabilities and high energy density. Recently, researchers have become increasingly interested in transition metal sulfides owing to their cost-effectiveness and remarkable specific capacity. However, their commercialization has been hindered by the expansion of material volume and low electrical conductivity during charging and discharging. We have successfully designed and synthesized MoS2 nanosheets loaded on carbon spheres with a 3D hollow structure starting from SiO2 as a template. Due to the doping of carbon materials and particular 3D hollow structures, the optimal C/MoS2-0.3 hollow nanocomposites exhibit excellent electrochemical performance. Following exposure to over 900 cycles at a 0.5 A g-1 ampere density, the materials exhibited an exceptional 958.50 mAh g-1 reversible capacity, demonstrating their remarkable performance.

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).

Poly(ethylenimine)-assisted synthesis of hollow carbon spheres comprising multi-sized Ni species for CO2 electroreduction

Poly(ethylenimine)-assisted synthesis of hollow carbon spheres comprising multi-sized Ni species for CO2 electroreduction

Enhancing hydrovoltaic power generation with carbon spheres coated on nickel foam/polyethylene terephthalate substrate

The present study aims to assess the viability of hydrovoltaic impact as a potential method for energy generation. This methodology utilizes the capillary action of water in devices composed of nickel (Ni) foam/polyethylene terephthalate (PET) substrates coated with hydrothermally synthesized carbon spheres at various temperatures (180, 200, and 220 °C). The prepared materials and devices were analyzed using a range of analytical techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR). The SEM images revealed the spherical morphology of the carbon particles and their presence on Ni foam, whereas the XRD patterns indicated that the carbon spheres were amorphous. Spectroscopic analysis revealed the presence of hydroxyl functional groups in all the samples. The performance of the devices was assessed by electrochemical tests, including open-circuit potential (OCP), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The device coated with carbon spheres synthesized at 180 °C demonstrated enhanced performance with an elevated OCP value of 0.077 V, increased surface charge area, lower resistance to water, and reduced charge transfer resistance. These findings indicate the successful production of hydrovoltaic energy by utilizing the capillary action of water in carbon-sphere-coated Ni foam/PET devices.

Fluorinated Hollow Porous Carbon Spheres as High-Performance Cathode Material for Primary Battery

Fluorinated carbon cathode materials have extremely high theoretical specific energy among known cathode materials of lithium primary batteries. Nevertheless, current fluorinated carbon cannot meet the performance demands of future applications due to the rate performance. This work innovatively applies hollow carbon spheres with a porous structure as carbon sources to prepare fluorinated hollow porous carbon spheres (FHPCS) with high energy density and power density. The porous structure provides more reaction sites for the fluorination process and also shortens the diffusion path of lithium ions during the discharge. Additionally, the hollow porous structure offers more interfacial contact areas and reduces volumetric expansion during discharge reactions. The Li/CFx primary battery has a maximum specific energy of 2007 Wh kg−1 and a maximum power density of 30,400 W kg−1 and can have a capacity retention rate of 80.8% at a current density of 16 A g−1. In addition, FHPCS also has the highest specific energy of 1999 Wh kg−1 and 1711 Wh kg−1 in Na/CFx and K/CFx primary batteries, respectively. The diffusion efficiency of an alkali metal ion is analyzed by the different discharge depths with electrochemical impedance spectroscopy and galvanostatic intermittent titration technique. This effort introduces a new high-performance fluorinated carbon featuring a hollow porous structure and puts forward an innovative approach to designing fluorinated carbon materials.

Disposable electrochemical aptasensor with mesoporous carbon spheres modified screen-printed dual-working electrodes for Pb2+ and Hg2+ detection

Electrochemical biosensing combined with screen-printed paper technology provides an effective strategy for the quantitative analysis of metal ions, particularly suitable for in-situ determination. In this study, a disposable, economical and user-friendly screen-printed dual-working electrodes (SPDEs) aptasensor system for the determination of lead ions (Pb2+) and mercury ions (Hg2+) was described. The sensor system consists of dual-working electrodes, a counter electrode and a reference electrode fabricated using screen printing technology. The aptasensor demonstrates high sensitivity and selectivity towards Pb2+ and Hg2+, owing to the larger specific surface area (1334.7 m2/g) and excellent conductivity of mesoporous carbon nanoparticles (MCNs). Additionally, the specific recognition ability and high affinity of G-quadruplex and T-Hg2+-T structures for Pb2+ and Hg2+, respectively, further enhance the performance. Under optimized experimental conditions, the aptasensor achieves a low limit of detection (LOD) of 0.088 ng/mL for Pb2+ and 0.0007 ng/mL for Hg2+ (S/N = 3), a wide linear range (0.1–1000.0 ng/mL for Pb2+ and 0.001–100.0 ng/mL for Hg2+), and high accuracy (relative standard deviation, RSD≤10.0 %) and selectivity. Importantly, the SPDEs aptasensor can detect Pb2+ and Hg2+ in a sample without competition and interference, achieving accuracy comparable to that of commercial inductively coupled plasma mass spectrometry (ICP-MS). These advantages make the SPDEs aptasensor highly suitable for practical applications in environmental monitoring, food safety, and clinical diagnosis.

Development and application of metal–organic frameworks and spherical carbon particles for efficient recovery of phenols and oils from coal chemical wastewater: A new full-process adsorption treatment mode

To address the challenges of high energy consumption and low efficiency in recovering phenols and oils from coal chemical wastewater (CCW), this study focused on the design and synthesis of metal–organic frameworks and spherical carbon particle (MOFs/SCP) adsorbents with a high adsorption capacity and ease of desorption. Additionally, a new comprehensive treatment mode named “adsorption-desorption-regeneration-recovery” (ADRR) was developed to efficiently recover phenols and oils from CCW. The results revealed that the ADRR treatment mode maintained high adsorption and desorption efficiencies of MOFs/SCP, which remained consistently above 95 %. Additionally, methanol regeneration reached ∼ 90 %, and the recovery efficiency of phenols and oils was ∼ 83 %. The analysis of the adsorption behavior model indicated that the adsorption of phenols and oils by MOFs/SCP mainly involved monolayer chemical adsorption characterized by spontaneity, heat absorption, and disorder. The dynamic adsorption model exhibited a strong correlative ability to predict and assess the adsorption capacity, rate, equilibrium, and operating parameters. Finally, structural analyses and molecular dynamics simulations revealed that the micro-interaction mechanisms between MOFs/SCP and phenols and oils mainly depended on the distinctive hydrophobic nature and porous adsorption capabilities of MOFs/SCP. These interactions were mainly facilitated by electrostatic interactions, π–π interactions, and hydrogen bonding. The findings of the study are crucial for achieving high-value recovery of phenols and oils from CCW and, promoting the clean and sustainable growth of the coal chemical industry.

Wrinkled hierarchical porous carbon spheres with interconnected multi-cavity for ultrahigh capacitive deionization

As one of the most promising electrode materials for capacitive deionization (CDI), the development of carbon materials with controllable pore structure and continuous mass production is essential for their practical application. Herein, a facile ultrasonic spray pyrolysis method was developed to synthesize surface-functionalized wrinkled hierarchical porous carbon spheres (HCS) with unique interconnected multi-cavity structures. The wrinkled and interconnected multi-cavity hierarchical pores of the HCS play a crucial role in providing accessible ion adsorption sites and promoting ion diffusion and storage in the “multi-cavity warehouse”. The carboxyl groups on the surface of HCS generate a negative charge that promotes the adsorption of cations. The optimized HCS possesses outstanding desalination capacity (114.25 mg g−1), fast adsorption rate (6.57 mg g−1 min−1), and superior cycling stability (95%). Meanwhile, the HCS exhibited impressive desalination capacities in brackish water. Furthermore, the density functional theory calculation results confirmed that the synergistic effect of carboxyl groups and defects significantly enhanced the Na+ adsorption capacity and facilitated ion diffusion. This study extends the synthesis method of surface-functionalized hierarchical porous carbon, which is expected to facilitate the development of CDI electrode materials.