Mesoporous Carbon Nanospheres Research Articles

Synergistic effects of nitrogen/oxygen co-doping in 3D mesoporous carbon nanospheres for enhanced microwave absorption

Mesoporous carbon nanospheres have attracted significant attention in the microwave absorption (MA) field due to the broad benefits provided by their mesoporous structure. This study presents a facile hard template strategy to construct distinctive 3D N/O co-doped mesoporous carbon nanospheres (NOCS). The high surface area, abundant mesopores, and high nitrogen (N) doping levels, with proper defects on the surface provide multiple sites to absorb electromagnetic waves (EMW). Mesoporous carbon nanospheres achieve significant reflection loss (RL) of −48.19 dB and extensive effective absorption bandwidth (EAB) up to 5.52 GHz. Moreover, computer simulation technology (CST) demonstrated that all simulated Radar cross-section (RCS) values were below 20 dB m2. Thus, this work holds significant promise for effective microwave absorbers using mesoporous carbon nanospheres.

Synthesis of ultra-high nitrogen doped hollow mesoporous carbon nanospheres via a universal solid–liquid interface self-assembly strategy

Functional mesoporous polymers, particularly their derived hollow mesoporous carbon spheres (HMCS), have introduced new opportunities in the field of energy storage. Traditional synthesis methods for HMCS typically rely on chemical etching, which often results in uniform chemical properties and structural control, thereby limiting their application in large-scale production and diverse fields. Therefore, in this study, we report a novel strategy for obtaining HMCS through the direct pyrolysis of a core matrix, melamine–formaldehyde resin (MF), to achieve hollow structures and ultra-high nitrogen doping (approximately 14.8 wt%). This new solid–liquid interfacial self-assembly approach enables the production of HMCS with remarkable electrochemical performance and practical application prospects in sodium-ion half-cells and full cells, thanks to the high nitrogen doping and unique structure. Notably, this strategy has been validated for its general applicability across 1D, 2D, and 3D solid matrices. Additionally, by adjusting the calcination temperature, this method allows for precise control over both the core size and nitrogen content of the egg yolk-shell structure mesoporous carbon spheres. In summary, the mesoporous materials developed in this study demonstrate flexibility, simplicity, versatility, and structural diversity, offering significant insights for future applications in energy storage and other fields.

Nanoporous Carbon Materials as Solid Contacts for Microneedle Ion-Selective Sensors.

Continuous sensing of biomarkers, such as potassium ions or pH, in wearable patches requires miniaturization of ion-selective sensor electrodes. Such miniaturization can be achieved by using nanostructured carbon materials as solid contacts in microneedle-based ion-selective and reference electrodes. Here we compare three carbon materials as solid contacts: colloid-imprinted mesoporous (CIM) carbon microparticles with ∼24-28 nm mesopores, mesoporous carbon nanospheres with 3-9 nm mesopores, and Super P carbon black nanoparticles without internal porosity but with textural mesoporosity in particle aggregates. We compare the effects of carbon architecture and composition on specific capacitance of the material, on the ability to incorporate ion-selective membrane components in the pores, and on sensor performance. Functioning K+ and H+ ion-selective electrodes and reference electrodes were obtained with gold-coated stainless-steel microneedles using all three types of carbon. The sensors gave near-Nernstian responses in clinically relevant concentration ranges, were free of potentially detrimental water layers, and showed no response to O2. They all exhibited sufficiently low long-term potential drift values to permit calibration-free, continuous operation for close to 1 day. In spite of the different specific capacitances and pore architecture of the three types of carbon, no significant difference in potential stability for K+ ion sensing was observed between electrodes that used each material. In the observed drift values, factors other than the carbon solid contact are likely to play a role, too. However, for pH sensing, electrodes with CIM as a carbon solid contact, which had the highest specific capacitance and best access to the pores, exhibited better long-term stability than electrodes with the other carbon materials.

Tailored Hollow Mesoporous Carbon Nanospheres from Soft Emulsions Enhance Kinetics in Sodium Batteries.

Mesoporous materials endowed with a hollow structure offer ample opportunities due to their integrated functionalities; however, current approaches mainly rely on the recruitment of solid rigid templates, and feasible strategies with better simplicity and tunability remain infertile. Here, we report a novel emulsion-driven coassembly method for constructing a highly tailored hollow architecture in mesoporous carbon, which can be completely processed on oil-water liquid interfaces instead of a solid rigid template. Such a facile and flexible methodology relies on the subtle employment of a 1,3,5-trimethylbenzene (TMB) additive, which acts as both an emulsion template and a swelling agent, leading to a compatible integration of oil droplets and composite micelles. The solution-based assembly process also shows high controllability, endowing the hollow carbon mesostructure with a uniform morphology of hundreds of nanometers and tunable cavities from 0 to 130 nm in diameter and porosities (mesopore sizes 2.5-7.7 nm; surface area 179-355 m2 g-1). Because of the unique features in permeability, diffusion, and surface access, the hollow mesoporous carbon nanospheres exhibit excellent high rate and cycling performances for sodium-ion storage. Our study reveals a cooperative assembly on the liquid interface, which could provide an alternative toolbox for constructing delicate mesostructures and complex hierarchies toward advanced technologies.

KOH-activated hollow carbon spheres with surface functionalization for high-capacity and long-cycle-life lithium-selenium batteries

Lithium-selenium (Li-Se) batteries are considered promising alternatives to lithium-ion batteries due to their higher volumetric capacity and energy density. However, they still face limitations in efficiently utilizing the active selenium. Here, we develop surface-functionalized mesoporous hollow carbon nanospheres as the selenium host. By using KOH activation, the surface of the carbon nanospheres is functionalized with hydroxyl groups, which greatly improve the utilization of selenium and facilitate the conversion of lithium selenides, leading to much higher capacities compared to ZnCl2 activation and untreated carbon nanospheres. Theory and experimental evidence suggest that surface hydroxyl groups can enhance the reduction conversion of polyselenides to selenides and facilitate the oxidation reaction of selenides to elemental selenium. In-situ and ex-situ characterization techniques provided additional confirmation of the hydroxyl groups electrochemical durability in catalyzing selenium conversion. The meticulously engineered Se cathode demonstrates a high specific capacity of 594 mA h g−1 at 0.5C, excellent rate capability of 464 mA h g−1 at 2C, and a stable cycling performance of 500 cycles at 2C with a capacity retention of 84.8 %, corresponding to an ultra-low-capacity decay rate of 0.0144 % per cycle, surpassing many reported lithium-selenium battery technologies.

Preparation of inorganic oil-containing carbon nanocapsules and tribological properties of PA6 composites

Oil-containing polymer composites have garnered significant attention in the field of tribology due to their remarkable environmental stability and outstanding self-lubricating performance. It is important to develop an oil-containing polymer composite with excellent self-lubricating properties and mechanical properties. In this study, we successfully synthesized hollow mesoporous carbon nanospheres (HMCNs) with a particle size of about 200 nm and explored the key factors affecting their preparation. Subsequently, an impregnation technique was employed to create oil-containing nanocapsules (Oil@C) by using PAO40 lubricant as core material and HMCNs as wall material. Self-lubricating PAO40@HMCNs nanocapsules have an oil content of approximately 51.6 wt%. The unique mesoporous structure of HMCNs facilitates the controlled release of lubricants. During friction, the Oil@C in the polymer composites continuously provided lubricant to the worn surface, resulting in a remarkable 72.8 % reduction in the coefficient of friction and an 83.2 % decrease in wear rate. Analysis of the friction pair revealed that the PAO40 lubricant released from the nanocapsules played a crucial role in improving the tribological properties of the composites. The prepared PA6 composites exhibit outstanding tribological and self-lubricating properties, making them promising candidates for applications in mechanical parts, such as self-lubricating slide bearings.

Boosting anions storage via union of in-situ N doping and mesoporous hollow hard carbon nanospheres for advanced dual-ion capacitors

High structural strength in-situ N-doped mesoporous hollow hard carbon nanospheres (NMHS) is prepared to overcome the low anions storage capacity (93 mAh g−1) of easy exfoliated graphite for dual-ion capacitors (DICs). The rich mesoporous structure facilitates the anions diffusion, and the hollow cavity provides expansion space in storage and weakens the high diffusion resistance in the nuclear bulge. With the synergistic effect, The NMHS delivers a high reversible capacity of 100 mAh g−1 with a low decay of 8 % over 5000 cycles at 2 A g−1. In-situ Raman reveals the storage mechanism on hard carbon is “adsorption (major)-intercalation (minor)”. DFT calculations decode the effective storage action of graphitic N and pyridinic N. Consequently, the assembled NMHS-DICs exhibit good long-cycle performance and heterotherm stability, providing a high energy/power density of 200 Wh kg−1 and 11858 W kg−1. This work verifies a feasible cathode design strategy with future application potential on DICs.

Carbon Nanospheres Loaded with Ir Single Atoms: Enhancing the Activity toward Formic Acid Oxidation by Increasing the Porosity

Theoretically, single‐atom catalysts (SACs) offer 100% atom utilization, making them strong candidates to replace expensive nanoparticles for catalysis. However, the structural supports used to anchor the SACs dramatically reduce the utilization efficiency of atoms (i.e., the percent of atoms actually accessible by reactants) by either encapsulating the SACs completely or creating severe diffusion limitation. Either of which leads to an overall low atom utilization and thus poor electrocatalytic activity similar to that of nanoparticles. In addressing this issue, we systematically investigated how the porous structure of carbon nanospheres affects the activity of Ir‐SACs toward formic acid oxidation (FAO). Specifically, we utilized a kinetically‐controlled growth strategy to produce uniform carbon nanospheres featuring yolk‐shell, mesoporous, and hollow structures with Ir‐SACs loaded throughout the structure. At a high specific surface area of 441 m2 g‐1 and exposed metal content of 1.82 wt.%, the Ir‐SACs based on mesoporous carbon nanospheres showed a remarkable FAO peak current density of 30.6 mA cm‐2, which was 283 and 46 times greater when benchmarked against the catalysts based on solid carbon nanospheres and 20 wt.% Ir/C, respectively.

Nitrogen-doped magnetic porous carbon nanospheres derived from dual templates-induced mesoporous polydopamine coated Fe3O4 for efficient extraction and sensitive determination of volatile nitrosamines by gas chromatography-mass spectroscopy

N-nitrosamines (NAs) are highly carcinogenic compounds commonly found in food, beverages, and consumer products. Due to their wide polarity range, it is challenging to find a suitable carbon adsorbent that can simultaneously adsorb and enrich both polar and nonpolar NAs with good recovery. In this study, nitrogen-doped magnetic mesoporous carbon nanospheres (M-MCN) were prepared and employed as an adsorbent for magnetic solid-phase extraction (MSPE) to extract and concentrate four NAs. The introduction of nitrogen functional groups enhanced the hydrophilicity of the carbon material, allowing M-MCN to achieve a balance between hydrophilicity and hydrophobicity, resulting in good recovery for both polar and nonpolar NAs. A method combining MSPE with gas chromatography-mass spectrometry (GC-MS) was developed for the determination of NAs in processed meat and alcoholic beverages. The method exhibited a good linear range (1–100 ng g−1, r2 > 0.9967) and trace-level detection (0.53–6.6 ng g−1). The recovery rates for the four NAs ranged between 85.7 and 110.7 %, with intra-day precision expressed as relative standard deviation (RSD) between 4.1 and 10.7 %, and inter-day precision between 4.8 and 12.9 %. The results demonstrated not only good accuracy and precision but also provided a new adsorbent for the enrichment of trace-level NAs in processed meat and alcoholic beverage samples.

Ultrafine Ru nanoparticles anchored on N-doped mesoporous hollow carbon spheres as a highly efficient bifunctional catalyst for Li–CO2 batteries

Rechargeable Li–CO2 battery is a facilitative and promising device for the conversion of CO2 to electrochemical energy. However, it remains a challenge to enhance the sluggish decomposition kinetics of lithium carbonate as the discharge product. Herein, the Ru nanoparticles anchored on N-doped mesoporous hollow carbon nanospheres (Ru-AHCNs) are designed as cathode to enhance the electrochemical performance of Li–CO2 battery. The Ru-AHCNs cathode displays a high discharge specific capacity of 11194.4 mA h g−1 at the current density of 100 mA g−1. In addition, the Ru-AHCNs cathode can stably run over 50 cycles and maintain a small overpotential (<1.38 V) with a limited capacity of 1000 mA h g−1 at 100 mA g−1. The excellent stability and catalytic activity of the cathode are ascribed to the following factors: (i) Uniform deposition of Ru nanoparticles in hollow carbon nanospheres can enhance the decomposition of Li2CO3 and provide considerable exposure to active sites. (ii) N-doped mesoporous hollow carbon nanospheres can provide abundant electron transport channels and promote the nucleation of discharge products. These results evidently prove the reversible formation and decomposition of the discharge products, indicating that Ru-AHCNs cathode possesses excellent bifunctional catalytic activity.

Ultrasmall and Highly Dispersed Pt Entities Deposited on Mesoporous N-doped Carbon Nanospheres by Pulsed CVD for Improved HER.

Vapor-based deposition techniques are emerging approaches for the design of carbon-supported metal powder electrocatalysts with tailored catalyst entities, sizes, and dispersions. Herein, a pulsed CVD (Pt-pCVD) approach is employed to deposit different Pt entities on mesoporous N-doped carbon (MPNC) nanospheres to design high-performance hydrogen evolution reaction (HER) electrocatalysts. The influence of consecutive precursor pulse number (50-250) and deposition temperature (225-300°C) are investigated. The Pt-pCVD process results in highly dispersed ultrasmall Pt clusters (≈1nm in size) and Pt single atoms, while under certain conditions few larger Pt nanoparticles are formed. The best MPNC-Pt-pCVD electrocatalyst prepared in this work (250 pulses, 250°C) reveals a Pt HER mass activity of 22.2 ± 1.2Amg-1 Pt at -50mV versus the reversible hydrogen electrode (RHE), thereby outperforming a commercially available Pt/C electrocatalyst by 40% as a result of the increased Pt utilization. Remarkably, after optimization of the Pt electrode loading, an ultrahigh Pt mass activity of 56 ± 2Amg-1 Pt at -50mV versus RHE is found, which is among the highest Pt mass activities of Pt single atom and cluster-based electrocatalysts reported so far.

Revealing interfacial charge redistribution of homologous Ru-RuS2 heterostructure toward robust hydrogen oxidation reaction

Precisely tailoring the surface electronic structures of electrocatalysts for optimal hydrogen binding energy and hydroxide binding energy is vital to improve the sluggish kinetics of hydrogen oxidation reaction (HOR). Herein, we employ a partial desulfurization strategy to construct a homologous Ru-RuS2 heterostructure anchored on hollow mesoporous carbon nanospheres (Ru-RuS2@C). The disparate work functions of the heterostructure contribute to the spontaneous formation of a unique built-in electric field, accelerating charge transfer and boosting conductivity of electrocatalyst. Consequently, Ru-RuS2@C exhibits robust HOR electrocatalytic activity, achieving an exchange current density and mass activity as high as 3.56 mA cm−2 and 2.13 mA μgRu-1, respectively, exceeding those of state-of-the-art Pt/C and most contemporary Ru-based HOR electrocatalysts. Surprisingly, Ru-RuS2@C can tolerate 1000 ppm of CO that lacks in Pt/C. Comprehensive analysis reveals that the directional electron transfer across Ru-RuS2 heterointerface induces local charge redistribution in interfacial region, which optimizes and balances the adsorption energies of H and OH species, as well as lowers the energy barrier for water formation, thereby promoting the HOR performance.

An Enzyme‐Engineered Coppery Nanozyme for High‐Efficiency Mild Photothermal/Chemodynamic/Starvation Therapy Through Self‐Reinforcing Cancer Energy Metabolism Regulation

AbstractPhotothermal therapy (PTT) has a great prospect in further improving tumor therapeutic outcomes, whereas its efficiency is restrained by low light penetration, excessive heat damage to normal tissues, up‐regulated heat shock proteins (HSPs), and limited effect of single treatment. Herein, an enzyme‐engineered coppery nanozyme based on dendritic mesoporous coppery carbon nanosphere as the cornerstone to load with glucose oxidase (GOx) followed by modification with hyaluronic acid is constructed. Density functional theory calculations indicate that the obtained coppery nanozyme exhibits peroxidase and glutathione oxidase mimicking activities to improve hydroxyl radicals (•OH) production. Furthermore, both the generation of •OH production and GOx‐induced energy supply blockade can reduce HSPs expression to enhance the mild PTT (η = 34.9 %) of coppery nanozyme upon the irradiation of 1064 nm laser, and in turn, accelerate the catalytic processes of coppery nanozyme for more generation of •OH. Last but not least, the introduction of copper can induce lipoylated protein dihydrolipoamide S‐acetyltransferase aggregation to cause cellular cuproptosis. Due to the synergy of multiple therapies, the tumor inhibition rate can reach 93.4%. Overall, this work provides an effective strategy for potential tumor treatment on the basis of synergistic therapies.

Synergistic vacancy engineering of Co/MnO@NC catalyst for superior oxygen reduction reaction in liquid/solid zinc-air batteries

The pursuit of efficient and economically viable catalysts for liquid/solid-state zinc-air batteries (ZABs) is of paramount importance yet presents formidable challenge. Herein, we synthesized a vacancy-rich cobalt/manganese oxide catalyst (Co/MnO@NC) stabilized on a nitrogen-doped mesoporous carbon (NC) nanosphere matrix by leveraging hydrothermal and high-temperature pyrolysis strategy. The optimized Co/MnO@NC demonstrates fast reaction kinetics and large limiting current densities comparable to commercial Pt/C in alkaline electrolyte for oxygen reduction reaction (ORR). Moreover, the Co/MnO@NC serves as an incredible cathode material for both liquid and flexible solid-state ZABs, delivering impressive peak power densities of 217.7 and 63.3 mW cm−2 and robust long-term stability (459 h), outperforming the state-of-the-art Pt/C and majority of the currently reported catalysts. Research indicates that the superior performance of the Co/MnO@NC catalyst primarily stems from the synergy between the heightened electrical conductivity of metallic Co and the regulatory capacity of MnO on adsorbed oxygen intermediates. In addition, the abundance of vacancies regulates the electronic configuration, and superhydrophilicity facilitates efficient electrolyte diffusion, thereby effectively ensuring optimal contact between the active site and reactants. Besides, the coexisting NC layer avoids the shedding of active sites, resulting in high stability. This work provides a viable approach for designing and advancing high-performance liquid/solid-state ZABs, highlighting the great potential of energy storage technology.

Achieving long-life and efficient sodium storage through encapsulating Fe3Se4 nanoparticles within hollow mesoporous carbon nanospheres

The application of Fe3Se4 in sodium-ion batteries is limited due to its poor cycling performance and inferior rate capability. Herein, we employ a multi-step process, involving solution adsorption, molten adsorption, calcination and gaseous selenization, to encapsulate Fe3Se4 nanoparticles within monodispersed hollow mesoporous carbon nanospheres (Fe3Se4@HMCN). The space-confined effect of HMCNs refines Fe3Se4 nanoparticles, compelling Fe3Se4 to adhere to the internal wall of HMCNs. In half-cells, Fe3Se4@HMCN exhibits remarkable rate capability at current densities of 0.1–10 A g−1, and exceptional cycling performance (525 mAh g−1 at 1.0 A g−1 after 400 cycles, 282 mAh g−1 at 5.0 A g−1 after 1800 cycles, 204 mAh g−1 after 2000 cycles at 10.0 A g−1), surpassing both pure HMCNs and bare Fe3Se4. The composite structure significantly improves Na storage performance of Fe3Se4, while Fe3Se4 also contributes the majority of the capacity of the composite. Kinetic studies further unveil rapid Na+ transport, low reaction impedance and a predominant pseudocapacitive effect. In Fe3Se4@HMCN//Na3V2(PO4)3 full cell, Fe3Se4@HMCN sustains a discharge capacity of 175 mAh g−1 after 1200 cycles at 5.0 A g−1. The superior electrochemical performance is attributed to the nanoencapsulation structure based on HMCNs, which synergistically enhances electron conduction, ion transport and structural stability of Fe3Se4.

Kinetically promoted hydrogen generation by Ru nanoparticles decorated CoB2O4 on mesoporous carbon spheres with rich oxygen vacancies for NaBH4 hydrolysis

Developing heterostructured catalysts with highly active and reusable is an urgent task to achieve green hydrogen production via NaBH4. Herein, we proposed a novel NaCl template method, which involves solid-state physical grinding of metal salts, reducing agents and prepared carbon spheres with the participation of sodium chloride to synthesize Ru-particles decorated CoB2O4 supported on hollow mesoporous carbon nanospheres (Ru/CoB2O4@C) catalysts for efficient and durable H2 generation through alkaline hydrolysis of NaBH4. The optimized catalyst with a Ru content of 3.0 wt% exhibits a high hydrogen generation rate of 8139 mL min−1gcat-1 and a low activation energy of 33.2 kJ mol−1 for NaBH4 hydrolysis, which is one of the most efficient catalysts reported recently. The extraordinary performance is mainly attributed to the synergistic effect between Ru and CoB2O4 species and abundant oxygen vacancies, which facilitate charge redistribution and provide more active sites, thereby enhancing the catalytic activity. Density functional theory calculations support the proposed Michaelis-Menten mechanism, where BH4− and H2O are adsorbed on electron-rich Ru and electron-deficient CoB2O4 surfaces, respectively, and the reaction energy barrier for the rupture of the B-H bond as the rate-determining step is only 1.37 eV, synergistically promoting the hydrolysis of NaBH4. Our study provides an innovative method for designing efficient and stable catalysts for green hydrogen generation.

Efficient cationic dye removal from water through Arachis hypogaea skin-derived carbon nanospheres: a rapid and sustainable approach.

The present study investigates the potential of Arachis hypogaea skin-derived carbon nanospheres (CNSs) as an efficient adsorbent for the rapid removal of cationic dyes from aqueous solutions. The CNSs were synthesized through a facile, cost-effective, catalyst-free and environmentally friendly process, utilizing Arachis hypogaea skin waste as a precursor. This is the first reported study on the synthesis of mesoporous carbon nanospheres from Arachis hypogaea skin. The structural and morphological characteristics of the CNSs were confirmed by different nano-characterization techniques. The adsorption performance of the carbon nanospheres was evaluated through batch adsorption experiments using two cationic dyes-methylene blue (MB) and malachite green (MG). The effects of the initial dye concentration, contact time, adsorbent dosage, and pH were investigated to determine the optimal conditions for dye removal. The results revealed that the obtained CNSs exhibited remarkable adsorption capacity and rapid adsorption kinetics. Up to ∼98% removal efficiency was noted for both dyes in as little as 2 min for a 5 mg L-1 dye concentration, and the CNSs maintained their structural morphology even after adsorption. The adsorption data were fitted to various kinetic and isotherm models to gain insights into the adsorption mechanism and behaviour. The pseudo-second-order kinetic model and Redlich-Peterson model best described the experimental data, indicating multi-layer adsorption and chemisorption as the predominant adsorption mechanism. The maximum adsorption capacity was determined to be 1128.46 mg g-1 for MB and 387.6 mg g-1 for MG, highlighting the high affinity of the carbon nanospheres towards cationic dyes. Moreover, CNS reusability and stability were examined through desorption and regeneration experiments, which revealed sustained efficiency over 7 cycles. CNSs were immobilised in a membrane matrix and examined for adsorption, which demonstrated acceptable efficiency values and opened the door for further improvement.

A dual-template synergistic assembly strategy towards the synthesis of extra-small nitrogen-doped mesoporous carbon nanospheres with large pores.

Functional mesoporous carbon nanomaterials with large pores and small particle sizes have broad accessibility, but remain challenging to achieve. This study proposed a dual-template synergistic assembly strategy to facilely synthesize extra-small nitrogen-doped mesoporous carbon nanospheres with large pores in a low-cost manner. Directed by the synergistic effect of the combination of surfactants, sodium oleate (anionic surfactant) and triblock copolymer-P123 (nonionic surfactant) were selected as templates to construct nanomicelles (nanoemulsions), which were co-assembled with melamine-based oligomers to form composite nanomicelles, thus obtaining nitrogen-doped mesoporous polymer nanospheres (NMePS) and then nitrogen-doped mesoporous carbon nanospheres (NMeCS). Based on Schiff base chemistry, the melamine-based oligomers with self-assembly capability were synthesized as precursors, which is different from the conventional synthetic route of melamine-formaldehyde resin. The key parameters involved in the route were investigated comprehensively and correlated with the characterization results. Furthermore, the 50 nm-scale particle size and the large mesoporous size of 5.5 nm of NMeCS can facilitate effective mass transport, coupled with their high nitrogen content (15.7 wt%), contributing to their excellent performance in lithium-ion batteries.

Synthesis of multi-cavity mesoporous carbon nanospheres through solvent-induced self-assembly: Anode material for sodium-ion batteries with long-term cycle stability

Mesoporous carbon nanospheres (MCSs) are extensively employed in energy storage applications due to their ordered pore size, large specific surface area (SSA), and abundant active sites, resulting in excellent electrochemical performance for sodium storage. However, challenges persist in achieving precise structural control and stable synthesis reactions for these MCSs. Additionally, employing MCSs with a larger SSA in sodium storage applications can lead to increased side reactions and potential structural instability. To address these issues, we propose a solvent-induced self-assembly method for obtaining high nitrogen-containing multi-cavity MCSs with reduced SSA. The morphology and SSA of the nanospheres can be precisely adjusted by regulating the reaction time. Introducing an amine-phenol bridging structure into the polymer system significantly bolsters the structural and morphological stability of the mesoporous materials. The performance of these novel nanospheres in sodium-ion batteries (SIBs) is remarkable, exhibiting excellent sodium storage capability and exceptional ultra-long cycle stability. At a rate of 0.1 A g−1, the nanospheres achieved a high reversible capacity of 252 mAh g−1, and even after 20,000 cycles at 5 A g−1, a specific capacity of 136 mAh g−1 was retained. In summary, our study presents a novel approach for synthesizing mesoporous carbon materials and offers valuable insights for sodium storage research, opening new possibilities for enhancing energy storage applications.

Fluffy ultrathin WO3 nanoneedle clusters in-situ grown in mesoporous hollow carbon nanospheres as advanced anode for lithium-ion batteries

Fluffy ultrathin WO3 nanoneedle clusters are in-situ grown in mesoporous hollow carbon nanospheres (MHCSs) via unique material impregnation and confined molten reaction in MHCS nanoreactors. Through transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Raman spectra and X-ray photoelectron spectroscopy analyses, it can be found that WO3 nanoneedles with 5–10 nm in thickness and ∼140 nm in length are encapsulated within each MHCS with 150–250 nm in diameter and 30–40 nm in shell thick. Thermal gravimetric analysis reveals the WO3 content of 83.5 wt%. Lithium storage performance was evaluated by galvanostatic charge/discharge cycling, cyclic voltammogram and electrochemical impedance spectroscopy. The composite exhibits remarkable rate performance (average discharge capacity of 1352 mAh g−1 at 0.1 A g−1 and 105 mAh g−1 at 10 A g−1) and excellent cycling performance (1094 mAh g−1 at 0.2 A g−1 after 50 cycles, 760 mAh g−1 at 1 A g−1 after 500 cycles, 351 mAh g−1 at 5 A g−1 after 2000 cycles). The composite also presents outstanding kinetics properties, such as high Li+ diffusion coefficient, strong capacitive effect, and low electrochemical impedance. The superior electrochemical performance is attributed to unique “ship-in-a-bottle” structure. MHCSs facilitate electron transfer and ion diffusion, buffer volume change of WO3 and maintain the integrity of WO3. Furthermore, fluffy ultrathin nanoneedle cluster structure endows WO3 with high electrochemical activity.