Bowl-like Carbon Research Articles

Multi-shell bowl-like carbon microspheres for lightweight and broadband microwave absorption

Carbon materials have made significant progress in the field of microwave absorption (MA), but achieving wide effective absorption bandwidth (EAB) at low filler content still remains a great challenge. In this work, we design multi-shell bowl-like mesoporous carbon microspheres (MBMCs) by a facile hard template method for efficient MA. It is demonstrated that the spacing between inner and outer shell and second shell thickness play a vital role on the configuration of carbon microspheres. By controlling the second addition of silica template, the microstructure of carbon microsphere evolves from spherical to bowl shape geometry. Expanded shell spacing is beneficial for forming bowl-like microsphere. The dielectric loss and MA properties are highly associated with the configuration of MBMCs. Well-proportioned MBMCs with appropriate shell spacing present wide EAB of 7.3 GHz under a low filling ratio of 12 wt.%. This work paves a new way to broaden EAB and lower filling content of carbon materials via asymmetric multilayer microstructure design.

Novel bowl-like or capped carbon with a low carbon footprint as electrode material in EDLCs

Large surface area, excellent electrical conductivity, homogeneous structure, and extended cycling stability are desirable characteristics for energy materials. Carbon-derived structures exhibit porous structure, work well in a wide potential window, and are highly conductive. Hence, they can show enhanced rate capability and cycle life. Despite ongoing efforts, the synthesis of carbons at lower temperatures remains a challenge. In comparison, the high-temperature synthesis protocols lead to a high CO2 footprint. Here, we report the synthesis of unique carbon morphologies, namely capped carbon nanostructures (CCS) and bowl-like carbon structures (BCS). Their performances are either comparable or higher than those conventionally used morphologies of carbon, such as nanospheres, microspheres, nanotubes, graphene oxide, and layered structures. The four-sided opening in BCS particles ensures higher adsorption of electrolyte ions, which is even higher than hierarchical or spherical structures. The cap formation on the CCS acts like an additional layer on top of the sphere. Further, the CCS is arranged in a sequential honeycomb array, which leads to the formation of definitive channels for electrolyte diffusion. The unique carbon morphologies showed nearly ∼ 40 % increment in the specific capacitance values compared to other commonly used carbon structures. The novel morphologies also have a much lower carbon footprint, as shown by the life cycle assessment (LCA) studies.

Boosting the Energy Density of Bowl-Like MnO2@Carbon Through Lithium-Intercalation in a High-Voltage Asymmetric Supercapacitor with "Water-In-Salt" Electrolyte.

Highly concentrated "'water-in-salt"' (WIS) electrolytes are promising for high-performance energy storage devices due to their wide electrochemical stability window. However, the energy storage mechanism of MnO2 in WIS electrolytes-based supercapacitors remains unclear. Herein, MnO2 nanoflowers are successfully grown on mesoporous bowl-like carbon (MBC) particles to generate MnO2/MBC composites, which not only increase electroactive sites and inhibit the pulverization of MnO2 particles during the fast charging/discharging processes, but also facilitate the electron transfer and ion diffusion within the whole electrode, resulting in significant enhancement of the electrochemical performance. An asymmetric supercapacitor, assembled with MnO2/MBC and activated carbon (AC) and using 21m LiTFSI solution as the WIS electrolyte, delivers an ultrahigh energy density of 70.2Whkg-1 at 700W kg-1, and still retains 24.8Whkg-1 when the power density is increased to 28kWkg-1. The ex situ XRD, Raman, and XPS measurements reveal that a reversible reaction of MnO2 + xLi+ + xe-↔LixMnO2 takes place during charging and discharging. Therefore, the asymmetric MnO2/MBC//AC supercapacitor with LiTFSI electrolyte is actually a lithium-ion hybrid supercapacitor, which can greatly boost the energy density of the assembled device and expand the voltage window.

Heterostructure of 2D MoSe2 nanosheets vertically grown on bowl-like carbon for high-performance sodium storage

Heterostructure of 2D MoSe2 nanosheets vertically grown on bowl-like carbon for high-performance sodium storage

Ultrafast carbothermal shock strategy enabled highly graphitic porous carbon supports for fuel cells

The electronic conductivity and durability of porous carbon supports can be improved by increasing the degree of graphitization in the material; however, the preparation of highly graphitic porous carbon using conventional furnaces remains a significant challenge. Herein, we demonstrate a universal and highly efficient carbothermal shock strategy that significantly improves the degree of graphitization of porous carbon supports, including bowl-like carbon, hollow carbon spheres, ZIF8-derived carbon, BP2000, and Ketjen EC 300J. Taking bowl-like carbon as an example, we illustrate the synthesis of a graphitized bowl-like carbon (G-BC-S) support and evaluate the performance of PtCo/G-BC-S in the oxygen reduction reaction (ORR) in rotating disk electrodes (RDE) and H2/air PEM single cells. PtCo/G-BC-S exhibits faster ORR kinetics than PtCo/BC and Pt/C, with little loss of activity (25%) and only 13 mV of E1/2 decay after 20000 cycles accelerated stress testing under 1.0–1.5 V vs. a reversible hydrogen electrode (RHE).</a> The significantly enhanced performance of the PtCo/G-BC-S catalyst arises from the high activity and chemical/structural stability of the PtCo intermetallic nanoparticles and from the high degree of graphitization and well-defined porous structure of the bowl-like carbon support, which confers excellent electrical conductivity and oxygen transport properties. This study provides a reliable and universal strategy for the development of high-performance porous carbon supports for practical applications in fuel cells.

Ultra-lightweight hollow bowl-like carbon as microwave absorber owning broad band and low filler loading

With the development of military aircraft equipment and wearable civilian electronic equipment, lightweight is becoming more and more important in the design of absorbing materials. In this work, hollow bowl-like carbon (HBC) materials are controllably constructed by the hard template method, its tunable pore structure, surface properties as well as shell thicknesses lead to the excellent performance. The HBC with shell thickness of 3 nm shows the best wave-absorbing performance at the absorber content of 4%. Its minimum value of reflection loss is −50 dB with at a thin thickness of 2.26 mm, while its effective absorption bandwidth, at a fixed thin thickness of 2 mm, can be as wide as 7.04 GHz (10.96–18 GHz). On the one hand, thin shells are the key to achieve light weight, on the other hand, the bowl-like shape prevents the formation of percolative networks. Percolative behavior analysis demonstrates that with the low mass fraction of absorber content, the HBC materials can obtain the modest dielectric constant and loss, thus achieve good impedance matching and sufficient attenuation capacity. This work provides an effective and sustainable way to utilize porous carbon materials for developing lightweight and high-performance wave-absorbing materials.

Rational design of ultrafine FeSe2 nanocrystals embedded within hollow mesoporous carbon bowls for potassium-ion batteries with long-term cycling stability and high volumetric capacity

• Bowl-like carbon/FeSe 2 composites are successfully synthesized by a facile method • Ultrafine FeSe 2 nanocrystals are well embedded in bowl-like carbon matrix • Bowl structure has a higher packing density than the conventional hollow structure • Compared with hollow structure, the volumetric capacity of sample increased by 60% • The KIB full cell composed of FeSe 2 @HMCB//PB has been demonstrated Hollow structures are commonly used to alleviate the mechanical stress on electrode materials and to provide more active sites in potassium-ion batteries (KIBs). Nevertheless, the excessive internal voids within these structures significantly reduce the packing density of particles, resulting in a relatively low volumetric energy density of the fabricated electrodes, which is undesirable for practical use. We designed a hollow mesoporous carbon bowl embedded with ultrafine bis(selanylidene)iron (FeSe 2 ) nanocrystals (FeSe 2 @HMCB) via a controllable impregnation method and subsequent selenization process for high-performance KIBs. The as-obtained FeSe 2 @HMCB can inherit the advantages of conventional hollow carbon-based composites, such as alleviation of volume variation in active materials, abundant ion storage sites, and high electrical conductivity. Simultaneously, the bowl structure has a higher packing density than the conventional hollow structure, resulting in a significant increase in the volumetric energy density of the fabricated electrodes. Because of these advantages, the FeSe 2 @HMCB exhibits a high, stable reversible capacity of 326 mA h g −1 even after 1,000 cycles at 0.5 A g −1 , and excellent rate capacities (182 mA h g −1 at 3.0 A g −1 ). Compared with the hollow structured counterpart, the volumetric capacity (mA h cm −3 ) of FeSe 2 @HMCB increased by 60%. Furthermore, a full cell consisting of FeSe 2 @HMCB//Prussian blue (PB) exhibits excellent electrochemical performance (99 mA h g −1 after 100 cycles at 0.1 A g −1 ).

Bowl-shaped carbon loaded Co9S8 nanoparticles connected by carbon nanotubes with excellent rate performance for sodium-ion batteries

Sodium-ion batteries (SIBs) are expected to replace lithium-ion batteries in the energy storage sector owing to their low cost and abundant resources. However, developing suitable anode materials to meet the high energy density requirements of SIBs remains an ongoing challenge. Herein, we design a hollow nitrogen-doped bowl-like carbon decorated with Co9S8 nanoparticles linked by carbon nanotubes (HNBC@Co9S8@CNTs) as an anode material for SIBs. The HNBC@Co9S8@CNTs electrode exhibits impressive rate performance (449.3 mAh g−1 at 5 A g−1) and cycling stability (426.5 mAh g−1 after 500 cycles at high current density of 1 A g−1) due to the advantages of highly conductive three-dimensional (3D) interconnected structures. In addition, its pseudo-capacitance and sodium storage diffusion kinetics are analyzed in depth using Cyclic Voltammetry (CV) and galvanostatic intermittent titration technique (GITT). The results elucidate that the partially surface-induced capacitive sodium storage, highly conductive 3D interconnected structures, and fast reaction kinetics synergistically contribute to the high-rate performance. This work may provide new insights for the fabrication of various metal sulfide or sulfide composites with high sodium storage capacity.

N-doped porous bowl-like carbon with superhigh external surface area for ultrafast degradation of bisphenol A: Key role of site exposure degree

High-temperature nitrogen (N) doping boosts the activity of biochars for peroxymonosulfate (PMS) activation, but the N heat loss causes the unsatisfactory catalytic efficiency. Improving the surface area for obtaining the high exposure of N sites is a promising solution. Herein, a soft template-KHCO3 etching strategy is used to synthesize the N-doped porous bowl-like carbon (NPBC) with ultrahigh external surface area (1610.8 m2 g−1). The bowl-like structure eliminates inert bulk interior and allows unobstructed mass transfer of reactants onto both outer and inner surfaces, while the large pore channels by KHCO3 etching further improves the exposure degree of limited N sites. Although NPBC has only 0.43% N content, 93.1% of bisphenol A (BPA) is removed within 1 min through the electron-transfer pathway by fully utilizing the N active centers, and the kinetic rate constant (k) reaches 5.29 min−1, exceeding reported values by 2–270 times. Moreover, the NPBC/PMS system possesses excellent applicability for various organics and conditions, effectively mineralizes BPA and reduces effluent biotoxicity. A quantitative index W representing N exposure degree is first proposed and shows high linearity with the k values of BPA degradation (R2=0.992, 0 <W<3750 m2 g−1%−1), proving the critical role of W in determining catalytic efficiency.

Nitrogen-doped hollow bowl-like carbon as highly effective sensing material for electroanalysis

Hollow carbon nanosphere (HCS) has received considerable attentions in electroanalysis owing to its unique advantages in surface area, conductivity, stability and cost, while what is ignored is that the close structure with full sphere of HCS generally causes a great loss in its utility ratio of internal surface and its loading density. In this work, a novel hollow bowl-like carbon nanomaterial (HBCs) with open macropore network, nitrogen-doped HBCs (NHBCs), was designed and used as a highly effective sensing material in electroanalysis for the first time. Selecting carbendazim (CBZ), acetaminophen (ACAP) and dopamine (DA) as three representative analytes respectively from pesticides, environmental pollutants and biomolecules, the analytical performances of NHBCs modified electrode towards these analytes were evaluated. The results demonstrated that NHBCs can exhibit much better analytical performances than nitrogen doped HCS (NHCS). After optimizing various analytical conditions, NHBCs modified electrode possesses considerably low analytical limits and wide linearities towards three analytes: 2.7 nM and 0.005 to 8.0 μM for CBZ, 4.9 nM and 0.01 to 35.0 μM for ACAP, 7.6 nM and 0.05 to 125.0 μM for DA, revealing that the as-proposed HBCs-based material has great potential applications in electrochemical sensing.

In-situ etching-activation towards carbon bowl-like hemispheres for energy storage

Bowl-like hemisphere is an ideal choice to increase the packing density of carbonaceous materials for energy storage applications. However, there are few reports on the preparation of bowl-like carbon hemispheres (BCH) because of the complexity and particularity of their structures. Herein, we demonstrate that KNO3 can be applied into the in-situ etching-activation approach for the templating synthesis of BCH with controllable structures. Detailed experimental studies reveal that the structures in our system can be well adjusted by changing the amount of KNO3, realizing transformation from hollow spheres to hollow spheres with hole and then to bowl shape. The resultant BCH shows uniform open hemispherical structure, abundant nitrogen species, high surface area, and rich porous structure and, as a result, deliver high capability and rate capability for energy storage in supercapacitor. This facile in-situ etching-activation approach offers new opportunities in exploring sophisticated multimodal structures for innovative applications.

Exceptional capacitive deionization desalination performance of hollow bowl-like carbon derived from MOFs in brackish water

As a bright technology for desalinating brackish water, the desalination ability of capacitive deionization (CDI) has been limited by the electrode materials. However, it was still a challenge to adjust the construction of CDI electrode material to improve the salt removal ability. Here, nitrogen-doped hollow bowl-like carbon (HBC) has been successfully constructed in ZIF-8 by facile templating approaches. Physical measurements displayed that HBC had a hollow bowl-like structure, a certain number of nitrogen-containing groups and high specific surface area (1244 m2 g−1). These unique features made HBC have high capacitance (210.7F g−1), remarkable cycle stability and low charge transfer resistance in electrochemical double layer capacitors, indicating its promising application in CDI desalination. Due to the abundant ion accumulation active sites and rapid ion diffusion of HBC materials, provided by unique characteristics of regular hollow bowl-like structure, microporous dominated structure, interconnected channels and nano-scale wall thickness, HBC showed high salt removal ability of 28.06 mg g−1 with 1.2 V in 0.5 g L-1 NaCl solution. Besides, HBC exhibited excellent average salt ion adsorption rate (1.56 mg g−1 min−1) and initial salt adsorption capacity of 90% after 20 cycles.

Lithium Storage in Bowl-like Carbon: The Effect of Surface Curvature and Space Geometry on Li Metal Deposition

Lithium Storage in Bowl-like Carbon: The Effect of Surface Curvature and Space Geometry on Li Metal Deposition

Bowl-like carbon supported AuPd and phosphotungstic acid composite for electrooxidation of ethylene glycol and glycerol

In this study, a novel composite of bowl-like carbon nanomaterial supported AuPd nanoparticles and phosphotungstic acid is prepared. The morphology and chemical composition of the prepared composite are studied by a series of characterizations. Inspired by the development of anode electrocatalyst in direct alcohol fuel cell, the obtained composite is further applied as catalyst for ethylene glycol and glycerol electrooxidation. Electrochemical results show that the optimized composite exhibits enhanced electrocatalytic performance than the commercial Pd/C catalyst, which may promote the practical application in fuel cells.

Enhanced Electromagnetic Microwave Absorption Performance of Lightweight Bowl-like Carbon Nanoparticles

Rational structure design of microwave absorption material (MAM) is of fundamental significance in terms of enhancing the electromagnetic microwave absorption performance and deeply understanding the specific correlation between the material structure and its electromagnetic microwave absorption (EMA) performance. Here, bowl-like carbon nanoparticles (BLCNs) as novel MAM have been successfully fabricated via calcination of bowl-like polydopamine. Interestingly, BLCNs have exhibited dramatically enhanced EMA performance with a minimum reflection loss of −45.3 dB and an effective bandwidth of below −10 dB in the wide range of 4.2 GHz, implying the unique critical role of the microstructure in adjusting the EMA performance. Our work not only paves an attractive way for the design of advanced and lightweight MAM, but also provides valuable insights into the relationships between the material structure and its EMA performance.

CoFe2O4nanoparticles anchored on bowl-like carbon backbone for enhanced reversible lithium storage

A novel bowl-like carbon backbone supported CoFe2O4nanoparticles composite was facilely synthesized to favour enhancing of reversible lithium storage.

Bowl-like carbon sheet for high-rate electrochemical capacitor application

Simultaneously achieve high power and large energy capacity at a high rate is still difficult in the development of electrochemical double layer capacitors. We design a bowl-like carbon sheet (BCS), which is a promising electrode material for high-rate electrochemical double layer capacitor application. These BCSs have interconnected channels and hierarchical porosity for fast ion diffusion and can maintain 105 F g−1 at 100 A g−1. BCSs can maintain a rectangular degree at a high scan voltage of 1 V s−1. BCSs show the tendency of stack on top of each other, and such behavior can increase the bulk density and subsequently increase volumetric capacitance.

Fabrication of Monodisperse Bowl-like Carbon Nanoparticles with Controlled Porous Structure

Abstract Bowl-like carbon particles with a controlled morphology and porous structure were synthesized via carbonization of the post-treated polymer composite particles. The obtained bowl-like carbon particles had a uniform, monodisperse and mesoporous structure with a narrow pore size distribution. The pH value in the post-treatment process played an important role in the formation of the bowl-like morphology and had a remarkable influence on the pore structure, which can control the morphology and pore structure of the carbon particles.

Smaller Pt particles supported on mesoporous bowl-like carbon for highly efficient and stable methanol oxidation and oxygen reduction reaction

Bowl-like carbons (BLCs) with mesoporous structure are prepared using glucose as carbon source and solid core mesoporous shell silica spheres (SCMSSs) as templates. Pt particles are then loaded on the BLCs as electrocatalyst and used for both methanol oxidation and oxygen reduction reaction (ORR) in acidic media. Physical measurements display that the BLCs are formed due to flowing of melted glucose along the mesoporous shell of the SCMSSs. Moreover, the BLCs with high surface area (1108.3 m2 g−1), large pore volume (2.7 cm3 g−1) and mesoporous structure (9.4 nm in diameter) are beneficial for uniform dispersion and stable loading of smaller noble metal particles, and efficiently improve the mass transfer in catalytic reactions, compared to carbon powders. Cyclic voltammogram measurements show that the mass current densities on Pt/BLC electrocatalyst are 2.6 times (1846mAmgPt−1) for methanol oxidation and 1.6 times (180.6mAmgPt−1) for ORR as high as that of commercial Pt/C (TKK). Furthermore, the mesopores give Pt/BLC more electrocatalytic stability due to stronger physical interaction force.