Three-dimensional Carbon Nanosheets Research Articles

Preparation and properties of protein-derived carbon-modified CoS2 applied to high-performance lithium-sulfur battery

In this study, we utilized egg white as a carbon source and sublimated sulfur as a source to synthesize the carrier material with carbon nanosheet framework-modified CoS2 nanoparticles (CoS2@C) through a one-step method. We investigated the effect of temperature on the material's structure and chemical composition and the impact of the carrier material on the electrochemical performance of lithium-sulfur batteries. The results reveal that CoS2@C-600 synthesized at 600 °C exhibits an exceptional three-dimensional carbon nanosheet structure with well-defined crystallinity for CoS2. The three-dimensional carbon sheet framework possesses abundant porous structures and high conductivity, providing ample space for sulfur accommodation and physically inhibiting the dissolution of polysulfides. Additionally, electrochemical tests demonstrate that the material exhibits remarkable rate capability and cycling performance. At a current density of 0.5 A/g, the initial discharge-specific capacity reaches 1407 mAh/g, and after 100 cycles, the specific capacity remains at 824 mAh/g. Even under high current conditions of 5 A/g, the specific capacity is maintained at 256 mAh/g. The carrier material, possessing a well-designed structure and an efficient lithium polysulfide electrocatalyst, effectively improves the cycling stability and enhances the rate performance of lithium-sulfur batteries.

Boosting photocatalytic performance of silver phosphate via coupling with P-doped carbon for amoxicillin degradation

Amoxicillin (AMX) could result in risks to ecosystems and organisms in the environment, and photocatalysis is regarded as an effective technology for catalytic degradation of antibiotics. In this study, for the first time, we doped element P into ultra-thin three-dimensional carbon nanosheets to prepare P-doped carbon materials (PCs), and then coupled them with Ag3PO4 to prepare Ag3PO4 @PC composites successfully. The novel composite catalyst was used for photocatalytic degradation of AMX in aqueous solution. Results showed that the photocatalytic performance and cycle stability of Ag3PO4 @PC were much better than that of Ag3PO4 monomer. Under visible light conditions, the degradation efficiency of AMX by the composite catalyst under 3 min of light irradiation could reach 100%, and the corresponding apparent rate constant of AMX degradation was 0.0251 s−1. The DFT calculation results indicated that there was a large built-in potential well at the interface between PC and Ag3PO4, which can effectively reduce the internal recombination of photogenerated electron-hole pairs and improve the photocatalytic performance of the composite catalyst. This study provides an efficient visible light catalyst, and could be referred for appropriate design of innovative visible light photocatalysts.

Synthesis of Three-Dimensional Carbon Nanosheets and Its Flux Pinning Mechanisms in C-Doped MgB2 Superconductors.

Three-dimensional carbon nanosheets (3D-CNS) were synthesized by salt template spray-drying method in order to solve the agglomeration of 2D nanocarbon by a traditional mixing method. MgB2 bulks doped with 3D-CNS with molar ratio composition of MgB2-x(3D-CNS)x (x = 0, 0.1 and 0.2) have been prepared by in situ sintering process. The microstructure, critical current density and flux pinning of the sintered samples have been investigated. Differing from the structure in previous studies, the 3D-CNS doping is more efficient for the refinement of the MgB2 grains due to the 3D network structures. The results clearly show that more active C releasing from 3D-CNS at high temperature can provide effective flux pinning centers by the substitution of C for B in MgB2 lattice. Furthermore, the lattice distortion and increased grain boundaries should be responsible for the enhancement of critical current density (Jc) at high magnetic fields as well as the increased irreversible magnetic field (Hirr). However, the positive action in Jc at low field has been extremely offset by the concentration of impurities at MgB2 grain boundaries such as released extra C without substitution and MgO, which is considered to further deteriorate the grain connectivity.

Boron-doping nanoarchitectonics on three-dimensional carbon nanosheets with exaltation of hydrophilicity and conductivity for enhancing photocatalytic hydrogen evolution

Hydrogen evolution via dye-sensitized photocatalytic water reduction is a promising approach for storing solar energy due to high efficiency and good stability. The hydrophilic and electrical performances of sensitized matrix are critical for the reactant adsorption and photogenerated charge transport. Herein, theoretical simulation proves that the boron-doping nanoarchitectonics on three-dimensional carbon nanosheets (B-3DCNs) as a new-style sensitization matrix possesses a strong water adsorption capacity to show a stable disperse in water, as well as optimizes charge distribution to improve conductivity compared with pure material. So the boron dopants on the substrate surface can be used as an anchor for water and a booster for charge transfer. Based on the theoretical results, B-3DCNs with abundant and stable boron atoms is prepared by a solid-phase thermal doping technology using sodium borohydride as boron source. The hydrophilic and electrical properties of B-3DCNs is greatly optimized using a series of structural and performance testing, providing the prerequisite for large-scale applications in aqueous solution. Therefore, the constructed B-3DCNs/Pt photocatalyst displays a high photocatalytic hydrogen evolution rate under visible light in Eosin Y sensitized system, which is 5.9 and 2.3 times than the H2 evolved over bare Pt and 3DCNs/Pt.

Ni@Ni3N Embedded on Three-Dimensional Carbon Nanosheets for High-Performance Lithium/Sodium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries are recognized as one of the most promising next-generation energy storage devices, but their practical application is greatly limited by several obstacles, such as the highly insulating nature and sluggish redox kinetics of sulfur and the dissolution of lithium polysulfides. Herein, three-dimensional carbon nanosheet frameworks anchored with Ni@Ni3N heterostructure nanoparticles (denoted Ni@Ni3N/CNS) are designed and fabricated by a chemical blowing and thermal nitridation strategy. It is demonstrated that the Ni@Ni3N heterostructure can effectively accelerate polysulfide conversion and promote the chemical trapping of polysulfides. Meanwhile, the carbon nanosheet frameworks of Ni@Ni3N/CNS establish a highly conductive network for fast electron transportation. The cells with Ni@Ni3N heterostructures as the catalyst in the cathode show excellent electrochemical performance, revealing stable cycling over 600 cycles with a low-capacity fading rate of 0.04% per cycle at 0.5 C and high-rate capability (594 mAh g-1 at 3 C). Furthermore, Ni@Ni3N/CNS can also work well in room-temperature sodium-sulfur (RT-Na/S) batteries, delivering a high specific capacity (454 mAh g-1 after 400 cycles at 0.5 C). This work provides a rational way to prepare the metal-metal nitride heterostructures to enhance the performance both of Li-S and RT-Na/S batteries.

Rational design of carbon anodes by catalytic pyrolysis of graphitic carbon nitride for efficient storage of Na and K mobile ions

Sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) are potential cost-effective electrochemical energy storage devices for future grid-scale energy storage. However, the limited capacities of carbonaceous anodes hamper their commercial development. Edge-nitrogen doping has been demonstrated as an effective strategy to enhance the reversible capacities of carbonaceous anodes. In this work, we demonstrate a general strategy to synthesize three-dimensional high edge-nitrogen doped turbostratic carbons (3D-ENTC) through catalytic pyrolysis of graphitic carbon nitride, which is enabled by metal cyanamides. The 3D-ENTC exhibits a three-dimensional carbon nanosheet framework with a high edge-nitrogen doping level of 18.9 at% and a total nitrogen doping level of 21.2 at%. Further, 3D-ENTC displays high capacities of 420 and 403 mA h g−1 at a current density of 50 mA g−1, high rate capabilities, and superior cycling stability when used as the anodes of PIBs and SIBs, respectively. The different charge storage mechanisms of 3D-ENTC anodes in PIBs and SIBs are elucidated by in situ electrochemical impedance spectroscopy. We find that 3D-ENTC stores Na+ ions mainly by adsorption, while 3D-ENTC stores K+ ions by adsorption and intercalation. This work opens a new avenue for designing high edge-nitrogen doped carbon anodes for SIBs and PIBs.

Facile synthesis of Manganese selenide anchored in Three-Dimensional carbon nanosheet matrix with enhanced Lithium storage properties

Manganese selenide (MnSe), a conversion-type anode for Lithium-ion batteries with low cost and high specific capacity, is impeded the development by drastic volume changes and poor kinetics in Li+ insertion/desertion processes. In this study, we successfully synthesized uniform MnSe nanoparticles anchored in 3D carbon nanosheet matrix (MnSe ⊂ 3DCNM) via a facile sol–gel and selenation route. The obtained 3DCNM contributes high surface area, increased active sites for N-doping, excellent electric conductivity and stable nanostructure to MnSe ⊂ 3DCNM, thereby leading to full lithiation/delithiation reactions, excellent electrochemical kinetics and buffer volume expansion of MnSe nanoparticles. Among these MnSe ⊂ 3DCNM materials, MnSe ⊂ 3DCNM-1.92 exhibits superior cycle stability with a stable reversible capacity of 665.5 mA h g−1 after 200 cycles and excellent rate capabilities in half cells. When combined with LiMn2O4 cathode, the MnSe ⊂ 3DCNM-1.92//LiMn2O4 full cells also exhibit excellent electrochemical properties. The kinetic analysis and EIS results demonstrate the generation of intermediate LixMnSe phase and the irreversible phase transformation of α-MnSe → β-MnSe with decreased diffusion energy barriers mainly facilitate MnSe ⊂ 3DCNM-1.92 to exhibit high specific capacity, superior Li+ and electron transport kinetics. This facile strategy provides a guideline for the other transition metal selenides with high surface areas and stable nanostructures apply in storage systems, electrocatalysis, and semiconductors.

The formation of wrapping type Pt–Ni alloy on three-dimensional carbon nanosheet for electrocatalytic oxidation of methanol

In this paper, the PtNi alloy was embedded into the surface layer of three-dimensional carbon nanosheets (CNSs) with a special layered structure. We controllably adjusted the ratio of Pt/Ni to form large particle alloy with Pt coating Ni and a small number of hollow PtNi alloy pellets. The electro-catalytic methanol oxidation activity and durability of the catalysts were estimated by cyclic voltammetry and chronoamperometric techniques. The results indicated that the doping of Ni effectively improved the activity and anti-poisoning of the catalyst in the methanol electrocatalytic oxidation reaction (MOR). Transmission electron microscopy (TEM), Raman spectroscopy, nitrogen adsorption-desorption techniques, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to explore the composition, morphology and structure of these catalysts. It is discovered that the Pt–Ni/CNSs (2:1) sample exhibits the best MOR activity with a peak current density of 15.03 mA cm−2 at the forward scan due to the excellent lamellar structure, good crystallinity and abundant pore structure of CNSs, which is benefit to form ultrahigh specific surface area, superb electron and ionic conductivity.

Methanol electrocatalytic oxidation over Pt nanoparticles anchoring on three-dimensional carbon nanosheet rich in oxygen functional groups

In this paper, three-dimensional carbon nanosheets (CS) were treated at different temperatures in an atmosphere of ozone, then obtained a series of Pt/OCS-X catalysts through the loading of Pt, including Pt/CS, Pt/OCS-25, Pt/OCS-90, Pt/OCS-160 and Pt/OCS-200. To prove that ozone oxidation can effectively improve the activity of the catalyst, these catalysts were tested by methanol electrocatalytic oxidation reaction (MOR). It is discovered that ozone treatment could greatly increase the number of oxygen-containing functional groups, and the HO–CO content was greatly improved after the modulation of treated temperature. It is discovered that the Pt/OCS-160 sample exhibits the best activity with a peak current density of 37.7 mA cm−2 at the forward scan due to the excellent lamellar structure, good crystallinity, and abundant pore structure of CS, which is a benefit to form ultrahigh specific surface area, superb electron, and ionic conductivity. Meanwhile, the capacity of anti-poisoning of Pt/CS after O3 treatment is enhanced obviously.

In Situ Formation of Prussian Blue Analogue Nanoparticles Decorated with Three-Dimensional Carbon Nanosheet Networks for Superior Hybrid Capacitive Deionization Performance.

Capacitive deionization (CDI) is considered to be an alternative water purification technology because of its low cost and low driven energy. However, the desalination performance of traditional CDI still cannot meet the requirement of actual operations, which is the limited adsorption capacity of carbon electrodes. Here, we report a feasible and simple strategy for the synthesis of a three-dimensional hierarchical composite with homogeneous Prussian blue analogue nanoparticles, decorating hierarchical porous carbon nanosheet networks (NiHCF@3DC-2) as a redox-active intercalation electrode material for hybrid capacitive deionization (HCDI). The interconnected network structure, accompanied by its unique porous characteristic and uniform NiHCF nanoparticles, endows the prepared NiHCF@3DC-2 with enough straining space for alleviating the effect of volume change upon the regeneration process and guarantees fast transmission kinetics for both electrons and salt ions. As a consequence, an HCDI cell with NiHCF@3DC-2 and activated carbon showed superior desalination ability with a high ion removal capacity of 47.8 mg g-1 (107.5 mg g-1 NiHCF@3DC-2) and good cyclic regenerative performance. Moreover, the Na+ ions storage mechanism and the interfacial synergy of the NiHCF@3DC-2 were also explored by structure and electrochemistry analyses during the CDI process. Our work provides a promising redox-active intercalation electrode material to highly efficient hybrid capacitive deionization for brine.

The three-dimensional carbon nanosheets as high performance catalyst support for methanol electrooxidation

In this paper, we perform three typical oxidation treatments, such as O3, HNO3 and H2O2, to modify the surface structure of the novel three dimensional carbon nanosheets (3D CNSs). The different treatment generates kinds of oxygenated functional groups on the surface of support. One of them, the CNSs treated by ozone produces the greatest amount of carboxyl groups and keeps the original morphology, which can be used as the excellent support for the electrochemical oxidation of methanol in acidic medium. Through various characterizations, it is discovered that the PtCo/CNSs-1 shows the excellent lamellar structure, good crystallinity, abundant pore structure and large interlayer spacing, which provide ultrahigh specific surface area, superb electron and ionic conductivity. Furthermore, the superfine PtCo alloy nanoparticles evenly deposits on the 3D CNSs, which reveals superior electrocatalytic performance. More importantly, the capacity of anti-poisoning of which is enhanced obviously.

Three-dimensional carbon nanosheets derived from micro-morphologically regulated biomass for ultrahigh-performance supercapacitors

The exploration of diverse plant precursors has attracted intense attention in the development of advanced carbon materials for supercapacitors. However, tailoring the natural nanoarchitectures at plant-cell-wall level remains challenged. Herein, the micromorphological regulation of woody precursors for 3D scaffolding framework of 2D porous carbon nanosheets is demonstrated by sequential alkaline oxidation, bio-swelling and low-temperature carbonization. By featuring an outstanding N-doping level (8.7 at%), O-doping level (20.9 at%), rational hierarchical porosity and strengthened mechanical stability, the resulting carbon exhibits ultra-high gravimetric capacitances of 508 F g−1 and 360 F g−1 at 1.0 A g−1 in the three- and two-electrode system of 6 M KOH electrolyte, respectively. Moreover, an impressive rate capability (394 F g−1 at 50 A g−1) and long-cycling stability (95% after 12,000 cycles) have also been obtained. The fabricated symmetric supercapacitor in ionic liquid electrolyte further displays outstanding synergetic energy-power output properties (94.2 W h kg−1 at 0.5 kW kg−1 and 45.7 W h kg−1 at 21.1 kW kg−1). Stemming from the distorted layer structure of delignified and swelled cell walls, this strategy enables the penetration of chemical reagents into highly crystalline cellulose microfibrils. The scalable route to produce high-performance carbons from diverse plant candidates is thus extended.

Construction of 3D Carbon Nanostructure: Carbon Nanosheets Decorated Carbon Nanofiber As a Three-Dimensional Carbon Hybrid for High Performance Lithium-Sulfur Battery

Among the emerging energy storage methods, lithium-sulfur battery (LiS) has drawn plenty of attentions due to its high theoretical energy density (2600 Wh kg-1),1 economical cost and environmental benignity. Nevertheless, the insulating nature of sulfur and notorious polysulfides shuttling result in a low sulfur utilization and short cycling life.2 To address these problems, carbon material has been confirmed as an ideal sulfur host to promote LiS’s performance because of their low cost, high conductivity and controllable structure such as carbon spheres, carbon nanotube/fibers and carbon nanosheets. For example, one-dimensional carbon nanotube can increase the sulfur utilization by providing better electrical conductivity. However, its “open-to-electrolyte” structures cannot effectively prevent shuttling effect.3 As for zero-dimension carbon materials, core/yolk shell carbon spheres in particular, are less capable of establishing conductive networks, which in turns, compromise the sulfur utilization and rate capability.4 Thus, it is of great necessity to develop three-dimensional (3D) carbon materials with multiple functions in order to achieve high-performance lithium-sulfur batteries. Along this line, we prepared a three-dimensional carbon nanosheets modified carbon nanofiber (3DCNF) as high porosity sulfur host. After decorated with vertically aligned carbon nanosheets, the surface area of pristine carbon nanofiber was dramatically increased from 30 m2/g to 500 m2/g due to the expanded dimension. Although both 1D nanofiber and 2D nanosheets cannot effectively prevent polysulfides shuttling by themselves, the delicate combination of them endows new functions, where 3D carbon hybrid is capable of accommodating sulfur expansion and deterring polysulfides dissolution by the hierarchical porous structure and interconnected carbon nanosheets. At the same time, the 3D porous carbon nanofiber can also form conductive network that allows rapid electron transfer. With the structural advantages, the 3DCNF and sulfur composite delivered a capacity as high as 1266, 977 mAh/g at 0.1 and 0.5 C, respectively. After 500 cycles at 0.5 C, it still retains a capacity of 607 mAh/g (0.07% capacity fading per cycle), exhibiting excellent cycling capability. Reference M. K. Song, E. J. Cairns and Y. Zhang, Nanoscale, 2013, 5, 2186-2204.Y. Yang, G. Zheng and Y. Cui, Chem. Soc. Rev., 2013, 42, 3018-3032.X. Liang, Z. Wen, Y. Liu, H. Zhang, J. Jin, M. Wu and X. Wu, J. Power Sources, 2012, 206, 409-413.Y. J. Hong, J.-K. Lee and Y. Chan Kang, J. Mater. Chem. A, 2017, 5, 988-995. Figure 1

Cobalt sulfide nanoparticles anchored in three-dimensional carbon nanosheet networks for lithium and sodium ion batteries with enhanced electrochemical performance

In order to improve the conductivity and electrochemical activity, Co9S8 nanoparticles anchored in three-dimensional carbon nanosheet networks (3D Co9S8@CNNs) are fabricated by a simple strategy with the assistance of NaCl. Combining the advantages of nanoscale and porous structure, 3D Co9S8@CNNs can retard the aggregation of Co9S8 nanoparticles, provide abundant electrochemical active sites, as well as accommodate the mechanical stress during the cycling of lithium ion batteries (LIBs) or sodium ion batteries (SIBs). Thus, when evaluated as an anode for LIBs, the as-prepared 3D Co9S8@CNNs electrode exhibits outstanding electrochemical performance with a high reversible capacity of 935mAhg−1 after 200 cycles at 0.25Ag−1. As for SIBs, it also delivers superior cycling stability with a capacity of 249mAhg−1 after 50 cycles at 0.1Ag−1. These results demonstrate that 3D Co9S8@CNNs composite has potential to be utilized as an anode material for LIBs/SIBs with enhanced electrochemical performance.

Graphene-based ultrathin microporous carbon with smaller sulfur molecules for excellent rate performance of lithium–sulfur cathode

Ultrathin microporous carbon (UMPC) for lithium–sulfur (Li–S) cathode with uniform pore width of approximately 0.6 nm and dozens nm in thickness is synthesized with graphene oxide as template by glucose hydrothermal carbonization and surfactant-assisted assembling method. The UMPC supplies desirable S pregnancy space and the intimate contact between UMPC and S, therefore improving the conductivity of S@UMPC composite and dynamic performance. Smaller sulfur molecules limited in UMPC thoroughly prevent the formation of electrolyte-soluble polysulfides, hence excellent cycling performance with 900 mAh g−1 after 150 cycles is kept. Ultrathin three-dimensional carbon nanosheets are significant to fast electron transfer and Li+ diffusion contributing to excellent dynamic performance (710 mAh g−1 at 3 C).