Graphene-like Carbon Nanosheets Research Articles

Liquid-phase exfoliation of layered biochars into multifunctional heteroatom (Fe, N, S) co-doped graphene-like carbon nanosheets

• Developing a liquid exfoliation strategy for delaminating multilayered biochars. • The graphene-like carbon nanosheets (Fe-N-S-CNS) had multi-heteroatom co-doping. • Fe-N-S-CNS showed multifunctional electrochemical activity. • A higher ORR activity was obtained than that of commercial Pt/C. • The ionic liquid-based supercapacitor delivered an energy density of 54.1 Wh kg −1 . We here report a liquid-phase exfoliation strategy to delaminate multilayered biochars into multi-heteroatom (Fe, N, S) co-doped graphene-like carbon nanosheets, in which the multilayered biochars derived from naturally evolved layer-by-layer precursors. This strategy provides the versatile capability to tailor the textural properties of the as-synthesized carbon nanosheets, such as obtaining a controllable specific surface area of up to 2491 m 2 g −1 . Thanks to the unique integration of graphene-like microstructures with a thickness of 4.3 nm, large specific surface area and hierarchical pores, homogenous co-doping of N, S, and Fe, and high electronic conductivity, the as-synthesized Fe-N-S co-doped carbon nanosheets could act as multifunctional electrodes for electrocatalytic process of oxygen reduction reaction (ORR) and capacitive energy storage. The optimized nanosheets showed a better ORR catalytic performance than commercial Pt/C catalyst, with a more positive onset potential (1.026 V) and half-wave potential (0.829 V), higher long-term stability, and outstanding methanol tolerance in alkaline mediums. Furthermore, the porous carbon nanosheets exhibited excellent supercapacitive performances which delivered a high energy density of 29.1 Wh kg −1 at a high power density of up to 39.5 kW kg −1 in an ionic liquid electrolyte. This liquid-phase exfoliation strategy will offer new inspiration for the synthesis of various biomass-derived graphene-like carbon nanosheets for multifunctional applications.

Dual Carbon Potassium-Ion Capacitors: Biomass-Derived Graphene-like Carbon Nanosheet Cathodes.

Potassium-ion storage devices are attracting tremendous attention for wide-ranging applications on account of their low cost, fast charge transport in electrolytes, and large working voltage. However, developing cost-effective, high-energy electrodes with excellent structural stability to ensure long-term cycling performance is a major challenge. In this contribution, we have derived two different forms of carbon materials from almond shells using different chemical treatments. For instance, hard carbon (HC) and graphene-like activated carbon (AC) nanosheets are developed by employing simple carbonization and chemical activation routes, respectively. The resultant hard carbon (AS-HC) and activated carbon (AS-AC) exhibit outstanding electrochemical performance as negative and positive electrodes in a potassium-ion battery (KIB), respectively, through their tailor-made surface properties. These promising benefits pave a way to construct a biomass-derived carbon potassium-ion capacitor (KIC) by employing AS-HC as the negative electrode and AS-AC as the positive electrode in a K-based electrolyte. The as-fabricated KIC delivers a reasonable specific energy of 105 Wh/kg and excellent cycling life with negligible capacitance fading over 10 000 cycles. This "waste-to-wealth" approach can promote the development of sustainable KICs at low cost and inspire their use for fast-rate K-based energy storage applications.

Nitrogen-enriched graphene-like carbon architecture with tunable porosity derived from coffee ground as high performance anodes for lithium ion batteries

Nitrogen-enriched graphene-like carbon nanosheets were prepared using coffee ground as the carbon and nitrogen resource, calcium carbonate and iron nitrate and their derivatives as the structural templates and the graphitization catalysts. The wrinkled nanosheets are randomly intertangled and cross-linked, constructing a three-dimensional (3D) porous architecture. With various amount of the templates and catalysts, the obtained porous carbon materials exhibit moderate specific surface areas of 450–540 m3 g−1 with tunable pore sizes of 8.2–11.6 nm. As lithium ion battery anodes, the as-prepared carbon materials demonstrate significantly enhanced energy storage capability including improved specific capacity and rate capability due to the unique comprehensive structure feature that consists of both amorphous carbon and graphite components, enriched nitrogen species in carbon framework, and the optimized pore size. Additionally, the carbon materials exhibit superior cycling stability because of their stable structure, for example, a high reversible capacity of up to 760 mAh g−1 can be achieved at 100 mA g−1 after 100 discharge/charge cycles. This research indicates that the as-prepared porous carbon material could be a promising anode candidate for next-generation high performance lithium-ion battery with high energy density and high power density.

Lignin-Derived Graphene-Like Carbon Nanosheets as an Efficient Catalyst Support for Fischer-Tropsch Synthesis

Bio-renewable lignin has been used as a precursor for the preparation of various carbon materials, such as carbon fibers, ordered mesoporous carbon and graphite carbon cages. Nevertheless, up to now, there are few studies about prepare graphene-like carbon nanosheets derived from lignin. In this study, we synthesized graphene-like carbon nanosheets, using lignin as the precursor, via one-step pyrolysis route. Fortunately, physical and chemical characterization results indicate that it has high pore volume and hierarchical pore with wrinkled sheet graphene structure. Furthermore, the capability of graphene-like carbon nanosheets was investigated as a catalyst support in Fischer-Tropsch synthesis. The results of catalytic evaluation show that Fe₂O₃/GCNs has excellent catalytic activity and the selectivity of lower olefins, compared with Fe₂O₃/AC.

Rapid Gas-Engineering to the Manufacture of Graphene-Like Mesoporous Carbon Nanosheets with a Large Aspect Ratio.

Porous carbon nanosheets (PCNs) with a large two-dimensional morphology and high porosity have emerged as an important class of 2D materials, while developing novel technology to manufacture high-quality PCNs in terms of convenience, high output, and economic benefit remains a challenge. Herein, a rapid gas-engineering technology is developed to fabricate graphene-like mesoporous carbon nanosheets (MCNs) with large aspect ratios (>2500, length/thickness). By easy carbonization of calcium gluconate under reduced pressure, MCNs with ultrathin (∼12 nm) thickness, ultralarge (>20 μm) lamella morphology, and high surface area (∼1155 m2/g) are fabricated in kilogram scale. Two-dimensional lamella morphology transformation, pore architectures, and calcium compounds transformation mechanisms are unraveled by in situ variable temperature X-ray diffraction (VT-XRD), high-resolution transmission electron microscopy (HRTEM), ex situ scanning electron microscopy (SEM), and atomic force microscopy (AFM). The key to the synthesis is the negative pressure operation, which triggers the rapid gas expansion in a gas-solid system. This design relied on the gas expansion mechanism has realized producing of high-quality MCNs via a rapid, high-throughput, and cost-effective way. Due to high surface utilization and low weight density, when served as a lightweight separator coating layer, MCNs exhibit impressive capture ability toward polysulfides and achieve a high-stability lithium-sulfur battery.

Fe-assisted catalytic chemical vapor deposition of graphene-like carbon nanosheets over SrO

The application of graphene-like carbon nanosheets (GCN) for energy storage has attracted tremendous interest in industry. Thus, synthesis pathways producing GCN with high yield, good electrical conductivity and large accessible surface area are interesting option to obtain the desirable electrode materials. Here, a method to increase yield and functional properties of GCN is proposed using Fe-assisted catalytic chemical vapor deposition (CCVD) over SrO catalyst. In this process design, the ethanol vapor is passed through iron particle bed before reaching SrO catalyst for a CCVD synthesis at 950 °C. It is found that Fe modified conversion pathways of ethanol producing a material with 65% higher yield, better crystallinity and lower defect density compared to GCN synthesized over SrO only. Furthermore, the higher yield and low density of defects can also be retained in GCN after KOH activation (800 °C) resulting in a 3D hierarchically porous material with 34% higher specific capacitance, 12% higher capacitance retention and lower charge transfer resistance than materials obtained through a conventional CCVD process with SrO only. The obtained data suggest that the proposed Fe-assisted CCVD synthesis is a promising strategy towards the synthesis of advance functional materials, e.g. with applications in supercapacitors.

Iron Carbide Dispersed on Nitrogen-Doped Graphene-like Carbon Nanosheets for Fast Conversion of Polysulfides in Li–S Batteries

The lithium–sulfur (Li–S) battery has drawn tremendous interest because of its superior theoretical specific capacity, while the shuttle effect of lithium polysulfides (LPSs) has greatly hindered i...

Graphene-modified graphite paper cathode for the efficient bioelectrochemical removal of chromium

Metal-free electrocatalysts have been widely used as cathodes for the reduction of hexavalent chromium [Cr(VI)] in microbial fuel cells (MFCs). The electrocatalytic activity of such system needs to be increased due to the low anodic potential provided by bacteria. In this study, graphite paper (GP) was treated by liquid nitrogen to form three-dimensional graphite foam (3DGF), improving the Cr(VI) reduction by 17% and the total Cr removal by 81% at 30 h in MFCs. X-ray absorption spectroscopy confirmed the Cr(VI) reduction product as Cr(OH)3. Through the spectroscopy characterizations, electrochemical measurements, and density functional theory calculations, the porous structures, edges, and O-doped defects on the 3DGF surface resulted in a higher electro-conducting rate and a lower mass transfer rate, which provide more active sites for the Cr(VI) reduction. Additionally, the scrolled graphene-like carbon nanosheets and porous structures on the 3DGF surface might limit the OH− diffusion and result in a high local pH, which accelerated the Cr(OH)3 formation. The results of this study are expected to provide a simple method to manipulate the carbon materials and insights into mechanisms of Cr(VI) reduction in MFCs by the 3DGF with in situ exfoliated edges and O-functionalized graphene.

Fabrication of porous graphene-like carbon nanosheets with rich doped-nitrogen for high-performance electromagnetic microwave absorption

The facile fabrication of lightweight electromagnetic microwave (EM) absorption materials is still in urgent demand due to the increasingly serious electromagnetic pollution and the high requirements of military defense. Herein, nitrogen-rich graphene-like carbon nanosheets (NGs) with porous network structure have been prepared by g-C3N4 template-directed chemical vapor deposition combined with high-temperature treatment process which eliminates the cumbersome template removal, achieving the porosity engineering and high nitrogen doping simultaneously. The conduction loss could be tailored by the configurations of doping N atoms through our method, which plays a dominant role in determining the dielectric behavior in NG materials. The as-prepared NGs with intriguing features possess strong EM attenuation capacity originating from the dielectric loss, the multiple scatterings as well as the balanced impedance match. The optimized NG sample with low loading of only 5 wt% and thin thickness of only 1.8 mm exhibits effective EM absorption performance with the best RLmin of −50.2 dB and the effective absorption bandwidth is about 5.9 GHz at 2 mm. Our work not only provides a promising candidate as effective filler in lightweight EM absorption composites without decoration of other nanomaterials but also valuable insights into the mechanism.

Nitrogen and high oxygen-containing metal-free porous carbon nanosheets for supercapacitor and oxygen reduction reaction applications

Herein, the synthesis of heteroatom-containing graphene-like carbon nanosheets (HA-GCNs) by chemical activation of waste biomass, namely peanut shells. As characterized by a variety of analytical and spectroscopy techniques, the as-synthesized HA-GCNs material carbonized at 900 °C was found to possess sheet-like porous nanosheet morphology with high surface areas (>800 m2 g−1) and desirable of heteroatom contents such as nitrogen (N; 0.84 atom%), and oxygen (O) as high as 20.25 atom%, which greatly improved the electronic properties of the carbon substrate for prospective applications as metal-free electrodes and electrocatalytic materials. The HA-GCNs were found to exhibit a superior specific capacitance of 148, 145, 125, and 105 F g−1 corresponding to the KOH, NaOH, LiOH, and H2SO4 electrolyte solutions, respectively. Although, the HA-GCNs electrode exhibited extraordinary electrochemical performances and cyclic charge-discharge stabilities. Moreover, these novel HA-GCNs exhibited excellent electrocatalytic activities and cyclic stabilities for oxygen reduction reaction (ORR) with a desirable current density of 1.17 mA cm−2 in O2-saturated 0.1 M KOH solution, surpassing that of noble metal-incorporated activated carbons. The superior electrochemical and electrocatalytic performances observed for the HA-GCNs were attributed to the unique pseudocapacitive behavior of the oxygen surface functional groups as well as their unique textural properties, rendering practical applications as low-cost electrodes for supercapacitors and metal-free electrocatalysts for ORR.

Molten-salt/oxalate mediating Fe and N-doped mesoporous carbon sheet nanostructures towards highly efficient and durable oxygen reduction electrocatalysis

Abstract Designer Fe-N/C-type oxygen reduction electrocatalysts with ultrahigh active-sites density and distinctive physical properties are recently considered to be a new frontier in energy technology. In this work, we creatively propose a new strategy for the controllable synthesis of iron and nitrogen co-doped mesoporous Fe-N/C-type graphene-like carbon nanosheet structures via NaCl template-assisted two-step calcination of iron coordinated with triazine compounds using potassium oxalate as a pore-activator. The synthesized Fe-N/C electrocatalyst exhibits unexpectedly ORR catalytic performance with a half-wave potential of ca. 0.846 V and an onset potential of ca. 1.02 V that compare favourably with the best Pt/C catalyst, but its electrochemical stability and methanol-tolerant property are more excellent. It is found that the unique mesoporous structure, the excellent electro-conductivity and the full exposure of N-doped catalytic sites (e.g., pyridinic-N, graphitic-N and Fe-Nx) of the gained Fe-N/C catalyst can facilitate the transport of electrolyte ions, reaction intermediates and products, maintain continuous electron-transport pathways, and minimize the agglomeration of catalytic sites to further boost the reaction rate and ORR activity. This study provides a new avenue to design high-performance and low-cost nanocarbon-based catalytic materials with dense active sites for some important reactions in new energy devices.

Graphene-like nitrogen-doped porous carbon nanosheets as both cathode and anode for high energy density lithium-ion capacitor

Carbon materials have unique stability and controllable structure for all-carbon lithium-ion capacitors (LICs) electrode materials. In this paper, we used chitosan as a carbon source and self-doped nitrogen source, zinc nitrate as a templating agent. Hierarchical porous carbon nanosheets (PCNS) materials with graphene-like structure and abundant nitrogen doping were prepared through a one-step carbonization process. The PCNS materials were used as both capacitor-type cathode and battery-type anode for LICs. Due to the multi-mesoporous and ultrathin nanosheets structure, a large specific surface area (1321.3 m2 g−1) was obtained of PCNS materials, which ensures a high specific discharge capacity of 65.8 mAh g−1 at 3 A g−1 for the capacitor-type cathode. The interconnected graphene-like structure not only provides a large adsorbable area but also reduces the diffusion distannce of ions between the surface of the electrode and electrolyte. When the PCNS materials used as an anode for LIC, it also appeared a high specific discharge capacity of 285.0 mAh g−1 at a big current density of 20 A g−1. Finally, all-carbon symmetric LIC with a broad voltage window of 0.01–4.5 V was constructed successfully. The symmetric LIC shows a high energy density of 146 Wh kg−1 (at a power density of 1125 W kg−1) and an excellent capacity retention rate of 84.5% (10,000 cycles at 5 A g−1).

Optimized Enhancement Effect of Sulfur in Fe-N-S Codoped Carbon Nanosheets for Efficient Oxygen Reduction Reaction.

The study on the design and preparation of oxygen reduction reaction (ORR) electrocatalysts with high efficiency is currently attracting great concern. Among different types of catalysts, heteroatom-doped carbon-based catalysts have exhibited promising potential, and the exploration of optimized matching of the doping elements is crucial to the design and fabrication of this category of catalysts. Herein, by annealing commercially available and cost-effective precursors, Fe-N-S codoped graphene-like carbon nanosheet catalysts were prepared. The atomically dispersed Fe atoms coordinated with the N atoms to form FeN4 sites as proved by X-ray absorption spectroscopy. By facile modulation of the relative amount of the precursors, the contents of thiophene-S (Th-S) and Fe-N4 sites could be tuned and a series of catalysts with different Th-S/Fe ratios were prepared. The doped sulfur exhibited an enhancement effect on ORR performance, and strikingly, the enhancement efficiency could be optimized by fine modulation of the Th-S/Fe ratio in the catalysts. Furthermore, it was found that when the Th-S/Fe ratio reached an optimal value of 1.8, the ORR performance was significantly boosted, especially in acidic media. The experimental data were supported by density functional theory calculation results, which indicated that the ORR overpotential of the S2(FeN4) configuration model (corresponding to the Th-S/Fe ratio of 2) was lower than that of S3(FeN4) and S1(FeN4). The optimized catalyst (denoted as FeN/SNC-900-3) displayed highly efficient ORR activity in both alkaline and acidic media. In alkaline media, the half-wave potential was 49 mV more positive than that of the commercial Pt/C catalyst, and in acidic media, the half-wave potential was close to that of Pt/C. Moreover, the stability of FeN/SNC-900-3 was outstanding, and the relative current density showed only a slight decay in both alkaline and acidic media after 40,000 s. A primary Zn-air battery with FeN/SNC-900-3 as the cathode catalyst exhibited a high peak power density of up to 153 mW cm-2 and superior cycling stability over 200 cycles.

Graphene-like porous carbon nanosheets for ultra-high rate performance supercapacitors and efficient oxygen reduction electrocatalysts

Here, for the first time, graphene-like porous carbon nanosheets have been constructed by triethanolamine intercalation of layered peanut seed coats followed by simultaneously thermal exfoliation and pyrolysis. The as-prepared carbon nanosheets (GPCN-PSC-900) possess graphene-like nanostructure (with thickness of ~4 nm), high BET surface area (887 m2 g−1), and abundant nitrogen doping (3.4 at.%), which benefit the improvement of conductivity (8.1 S cm−1) and wettability. Due to these merits, the GPCN-PSC-900-based supercapacitor shows ultra-high rate capabilities (76.3% and 72.5% of capacity retention at 1–200 A g−1) and excellent stabilities (94.7% and 92.3% of capacity retention after 20,000 cycles at 10 A g−1) in 6.0 M KOH and 1.0 M Na2SO4 electrolytes, respectively. Furthermore, the GPCN-PSC-900 also exhibits excellent ORR activity (E0 = 0.970 V; E1/2 = 0.829 V vs. RHE) and high stability in alkaline media, which make it an efficient air cathode for the Zn–air battery. This work presents a new kind of GPCNs that derive from renewable biomass (peanut seed coats) for energy storage and conversion.

In situ integration of Co5.47N and Co0.72Fe0.28 alloy nanoparticles into intertwined carbon network for efficient oxygen reduction

Cost-effective electrocatalysts with excellent oxygen reduction reaction (ORR) activity are requisite for the commercial application fuel cells and zinc-air batteries. Herein, we prepare a series of carbon-based non-precious metal catalysts by simply carbonizing the mixture of FeCo-ZIF, melamine and soya-bean oil. The microstructure and electrochemical activity of the prepared catalysts highly depend on the adding amount of FeCo-ZIF. With proper addition, the FeCo-ZIF are transformed into Co5.47N and Co0.72Fe0.28 alloy nanoparticles, which are embedded in the in situ formed carbon network consisted of nitrogen-doped graphene-like carbon nanosheets and interwoven carbon nanotubes. The resulted catalyst (FeCo@NCs-0.15) with considerable specific surface area and high pore volume demonstrates a superior ORR catalytic activity than commercial Pt/C with a half-wave potential (E1/2) of 0.83 V (vs. RHE), onset potential (Eonset) of 0.97 V (vs. RHE) and 4-electron dominated reaction path. The durability and methanol resistance are also better than that of commercial Pt/C in alkaline solution. This study provides an inexpensive, facile and scalable strategy to simultaneously realize non-precious metal-based active sites, nitrogen-doping, porosity and highly conductive carbon matrix in one electrocatalyst by one step.

Liquid-to-gas transition derived cobalt-based nitrogen-doped carbon nanosheets with hierarchically porous for oxygen reduction reaction

Here, Co@CoOx-based three-dimensional nitrogen-doped graphene-like carbon nanosheets (denoted as 3D HPN-GCNS/Co@CoOx) are fabricated by controllable grading-pyrolysis strategy, in which they show 3D fluffy and hierarchically porous nanostructure in and out-of-plane; large numbers of Co@CoOx-based nanoparticles uniformly embedded on graphene-like C nanosheets and mesoporous active edge introduce more ORR active sites. When applied for ORR, hybrids exhibit a half-wave potential (E1/2) of 0.87 V and an onset potential (Eonset) of 0.92 V in 0.1 M KOH, comparable to that of commercial 20% Pt/C. The hybrids display better methanol tolerance and stability, with almost no change of ORR performance before and after 5000 cycles. H2O2 yield in ORR process is less than 5% and number of electron transfer is higher than 3.9. The remarkable features are mainly ascribed to synergistic enhancement effect, in which 3D fluffy and hierarchically porous nanostructure in and out-of-plane supplies large accessible specific activity area, allows species to efficiently participate in ORR and facilitates fast mass transfer; graphene-like C nanosheets with N-rich dopant promote O2 adsorption and assure fast electron transport; large numbers of Co@CoOx-based nanoparticles introduce more ORR active sites. All the advantages synergistically enhance the ORR efficiency and make it a highly efficient ORR catalyst.

Fe3C nanoparticles decorated Fe/N codoped graphene-like hierarchically carbon nanosheets for effective oxygen electrocatalysis

Hierarchically porous carbon sheets decorated with transition metal carbides nanoparticles and metal-nitrogen coordinative sites have been proposed as the promising non-precious metal oxygen electrocatalysts. In this work, we demonstrate a facile and low-cost strategy to in situ form Fe/N codoped hierarchically porous graphene-like carbon nanosheets abundant in Fe-Nx sites and Fe3C nanoparticles (Fe–N/C) from pyrolyzing chestnut shell precursor. The as-prepared Fe–N/C samples with abundant Fe-Nx sites and Fe3C nanoparticles show superior electrocatalytic activity to oxygen reduction reaction (ORR) in the alkaline medium as well as high stability and methanol tolerance due to the integration of multi-factors: the high content of Fe-Nx active sites, the coexistence of Fe3C, the unique hierarchically porous structure and high conductivity of carbon matrix. The optimal Fe–N/C-2-900 sample exhibits a more positive half-wave potential (−0.122 V vs. Ag/AgCl (3 M) reference electrode) than commercial 20 wt% Pt/C catalyst. This study provides a facile approach to synthesize Fe3C nanoparticles decorated Fe/N co-doped hierarchically porous carbon materials for effective oxygen electrocatalyst.

Graphene-like carbon nanosheets grown over alkali-earth metal oxides: Effects of chemical composition and physico-chemical properties

Catalytic effects of alkali-earth metal oxides (MgO, CaO, SrO and BaO) on the growth of graphene-like carbon nanosheets via catalytic chemical vapor deposition of ethanol at 950 °C under atmospheric pressure were investigated. Both commercially available alkali-earth metal oxides as well as three synthetic MgO catalysts were used in this study. Chemical composition and physico-chemical properties, such as morphology, crystal surface geometry and porosity of catalysts were demonstrated to influence the yield and quality of graphene-like carbon nanosheets. Among investigated oxides, the MgO, CaO and SrO displayed different catalytic ability towards the growth of graphene-like carbon nanosheets determined by chemical compositions. The effect of physico-chemical properties was suggested by different properties of carbon products over synthetic MgO. MgO catalysts synthesized with ammonia produced the lowest defect level (ID/IG = 0.26) while MgO synthesized with urea and ethylene glycol produced the highest yield (12.1% per catalyst mass) of graphene-like carbon nanosheets compared to the other catalysts. The lower defect level and higher graphitization degree were attributed to well-defined morphology with uniform oxide crystal particle size and improvement of crystal orientation along (200) lattice plane in the catalyst. The higher yield was related to the higher porosity of catalysts.

Cobalt-promoted fabrication of 3D carbon with a nanotube-sheet mutual support structure: scalable preparation of a high-performance anode material for Li-ion batteries

Currently, the design of carbon-based composite as a high-performance anode material for lithium-ion batteries (LIBs) presents challenges for commercial application. Herein, we developed a three-dimensional carbon-based material with a nanotube-sheet mutual support structure (MS-CNTS) engineered by the catalytic effect of Co species. The present work highlights a concise ‘solvent-free’ synthetic method allowing for large-scale output, which is potentially available for low cost commercial use. With the readily available acetylacetonate and cobalt (II) acetylacetonate as starting chemicals, this nanostructured carbonaceous material is fabricated with aldol condensation to construct a Co-contained carbon-link network polymer precursor followed by annealing under argon. It is composed of brim-curled graphene-like carbon nanosheets and carbon nanotubes, which support each other’s structures to effectively avoid agglomeration. Therefore, it enables high performance in LIBs. In spite of the trace amount of cobalt, the carbon-based MS-CNTS anode delivers a high charge capacity of 1028 mAh g−1 at 0.1 A g−1, high rate capacity of 495 mAh g−1 at 2 A g−1, and ultra-long cycling life with a very low capacity decay of 0.008% per cycle over 1000 cycles at 0.5 A g−1, accompanied by 100% Coulombic efficiency. From full cell measurements, we further confirm the considerable promise of MS-CNTS as anodes with a long cycling life.

Facile and friendly preparation of N/S Co-doped graphene-like carbon nanosheets with hierarchical pore by molten salt for all-solid-state supercapacitor

Two-dimensional carbon nanosheets have aroused extensive interest in the fields of electrochemical energy storage and conversion. In this work, a facile and friendly method was applied to fabricate nitrogen/sulfur co-doped graphene-like carbon nanosheets with hierarchical pore structure and large specific area (1753.01 m2 g−1) under the assistance of molten salt possessing the effects of template and activation. The typical morphology could provide abundant ion transport channels to enhance their diffusion and expose more accessibly active sites after doping heteroatoms simultaneously, which enabled the electrode to manifest a specific capacitance of 262.43 F g−1 under 1 A g−1, better capacitance retention of 78.05% after increasing current density to 20 A g−1 and superior cycle stability (96.28% after 10 000 cycles under 10 A g−1) in 6 M KOH. More importantly, the assembled all-solid-state supercapacitor with the as-obtained product as electrodes delivered higher energy densities of 22.26 Wh kg−1 and power density of 12 312.42 W kg−1 (1 M Na2SO4 electrolyte). This investigation may provide a strategy towards the simple and environmental preparation of carbon materials utilized in energy storage.