Carbon Protective Layer Research Articles

Designing advanced sandwiched 2D NC/MoSe2@N-doped carbon arrays as new anode materials for efficient sodium storage

The rational design and assembly specific structures consisting of multiple components with distinctive features are promising strategies for developing advanced materials for efficient sodium storage. Herein, a novel hierarchical sandwich-liked structure MoSe2 nanosheet array is designed and synthesized, in which MoSe2 nanosheet through strong interfacial interaction is encapsulated in two dimensional carbon framework that improves electrical conductivity and Na+ diffusion kinetic. Moreover, the carbon protective layer reinforces the stability of structure and maintains electrochemical activity during long-term charging/discharging process. The density functional theory calculation (DFT) further confirms carbon incorporation can reduce Na+ diffusion energy barrier for enhancing the reaction kinetics. With the obtained NC/MoSe2@NC as free-standing electrodes for SIBs, it achieves a reversible capacity of 632 mAh g−1 at 0.2 A g−1, or actual capacity of 421 mAh g−1 by removing contributed capacity of the carbon cloth substrate, and excellent long cycling stability. By matching with Na3V2(PO4)3/C cathode, the sodium full cell displays a high energy density of 186.2 Wh kg−1 with a power density of 121.2 W kg−1. This current design and fabrication strategy manifests promising prospect for exploring efficient electrode materials for sodium storage.

Double-buffer silicon-carbon anode material by a dynamic self-assembly process for lithium-ion batteries

The volume expansion of the silicon (Si) anode material is still a main bottle-neck problem limiting its battery application. Effective structure design needs to be studied continuously, meanwhile the process feasibility also cannot be ignored. Herein, a novel yet simple method to prepare double-buffer structure hybrids with a multilevel porous self-assembly structure induced by hydrogen bonding employing spray-drying methods is reported. The well-designed mesoporous hybrid with crosslinking conductive network shows multi-channels in the interior and carbon nanotubes (CNTs)-enhanced carbon protective layer in the exterior, which can effectively buffer the volume strain of Si and promote the electron/ion transfer. The hybrid anode presents a capacity of 1176.5 mAh g–1 with a high initial coulomb efficiency (ICE) of 87.04%, and maintains at 1006.6 mAh g–1 after 100 cycles with a current density of 200 mA g–1. The material also exhibits good rate properties and cycle performance at a current density of 500 mA g–1. The as-designed hybrid is promising in high-level Si-based anode material practical application, which is also important for prospective lithium ion battery industry.

Development and optimization of fire-protective coating composition based on epoxypolymers

The object of research is intumescent fire retardant coatings based on epoxy resins. The research is aimed at the development of mathematical models of the dependence of the swelling rate of intumescent fire retardant coatings on their composition. Considering the complexity of the processes during the formation of a protective carbon layer, it is advisable to select the optimal ratio of the components of an intumescent fire retardant coating experimentally, followed by the construction of mathematical dependences of the swelling ratio on the coating composition. Therefore, experimental studies aimed at developing and optimizing the composition of an intumescent fire retardant coating based on epoxy polymers are an important task. The studies were carried out in accordance with the theory of planning experiments with the construction of an orthogonal compositional plan of the second order. A linear swelling factor was chosen as the response function. Compositions based on the ED-20 epoxy oligomer, cured with polyethylene polyamine and filled with ammonium polyphosphate, aluminum hydroxide, and graphite additive were used for the study. Based on the results of processing the experimental results, a regression equation was obtained and response surfaces were constructed that describe the dependence of the linear swelling coefficient Cs of an intumescent composition based on an epoxy oligomer on the content of ammonium polyphosphate, aluminum hydroxide and graphite additive. A complex relationship is shown between the content of components and the linear swelling coefficient Cs with different ratios of the components. The optimum by the linear swelling coefficient (Cs=68.1) content of the components in the epoxy polymer was determined, amounting to 20 wt. including for ammonium polyphosphate, 15 mass parts including for aluminum hydroxide and 3 mass parts for the graphite additive. However, with such a ratio, the «self-extinguishing» condition is not met (Cs=27 %). Filling the composition with ammonium polyphosphate in an amount of 26.3 mass parts including, aluminum hydroxide 25 mass parts and 3.5 mass parts including graphite additives allows to get an intumescent fire retardant coating with a swelling ratio Cs over 63 and a reduced level of flammability (Ci=31 %)

Core-shell ZVI@carbon composites reduce phosphate inhibition of ZVI dissolution and enhance methane production in an anaerobic sewage treatment

Inhibitory effects of phosphate on zero-valent iron (ZVI) dissolution have been studied mainly focusing on a single chemical system. Little is known about inhibitory effects and the mechanism of phosphate on ZVI dissolution within a bioreactor during long-term operation. This study demonstrates the feasibility of achieving energy recovery from phosphate-containing domestic sewage using an efficient anaerobic reactor with micro-sized or nano-sized ZVI addition. The results indicate that the chemical oxygen demand (COD) removal and methane production are enhanced by ZVI addition. A maximum COD removal efficiency of 89% and methane content of 60% was achieved. However, the strengthening effect of ZVI on methane production is weakened by the presence of phosphate in domestic sewage. Analyzing the variations of Fe2+ ions and phosphate concentrations and characterizing the micro-morphology of corroded ZVI proved that the generated Fe2+ ions reacts with phosphate and forms a passivation layer on the ZVI surface, inhibiting further dissolution of ZVI. As an improved alternative, we chose the double layered core-shell structured ZVI@carbon composite as an excellent candidate to reduce the inhibitory effects of phosphate on ZVI dissolution. In this way, the direct formation of precipitates on the ZVI surface can be avoided due to the protective carbon layer which adjusts the ion transfer. Adding ZVI@carbon composites accelerate the methane content by 16%. To our knowledge, this is the first report on adding ZVI@carbon composites to promote the anaerobic metabolism in studies, which are focusing on reducing the inhibition of ZVI by phosphate.

N-Doped Carbon-Wrapped Cobalt–Manganese Oxide Nanosheets Loaded into a Three-Dimensional Graphene Nanonetwork as a Free-Standing Anode for Lithium-Ion Storage

A high-quality and centimeter-level three-dimensional (3D) nitrogen-doped graphene (NG) nanonetwork is synthesized via a chemical vapor deposition method to serve as a substrate and a current collector, which directly germinates active metal oxides to act as a free-standing electrode in lithium-ion batteries. By means of facile electrodeposition and annealing processes, the tetragonal spinel cobalt–manganese oxide nanosheets wrapped with polypyrrole pyrolytic carbon are in situ hybridized with a 3D NG nanonetwork. In particular, the introduced carbon protective layer can enhance the Li-ion storage capacity and cycle stability of the composite electrode. The metallic synergistic effect and rational carbonaceous hybridization jointly provide high-performance charge storage and cycle stability. Notably, the surface-controlled capacitive effect stands out contributing to the total charge storage more than ever in nanostructure electrodes.

Effectiveness of reducing the influence of CTAB at the surface of metal nanoparticles during in situ heating studies by TEM

In situ TEM is a valuable technique to offer novel insights in the behavior of nanomaterials under various conditions. However, interpretation of in situ experiments is not straightforward since the electron beam can impact the outcome of such measurements. For example, ligands surrounding metal nanoparticles transform into a protective carbon layer upon electron beam irradiation and may impact the apparent thermal stability during in situ heating experiments. In this work, we explore the effect of different treatments typically proposed to remove such ligands. We found that plasma treatment prior to heating experiments for Au nanorods and nanostars increased the apparent thermal stability of the nanoparticles, while an activated carbon treatment resulted in a decrease of the observed thermal stability. Treatment with HCl barely changed the experimental outcome. These results demonstrate the importance of carefully selecting pre-treatments procedures during in situ heating experiments.

A novel visible-light-driven ternary magnetic photocatalyst MnxZn1-xFe2O4/C/CdS: Fabrication, characterization and application

A novel composite magnetic photocatalyst MnxZn1-xFe2O4/C/CdS (MCC) was prepared via hydrothermal and chemical precipitation method. This work hopes to provide an operable and simple method for the improvement of toxic photocatalysts with excellent photocatalytic activity. The CdS-based photocatalyst (MCC10) with 10 wt% MnxZn1-xFe2O4/C (MC) magnetic carbon protective layer shows the optimum photocatalytic activity in degradation of Rhodamine B (RhB) under visible light irradiation (λ ≥ 420 nm). This nanocomposite exhibits superparamagnetic property with a saturation magnetization of 2.17 emu/g. Besides, it is demonstrated that the ternary magnetic nanocomposite has superior stability and reusability during five recycling experiments. The introduction of the carbon interlayer can restrain the direct contact of the MnxZn1-xFe2O4 and CdS to a great extent, resulting in the increase separation efficiency of the photo-induced electron-hole pairs, photo-corrosion resistance and then highly visible-light-driven photodegradation capability. Moreover, the analysis of the radical scavengers confirmed that ·O2− is the primary reactive species to cause the degradation of the RhB.

Increasing Electrocatalytic Oxygen Evolution Efficiency through Cobalt-Induced Intrastructural Enhancement and Electronic Structure Modulation.

Electrolytic water splitting using surplus electricity represents one of the most cost‐effective and promising strategies for hydrogen production. The high overpotential of the oxygen‐evolution reaction (OER) caused by the multi‐electron transfer process with a high chemical energy barrier, however, limits its competitiveness. Here, a highly active and stable OER electrocatalyst was designed through a cobalt‐induced intrastructural enhancement strategy combined with suitable electronic structure modulation. A carved carbon nanobox was embedded with tri‐metal phosphide from a uniform Ni−Co−Fe Prussian blue analogue (PBA) nanocube by sequential NH3 ⋅ H2O etching and thermal phosphorization. The sample exhibited an OER activity in an alkaline medium, reaching a current density of 10 mA cm−2 at an overpotential of 182 mV and displayed a small Tafel slope of 47 mV dec−1, superior to the most recently reported OER electrocatalysts. Moreover, it showed impressive electrocatalytic durability, increasing by approximately 2.7 % of operating voltage after 24 h of continuous testing. The excellent OER activity and stability are ascribed to a favorable transfer of mass and charge provided by the porous carbon shell, synergistic catalysis between the three‐component metal phosphides originating from appropriate electronic structure modulation, more exposed catalytic sites on the hollow structure, and chainmail catalysis resulting from the carbon protective layer. It is foreseen that this successfully demonstrated design concept can be easily extended to other heterogeneous catalyst designs.

Co‐Construction of Sulfur Vacancies and Heterojunctions in Tungsten Disulfide to Induce Fast Electronic/Ionic Diffusion Kinetics for Sodium‐Ion Batteries

Engineering novel electrode materials with unique architectures has a significant impact on tuning the structural/electrochemical properties for boosting the performance of secondary battery systems. Herein, starting from well-organized WS2 nanorods, an ingenious design of a one-step method is proposed to prepare a bimetallic sulfide composite with a coaxial carbon coating layer, simply enabled by ZIF-8 introduction. Rich sulfur vacancies and WS2 /ZnS heterojunctions can be simultaneously developed, that significantly improve ionic and electronic diffusion kinetics. In addition, a homogeneous carbon protective layer around the surface of the composite guarantees an outstanding structural stability, a reversible capacity of 170.8 mAh g-1 after 5000 cycles at a high rate of 5 A g-1 . A great potential in practical application is also exhibited, where a full cell based on the WS2- x /ZnS@C anode and the P2-Na2/3 Ni1/3 Mn1/3 O2 cathode can maintain a reversible capacity of 89.4 mAh g-1 after 500 cycles at 1 A g-1 . Moreover, the underlying electrochemical Na storage mechanisms are illustrated in detail by theoretical calculations, electrochemical kinetic analysis, and operando X-ray diffraction characterization.

In situ confine of Co3ZnC/Co in N-doped carbon nanotube-grafted graphitic carbon nanoflakes as 1D-2D hierarchical catalysts toward superior redox activity

A novel 1D-2D hierarchical catalyst comprising of Co3ZnC/Co nanoparticles (NPs) confined in N-doped carbon nanotube-grafted graphitic carbon nanoflakes (Co3ZnC/Co@NCNTFs) has been reasonably designed and constructed in situ by controllable pyrolysis of bimetallic CoZn-ZIF in N2. The 1D N-doped CNTs with closed ends can afford fast electron transportation path, extra interface/dipole polarization, more exposed active sites as well as hierarchical structure to achieve excellent charge transfer and microwave (MW)-harvesting ability. Benefiting from the grafted CNTs structure, well-dispersed/confined Co3ZnC/Co NPs, thin carbon protective layer as well as good impedance matching, the resulting Co3ZnC/Co@NCNTFs exhibit remarkable catalytic activities in both MW-driven oxidation of lomefloxacin (LOM) and direct reduction of 4-nitrophenol (4-NP). Moreover, the oxidation and reduction process can be well-explained by Localized surface plasmon resonance (LSPR) effect and electronic relay mechanism, respectively. This work offers a simple strategy to construct 1D-2D architectures in situ and elucidates their potential applications in environmental water restoration.

Direct Synthesis of Intermetallic Platinum-Alloy Nanoparticles Highly Loaded on Carbon Supports for Efficient Electrocatalysis.

Compared to nanostructured platinum (Pt) catalysts, ordered Pt-based intermetallic nanoparticles supported on a carbon substrate exhibit much enhanced catalytic performance, especially in fuel cell electrocatalysis. However, direct synthesis of homogeneous intermetallic alloy nanocatalysts on carbonaceous supports with high loading is still challenging. Herein, we report a novel synthetic strategy to directly produce highly dispersed MPt alloy nanoparticles (M = Fe, Co, or Ni) on various carbon supports with high catalyst loading. Importantly, a unique bimetallic compound, composed of [M(bpy)3]2+ cation (bpy = 2,2'-bipyridine) and [PtCl6]2- anion, evenly decomposes on carbon surface and forms uniformly sized intermetallic nanoparticles with a nitrogen-doped carbon protection layer. The excellent oxygen reduction reaction (ORR) activity and stability of the representative reduced graphene oxide (rGO)-supported L10-FePt catalyst (37 wt %-FePt/rGO), exhibiting 18.8 times higher specific activity than commercial Pt/C catalyst without degradation over 20 000 cycles, well demonstrate the effectiveness of our synthetic approach toward uniformly alloyed nanoparticles with high homogeneity.

The Effect of Graphene Oxide on Flame Retardancy of Polypropylene and Polystyrene

Abstract This study discusses how a graphene oxide (GO) has been developed to improve flame resistance, ignitability, and flame threats of polystyrene (PS) and polypropylene (PP). For reasons where high thermal stability alongside fire-resistant parts for vehicles or airships is essential, the manufacture of lightweight products appears to have promising outcomes. Cone calorimeter and limiting oxygen index experiments were used to measure heat and fire experiments of PS and PP nanocompounds. The incorporation of GO into PS and PP structures has reduced the heat release rate as measured through cone calorimeter. The characterization implied that without clear accumulations, the GO nanolayers were properly distributed throughout the PS structure, resulting in an outstanding upgrade of thermal strength and fire safety characteristics. During the ignition period, GO dispersal in PS and PP accelerated the ignition period and lowered the heat release rate. In addition, the incorporation of GOs reduced the PP’s combustion rate as a result of developing a carbon protective layer that acts as a heat and mass transfer barrier. However, during combustion experiments, nanocompounds PS/GO and PP/GO generate a thermal insulation intumescent that protects the sublayers of the polymer. The peak of the heat release rate was reduced by 23 % for PP/GO and 53 % for PS/GO under flaming circumstances. The maximum thermal release rate indicates a substantial reduction for PP/GO 2.0 weight percent of nanocomposite compared to pure PP. This research shows that even GO inclusion does not change the limiting oxygen index values, but the development of an intumescent char protects the polymer sublayers properly. This feature offers a distinctive modification strategy to enhance GO’s flame-resistant effectiveness. This research offers excellent insights into PP and PS nanocompounds’ ignitability behavior with the inclusion of GO filler. This study delivers an appropriate choice to evaluate the potential for fire safety using graphene in polymers and flame-retarded polymers.

Flame retardant effect of 1-aminoethyl-3-methylimidazolium hexafluorophosphate in thermoplastic polyurethane elastomer

In this paper, 1-aminoethyl-3-methylimidazolium hexafluorophosphate ([APMIm]PF6) and 1-butyl-3-methylimidazolium hexafluorophosphate ([EMIM]PF6) were used as flame retardant additives in thermoplastic polyurethane elastomer (TPU). The flame retardant effect of [APMIm]PF6 and [EMIM]PF6 in TPU had been investigated by cone calorimeter (CCT), scanning electron microscope (SEM), energy-dispersive spectroscopy (EDS), microcombustion calorimeter (MCC), fourier transform infrared spectroscopy (FT-IR), smoke density test (SDT), thermogravimetric analysis (TG) and thermogravimetric/fourier transform infared spectroscopy (TG-IR), respectively. The results indicated that TPU/[APMIm]PF6 had better thermal properties compared with pure TPU and TPU/[EMIM]PF6. The peak heat release rate (pHRR) of TPU/A-1.0 was remarkably reduced by 32.97% and 19.15%, in comparison with that of TPU and TPU/E-1.0. Moreover, the total heat release (THR) and smoke production rate (SPR) of TPU/A-1.0 were the lowest among all samples. And, in the early stage of fire, [APMIm]PF6 can promote the formation of protective carbon layer, reduce the HRR and SPR. Therefore, it is necessary to develop environment-friendly green flame retardants.

Nanosized α-MnS homogenously embedded in axial multichannel carbon nanofibers as freestanding electrodes for lithium-ion batteries

To buffer the unavoidable volume expansion and structure collapse problems of transitional metal sulfides during lithiation process, herein, nanosized α-MnS homogenously embedded in axial multichannel carbon nanofibers was well designed and directly used as freestanding anodes for lithium-ion batteries (LIBs). The obtained carbon nanofibers were interwoven into a flexible and cross-linked film, which offered a 3D successive conductive networks and guaranteed sufficient contact interface for electrode/electrolyte. The nanosized α-MnS was homogenously embedded into the carbon nanofiber framework and surrounded with a thin protective carbon layer, which effectively maintained the structural integrity for a satisfied cycling performance. The high aspect ratio carbon nanofibers with axial open channels supplied sufficient active sites and formed long-range electronic pathways along the axial carbon wall. Meanwhile, the radial voids provided enormous accommodation space to alleviate volume expansion and shortened diffusion paths for faster ionic transfer. Benefitting from the above unique merits, the freestanding electrodes delivered excellent lithium storage performances and remarkable long-term cycling stability, including a high initial reversible capacity of 772 mAh g−1 and excellent cycling capacity retention of 93.4% after 100 cycles at a current density of 0.5 A g−1.

Mesopores octahedron GCNOX/Cu2O@C inhibited photo-corrosion as an efficient visible-light catalyst derived from oxidized g-C3N4/HKUST-1 composite structure

Photo-corrosion of Cu2O photocatalyst considered as an important factor extremely restricts its catalytic activity. However, so far, there are few comprehensive reports on the mechanism of photo-corrosion inhibition and stability improvement of Cu2O in photocatalytic degradation. In this work, oxidized g-C3N4/Cu2O@C (GCNOX/Cu2O@C) visible-light catalysts with protective carbon layer were first prepared using the copper-based metal–organic frameworks (HKUST-1) composite as precursors. The UV–visible DRS, PL, XPS valence-band and Mott-Schottky curves were used to characterize that the formation of carbon layer leads to establishing built-in electric field, shifting of energy bands and photogenerated carrier separation. Linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) revealed that GCNOX/Cu2O@C had the strongest photo-response current and the lowest interface contact resistance. The photodegradation activity of GCNOX/Cu2O@C was analyzed for Rhodamine B (RhB) and ciprofloxacin (CIP) under low energy visible light irradiation and the degradation kinetic constants were 0.01413 min−1 and 0.03958 min−1, respectively, which were much higher than other as-prepared catalysts. It also exhibited outstanding stability with the 87.4% degradation efficiency in 90 min after four recycles. Furthermore, the characterization of GCNOX/Cu2O@C after the cyclic reactions further proved the ultra-high stability of the carbonized materials. Additionally, on the basis of degradation experiments and photoelectrochemical results, the possible transfer path of photocarriers between material interfaces, photo-corrosion inhibition mechanism of cuprous oxide and the transformation mechanism of active radicals were proposed. This work provided a novel insight for MOFs-derived composites as a highly efficient and stable visible-light catalyst.

Mixed Metal Phosphide Chainmail Catalysts Confined in N-Doped Porous Carbon Nanoboxes as Highly Efficient Water-Oxidation Electrocatalysts with Ultralow Overpotentials and Tafel Slopes.

Electrocatalytic hydrogen production driven by surplus electric energies is considered a promising sustainable process for hydrogen supply. The high overpotential and low energy-conversion efficiency caused by the slow kinetics of the four-electron transfer oxygen-evolution reaction (OER), however, hamper its competitiveness. Herein, a highly stable, efficient OER catalyst was developed, taking the effects of both composition and nanostructure into account for the catalyst design. N-doped carbon-armored mixed metal phosphide nanoparticles confined in N-doped porous carbon nanoboxes, a particle-in-box nanostructure, were synthesized from monodisperse Ni3[Fe(CN)6]2·H2O nanocubes through sequential conformal polydopamine coating, ammonia etching, and thermal phosphorization. The product exhibited outstanding catalytic abilities for the OER in 1.0 M KOH, delivering 10, 100, and 250 mA/cm2 at ultrasmall overpotentials of 203, 242, and 254 mV, respectively, with an ultrasmall Tafel slope of 38 mV/dec, outperforming most recently reported top-notch iron-group-based OER catalysts. The long-term stability was also excellent, showing a small chronopotentiometric decay of 2.5% over a 24 h operation at 50 mA/cm2. The enhanced catalytic efficiency and stability may be attributable to the unique particle-in-box structure as a nanoreactor offering a local, fast reaction environment, the conductive N-doped porous carbon shell for fast charge and mass transport, the synergistic effect between multicomponent metal phosphides for enhanced intrinsic activities, and the carbon protection layer to prevent/delay the catalyst core from being deactivated. This combined particle-in-box and chainmail design concept for electrocatalysts is unique and advantageous and may be readily applied to the general field of heterogeneous reactions.

Dendrite-free Zn anodes enabled by functional nitrogen-doped carbon protective layers for aqueous zinc-ion batteries.

Rechargeable aqueous zinc-ion batteries possess the merits of good environmental benignity, high operational safety and high energy density. Nevertheless, the practical application of zinc-ion batteries is severely obstructed by the inhomogeneous deposition of metallic Zn on the anode, which results in serious capacity fading, poor coulombic efficiency, and electrolyte consumption. Herein, we propose a simple strategy of constructing a functional nitrogen-doped carbon network coating layer on zinc foil for dendrite-free Zn stripping/plating. On one hand, the good conductivity of the artificial Zn/electrolyte interface can quickly balance the electric field and lower the nucleation overpotential. On the other hand, the porosity feature and functional groups of the protective layer can provide a fast Zn2+ transportation pathway and generate well-dispersed nucleation seeds. Therefore, the protective layer can effectively hamper the growth of metallic Zn dendrites and resist side reactions. The as-prepared N-C/Zn anode displays superior cycling stability (800 h at 2 mA cm-2 with the capacity of 2 mA h cm-2) and a satisfactory coulombic efficiency of 98.76% during the Zn stripping/plating process. A long cycle life and high specific capacity (162.10 mA h g-1 after 500 cycles at 2.0 A g-1) are also obtained for N-C/Zn||ZnSO4||V2O5 full cells. The strategy provides a facile and effective opportunity for constructing high-performance rechargeable aqueous zinc-ion batteries.

Sample preparation by focused ion beam without argon ion milling for quantitative electron holography of p-n junctions

A method is suggested to prepare lamella for quantitative electron holography by focused ion beam without the need for postprocessing. It relies on thinning of a lamella from the back side of the Si substrate and removal of the protective layers with Ga ions with progressively lower energies down to 2 kV. It is shown that variations of the dopant potential across a one-dimensional p+/n junction in Si, which are derived by electron holography and from the results of secondary ion mass spectrometry, agree to much better values than 50 mV. The effect of the protective layer deposited during TEM sample preparation on the results of electron holography was evaluated. The Si oxide protective layer, which was deposited onto the Si surface, showed a limited charging effect while oxidizing the top of the Si surface. The carbon protective layer showed no surface erosion, yet it has revealed strong charging effects. The deposition process of the protective layer needs to be optimized for a given application in future work.

1T′‐ReS2 Confined in 2D‐Honeycombed Carbon Nanosheets as New Anode Materials for High‐Performance Sodium‐Ion Batteries

AbstractReS2 (rhenium disulfide) is a new transition‐metal dichalcogenide that exhibits 1T′ phase and extremely weak interlayer van der Waals interactions. This makes it promising as an anode material for sodium‐ion batteries. However, achieving both a high‐rate capability and a long‐life has remained a major research challenge. Here, a new composite is reported, in which both are realized for the first time. 1T′‐ReS2 is confined through strong interfacial interaction in a 2D‐honeycombed carbon nanosheets that comprise an rGO inter‐layer and a N‐doped carbon coating‐layer (rGO@ReS2@N‐C). The strong interfacial interaction between carbon and ReS2 increases overall conductivity and decreases Na+ diffusion resistance, whilst the intended 2D‐honeycombed carbon protective layer maintains structural morphology and electrochemical activity during long‐term cycling. These findings are confirmed by advanced characterization techniques, electrochemical measurement, and density functional theory calculation. The new rGO@ReS2@N‐C exhibits the greatest rate performance reported so far for ReS2 of 231 mAh g−1 at 10 A g−1. Significantly, this is together with ultra‐stable long‐term cycling of 192 mAh g−1 at 2 A g−1 after 4000 cycles.

Well-dispersed MnO-quantum-dots/N-doped carbon layer anchored on carbon nanotube as free-standing anode for high-performance Li-Ion batteries

MnO is one of the most attractive anode materials for Li ion batteries (LIBs) due to its high theoretical capacity and low voltage hysteresis. However, its inherent low conductivity and large volume expansion hinder real application. Herein, we construct a flexible freestanding film of MnO quantum dots, N-doped carbon layer and carbon nanotubes by an effective method and demonstrate its direct application as an anode for LIBs. The microstructure observations reveal that well-dispersed MnO quantum dots with the average of 2–5 nm attach tightly on highly conductive carbon nanotube substrates and covered by N-doped carbon layers. Such unique nanocomposite structure provides effective carbon protective layers to accommodate volume change, ensure almost the whole surface of each MnO quantum dots to attend electrochemical reaction, and increases electron conductivity and reduces Li+ diffusion distance. Furthermore, kinetic analysis and characterization tests indicate that capacitive contribution for Li storage in the freestanding film is calculated to be high and further oxidation of Mn2+ to higher valence state upon cycling generates lots of specific capacity, thus endowing it with excellent rate, ultrahigh capacity and outstanding cycling stability. The flexible freestanding anode delivers ultrahigh capacity of 1741mAh g−1 after 120 cycles at 0.1 A g−1, a high-rate capability of 858 mAh g−1 at 3.2 A g−1 after 120 cycles at 0.1 A g−1, and long-term cycling stability with a capacity of 136.5% at 1.0 A g−1 after 1000 cycles. The unique nanostructure design is believed to have great potential in general synthesis of the composite consisted of CNT and oxide quantum dots for energy storage.