Ultrathin MoS2 Nanosheets Research Articles

Vertically Aligned MoS2 Nanosheets on Nitrogen‐Doped Carbon Sheets for Enhanced Electrocatalytic Hydrogen Evolution

AbstractFabrication of two‐dimensional electrocatalysts with low cost and high efficiency is of great significance for electrochemical hydrogen evolution reaction (HER). Molybdenum disulfide (MoS2) is one of the most promising alternatives to Pt‐based HER catalysts, however its electrocatalytic performance is greatly limited by insufficient active edge sites and poor conductivity. Herein, ZIF‐8‐derived nitrogen‐doped carbon sheet (NCS) is utilized as the support, and the heterostructure of NCS@MoS2 is assembled by a facile hydrothermal reaction between MoS2 precursor and NCS. This is the first example of NCS‐supported MoS2 structures for HER application. The results show that defect‐rich MoS2 ultrathin nanosheets are uniformly and vertically aligned on NCS, and the dispersion degree of MoS2 can be well controlled by adjusting the surface modification of NCS. As expected, the optimized catalyst possesses a superior catalytic performance to pristine MoS2 evidenced by a low overpotential (250 mV) to afford 10 mA cm−2, and a small Tafel slope (74 mV dec−1) with good stability in acidic media. The intriguing HER activity is attributed to the synergistic effect of abundantly exposed active sites and high conductivity.

Ultrathin MoSe2 nanosheets decorated on carbon aerogel microspheres for high-capacity supercapacitor electrodes

A new MoSe 2 /CRF electrode was successfully constructed, which possessed enhanced specific capacitance and high cycling stability via the synergistic effect of MoSe 2 nanosheets and carbon aerogel microspheres. • MoSe 2 nanosheets and carbon aerogel microspheres hybrid via solvent-thermal method was prepared. • MoSe 2 NSs/CRF electrode exhibits an excellent specific capacitance and a high cycling stability. • Porous carbon aerogel microspheres restrict the aggregation of MoSe 2 nanosheets. • MoSe 2 NSs/CRF has potential as an electrode material in supercapacitor fields. Two-dimensional layered molybdenum selenide nanosheets have been a promising electrode material for electrochemical energy storage because of their high theoretical capacitance. However, the intrinsic low electrical conductivity and inferior structural stability impede its real application. Herein, MoSe 2 nanosheets are incorporated into carbon aerogel microspheres (MoSe 2 NSs/CRF) via a facile solvent-thermal method. The specific surface area and electric conductivity of the MoSe 2 NSs/CRF electrode were increased simultaneously because of its incorporation with porous carbon aerogel microspheres. As a result, the MoSe 2 NSs/CRF electrode exhibits an excellent specific capacitance of 498F g −1 at a current density of 1 A g −1 , which is 3 times higher than that (136F g −1 ) of the pristine MoSe 2 nanosheets. With a 5-fold increase to 5 A g −1 , it still retains 278F g -1 and high cycling stability of 127.2% of the initial retention after 2500 cycles at 100 mV s −1 . Moreover, we fabricated a symmetric supercapacitor (SC) using a composite composed of MoSe 2 NSs/CRF. The symmetric supercapacitor showed capacitance of 124F g −1 with an energy density of 8.5 W h Kg −1 at a power density of 264.8 W Kg −1 at a current density of 1 A g −1 . The superior electrochemical performances demonstrating that the MoSe 2 NSs/CRF has potential as an electrode material for energy storage application in high-performance supercapacitor fields.

Construction of N-doped C@MoS2 heteroshell with the yolk of Sn nanoparticles as high-performance anodes for sodium-ion batteries

Herein, we demonstrate the reasonable design and preparation of yolk-heteroshell Sn@N-doped C@MoS2 nanospheres as anode materials in sodium-ion battery. Through an effective multi-step strategy, Sn nanoparticles are encapsulated in N-doped C nanocage surrounded by ultra-thin MoS2 nanosheets to form Sn@N-doped C@MoS2 nanospheres. In this novel structure, Sn nanoparticles with high theoretical capacity improve the space utilization inside the heteroshell; the N-doped carbon nanocage as the skeleton not only inhibits the mutual accumulation of Sn and MoS2, but also improves conductivity; the outer MoS2 ultra-thin sheets can consolidate C@MoS2 heteroshell, provide numerous active sites and favor the fast diffusion of Na+/e-. Notably, the combination of carbon nanocage and MoS2 sheets in the yolk-heteroshell structure can effectually buffer the volume expansion of Sn nanoyolks and reinforce C@MoS2 heteroshell while reducing the carbon content. Therefore, the yolk-heteroshell structure plays a crucial role in enhanced reversible capacity and cyclic stability of Sn@N-doped C@MoS2 nanospheres, which activates their sodium storage potential. The yolk-heteroshell Sn@N-doped C@MoS2 nanospheres exhibit high reversible capacity of 488.4 mAh g−1 at 0.1 A g−1 after 300 cycles and long-cycle stability of 350.6 mAh g−1 at 0.5 A g−1 after 500 cycles. Moreover, their full cell delivers a stable reversible discharge capacity of about 80.1 mAh g−1 after 30 cycles at 0.5 C. This work provides a feasible yolk-heteroshell strategy for Sn-based composite nanomaterials.

Porous cobalt ferrite microspheres decorated two-dimensional MoS2 as an efficient and wideband microwave absorber

In this article, the CoFe2O4/MoS2 composites have been well constructed via a facial hydrothermal method, from which the porous CoFe2O4 microspheres were embedded into MoS2 ultrathin nanosheets. As a typical two-dimensional transition metal sulfide, MoS2 with high electrical conductivity and flexible properties is expected to exhibit high dielectric loss and magnetic loss when combined with magnetic material CoFe2O4. Meanwhile, the unique hierarchical structure of as-synthesized MoS2 nanoflowers is conducive to scattering and reflection of electromagnetic waves, and endows designed composites with competitive microwave absorption properties. Notably, although the saturation magnetization of MoS2/CoFe2O4 composites is significantly decreased compared to pure CoFe2O4 microspheres, the coercivity still maintains a high value of 626.1 Oe. As expected, the results demonstrate that as-fabricated MoS2/CoFe2O4 composites do have superior microwave absorption properties in comparison with CoFe2O4 and MoS2. It is found that the complex permittivity is enhanced with increasing filling ratio from 45 wt% to 60 wt%, which is helpful for obtaining a moderate permittivity value. When the filling ratio is 50 wt%, the MoS2/CoFe2O4 composites exhibit a minimum reflection loss (RLmin) of − 53.1 dB at 12.08 GHz when the thickness is 2.5 mm. An effective absorption bandwidth less than − 10 dB of 6.61 GHz from 11.28 to 17.89 GHz is achieved with a thin thickness of 2.2 mm, almost covering the whole Ku-band. The improvement in microwave absorption properties can be ascribed to the synergistic effect of the magnetic CoFe2O4 and dielectric MoS2. The impedance matching characteristic and interfacial polarization are significantly optimized by inserting CoFe2O4 spheres onto the surface of MoS2 nanosheets. Considering the excellent performance of as-fabricated MoS2/CoFe2O4 composites, it is believed that the MoS2-based composites can be applied as a promising candidate of highly effective microwave absorbers with strong absorption intensity and broad absorption frequency.

Enhancement of pollutant degradation and solar-driven water evaporation by architecting hierarchical 1D/2D TiO2 @ MoS2 core–shell networks

Solar absorbers with a wider absorption range are attracting extensive interest in the fields of photocatalysis and solar-driven water evaporation. Here we designed hierarchical TiO2 nanowire arrays (TiO2 NWAs) in situ grown on Ti mesh, and utilizing the microstructure engineering strategy, ultrathin MoS2 nanosheets were further decorated on the surface of TiO2 NWAs (TiO2 NWAs @ MoS2). The multistage 1D TiO2 NWAs @ 2D MoS2 core–shell networks enhanced the light trapping in the full solar spectrum in comparison to bare MoS2 nanosheet arrays (MoS2 NSAs), which benefitted photocatalysis and solar-driven water evaporation. The number of photogenerated charge carriers on the surface of TiO2 NWAs @ MoS2 increased, which dramatically enhanced the photocatalytic rate constant by over an order of magnitude relative to MoS2 NSAs. As for solar-driven water evaporation, TiO2 NWAs @ MoS2 achieved a light absorption of 96.5% and a water evaporation rate of 1.42 kg m–2h−1 under one sun. In addition, the self-supporting solar absorber with favorable stability overcame the intractable recovering of photocatalysts from treated water. This study provided a pathway for designing efficient semiconductor-based solar absorbers used in solar energy conversion.

S defect-rich ultrathin 2D MoS2: The role of S point-defects and S stripping-defects in the removal of Cr(VI) via synergistic adsorption and photocatalysis

In the field of photocatalysis, one focus is on high-performance visible light catalysis. For this study, which follows the defect engineering strategy, ultrathin two-dimensional (2D) S defect-rich MoS2 nanosheets were created in situ by ball-milling MoS2 nanosheets with ascorbic acid and then used for the removal of Cr(VI) from wastewater. The results show that ascorbic acid increases both the specific surface area of MoS2 nanosheets and the concentration of S stripping-defects significantly. Of the samples, D-MoS2-3 (i.e., S defect-rich ultrathin 2D MoS2 nanosheets) exhibited the best Cr(VI) adsorption capacity and photocatalytic activity thanks to its large specific surface area and a high concentration of total S defects (18.5%), 311.1% better than for P-MoS2 (i.e., pristine MoS2 nanosheets) (4.5%). The concentration of S point-defects in D-MoS2-3 is only a little greater than in P-MoS2, but the concentration of S stripping-defects is significantly greater. S point-defects at such a high concentration readily act as recombination centers for photogenerated carriers. By contrast, S stripping-defects that lack dangling Mo-S bonds trap photogenerated holes and add to the separation efficiency of photogenerated electron-hole pairs. As a consequence, the photocatalytic performance of D-MoS2-3 in removing Cr(VI) is significantly better. Given this finding, the present study offers a new design pathway and a reference for the practical application of defect engineering to ultrathin 2D materials.

Pt and Te codoped ultrathin MoS2 nanosheets for enhanced hydrogen evolution reaction with wide pH range

Pt and Te codoped ultrathin MoS2 nanosheets for enhanced hydrogen evolution reaction with wide pH range

Hybrid heterojunction of molybdenum disulfide/single cobalt atoms anchored nitrogen, sulfur-doped carbon nanotube /cobalt disulfide with multiple active sites for highly efficient hydrogen evolution

A multicomponent 3D monolithic electrode was designed that consists of Co single atoms anchored/nitrogen, sulfur co-doped carbon nanotubes (CoSAs-NS-CNTs) on carbon cloth (CC) with ultra-thin MoS2 nanosheets externally decorated and ultra-small CoS2 nanodots internally confined (MoS2/CoSAs-NS-CNTs@CoS2/CC) to form a hybrid heterojunction electrode with double interfaces as vectorial electron transport pathways for promoting electrocatalytic performance. The integration of well-distributed MoS2 nanosheets and CoS2 nanodots linked with Co single atoms anchored/N, S co-doped CNTs endows abundant multiple active sites, outstanding conductivity, and the downshifted d-band center with a thermodynamically favorable hydrogen adsorption free energy (ΔGH*) for effectively catalyzing hydrogen evolution reaction (HER). As a result, the optimal MoS2/CoSAs-NS-CNTs@CoS2/CC electrode exhibits outstanding HER performance with overpotentials of 72 and 56 mV at 10 mA cm−2 and small Tafel slopes of 59.4 and 43.2 mV dec-1 in acidic and alkaline solutions, respectively, outperforming most of the previously reported molybdenum/cobalt sulfide-based electrocatalysts. Moreover, the electrode also displays good durability and stability reflected from the small decrease on activity after 5000 CV cycles and nearly no decay in current density after electrolysis for 20 h.

Coupling Fe3O4/Fe1-xS@Carbon with carbon-coated MoS2 nanosheets as a superior anode for sodium-ion batteries

Considering the natural reserves, distribution and cost of sodium resources, sodium-ion batteries (SIBs) have been regarded as a potential alternative to lithium-ion batteries. However, it remains challenging to develop the excellent electrode materials for SIBs owing to larger Na ionic radius. Herein, multicomponent Fe3O4/Fe1-xS@C@MoS2@C hybrid has been designed by using bone-like Fe3O4@C particles and carbon-coated MoS2 nanosheets as the core and shell, respectively, followed by sulfurization. On one hand, several high-capacity active materials are well organized together, which can fully exert the synergies among them. Meanwhile, ultrathin MoS2 nanosheets with expanded interlayer spacing of 0.80 nm are confined between two carbon layers, resulting in the high conductivity and good structural stability of the whole electrode. Consequently, the prepared Fe3O4/Fe1-xS@C@MoS2@C anode for SIBs exhibits a large reversible capacity of 589.8 mA h/g at 100 mA/g after 200 cycles. Even at a higher current density of 2 A/g, it still keeps a high specific capacity of 503.7 mA h/g. The theoretical calculations further show that the surface of Fe1-xS is more advantageous for Na+ adsorption in comparison to that of Fe3O4, due to the stronger charge transfer between Na and neighboring S atoms, which greatly boosts the sodium storage capability of Fe3O4/Fe1-xS@C@MoS2@C.

Ultra-thin pine tree-like MoS2 nanosheets with maximally exposed active edges terminated at side surfaces on stainless steel fiber felt for hydrogen evolution reaction

High active edge sites guarantee MoS2 as a promising electrocatalyst alternative for the costly Pt based materials. However, the inherent high surface energy nature of the layer edges thermodynamically blocks the large scale synthesis, and meanwhile poses instability problems. In this work, vertically grown ultra-thin MoS2 nanosheets with a large proportion of exposed edges on commercially available 316L stainless steel fiber felts (SSF) via a simple one-step kinetically controlled hydrothermal process is reported aiming for electrocatalytic H2 production. Notably, the synthesized MoS2 nanosheet presents a three dimensional pine tree-like structure featured by the maximally exposed active edges toward side surfaces. Abundant gaps between the MoS2 nanosheets together with impressive super-hydrophilic property assure the large density of effective edge sites that accessible to electrochemical reaction and the rapid desorption of H2 products, and thus high intrinsic hydrogen evolution reaction (HER) activity. In addition to those electrochemically desired properties, the reliable contact of the MoS2 sheet on the SSF substrate together with the low price, porosity, high conductivity and high chemical corrosion resistance properties of the SSF substrate guarantee the MoS2/SSF electrode as an efficient and durable HER electrode in both strong acidic and alkaline medium for potential commercial applications.

Using a Dopamine‐Modified Magnetic Nano‐flower Material for the Solid Phase Extraction of Cyromazine and Melamine in Food Samples

AbstractThis work reported a simple method to prepare MGO@PDA@MoS2 nano‐flower by in situ growth of MoS2 on the poly‐dopamine (PDA) modified Fe3O4@GO (MGO) nanosheets. The novel material was composed of PDA modified MGO nanosheets and flower‐like MoS2 microspheres which two‐dimension ultrathin MoS2 nanosheets were grown in situ on the surface of MGO@PDA and self‐assembled. The material could be used as a new adsorbent for magnetic solid phase extraction (m‐SPE). The nano‐composite was characterized by TG, VSM, SEM, TEM, XRD, XPS and FT‐IR. The extraction parameters were investigated, including initial concentration, extraction time, pH, ionic strength and desorption conditions. The adsorption behaviors of the material were explored via isotherm and kinetic adsorption experiments, which demonstrated that Langmuir adsorption isotherm model and pseudo‐second‐order kinetic model were more appropriate to describe the adsorption process on MGO@PDA@MoS2. A rapid, safe, sensitive, easy, and effective method has been developed for detecting cyromazine and melamine simultaneously in real samples including beef, protein powder and milk by combining with HPLC. Under optimized conditions, the proposed method has a good trueness, wide linear range of 0.1‐100 μg mL−1, low limits of detection (LOD), satisfactory repeatability and reproducibility. Excellent recoveries for the determination of cyromazine and melamine were obtained in spiked real samples. In a word, the nano‐composite material has the advantages of magnetic separation and high adsorption affinity for cyromazine and melamine, and it is a promising adsorbent for extracting cyromazine and melamine from real samples.

Improved morphology and excitonic emission of 2D MoS2 by incorporating mechanical grinding in the liquid phase exfoliation synthesis process

Abstract MoS2 nanosheets are synthesized by incorporating a manual grinding of the bulk powder prior to the sonication in the standard liquid phase exfoliation process. The light emission properties of MoS2 is thereby found to be significantly improved. Transmission electron microscopy shows continuous ultrathin MoS2 nanosheets of larger dimensions in the grinding-assisted synthesis. Raman spectroscopy measurements show that MoS2 is exfoliated down to 3–4 layers by an inclusion of the grinding. UV–visible and photoluminescence spectroscopy were used to analyze the changes in the optical properties. Grinding helps to reduce the influence of the degradation of the NMP solvent on the emission characteristics of the exfoliated material. The strong visible photoluminescence emission due to sonochemical degradation of NMP is suppressed and the excitonic emission due to the A and B excitons relative to NMP emission is significantly enhanced. The results suggest an easy and reliable approach to enhance the optical emission of two-dimensional MoS2 appreciably.

In situ growth of vertically aligned ultrathin MoS2 on porous g-C3N4 for efficient photocatalytic hydrogen production

Ultrathin MoS2 nanosheets are grown in situ on the surface of porous g-C3N4 by a facile solid-state method. HAADF–STEM and HRTEM images show that ultrathin MoS2 (1–3 layers) with a 2H phase vertically stand on (arch bridge-like morphology) the surface of porous g-C3N4. Photoelectrochemical measurements indicate that electrons rapidly migrate from porous g-C3N4 to MoS2 because of the strong interfacial contact formed by in situ growth, thus promoting the separation of photoinduced carriers. The special ultrathin and vertical structures of MoS2 not only shorten the charge migration distance but also expose active edge sites on its surface, facilitating the occurrence of the H2 evolution reaction. In this study, 2.0% MoS2/porous g-C3N4 (in situ growth) exhibits the highest H2 evolution rate of 3570 μmol∙h−1∙g−1 with an apparent quantum yield (AQY) of 8.8% at λ = 420 nm, which is almost equal to that of 2.0% Pt/porous g-C3N4. This work provides a new design for MoS2 cocatalysts with high performance and provides a deeper understanding of the interfacial transport of carriers between g-C3N4 and MoS2.

Two dimensional ultrathin MoSe2 bedecked Zn0.5Cd0.5S for reinforced photocatalytic H2 generation and toxic Cr (VI) reduction

Metallic MoSe2 with distinct platinum-like electronic configuration and compelling band gap structure exhibits zero approaching Gibbs free energy for H atom, hence can be approved as an ideal cocatalysts for H2 evolution. However, the reports on MoSe2 cocatalyst still leaves much room. Here, two dimensional ultrathin MoSe2 nanosheets bedecked Zn0.5Cd0.5S nanoparticles were reported as efficient photocatalyst, in which metallic MoSe2 nanosheets cocatalyst will do duty for electron sink to promote the separation of charge carriers and prolong the electrons lifetime, thus benefiting the improved photocatalytic H2 evolution activity. As a result, Zn0.5Cd0.5S/MoSe2 composite with an optimized 9 wt% MoSe2 presents a higher H2 evolution activity of 4853.3 μmol g-1h−1, 3.57 folds of pure Zn0.5Cd0.5S sample (1361.0 μmol g-1h−1). Meanwhile, the greatly enhanced photo-reduction efficiency for toxic heavy metal Cr (VI) ion by Zn0.5Cd0.5S/MoSe2 composite further certifies the promoted separation of electron- hole pairs. These results turned out that MoSe2 is qualitied as candidate to serve as promising co-catalyst for photocatalyst energy conversion and decontamination.

Hydrothermal construction of flower-like MoS2 on TiO2 NTs for highly efficient environmental remediation and photocatalytic hydrogen evolution

The convenient and efficient anodic oxidation method was used to grow TiO2 nanotubes (NTs) on Ti sheets as the substrate, and then ultrathin MoS2 nanosheets were assembled on TiO2 NTs to construct flower-like structure composite photocatalyst in the hydrothermal process. The abundant reactive centers in the photocatalytic reaction were attributed to the thinness and wrinkling of MoS2 nanosheets. The superior carrier separation and migration capacity of the photocatalyst was verified by electrochemical characterization and photoluminescence spectroscopy analysis. The loading amount effect of MoS2 on the degradation efficiency of RhB and MB was explored. Evidently, the ability of the photocatalyst to degrade pollutants was significantly improved, and the optimal degradation efficiency of RhB and MB reached 76.33% and 100%, respectively. Assisted by adding sacrificial agent and external voltage, the outstanding photocatalytic hydrogen evolution was detected, and the optimal H2 production could reach 900.9 μmol. The mechanism of pollutant removal and hydrogen generation by TiO2 NTs/MoS2 heterojunction was proposed and analyzed based on the energy band structure and free radical capture experiments of photocatalysts.

MoS2 Nanosheet-Polypyrrole Composites Deposited on Reduced Graphene Oxide for Supercapacitor Applications

Vertically aligned MoS2 nanosheet-polypyrrole (PPy) composites on reduced oxygen graphene (rGO) are fabricated by a one-step hydrothermal strategy (MP-rGO). The ultrathin MoS2 nanosheets mixed with...

Hierarchical Co and Nb dual-doped MoS2 nanosheets shelled micro-TiO2 hollow spheres as effective multifunctional electrocatalysts for HER, OER, and ORR

Abstract Heteroatom doping engineering has emerged as an intriguing strategy to enhance electrocatalytic efficiency. Herein, a multiple transition metal doping approach is developed through the incorporation of both Co and Nb into hierarchical MoS2 ultrathin nanosheets directly grown on micro-TiO2 hollow spheres (Co,Nb-MoS2/TiO2 HSs) to boost the hydrogen evolution (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR). The Co and Nb dual-doping effects modify the electronic structure of the host MoS2 towards maximizing the HER, OER, and ORR performance. Additionally, the unique hollow spherical structure and heterostructured synergistic effects between the TiO2 core and MoS2 shell provide effective channels for electron transfer and large surface area with abundant exposed void spaces for ion diffusion/penetration. Therefore, the Co,Nb-MoS2/TiO2 HSs catalyst demonstrates extraordinary activity and stability with small overpotentials of 58.8 and 260.0 mV at 10 mA cm−2 for the HER and OER, respectively. When employed as both cathodic and anodic electrode in an electrolyzer, the catalyst requires an operating voltage of 1.57 V to achieve 10 mA cm−2. The catalyst also exhibits great potential for the ORR with high onset potential of + 0.96 V and half-wave potential of +0.87 V, as well as direct four-electron transfer process.

Separable magnetic MoS2@Fe3O4 nanocomposites with multi-exposed active edge facets toward enhanced adsorption and catalytic activities

We synthesized fluffy MoS2 material stacked by ultrathin nanosheets through adjusting different mass ratios of starting materials via a facile hydrothermal method. Surprisingly, XRD characterization results demonstrated that the intensity ratio of (100) to (002) of ultrathin MoS2 nanosheets was 0.90 with a 4:5 (CH3CSNH2: Na2MoO4·2H2O) mass ratio (M4-5). To the best of our knowledge, this value should be high, implying that the obtained MoS2 nanosheets exposed considerable (100) facets. Because the noncentrosymmetric Mo-2S on edges terminated by dangling bonds exhibits rich defects, high active MoS2 edge planes (100) prevail over inert MoS2 basal planes (002). To overcome its easy suspension and difficult recovery, the magnetic Fe3O4 was selected for in situ doping with ultrathin M4-5, and a unique structure of stable MoS2@Fe3O4 (M@F) nanocomposites-like randomly stacked rose petals-wrapped spherical chocolate beans was obtained for the first time. The introduction of Fe3O4 has to sacrifice some edge active sites, but after balancing the magnetic and active sites, (100)/(002) of MoS2 in M@F can also reach 0.56, showing that edges of MoS2 nanosheets are still multi-exposed. Abundant exposed edges of M@F provide numerous active centers, so M@F nanocomposites exhibited excellent performance for both the 4-nitrophenol (4-NP) reduction and dye adsorption. Therefore, it has great application prospects in wastewater treatment and reduction reaction and is also worth exploring in other applications.

Ultrathin MoS2 nanosheets hybridizing with reduced graphene oxide for high-performance pseudocapacitors

Layered molybdenum disulfide (MoS2) is a promising candidate of electrode material for supercapacitors due to its intercalation chemistry and high theoretical capacitance, but still suffers limited practical performances arising from the low electroactive area and sluggish charge transfer kinetics. Herein, we report the few-layered MoS2 nanosheets hybridizing with reduced graphene oxide (MoS2/rGO) which present high specific capacitance of 361 F g−1 at 5 mV s−1, good rate capability and long-life stability in 1.0 mol L−1 H2SO4. The symmetric supercapacitor exhibits high energy density of 23.0 Wh kg−1@0.37 kW kg−1 and 5.2 Wh kg−1@62.0 kW kg−1, along with high cyclability. The excellent electrochemical performance is attributed to the much improved conductivity, active sites and redox kinetics owing to the hybridization, which leads to the predominant capacitive behavior as demonstrated by the detailed analysis on the charge transfer kinetics. This study demonstrates a simple strategy to develop hybrid electrodes of layered materials and nanocarbons for high-efficient energy storage.

Adopting sulfur-atom sharing strategy to construct CoS2/MoS2 heterostructure on three-dimensional nitrogen-doped graphene aerogels: A novel photocatalyst for wastewater treatment

One of the significant challenges arising from the design of the structure of photocatalytic materials lies in the control over how the photogenerated electrons and hole pairs on semiconductors are re-combined to accelerate the surface catalytic reaction. In this work, the bottom-up approach is applied to design three-dimensional (3D) CoS2/MoS2-nitrogen-doped graphene aerogel (CoS2/MoS2-NGA) photocatalyst, where a large number of small-sized ultra-thin MoS2 nanosheets are connected to CoS2 nanoparticles by means of sulfur-atoms (S-atoms) sharing, and covered on the CoS2 surface uniformly. The chemical bonding between the CoS2 and MoS2 completely restricts the aggregation of nanoscale MoS2 so as to expose more edge active sites. In the meantime, it is demonstrated that CoS2 plays a critical role in accelerating charge separation at the heterojunction interface and in preventing electron-hole recombination. As indicated by the results, CoS2/MoS2-NGA possesses excellent photocatalytic properties and high cycle stability when applied for the photodegradation of organic pollutants, which provides a potential solution to the treatment of wastewater in practice.