Synthesis of Double-Layer Nitrogen-Doped Microporous Hollow Carbon@MoS2/MoO2 Nanospheres for Supercapacitors

Transition metal phosphide/ molybdenum disulfide heterostructures towards advanced electrochemical energy storage: recent progress and challenges

Transition metal phosphide @ molybdenum disulfide (TMP@MoS2) heterostructures, consisting of TMP as the core main catalytic body and MoS2 as the outer shell, can solve the three major problems in the field of renewable energy storage and catalysis, such as lack of resources, cost factors, and low cycling stability. The heterostructures synergistically combine the excellent conductivity and electrochemical performance of transition metal phosphides with the structural robustness and catalytic activity of molybdenum disulfide, which holds great promise for clean energy. This review addresses the advantages of TMP@MoS2 materials and their synthesis methods-e.g., hydrothermal routes and chemical vapor deposition regarding scalability and cost. Their electrochemical energy storage and catalytic functions e.g., hydrogen and oxygen evolution reactions (HER and OER) are also extensively explored. Their potential within battery and supercapacitor technologies is also assessed against leading performance metrics. Challenges toward industry-scale scalability, longevity, and environmental sustainability are also addressed, as are optimization and large-scale deployment strategies.

Pseudocapacitive Storage in Molybdenum Oxynitride Nanostructures Reactively Sputtered on Stainless-Steel Mesh Towards an All-Solid-State Flexible Supercapacitor

Exploiting pseudocapacitance in rationally engineered nanomaterials offers greater energy storage capacities at faster rates. The present research reports a high-performance Molybdenum Oxynitride (MoON) nanostructured material deposited directly over stainless-steel mesh (SSM) via reactive magnetron sputtering technique for flexible symmetric supercapacitor (FSSC) application. The MoON/SSM flexible electrode manifests remarkable Na+-ion pseudocapacitive kinetics, delivering exceptional ≈881.83 F g-1 capacitance, thanks to the synergistically coupled interfaces and junctions between nanostructures of Mo2N, MoO2, and MoO3 co-existing phases, resulting in enhanced specific surface area, increased electroactive sites, improved ionic and electronic conductivity. Employing 3D Bode plots, b-value, and Dunn's analysis, a comprehensive insight into the charge-storage mechanism has been presented, revealing the superiority of surface-controlled capacitive and pseudocapacitive kinetics. Utilizing PVA-Na2SO4 gel electrolyte, the assembled all-solid-state FSSC (MoON/SSM||MoON/SSM) exhibits impressive cell capacitance of 30.7 mF cm-2 (438.59 F g-1) at 0.125 mA cm-2. Moreover, the FSSC device outputs a superior energy density of 4.26 µWh cm-2 (60.92 Wh kg-1) and high power density of 2.5 mW cm-2 (35.71 kW kg-1). The device manifests remarkable flexibility and excellent electrochemical cyclability of ≈91.94% over 10,000 continuous charge-discharge cycles. These intriguing pseudocapacitive performances combined with lightweight, cost-effective, industry-feasible, and environmentally sustainable attributes make the present MoON-based FSSC a potential candidate for energy-storage applications in flexible electronics.

Pseudocapacitive Kinetics in Synergistically Coupled MoS2-Mo2N Nanowires with Enhanced Interfaces toward All-Solid-State Flexible Supercapacitors

Pseudocapacitive kinetics in rationally engineered nanostructures can deliver higher energy and power densities simultaneously. The present report reveals a high-performance all-solid-state flexible symmetric supercapacitor (FSSC) based on MoS2-Mo2N nanowires deposited directly on stainless steel mesh (MoS2-Mo2N/SSM) employing DC reactive magnetron co-sputtering technology. The abundance of synergistically coupled interfaces and junctions between MoS2 nanosheets and Mo2N nanostructures across the nanocomposite results in greater porosity, increased ionic conductivity, and superior electrical conductivity. Consequently, the FSSC device utilizing poly(vinyl alcohol)-sodium sulfate (PVA-Na2SO4) hydrogel electrolyte renders an outstanding cell capacitance of 252.09 F·g-1 (44.12 mF·cm-2) at 0.25 mA·cm-2 and high rate performance within a wide 1.3 V window. Dunn's and b-value analysis reveals significant energy storage by surface-controlled capacitive and pseudocapacitive mechanisms. Remarkably, the symmetric device boosts tremendous energy density ∼10.36 μWh·cm-2 (59.17 Wh·kg-1), superb power density ∼6.5 mW·cm-2 (37.14 kW·kg-1), ultrastable long cyclability (∼93.7% after 10,000 galvanostatic charge-discharge cycles), and impressive mechanical flexibility at 60°, 90°, and 120° bending angles.

2D nanocomposite materials for HER electrocatalysts - a review

Hydrogen energy has the potential to be a cost-effective and strong technology for brighter development. Hydrogen fuel production by water electrolyzers has attracted attention. 2D nanocomposites with distinctive properties have been extensively explored for various applications from hydrogen evolution reactions to improving the efficiency of water electrolyzer, which is the most eco-friendly, and high-performance for hydrogen production. Recently, typical 2D nanocomposites such as Metal-Free 2D, TMDs, Mxene, LDH, organic composites, and Heterostructure have recently been thoroughly researched for use in the HER. We discuss effective ways for increasing the HER efficiency of 2D catalysts in this paper, And the unique advantages and mechanisms for specific applications are highlighted. Several essential regulating strategies for developing 2D nanocomposite-based HER electrocatalysts are included such as interface engineering, defect engineering, heteroatom doping, strain & phase engineering, and hybridizing which improve HER kinetics, the electrical conductivity, accessibility to catalytic active sites, and reaction energy barrier can be optimized. Finally, the future prospects for 2D nanocomposites in HER are discussed, as well as a thorough overview of a variety of methodologies for designing 2D nanocomposites as HER electrocatalysts with excellent catalytic performance. We expect that this review will provide a thorough overview of 2D nanocatalysts for hydrogen production.

Terephthalic Acid Intercalated CoNi-LDH Materials for Improved Li-O2 Battery

CoNi-LDH (layered CoNi double hydroxides) hollow nanocages with specific morphology are obtained by Ni ion etching of ZIF-67 (Zeolitic imidazolate framework-67). The structure of the layered materials is further modified by molecular intercalation. The original interlayer anions are replaced by the ion exchange effect of terephthalic acid, which helps to increase the interlayer distance of the material. The intercalated cage-like structures not only benefit for the storage of oxygen, and the discharge product reaction, but also have more support between the material layers. The experimental results show that the excessive use of intercalation agent will affect structural stability of the intercalated CoNi-LDH. By adjusting the amount of terephthalic acid, the intercalated CoNi-LDH-2 (with 0.02 mmol terephthalic acid intercalated) is not easy to collapse after 209 cycles and shows the best electrochemical performance in Li-O2 battery.

Preparation and Photocatalytic Performance of MoS2/MoO2 Composite Catalyst

Solar energy is an inexhaustible clean energy providing a key solution to the dual challenges of energy and environmental crises. Graphite-like layered molybdenum disulfide (MoS₂) is a promising photocatalytic material with three different crystal structures, 1T, 2H and 3R, each with distinct photoelectric properties. In this paper, 1T-MoS₂ and 2H-MoS₂, which are widely used in photocatalytic hydrogen evolution, were combined with MoO₂ to form composite catalysts using a bottom-up one-step hydrothermal method. The microstructure and morphology of the composite catalysts were studied by XRD, SEM, BET, XPS and EIS. The prepared catalysts were used in the photocatalytic hydrogen evolution of formic acid. The results show that MoS₂/MoO₂ composite catalysts have an excellent catalytic effect on hydrogen evolution from formic acid. By analyzing the photocatalytic hydrogen production performance of composite catalysts, it suggests that the properties of MoS₂ composite catalysts with different polymorphs are distinct, and different content of MoO₂ also bring differences. Among the composite catalysts, 2H-MoS₂/MoO₂ composite catalysts with 48% MoO₂ content show the best performance. The hydrogen yield is 960 µmol/h, which is 1.2 times pure 2H-MoS₂ and two times pure MoO₂. The hydrogen selectivity reaches 75%, which is 22% times higher than that of pure 2H-MoS₂ and 30% higher than that of MoO₂. The excellent performance of the 2H-MoS₂/MoO₂ composite catalyst is mainly due to the formation of the heterogeneous structure between MoS₂ and MoO₂, which improves the migration of photogenerated carriers and reduces the possibilities of recombination through the internal electric field. MoS₂/MoO₂ composite catalyst provides a cheap and efficient solution for photocatalytic hydrogen production from formic acid.

Recent Progress of Hollow Carbon Nanocages: General Design Fundamentals and Diversified Electrochemical Applications

Hollow carbon nanocages (HCNCs) consisting of sp2  carbon shells featured by a hollow interior cavity with defective microchannels (or customized mesopores) across the carbon shells, high specific surface area, and tunable electronic structure, are quilt different from the other nanocarbons such as carbon nanotubes and graphene. These structural and morphological characteristics make HCNCs a new platform for advanced electrochemical energy storage and conversion. This review focuses on the controllable preparation, structural regulation, and modification of HCNCs, as well as their electrochemical functions and applications as energy storage materials and electrocatalytic conversion materials. The metal single atoms-functionalized structures and electrochemical properties of HCNCs are summarized systematically and deeply. The research challenges and trends are also envisaged for deepening and extending the study and application of this hollow carbon material. The development of multifunctional carbon-based composite nanocages provides a new idea and method for improving the energy density, power density, and volume performance of electrochemical energy storage and conversion devices.

Enhanced Kinetic Behaviors of Hollow MoO2/MoS2 Nanospheres for Sodium-Ion-Based Energy Storage

Mo-based heterostructures offer a new strategy to improve the electronics/ion transport and diffusion kinetics of the anode materials for sodium-ion batteries (SIBs). MoO₂/MoS₂ hollow nanospheres have been successfully designed via in-situ ion exchange technology with the spherical coordination compound Mo-glycerates (MoG). The structural evolution processes of pure MoO₂, MoO₂/MoS₂, and pure MoS₂ materials have been investigated, illustrating that the structureofthenanospherecan be maintained by introducing the S-Mo-S bond. Based on the high conductivity of MoO₂, the layered structure of MoS₂ and the synergistic effect between components, as-obtained MoO₂/MoS₂ hollow nanospheres display enhanced electrochemical kinetic behaviors for SIBs. The MoO₂/MoS₂ hollow nanospheres achieve a rate performance with 72% capacity retention at a current of 3200 mA g^-1 compared to 100 mA g^-1. The capacity can be restored to the initial capacity after a current returns to 100 mA g^-1, while the capacity fading of pure MoS₂ is up to 24%. Moreover, the MoO₂/MoS₂ hollow nanospheres also exhibit cycling stability, maintaining a stable capacity of 455.4 mAh g^-1 after 100 cycles at a current of 100 mA g^-1. In this work, the design strategy for the hollow composite structure provides insight into the preparation of energy storage materials.

High-Performance Flexible Energy Storage Devices Based on Graphene Decorated with Flower-Shaped MoS2 Heterostructures

MoS₂, owing to its advantages of having a sheet-like structure, high electrical conductivity, and benign environmental nature, has emerged as a candidate of choice for electrodes of next-generation supercapacitors. Its widespread use is offset, however, by its low energy density and poor durability. In this study, to overcome these limitations, flower-shaped MoS₂/graphene heterostructures have been deployed as electrode materials on flexible substrates. Three-electrode measurements yielded an exceptional capacitance of 853 F g^-1 at 1.0 A g^-1, while device measurements on an asymmetric supercapacitor yielded 208 F g^-1 at 0.5 A g^-1 and long-term cyclic durability. Nearly 86.5% of the electrochemical capacitance was retained after 10,000 cycles at 0.5 A g^-1. Moreover, a remarkable energy density of 65 Wh kg^-1 at a power density of 0.33 kW kg^-1 was obtained. Our MoS₂/Gr heterostructure composites have great potential for the development of advanced energy storage devices.

One-Step Hydrothermal Synthesis of MoO2/MoS2 Nanocomposites as High-Performance Electrode Material for Supercapacitors

By only changing the ratio of Mo to S source, a distinctive single phase MoO2 or MoS2 and MoO2/MoS2 nanocomposites (NCs) are obtained through a simple one-step hydrothermal method based on CH4N2S as a sulfur source and (NH4)6Mo7O24·4H2O as a source of Mo in oxalic acid. The effect of ratio of Mo to S source on the composition, structure, and electrochemical performance are systematically researched. Due to its unique design, abundant macropores active sites in MoO2/MoS2 NCs induce superior rate property (55.30% capacitance retention to 20 from 1 A g-1) and larger specific capacitance (1667.3 F g-1 at 1 A g-1) and longer cycle life (94.75% after 5000 cycles) as used directly as an electrode. Furthermore, at a power density of 225 W kg-1, a maximal energy density of 21.85 Wh kg-1 is provided by the asymmetric supercapacitor (MoO2/MoS2//AC). The capacitance of asymmetric supercapacitor (ASC) is remarkably enhanced by 129.02% under 5000 cycles at a current density of 1.5 A g-1, demonstrating outstanding cycle property. These results imply the prepared MoO2/MoS2 NCs have promising applications in advanced energy storages. It is important and should be noted that NCs of oxide and sulfide are prepared with only a simple one-step process.

Self-Assembly Vertical Graphene-Based MoO3 Nanosheets for High Performance Supercapacitors

Supercapacitors have been extensively studied due to their advantages of fast-charging and discharging, high-power density, long-cycling life, low cost, etc. Exploring novel nanomaterial schemes for high-performance electrode materials is of great significance. Herein, a strategy to combine vertical graphene (VG) with MoO₃ nanosheets to form a composite VG/MoO₃ nanostructure is proposed. VGs as transition layers supply rich active sites for the growth of MoO₃ nanosheets with increasing specific surface areas. The VG transition layer further improves the electric contact and adhesion of the MoO₃ electrode, simultaneously stabilizing its volume and crystal structure during repeated redox reactions. Thus, the prepared VG/MoO₃ nanosheets have been demonstrated to exhibit excellent electrochemical properties, such as high reversible capacitance, better cycling performance, and high-rate capability.

Recent progress of hierarchical MoS2 nanostructures for electrochemical energy storage

Hierarchical MoS2 nanostructures are of increasing importance in energy storage via batteries or supercapacitors. Herein, the various hierarchical MoS2 materials as electrochemical electrode are reviewed in detail by classifying the...

NiCo2S4nanosheets decorated on nitrogen-doped hollow carbon nanospheres as advanced electrodes for high-performance asymmetric supercapacitors

Taking advantage of both Faradaic and carbonaceous materials is an efficient way to synthesize composite electrodes with enhanced performance for supercapacitors. In this study, NiCo₂S₄nanoflakes were grown on the surface of nitrogen-doped hollow carbon nanospheres (NHCSs), forming a NiCo₂S₄/NHCS composite with a core-shell structure. This three-dimensionally confined growth of NiCo₂S₄can effectively inhibit its aggregation and facilitate mass transport and charge transfer. Accordingly, the NiCo₂S₄/NHCS composite exhibited high cycling stability with only 9.2% capacitance fading after 10 000 cycles, outstanding specific capacitance of 902 F g^-1at 1 A g^-1, and it retained 90.6% of the capacitance at 20 A g^-1. Moreover, an asymmetric supercapacitor composed of NiCo₂S₄/NHCS and activated carbon electrodes delivered remarkable energy density (31.25 Wh kg^-1at 750 W kg^-1), excellent power density (15003 W kg^-1at 21.88 Wh kg^-1), and satisfactory cycling stability (13.4% capacitance fading after 5000 cycles). The outstanding overall performance is attributed to the synergistic effect of the NiCo₂S₄shell and NHSC core, which endows the composite with a stable structure, high electrical conductivity, abundant active reaction sites, and short ion-transport pathways. The synthesized NiCo₂S₄/NHCS composite is a competitive candidate for the electrodes of high-performance supercapacitors.

In-situsputtered 2D-MoS2nanoworms reinforced with molybdenum nitride towards enhanced Na-ion based supercapacitive electrodes

We report the fabrication of binder-free, low-cost and efficient hybrid supercapacitive electrode based on the hexagonal phase of two-dimensional MoS₂nanoworms reinforced with molybdenum nitride nanoflakes deposited on stainless steel (SS) substrate using reactive magnetron sputtering technique. The hybrid nanostructured MoS₂-Mo₂N/SS thin film working electrode delivers a high gravimetric capacitance (351.62 F g^-1at 0.25 mA cm^-2) investigated in 1 M Na₂SO₄aqueous solution. The physisorption/intercalation of sodium (Na⁺) ions in electroactive sites of MoS₂-Mo₂N composite ensures remarkable electrochemical performance. The deposited porous nanostructure with good electrical conductivity and better adhesion with the current collector demonstrates a high-energy density of 82.53 Wh kg^-1in addition to a high-power density of 24.98 kW kg^-1. Further, excellent capacitance retention of 93.62% after 4000 galvanostatic charge-discharge cycles elucidated it as a promising candidate for realizing high-performance supercapacitor applications.

Construction of MoO2@MoS2 heterostructures in situ on carbon cloth for the hydrogen evolution reaction

MoO2@MoS2 heterostructures in situ grown on carbon cloth were developed for efficient hydrogen evolution reaction.

Ni or FeO nanocrystal-integrated hollow (solid) N-doped carbon nanospheres: preparation, characterization and electrochemical properties

In this paper, phase-pure monodisperse NiO nanocrystals were prepared in a temperature-dependent manner via a thermal decomposition approach, showing sphere-like shapes and snowflake-like NiO arrays. Such hydrophobic NiO nanocrystals were converted into hydrophilic nickel oxide-sodium oleate-Pluronic P123 (NiO-SO-P123) micelles in aqueous solution. Phenolic resin (PR) formed in situ was successfully deposited on the hydrophilic area of the NiO-SO-P123 micelles via a heterogeneous nucleation mechanism to form NiO-phenolic resin nanospheres (NiO-PRNSs) with uniform particle size. By adjusting the size and amount of NiO nanocrystals used, the diameter of the obtained NiO-PRNSs can be effectively controlled from 185 to 103 nm, and a narrow size distribution is seen, revealing the effects of the NiO nanocrystals on the reconstructed NiO-integrated micellar size. Meanwhile, the morphology (ring buoy, semi-bowl, sphere) depends upon the initial amount of NiO. The carbonization of NiO-PRNSs produced Ni(0)-integrated hollow N-doped carbon nanospheres (Ni(0)-HNCNSs), which involved the conversion of NiO to Ni(0) and the contraction of particle size, and the size and distribution was affected by the starting amount of NiO. However, upon using monodisperse and polyhedral FeO nanocrystals, the obtained FeO-free/-incompletely-filled/-fully-filled core-shell structured Fe-PRNSs showed relatively uniform particle size, except for when multiple FeO cores formed large FeO-PR nanospheres after starting with the same initial FeO size. The carbonized FeO-HNCNSs still preserved a pomegranate-like core-shell structure with uniform size and there was no change in the size of the FeO nanocrystals. Moreover, high-loaded Ni(0)-integrated hollow or solid N-doped carbon microspheres or flakes can be synthesized via a one-pot method, but with a broad size range, showing highly uniform Ni distribution with a Ni size as small as 8.5 nm. Note that Ni(0)- and FeO-HNCNSs were prepared for the first time according to our knowledge. Finally, low-loaded Ni- and FeO-HNCNSs with uniform morphology and size were chosen as representatives to investigate their electrochemical properties for lithium-ion batteries (LIBs), showing excellent lithium storage properties and superior reversibility. This study provides a potential strategy for controlling the sizes and morphologies of metal-integrated carbon materials to obtain adjustable electrochemical properties.

One-Step Sublimation and Epitaxial Growth of CdS-Cd Heterogeneous Nanoparticles on S-Doped MoO2 Nanosheets for Efficient Visible Light-Driven Photocatalytic H2 Generation

As a green, pollution-free, and renewable clean energy source, photocatalytic H₂ production has attracted great attention. Here, epitaxial growth of pyramidal CdS-Cd nanoparticles on S-doped MoO₂ nanosheets (CdS-Cd/S-MoO₂) was prepared by one-step co-sublimation of CdS and MoO₃. The photogenerated electrons of CdS as a photocatalyst are transferred to Cd and S-MoO₂ as co-catalysts for H₂ production, which is observed by surface photovoltage (SPV) under visible light irradiation. At last, the obtained CdS-Cd/S-MoO₂ presented an efficient photocatalytic performance under the visible light (>420 nm) with a prominent H₂ generation rate of as high as 24.98 μmol h^-1 mg^-1, which is 11 times higher than that of the CdS-Cd nanoparticles (2.26 μmol h^-1 mg^-1), and it is superior than that of the CdS (1.51 μmol h^-1 mg^-1).

An in Situ Template for the Synthesis of Tunable Hollow Carbon Particles for High-Performance Lithium-Sulfur Batteries

Nanostructured materials with hollow interior voids are gaining great attention due to their fantastic geometries and unique physicochemical properties competent for many applications. However, the development of a fast approach to prepare the hollow structured particles remains challenging. Herein, a new and efficient in situ hard-template method was developed to synthesize hollow carbon nano- and microparticles using the as-prepared SiO₂ particles as a hard template directly, without any separation, drying, or redispersion. In this way, the hollow carbon particles with tunable diameters and shell thickness can be synthesized readily, which is simpler and more efficient than the traditional ones. In addition, the universality of this strategy allows us to study the different behaviors of hollow carbon particles in lithium-sulfur batteries when the architectures of hollow particles (i.e., diameter, shell thickness, etc.) were changed. We believe that this in situ method is applicable for synthesizing other core-shell or hollow structured materials (e.g., metal oxide), and also, the high performance of hollow carbon particles in lithium-sulfur batteries and beyond can be further explored.

Hydrogen Bond between Molybdate and Glucose for the Formation of Carbon-Loaded MoS2 Nanocomposites with High Electrochemical Performance

The effects of glucose on the growth and surface properties of MoS₂ with a nanosheet structure were investigated in detail. In the presence of glucose, the hydrothermal reaction of sodium molybdate and thiourea yields carbon-loaded MoS₂ nanocomposites (C/MoS₂). Compared with bare MoS₂ nanosheets with more than six layers obtained in the absence of glucose and carbon spheres with a diameter of 500 nm prepared from the carbonization of glucose, C/MoS₂ consists of one- or three-layered MoS₂ and carbon spheres with a diameter less than 1 nm to give a large Brunauer-Emmett-Teller surface area (3-20 times larger than the individual materials). The surface characterizations reveal that both MoS₂ and carbon spheres of C/MoS₂ have a negative charge on the surface, suggesting that the previously reported explanation, in which the adsorption of MoS₂ and/or molybdate ions on carbon spheres inhibits the growth and aggregation of MoS₂, is not correct. Based on Fourier transform infrared and ¹H NMR spectra, it is demonstrated that glucose acts as the hydrogen bond donor toward polyoxomolybdate species such as Mo₈O₂₆^4-, Mo₇O₂₄^6-, and MoO₄^2- in the range of pH = 2-12. The intermolecular hydrogen bond not only inhibits the growth of both the (002) plane of MoS₂ and carbon spheres, but also enables the formation of C-O-Mo bonds in the in situ generated C/MoS₂. Compared with bare MoS₂, C/MoS₂ not only show a lower over-potential by 60 mV for the electrocatalytic evolution of hydrogen, but also has a larger mass specific capacitance by three times, due to the larger surface area and the interfacial interaction through the C-O-Mo bonds.

Sb2S3 Nanoparticles Anchored or Encapsulated by the Sulfur-Doped Carbon Sheet for High-Performance Supercapacitors

The specific capacitance and energy density of antimony trisulfide (Sb₂S₃)@carbon supercapacitors (SCs) have been limited and are in need of significant improvement. In this work, Sb₂S₃ nanoparticles were selectively encapsulated or anchored in a sulfur-doped carbon (S-carbon) sheet depending on the use of microwave-assisted synthesis. The microwave-triggered Sb₂S₃ nanoparticle growth resulted in core-shell hierarchical spherical particles of uniform diameter assembled with Sb₂S₃ as the core and an encapsulated S-carbon layer as the shell (Sb₂S₃-M@S-C). Without the microwave mediation, the other nanostructure was found to comprise fine Sb₂S₃ nanoparticles widely anchored in the S-carbon sheet (Sb₂S₃-P@S-C). Structural and morphological analyses confirmed the presence of encapsulated and anchored Sb₂S₃ nanoparticles in the carbon. These two materials exhibited higher specific capacitance values of 1179 (0 to +1.0 V) and 1380 F·g^-1 (-0.8 to 0 V) at a current density of 1 A·g^-1, respectively, than those previously reported for Sb₂S₃ nanomaterials in considerable SCs. Furthermore, both materials exhibited outstanding reversible capacitance and cycle stability when used as SC electrodes while retaining over 98% of the capacitance after 10 000 cycles, which indicates their long-term stability. Furthermore, a hybrid Sb₂S₃-M@S-C/Sb₂S₃-P@S-C device was designed, which delivers a remarkable energy density of 49 W·h·kg^-1 at a power density of 2.5 kW·kg^-1 with long-term cycle stability (94% over 10 000 cycles) and is comparable to SCs in the recent literature. Finally, a light-emitting diode (LED) panel comprising 32 LEDs was powered using three pencil-type hybrid SCs in series.

Solution Self-Assembly of an Alternating Copolymer toward Hollow Carbon Nanospheres with Uniform Micropores

Controllable preparation of porous hollow carbon spheres (HCSs) has attracted considerable attention due to their potential applications, e.g., in energy conversion and storage. We report for the first time the synthesis of narrowly size-distributed HCSs with uniform micropores in the wall, through a simple template-free approach, which employs the solution self-assembly of an alternating copolymer (poly(9,9'-bis(4-glycidyloxyphenyl)fluorene-alt-2,3-dihydroxy-butylene dithioether) (P(BGF-a-DHBDT))). This alternating copolymer first self-assembled into previously undocumented hollow polymeric spheres (HPSs) in an N,N-dimethylformamide (DMF)/H₂O solvent mixture. After the cross-linking of the BGF segments in the spheres, the stabilized HPSs (CL-HPSs) were carbonized at 800 °C under N₂ atmosphere, yielding porous HCSs with uniform micropores of very narrow size distribution (0.4-0.8 nm) in the wall, benefiting from the uniform DHBDT block length in the alternating copolymer. Through KOH activation, which made the internal pores fully interconnected, uniform micropores (0.5-1.0 nm) of a narrow size distribution were retained within the activated HCSs (A-HCSs), while their specific surface areas (SSAs) were much increased to 2580 m² g^-1. As a proof of concept, the A-HCSs were applied as electrode materials of supercapacitors. They exhibited superior electrochemical performance with a high specific capacitance (292 F g^-1 at 0.2 A g^-1), good rate capability, and outstanding cycling stability with no apparent capacitance loss after 10 000 cycles.

Toward a high performance asymmetric hybrid capacitor by electrode optimization

Molybdenum disulfide (MoS₂) is an extremely promising electrode material for supercapacitors due to its superior electrochemical performance and conductivity.