Construction of hierarchical cobalt-molybdenum selenide hollow nanospheres architectures for high performance battery-supercapacitor hybrid devices

Amorphous/polycrystalline NiMn selenide for high-performance supercapacitors

Transition-metal selenides have been extensively studied as promising electrode materials for supercapacitors. Engineering amorphous/crystalline heterostructures is an effective strategy to improve rich active sites for accelerating redox reaction kinetics but still lacks exploration. In this study, an amorphous/crystalline heterostructure was designed and constructed by selenizing the self-sacrificial template NiMnS to generate amorphous Mn/polycrystalline Ni0.85Se-NiSe2 heterophase via the phase transformation from metal sulfide into metal selenide. The synergy of the complementary multi-components and amorphous/polycrystalline heterophase could enrich electron/ion-transport channels and expose abundant active sites, which accelerated electron/ion transfer and Faradaic reaction kinetics during charging/discharging. As expected, the optimal NiMnSe exhibited a high specific charge (1389.1 C g-1 at 1 A g-1), a good rate capability, and an excellent lifespan (88.9% retention). Moreover, the fabricated NiMnSe//activated carbon device achieved a long cycle life and energy density of 48.0 W h kg-1 at 800 W kg-1, shedding light on the potential for use in practical applications, such as electrochemical energy-storage devices.

V-MXenes for Energy Storage/Conversion Applications

MXenes, a two-dimensional (2D) material, exhibit excellent optical, electrical, chemical, mechanical, and electrochemical properties. Titanium-based MXene (Ti-MXene) has been extensively studied and serves as the foundation for 2D MXenes. However, other transition metals possess the potential to offer excellent properties in various applications. This comprehensive review aims to provide an overview of the properties, challenges, key findings, and applications of less-explored vanadium-based MXenes (V-MXenes) and their composites. The current trends in V-MXene and their composites for energy storage and conversion applications have been thoroughly summarized. Overall, this review offers valuable insights, identifies potential opportunities, and provides key suggestions for future advancements in the MXenes and energy storage/conversion applications.

Advances in Mn-Based MOFs and Their Derivatives for High-Performance Supercapacitor

As the most widely used metal material in supercapacitors, manganese (Mn)-based materials possess the merits of high theoretical capacitance, stable structure as well as environmental friendliness. However, due to poor conductivity and easy accumulation, the practical capacitance of Mn-based materials is far lower than that of theoretical value. Therefore, accurate structural adjustment and controllable strategies are urgently needed to optimize the electrochemical properties of Mn-based materials. Metal-organic frameworks (MOFs) are porous materials with high specific surface area (SSA), tunable pore size, and controllable structure. These features make them attractive as precursors or scaffold for the synthesis of metal-based materials and composites, which are important for electrochemical energy storage applications. Therefore, a timely and comprehensive review on the classification, design, preparation and application of Mn-based MOFs and their derivatives for supercapacitors has been given in this paper. The recent advancement of Mn-based MOFs and their derivatives applied in supercapacitor electrodes are particularly highlighted. Finally, the challenges faced by Mn-MOFs and their derivatives for supercapacitors are summarized, and strategies to further improve their performance are proposed. The aspiration is that this review will serve as a beneficial compass, guiding the logical creation of Mn-based MOFs and their derivatives in the future.

Designing transition metal-based porous architectures for supercapacitor electrodes: a review

Over the past decade, transition metal (TM)-based electrodes have shown intriguing physicochemical properties and widespread applications, especially in the field of supercapacitor energy storage owing to their diverse configurations, composition, porosity, and redox reactions. As one of the most intriguing research interests, the design of porous architectures in TM-based electrode materials has been demonstrated to facilitate ion/electron transport, modulate their electronic structure, diminish strain relaxation, and realize synergistic effects of multi-metals. Herein, the recent advances in porous TM-based electrodes are summarized, focusing on their typical synthesis strategies, including template-mediated assembly, thermal decomposition strategy, chemical deposition strategy, and host-guest hybridization strategy. Simultaneously, the corresponding conversion mechanism of each synthesis strategy are reviewed, and the merits and demerits of each strategy in building porous architectures are also discussed. Subsequently, TM-based electrode materials are categorized into TM oxides, TM hydroxides, TM sulfides, TM phosphides, TM carbides, and other TM species with a detailed review of their crystalline phase, electronic structure, and microstructure evolution to tune their electrochemical energy storage capacity. Finally, the challenges and prospects of porous TM-based electrode materials are presented to guide the future development in this field.

Coupling MoSe2 with Non-Stoichiometry Ni0.85 Se in Carbon Hollow Nanoflowers for Efficient Electrocatalytic Synergistic Effect on Li-O2 Batteries

Li-O2 batteries could deliver ultra-high theoretical energy density compared to current Li-ion batteries counterpart. The slow cathode reaction kinetics in Li-O2 batteries, however, limits their electrocatalytic performance. To this end, MoSe2 and Ni0.85 Se nanoflakes were decorated in carbon hollow nanoflowers, which were served as the cathode catalysts for Li-O2 batteries. The hexagonal Ni0.85 Se and MoSe2 show good structural compatibility with the same space group, resulting in a stable heterogeneous structure. The synergistic interaction of the unsaturated atoms and the built-in electric fields on the heterogeneous structure exposes abundant catalytically active sites, accelerating ion and charge transport and imparting superior electrochemical activity, including high specific capacities and stable cycling performance. More importantly, the lattice distances of the Ni0.85 Se (101) plane and MoSe2 (100) plane at the heterogeneous interfaces are highly matched to that of Li2 O2 (100) plane, facilitating epitaxial growth of Li2 O2 , as well as the formation and decomposition of discharge products during the cycles. This strategy of employing nonstoichiometric compounds to build heterojunctions and improve Li-O2 battery performance is expected to be applied to other energy storage or conversion systems.

Coaxial nickel cobalt selenide/nitrogen-doped carbon nanotube array as a three-dimensional self-supported electrode for electrochemical energy storage

Herein, we propose a one-step urea pyrolysis method for preparing a nitrogen-doped carbon nanotube array grown on carbon fiber paper, which is demonstrated as a three-dimensional scaffold for constructing a nickel cobalt selenide-based coaxial array structure. Thanks to the large surface area, interconnected porous structure, high mass loading, as well as fast electron/ion transport pathway of the coaxial array structure, the nickel cobalt selenide/nitrogen-doped carbon nanotube electrode exhibits over 7 times higher areal capacity than that directly grown on carbon fiber paper, and better rate capability. The cell assembled by a nickel cobalt selenide/nitrogen-doped carbon nanotube positive electrode and an iron oxyhydroxide/nitrogen-doped carbon nanotube negative electrode delivers a volumetric capacity of up to 22.5 C cm-3 (6.2 mA h cm-3) at 4 mA cm-2 and retains around 86% of the initial capacity even after 10 000 cycles at 10 mA cm-2. A volumetric energy density of up to 4.9 mW h cm-3 and a maximum power density of 208.1 mW cm-3 are achieved, and is comparable to, if not better than, those of similar energy storage devices reported previously.

Hierarchical Mn3O4/NiSe2-MnSe2: A Versatile Electrode Material for High-Performance All-Solid-State Hybrid Pseudocapacitors with Supreme Working Durability

As highly efficient electrochemical energy storage devices are in indispensable demand for numerous modern-day technologies, herein sluggish precipitation followed by an anion exchange procedure has been developed to synthesize an oxide-selenide mixed phase (Mn3O4/NiSe2-MnSe2) novel electrode material with high surface area and porosity for high-performance all-solid-state hybrid pseudocapacitors (ASSHPC). Mn3O4/NiSe2-MnSe2 shows a rich Tyndall effect (in H2O) and possesses randomly arranged low-dimensional crystallites of nearly similar size and uniform shape. The electrochemical analyses of Mn3O4/NiSe2-MnSe2 corroborate good electrochemical reversibility during charge transfer, superior pseudocapacitive charge-storage efficiency, and very low charge transfer and series resistance, ion-diffusion resistance, and relaxation time, which endorse the quick pseudocapacitive response of the material. The Mn3O4/NiSe2-MnSe2||N-rGO ASSHPC device demonstrates excellent charge-storage physiognomies suggestive of rich electrochemical and electromicrostructural compatibility between the electrode materials in the fabricated assembly. The Mn3O4/NiSe2-MnSe2||N-rGO ASSHPC device delivers high mass and area specific capacitance/capacity, very low charge-transfer resistance (∼0.74 Ω), total series resistance (∼0.76 Ω), diffusion resistance, and a relaxation time constant, which endorse the quick pseudocapacitive response of the device. The device delivers higher energy and power density (∼34 W h kg-1 at ∼2994 W kg-1), rate efficiency (∼17 W h kg-1 at ∼11,995 W kg-1), and cyclic performance (∼97.2% specific capacity/capacitance retention after 9500 continuous GCD cycles). The superior Ragone and cyclic efficiencies of the ASSHPC device are ascribed to the multiple redox-active Ni and Mn ions which lead to the supplemented number of redox reactions; "electroactive-ion buffering pool"-like physiognomics of Mn3O4/NiSe2-MnSe2, which facilitate the electrolyte ion dissemination to the electroactive sites even at high rate redox condition; and ideal electro-microstructural compatibility between the electrode materials, which leads to assisted charge transfer and absolute ion dissemination during the charge-storage process.

Multifunctional metal selenide-based materials synthesized via a one-pot solvothermal approach for electrochemical energy storage and conversion applications

Highly-efficient electroactive materials with distinctive electrochemical features, along with suitable strategies to prepare hetero-nanoarchitectures incorporating two or more transition metal selenides, are currently required to increase charge storage ability. Herein, a one-pot solvothermal approach is used to develop iron-nickel selenide spring-lawn-like architectures (FeNiSe SLAs) on nickel (Ni) foam. The porous Ni foam scaffold not only enables the uniform growth of FeNiSe SLAs but also serves as an Ni source. The effect of reaction time on their morphological and electrochemical properties is investigated. The FeNiSe-15 h electrode shows high areal capacity (493.2 μA h cm-2) and superior cycling constancy. The as-assembled aqueous hybrid cell (AHC) demonstrates high areal capacity and a decent rate capability of 59.4% (50 mA cm-2). The AHC exhibits good energy and power densities, along with excellent cycling stability. Furthermore, to confirm its practicability, the AHC is employed to drive portable electronic appliances by charging it with wind energy. The electrocatalytic activity of FeNiSe-based materials to complete the oxygen evolution reaction (OER) is explored. Among them, the FeNiSe-15 h catalyst shows good OER performance at a current density of 50 mA cm-2. This general synthesis approach may initiate a strategy of advanced metal selenide-based materials for multifunctional applications.

Cobalt-molybdenum-selenide nanoflowers for bifunctional visible light photocatalysis

The renewability and zero carbon emissions of hydrogen make it a promising clean energy resource to meet future energy demands. Owing to its benefits, photocatalytic water-splitting has been extensively investigated for hydrogen production. However, the low efficiency poses a serious challenge to its implementation. Herein, we attempted to synthesize bimetallic transition metal selenides, namely Co/Mo/Se (CMS) photocatalysts, with varying atomic compositions (CMSa, CMSb, and CMSc) and investigated their photocatalytic water splitting efficiencies. The observed hydrogen evolution rates were as follows: 134.88 μmol g^-1 min^-1 for CoSe₂, 145.11 μmol g^-1 min^-1 for MoSe₂, 167.31 μmol g^-1 min^-1 for CMSa, 195.11 μmol g^-1 min^-1 for CMSb, and 203.68 μmol g^-1 min^-1 for CMSc. Hence, we deemed CMSc to be the most potent photocatalytic alternative among the compounds. CMSc was also tested for its efficiency towards degradation of triclosan (TCN), and results substantiated that CMSc succeeded degrading 98% TCN while CMSa and b were able to degrade 80 and 90% TCN respectively-the attained efficiency being exponentially higher than CoSe₂ and MoSe₂ taken for comparative analysis in addition to complete degradation of the pollutants leaving no harmful intermediaries during the process. Thus, CMSc shall be identified as a highly potential photocatalyst with respect to both environmental and energy applications.

Synthesis and Nanostructure Investigation of Hybrid β-Ga2 O3 /ZnGa2 O4 Nanocomposite Networks with Narrow-Band Green Luminescence and High Initial Electrochemical Capacity

The material design of functional "aero"-networks offers a facile approach to optical, catalytical, or and electrochemical applications based on multiscale morphologies, high large reactive area, and prominent material diversity. Here in this paper, the synthesis and structural characterization of a hybrid β-Ga₂ O₃ /ZnGa₂ O₄ nanocomposite aero-network are presented. The nanocomposite networks are studied on multiscale with respect to their micro- and nanostructure by X-ray diffraction (XRD) and transmission electron microscopy (TEM) and are characterized for their photoluminescent response to UV light excitation and their electrochemical performance with Li-ion conversion reaction. The structural investigations reveal the simultaneous transformation of the precursor aero-GaN(ZnO) network into hollow architectures composed of β-Ga₂ O₃ and ZnGa₂ O₄ nanocrystals with a phase ratio of ≈1:2. The photoluminescence of hybrid aero-β-Ga₂ O₃ /ZnGa₂ O₄ nanocomposite networks demonstrates narrow band (λ_em  = 504 nm) green light emission of ZnGa₂ O₄ under UV light excitation (λ_ex  = 300 nm). The evaluation of the metal-oxide network performance for electrochemical application for Li-ion batteries shows high initial capacities of ≈714 mAh g^-1 at 100 mA g^-1 paired with exceptional rate performance even at high current densities of 4 A g^-1 with 347 mAh g^-1 . This study provides is an exciting showcase example of novel networked materials and demonstrates the opportunities of tailored micro-/nanostructures for diverse applications a diversity of possible applications.

Kappa-carrageenan for benign preparation of CdSeNPs enhancing the electrochemical measurement of AC symmetric supercapacitor device based on neutral aqueous electrolyte

This study presents the development of an electrochemical supercapacitor with a cadmium selenide nanoparticles (CdSeNPs) electrode utilizing a straightforward and economical method based on kappa-carrageenan (κ-CGN). The structural, morphological, and optical characteristics of CdSeNPs were assessed. Activated carbon (AC) and green-prepared CdSeNPs were easily mixed to achieve excellent electrochemical properties. The nanoelectrode (AC@CdSe) was tested in an aqueous electrolyte of sodium sulfate (Na₂SO₄) with a concentration of 1 Molar. Specific capacitance (Csp) for the AC electrode and the AC@CdSe electrode at 1 A g^-1 was calculated to be 103 and 480 F g^-1, respectively. Besides, the symmetric supercapacitor AC@CdSe/AC@CdSe device has a high specific energy of 52 Wh kg^-1 and a maximum specific power of 2880 W kg^-1, with a specific capacitance of 115.5 F g^-1. With a coulombic efficiency of between 82 % and 100 %, the device continues to maintain excellent capacitance after 10.000 cycles.

H-CoNiSe2/NC dodecahedral hollow structures for high-performance supercapacitors

The synergistic effect between metal ions and increasing the surface area leads to the fabrication of supercapacitor materials with high capacities. It is predicted that transition metal selenide compounds will be ideal electrode materials for supercapacitors. However, the defects of poor conductivity and volume expansion of the compounds are fundamental problems that must be solved. In this work, we successfully synthesized the cobalt-nickel selenide nitrogen-doped carbon (H-CoNiSe₂/NC) hollow polyhedral composite structure using ZIF-67 as a precursor. The CoSe₂ and NiSe₂ nanoparticles embedded in the NC polyhedral framework offer a wealth of active sites for the whole electrode. Moreover, the presence of the NC structure in the proposed composite can simultaneously lead to improved conductivity and reduce the volume effect created during the cycling procedure. The H-CoNiSe₂/NC electrode provides high specific capacity (1131 C/g at 1.0 A/g) and outstanding cyclic stability (90.2% retention after 6000 cycles). In addition, the H-CoNiSe₂/NC//AC hybrid supercapacitor delivers ultrahigh energy density and power density (81.9 Wh/kg at 900 W/kg) and excellent cyclic stability (92.1% of the initial capacitance after 6000 cycles). This study will provide a supercapacitor electrode material with a high specific capacity for energy storage devices.Please confirm the corresponding affiliation for the 'Ali A. Ensafi' author is correctly identified.Error during converting author query response. Please check the eproofing link or feedback pdf for details.

Bimetallic CoSe2/FeSe2 hollow nanocuboids assembled by nanoparticles as a positive electrode material for a high-performance hybrid supercapacitor

Design and fabrication of impressive and novel electrode materials for energy storage devices, especially supercapacitors, are of great importance. Herein, bimetallic CoSe₂/FeSe₂ hollow nanocuboid nanostructures derived from Co/Fe-Prussian Blue analogues (denoted as CoSe₂/FeSe₂ HNCs) are successfully designed and fabricated as a remarkable positive electrode material for high-performance supercapacitors. The bimetallic CoSe₂/FeSe₂ HNC nanostructures can have increased active sites and short electron-ion diffusion pathways. Bimetallic CoSe₂/FeSe₂ HNCs@NiF as a positive electrode showed efficient supercapacitive properties with a great specific capacity of 332.75 mA h g^-1 (1197.90 C g^-1) at 1 A g^-1, retaining 80.61% of its initial capacity at 20 A g^-1, considerable longevity (91.47% of its initial capacity after 10 000 cycles) and an excellent coulombic efficiency of 98.49%. Also, the designed and fabricated CoSe₂/FeSe₂ HNCs@NiF||AC@NiF hybrid supercapacitor device using bimetallic CoSe₂/FeSe₂ HNCs@NiF (positive electrode) and activated carbon@NiF (AC, negative electrode) exhibited an efficient energy density of 63.62 W h kg^-1 and a superior durability of 91.14% after 10 000 cycles.

Selenization governs the intrinsic activity of copper-cobalt complexes for enhanced non-radical Fenton-like oxidation toward organic contaminants

Non-radical oxidation pathways in the Fenton-like process have a superior catalytic activity for the selective degradation of organic contaminants under complicated water matrices. Whereas the synthesis of high-performance catalysts and research on reaction mechanisms are unsatisfactory. Herein, it was the first report on copper-cobalt selenide (CuCoSe) that was well-prepared to activate hydrogen peroxide (H₂O₂) for non-radical species generation. The optimized CuCoSe+H₂O₂ system achieved excellent removal of chlortetracycline (CTC) in 10 min at neutral pH along with pleasing reusability and stability. Moreover, it exhibited great anti-interference capacity to inorganic anions and natural organic matters even in actual applications. Multi-surveys verified that singlet oxygen (¹O₂) was the dominant active species in this reaction and electron transfer on the surface-bound of CuCoSe and H₂O₂ likewise played an important role in direct CTC oxidation. Where the synergetic metals of Cu and Co accounted for the active sites, and the introduced Se atoms accelerated the circulation efficiency of Co³⁺/Co²⁺, Cu²⁺/Cu⁺ and Cu²⁺/Co²⁺. Simultaneously, the produced Se/O vacancies further facilitated electron mediation to enhance non-radical behaviors. With the aid of intermediate identification and theoretical calculation, the degradation pathways of CTC were proposed. And the predicted ecotoxicity indicated a decrease in underlying environmental risk.

In-situ construction of heterostructure (Ni, Co)Se2 nanoarrays derived from cone-like ZIF-L for high-performance hybrid supercapacitors

The construction of heterostructure could enhance the electron transfer efficiency and increase the number of active sites, which can further develop high-performance electrode materials of supercapacitors. Herein, (Ni, Co)Se₂ nanorod arrays were prepared based on the NiCo-LDH derived from a conical ZIF-L. Significantly, the single nanorod is composed of interconnected NiSe₂ and CoSe₂ nanoparticles, the heterostructure can expose higher conductivity, more sufficient redox reaction active sites and larger specific surface area. The as-obtained CF@(Ni, Co)Se₂ achieved a high specific capacity of 188.8 mAh g^-1 at the current density of 1.0 A g^-1 and an outstanding cycling stability with a high capacity retention of 90% after 8000 cycles. Finally, an hybrid supercapacitor device composed of activated carbon (AC) as negative electrode and CF@(Ni, Co)Se₂ as positive electrode was designed, which revealed an ideal voltage window of 0-1.6 V and exhibited a great energy density of 36.02 Wh kg^-1 at the power density of 800 W kg^-1, such surpassing energy storage characteristics evidently testify that (Ni, Co)Se₂ nanorod arrays can be as the potential electrode material to promote the development of high-performance supercapacitors.

Recent progress on transition metal diselenides from formation and modification to applications

The development of graphene promotes the research of similar two-dimensional (2D) materials, especially 2D transition metal dichalcogenides (TMDCs) with semiconductor properties. Monolayer or few-layer TMDCs have several advantages, such as direct band gap, weak interlayer van der Waals force, large interlayer spacing, and abundant marginal active sites, which make them widely used in catalysis, optoelectronics, as well as energy conversion and storage devices. In addition, transition metal diselenides (TMDSs) also possess many intriguing characteristics. For instance, transition metal diselenides (e.g., MoSe₂) have a more stable 1T phase, larger interlayer spacing, smaller band gap, and more obvious metallic property of Se than TMDCs (e.g., MoS₂). Thus, it has become one of the most attractive research topics branching out from TMDCs. Herein, this review unveils the structures, synthesis, properties, modifications, applications, and perspectives for TMDSs.

Three-dimensional graphene encapsulated hollow CoSe2-SnSe2nanoboxes for high performance asymmetric supercapacitors

Construction of metal selenides with a large specific surface area and a hollow structure is one of the effective methods to improve the electrochemical performance of supercapacitors. However, the nano-material easily agglomerates due to the lack of support, resulting in the loss of electrochemical performance. Herein, we successfully design a three-dimensional graphene (3DG) encapsulation-protected hollow nanoboxes (CoSe₂-SnSe₂) composite aerogel (3DG/CoSe₂-SnSe₂) via a co-precipitation method coupled with self-assembly route, followed by a high temperature selenidation strategy. The obtained aerogel possesses porous 3DG conductive network, large specific surface area and plenty of reactive active sites. It could be used as a flexible and binder-free electrode after a facile mechanical compression process, which provided a high specific capacitance of 460 F g^-1at 0.5 A g^-1, good rate capability of 212.7 F g^-1at 10 A g^-1The capacitance retention rate is 80% at 2 A g^-1after 5000 cycles due to the fast electron/ion transfer and electrolyte diffusion. With the as-prepared 3DG/CoSe₂-SnSe₂as positive electrodes and the AC (activated carbon) as negative electrodes, an asymmetric supercapacitor (3DG/CoSe₂-SnSe₂//AC) was fabricated, which delivered a high specific capacity of 38 F g^-1at 1 A g^-1and an energy density of 11.89 Wh kg^-1at 749.9 W kg^-1, as well as excellent cycle stability. This work provides a new method for preparing electrode material.

A 2H-MoS2/carbon cloth composite for high-performance all-solid-state supercapacitors derived from a molybdenum dithiocarbamate complex

A molecular complex Mo₂O₂(μ-S)₂(Et₂dtc)₂ (dtc = dithiocarbamate) is prepared and loaded onto carbon cloth (CC) through facile solvothermal treatment, followed by subsequent single-source pyrolysis. This results in a highly porous 2H-MoS₂/CC composite with a sponge-like stacked lamellar morphology. Due to its high porosity and unique nano/microstructure, the MoS₂/CC composite exhibits a specific capacitance of 550.0 F g^-1 at 1 A g^-1, outperforming some 1T-MoS₂ based electrodes. The composite is further assembled into a symmetric all-solid-state supercapacitor, which can be operated stably at a wide potential window and shows a specific capacitance of 127.5 F g^-1 at 1 A g^-1. In addition, the device delivers a high energy density of 70.8 W h kg^-1 at 1 kW kg^-1, which still remains 15.0 W h kg^-1 at 18.0 kW kg^-1. 75% of the performance of the device can be retained after 8000 cycles. Such remarkable electrochemical performance is attributed to its novel nano/microstructures with a large surface area, convenient ion transport pathways, enhanced conductivity, and improved structural stability. Thus, this work demonstrates a highly promising dithiocarbamate-based single-precursor pyrolysis route towards the fabrication of metal sulfides/carbon composites for energy storage applications.

Metal-organic-framework derived hollow manganese nickel selenide spheres confined with nanosheets on nickel foam for hybrid supercapacitors

Metal-organic framework (MOF) derived nanoarchitectures have special features, such as high surface area (SA), abundant active sites, exclusive porous networks, and remarkable supercapacitive performance when compared to traditional nanoarchitectures. Herein, we propose a viable strategy for the synthesis of hollow manganese nickel selenide spheres comprising nanosheets supported on the nickel foam (denoted as MNSe@NF) from the MOF. The MNSe nanostructures can demonstrate enriched active sites, and shorten the ion-electron diffusion pathways. When the MNSe@NF electrode is used as a cathode electrode for a hybrid supercapacitor, the electrode reflected impressive supercapacitive properties with a high capacity of 325.6 mA h g-1 (1172.16 C g-1) at 2 A g-1, an exceptional rate performance of 86.6% at 60 A g-1, and remarkable longevity (3.2% capacity decline after 15 000 cycles). Also, the assembled MNSe@NF∥AC@NF hybrid supercapacitors employing activated carbon on the nickel foam (AC@NF, anode electrode) and MNSe@NF (cathode electrode) revealed an impressive energy density of 66.1 W h kg-1 at 858.45 W kg-1 and an excellent durability of 94.1% after 15 000 cycles.

Transition metal dichalcogenide (TMDs) electrodes for supercapacitors: a comprehensive review

As globally, the main focus of the researchers is to develop novel electrode materials that exhibit high energy and power density for efficient performance energy storage devices. This review covers the up-to-date progress achieved in transition metal dichalcogenides (TMDs) (e.g. MoS₂, WS₂, MoSe_2,and WSe₂) as electrode material for supercapacitors (SCs). The TMDs have remarkable properties like large surface area, high electrical conductivity with variable oxidation states. These properties enable the TMDs as the most promising candidates to store electrical energy via hybrid charge storage mechanisms. Consequently, this review article provides a detailed study of TMDs structure, properties, and evolution. The characteristics technique and electrochemical performances of all the efficient TMDs are highlighted meticulously. In brief, the present review article shines a light on the structural and electrochemical properties of TMD electrodes. Furthermore, the latest fabricated TMDs based symmetric/asymmetric SCs have also been reported.

Organic phosphomolybdate: a high capacity cathode for potassium ion batteries

This work firstly introduces tetra-n-butylammonium phosphomolybdate into potassium ion batteries as a high capacity cathode.