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Summary: The pyrolysis of metal‐organic frameworks (MOFs) to derive porous nanocarbons and metal oxides has attracted scientific attention due to the advantageous properties of the final products (eg, high surface areas). In the present research, MIL‐125 (MIL = Materials of Institute Lavoisier, a Ti‐based MOF) has been subjected to a single‐step pyrolysis treatment in argon atmosphere. The combination of uniformly linked titanium metal cluster and oxygen‐enriched organic linker has acted as a template to yield a titanium dioxide (TiO2)–carbon nanocomposite. The TiO2 nanoparticles infused in carbon skeleton structure (TiO2/C) has been investigated as an electrode material for supercapacitor applications. TiO2/C electrodes have delivered an excellent electrochemical performance, for example, in terms of charging–discharging efficiency. Two equally weighed TiO2/C electrodes have been used to assemble a solid‐state symmetrical supercapacitor (SC) device, containing a gel electrolyte (poly vinyl alcohol in 1 M H2SO4). The above device has delivered a high value of energy density (43.5 Wh/kg) and an excellent power output of 0.865 kW/kg. The symmetrical SC could retain almost 95% of its initial capacitance even after 2000 charging–discharging cycles. The electrochemical performance of the TiO2/C SC was better than most MOF‐based SCs reported previously. Such performance is attributed to the synergistic combination of electrically conducting MOF‐derived carbon and redox active TiO2 nanocrystals with a large specific surface area. [ABSTRACT FROM AUTHOR]

The selection of appropriate electrode materials and electrolytes in addition to optimization of their combinations is a key to improve the performance of supercapacitors. Among the new electrode materials, metal‐organic frameworks (MOFs) based electrodes are attracting attention in energy storage devices, including supercapacitors and batteries. In recent years, the redox additive electrolytes have been projected as efficient options over simple aqueous electrolytes. The present work reports the synthesis of a layered MOF, i. e. manganese‐1,4‐ benzene dicarboxylate (Mn‐BDC) and explores its utility as a supercapacitor electrode in the presence of an optimized redox additive electrolyte (0.2 M K3[Fe(CN)6] in 1 M Na2SO4 (0.2 M KFCN)). As demonstrated for the first time in this study, the combined use of the porous Mn‐BDC electrode and KFCN electrolyte has provided a synergistic enhancement in the supercapacitor performance. The present Mn‐BDC/KFCN combination has delivered a high specific capacitance of 1590 F/g at a current density of 3 A/g. Furthermore, the Mn‐BDC electrode could retain around 82% of its initial specific capacitance even after 3000 continuous charge‐discharge cycles. In view of its encouraging electrochemical performance parameters, the proposed system can be touted as an efficient supercapacitor assembly. Manganese‐1,4‐benzene dicarboxylate (Mn‐BDC) is a layered MOF synthesized using one‐pot hydrothermal route. An electrode of Mn‐BDC is prepared and employed as a supercapacitor electrode in presence of an optimized redox additive electrolyte. The proposed system has delivered a high specific capacitance of 1590 F/g at a current density of 3 A/g. The Mn‐BDC electrode retains around 82% of its initial specific capacitance even after 3000 continuous charge‐discharge cycles. [ABSTRACT FROM AUTHOR]

Transition metal dichalcogenides (TMDs) are gaining interest in the energy sector due to its 2D chemistry and heterogeneous characteristics however its stability for the long run and poor electrical conductivity are pushing the researchers to make their hybrid. Herein we synthesized the hybrid WS 2 nanorods and Co 3 S 4 microspheres composite material which attained a high energy density of 47.3 Wh/kg along at a high-power density of 512 W/kg. The hollow Co 3 S 4 microspheres were synthesized using highly porous ZIF-67 as a precursor. Furthermore, these hollow Co 3 S 4 microspheres are in-situ modified by combining with WS 2 nanostructures to enhance its energy density. The electrodes with the synthesized hybrid material deliver the specific capacitance of 412.7 F/g at the current density of 1 A/g, Additionally, two equal weighted Co 3 S 4 /WS 2 composite electrodes are used to fabricate an all-solid-state symmetrical supercapacitor device with PVA-1M H 2 SO 4 polymer gel electrolyte, exhibiting a wide potential window of 2 V with 92% cyclic stability (2000 charge-discharge cycles) demonstrates its potential applicability for the supercapacitor application. The excellent electrochemical performance and splendid cyclic stability are attributed to the synergy of high surface area ZIF-67 derived Co 3 S 4 microsphere for fast charge transfer with 2D networked WS 2 material responsible to provide high energy density. Image 1 • A hybrid Co 3 S 4 /WS 2 composite was prepared using a one-step solvothermal method. • The hybrid composites deliver the highest specific capacitance of 412.7 F/g at the current density of 1 A/g. • A solid-state symmetrical supercapacitor was assembled with PVA-1M H 2 SO 4 gel electrolyte as a separator. • With wide potential window of 2 V, the fabricated device attained a high energy density of 47.3 Wh/kg along at a high-power density of 512 W/kg. [ABSTRACT FROM AUTHOR]