Activated Functionalized Carbon Nanotubes and 2D Nanostructured MoS₂ Hybrid Electrode Material for High‐Performance Supercapacitor Applications

Abstract

Alkali‐activated functionalized carbon nanotubes (AFCNTs) and 2D nanostructured MoS2 are investigated as a novel hybrid material for energy‐storage applications. The nanoflower‐like 2D MoS2 is grown on the surface of AFCNT using the controlled one‐step hydrothermal technique. The activation of functionalized carbon nanotubes results in greater performance due to the improved surface area. The Brunauer–Emmett–Teller (BET) surface area of the AFCNTs is found to be 594.7 m2 g−1 which is almost 30 times of the as‐prepared carbon nanotubes (CNTs). The improved surface area with attached hydroxyl and carboxylic functional groups helps in the attachment of MoS2 nanoflowers onto the AFCNT, thus reducing the interfacial resistance and providing an easy path for electron transfer. The electrochemical analysis shows a high specific capacitance of 516 F g−1 at 0.5 A g−1 with a corresponding energy density of 71.76 Wh kg−1, which is an encouraging reported value from AFCNT and MoS2 hybrid material. To the best of our knowledge, herein, the first report on AFCNTs and 2D MoS2 nanostructured hybrid electrode material for supercapacitor applications is provided, and promising results in terms of specific capacitance, energy density, and power density by boosting the properties of individual material are explained.

Functionalized Carbon Nanotube and MnO2 Nanoflower Hybrid as an Electrode Material for Supercapacitor Application

“…Figure 2 a,b clearly show nanoflower like morphology of MnO 2 on FCNT surface similar like seen in previous published results [ 24 , 45 ]. The evidence of the coupling between CNT and other material in the hybrid can be seen from the results of EDS, FESEM, and TEM in other published literatures like Bi 2 S 3 @CNT [ 49 ], Ag/CNT [ 50 ], CNT-MoS 2 [ 9 ] and CNT-MnO 2 [ 51 ]. Besides that, Figure 2 c reveals the high resolution TEM image of FCNT-MnO 2 , which confirms two different lattice-spacings that belong to FCNT and MnO 2 within a given area.…”

“…As prepared CNTs have limited chemical interactions with other compounds and they tend to agglomerate due to high van der Waals force between the tube surfaces. The functionalization of CNTs can alter the surface energy and attached carboxylic or hydroxyl functional groups can improve their chemical reactivity and compatibility [ 9 , 38 ]. The –OH and –COOH functional groups help in the binding of pseudo material MnO 2 on to the surface of FCNT.…”

“…Based on their mechanism, supercapacitors are classified into two foremost types, electric double layer capacitor (EDLC) and pseudo-capacitor [ 4 , 5 , 6 ]. While, a third classification includes the combination of both EDLC and pseudo materials and is termed ‘hybrid’ supercapacitor [ 7 , 8 , 9 , 10 ]. EDLC involves carbon-based materials [ 11 , 12 ] such as activated carbon [ 13 ], carbon nanotubes [ 14 ], and reduced graphene oxide/graphene [ 15 , 16 , 17 ] as active electrode materials, while the pseudo-capacitor is based on metal-oxides [ 18 ], -hydroxides [ 19 ], -sulfides [ 20 ], -nitrides [ 21 ], and conducting polymers [ 22 , 23 ].…”

Recent progress of defect chemistry on 2D materials for advanced battery anodes

“…[64,65] The chemical functionalization of 2D materials has become indispensable for a wide variety of new energy storage applications, including hydrogen storage, gas sensing, supercapacitors, and rechargeable batteris electrodes. [14,[66][67][68][69][70] One can distinguish two essential forms of chemical functionalization: the first one, known as covalentfunctionalization, consist in the creation of covalent bonds, and the second one, non-covalent functionalization involving the physisorption or physical-adsorption of molecules on the surface of 2D structure. The first one leads to a significant change on the geometry as well as in the characteristics of 2D materials.…”

Energy storage performance of 2D MoS2and carbon nanotube heterojunctions in symmetric and asymmetric configuration

“…The most well-studied energy storage devices for storing the energy generated from renewable sources are batteries and supercapacitors [1]. Supercapacitors have received considerable interest compared to batteries as an energy storage system due to low maintenance costs, compact design, ease of fabrication, improved energy and power densities, high efficiency, fast charging and discharge characteristics [2]. However, the properties of supercapacitors are strongly influenced by design, sealing and packaging techniques, electrolytes, separators, current collectors and, above all, materials for electrode [3].…”