Abstract
In this work, silver nanoparticles decorated on reduced graphene oxide (rGO) wrapped manganese oxide nanorods (Ag-rGO@MnO2) were synthesized for an active electrode material. MnO2 nanorods were synthesized via a hydrothermal route, and their coating with GO and subsequent reduction at a higher temperature resulted in rGO@MnO2. A further addition of Ag on rGO@MnO2 was performed by dispersing rGO@MnO2 in AgNO3 solution and its subsequent reduction by NaBH4. X-ray diffraction (XRD) analysis showed peaks corresponding to MnO2 and Ag, and the absence of a peak at 2θ = 26° confirmed a few layered coatings of rGO and the absence of any graphitic impurities. Morphological analysis showed Ag nanoparticles anchored on rGO coated MnO2 nanorods. Apart from this, all other characterization techniques also confirmed the successful fabrication of Ag-rGO@MnO2. The electrochemical performance examined by cyclic voltammetry and the galvanic charge–discharge technique showed that Ag-rGO@MnO2 has a superior capacitive value (675 Fg−1) as compared to the specific capacitance value of rGO@MnO2 (306.25 Fg−1) and MnO2 (293.75 Fg−1). Furthermore, the electrode based on Ag-rGO@MnO2 nanocomposite showed an excellent capacity retention of 95% after 3000 cycles. The above results showed that Ag-rGO@MnO2 nanocomposites can be considered an active electrode material for future applications in electrochemical devices.
Highlights
Based on the above idea, binary reduced graphene oxide (rGO)/MnO2 composite was decorated by Ag nanoparticles to produce Ag-rGO@MnO2 ternary composite with improved conductivity and capacitive performance
High purity polyvinylidene fluoride (PVDF) was obtained from Daejung Chemicals and Meal Co, Ltd. (Gyeonggi, South Korea), and graphite flakes were procured from Asbury Inc. (Asbury, NJ, USA)
The whole system was left under stirring conditions for 15 min, and the subsequently obtained dark-brownish mixture was transferred into a Teflon-lined hydrothermal reactor and heated at 140 ◦C for 24 h
Summary
Worldwide, energy consumption is continuously increasing, and current energy resources are insufficient to sustain our energy demands. By incorporating metal oxides, sulfides, and conducting polymers in carbon materials, the electrical conductivity of the electrodes based on carbon materials can be enhanced, which, in turn, increases the specific surface area as well as the energy-storage capacity through pseudocapacitance [8]. Carbon-based materials such as graphene (GN)and multiwalled carbon nanotubes (MWCNTs) are highly promising, owing to their exceptional electrical, thermal, and mechanical properties They can facilitate the charge transfer mechanism, which increases electrochemical characteristics such as capacitance, power density, and cycling stability [12]. GN materials have limited double-layer capacitive charge storage, but they have a high electrical conductivity by providing a conductive platform to accelerate electron transport, whereas pseudocapacitive materials possesses a low conductivity but a high specific capacitance [36,37] Both materials complement each other; combining both into a composite might provide an ideal electrode material. Based on the above idea, binary rGO/MnO2 composite was decorated by Ag nanoparticles to produce Ag-rGO@MnO2 ternary composite with improved conductivity and capacitive performance
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