(Digital Presentation) In-Situ Growth of SnO₂ Quantum Dots Onto Rgo for Supercapacitor Anodes

SnO2 has been studied as a negative electrode material for supercapacitors [1]. However, direct use of pure SnO2 is not suitable because of its poor electrical conductivity. In order to mitigate this issue, various materials have been incorporated with pure SnO2, including graphene which is most favourable because of its high electrical conductivity (106 S/cm) and surface area (2630 m2/g), leading to highly conductive nanocomposites, and consequently high electrode capacitance [2]. Therefore, there is a growing interest to develop SnO2 anchored graphene nanocomposites for fabrications of the supercapacitors negative electrode. In-situ growth and homogeneous distribution of the SnO2 on the graphene flakes are highly desirable, as the maximum interaction of SnO2 with the graphene would occur, resulting in high electrochemical performance. Besides, SnO2 quantum dots (TOQDs), which is a 0D material, exhibit remarkable efficiency towards supercapacitors, as they have more surface area compared to 1D, 2D and 3D nanomaterials. However, the fabrication of the TOQDs is still challenging [3]. Therefore, in-situ and homogeneous distribution of the TOQDs on graphene flakes could yield an attractive nanocomposite for the supercapacitor studies. We have synthesized TOQDs embedded reduced graphene oxide (RGO) flakes i.e.; (TOQDs/RGO) nanocomposite. A nanofluidic synthesis approach, which was applied to synthesis the TOQDs/RGO nanocomposite, leads to give in-situ and homogeneous growth of the SnO2-QDs on graphene flakes. The nanofluidic synthesis approach comprises the dropwise addition of a 1D-Sn(OH)4 nanofluid [4] with graphene oxide (GO) nanofluid [5] at room temperature followed by a stirring, sonication and freeze-drying process, respectively. Finally the freeze-dried sample was calcined at 600 °C for 6 hrs under nitrogen gas to obtain the TOQDs/RGO nanocomposite. The synthesis approach with prime electrochemical studies performance is illustrated in Figure 1. A three-electrode supercapacitor was individually constructed to perform cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). It is found that the developed TOQDs/RGO nanocomposite exhibits high capacitance. The results of these electrochemical studies revealed that the developed TOQDs/RGO nanocomposite can be used for high-performance supercapacitors. References: M. Hassan et al., Tin-Based Materials for Supercapacitor. Inorganic Nanomaterials for Supercapacitor Design, CRC Press: 2019; pp 119-131. Lakra et al., A mini-review: Graphene based composites for supercapacitor application. Inorg. Chem. Commun. 2021, 133, 108929. Inomata et al., Dendrimer-templated synthesis and characterization of tin oxide quantum dots deposited on a silica glass substrate. Chem. Mater. 2019, 31 (20), 8373-8382. I. U. Hoque et al., One-dimensional Sn (iv) hydroxide nanofluid toward nonlinear optical switching. Mater. Horiz. 2020, 7 (4), 1150-1159. A. Khan et al., Synthesis of graphene oxide nanofluid based micro-nano scale surfaces for high-performance nucleate boiling thermal management systems. Case Stud. Therm. Eng. 2021, 28, 101436. Figure 1