High areal capacitance polyoxotungstate-reduced graphene oxide-based supercapacitors

• The modern lifestyle has driven the advent of high-power electronic gadgets to need high-efficiency energy storage devices. Towards that goal, reduced graphene oxide (rGO) mediated polyoxometalates (POMs) based electrode materials are increasingly showing promising performance for building efficient energy storage devices primarily due to their redox properties. In this report, the silicotungstate [K5[SiVW11O40]. nH2O (SiVW11) embedded rGO nanocomposites as electrode materials in supercapacitor applications were synthesized via chemical and hydrothermal methods. The synthesized nanocomposites were characterized by various techniques, such as Fourier-Transform-Infrared (FTIR) Spectroscopy, Powder X-ray Diffraction (XRD) and Energy Dispersive X-ray Spectroscopy (EDS), Thermogravimetric Analysis (TGA), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) measurement. The nanocomposites electrochemical properties were examined by adopting a two-electrode setup with cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) in a 0.5 M H2SO4 electrolyte medium. The hydrothermally reduced graphene oxide (HrGO) nanocomposite exhibited a noticeable surge in areal capacitance of 377.4 mF/cm2 at a current density of 1.5 mA/cm2. The resulting composite had 52.4 & mu;Wh/cm2 and 1500 & mu;W/cm2 as energy and power density, respectively at 1.5 mA/cm2 current density. In addition, the capacitance retention is over 81% after 5000 cycles at a current density of 9 mA/ cm2. The highest specific power of 5000 & mu;W/cm2 was obtained at 5 mA/cm2 current density. On the other hand, chemically reduced graphene (CrGO) nanocomposite showed an areal capacitance of 277.2 mF/cm2 at the same current density. As a result, the SiVW11 clusters coupled with the rGO increase the areal capacitance of nanocomposites with exceptional electrical and mechanical stability. From an application standpoint, both composites were employed successfully for running a DC motor in a series cell connection.

Ämnesord

NATURVETENSKAP  -- Kemi -- Oorganisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Inorganic Chemistry (hsv//eng)

Nyckelord

Reduced graphene oxide; Polyoxometalates; Nanocomposite; Hydrothermal; Symmetric supercapacitors

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