WO3·2H2O/Bamboo Charcoal Hybrids as Enhanced Supercapacitors

Electrochemical supercapacitors have become prominent energy storage devices due to their excellent capacitance behavior, unparalleled power and energy density, and excellent cycle stability.Tungsten trioxide (WO3) has the advantages of various shapes, high theoretical specific capacitance, environmental friendliness, and low cost. It is a promising electrode material. However, its low conductivity (10-5-10-6 S cm-1) limits its wide application. Doping or dispersing WO3 with highly conductive carbon materials is a solution to overcome these shortcomings.

WO3·2H2O/bamboo charcoal (BC) hybrids have been successfully prepared as enhanced supercapacitors and showed higher specific capacitance and superior cyclic stability. The combination of bamboo charcoal (EDLC) and WO3·2H2O (pseudocapacitance) provided short ion diffusion path and fast electron transport, leading to a great supercapacitor. The synthesis process of WO3·2H2O/BC Hybrids is as below:

First, the WO3·2H2O/BC hybrid is prepared as follows. WCl6 (3 mg) was added to isopropanol (20 mL) with stirring in a glass vial at room temperature for 20 minutes. Bamboo charcoal is prepared by carbonizing natural bamboo with a KOH modification method.Then, slowly impregnate the bamboo charcoal monolith (0.2 g) with 10 ml WCl6 solution. After stirring continuously for 30 minutes, add an appropriate amount of 2-propanol to remove H* and OH* free radicals generated during the irradiation process. The mixture was irradiated with a 60Co γ-ray source at a dose rate of 200 Gy min-1 at room temperature, with a total dose of 500 kGy. The product was collected by centrifugation, washed several times with deionized water and ethanol, and then dried at 60°C for 12 hours.

In conclusion, tungsten dihydrate and bamboo charcoal have been combined to prepare WO3·2H2O/bamboo charcoal hybrids as enhanced supercapacitors. The hybrid material showed enhanced the specific capacitance and superior cyclic stability of the WO3·2H2O/BC hybrid electrode. The WO3·2H2O/BC hybrids showed the higher specific capacitance (391 F g−1 at 0.5 A g−1 over the voltage range from −1 to 0 V), compared with BC (108 F g−1) in 6 M KOH solution. 

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