Facile electrochemical polymerization of 2-(thiophen-2-yl)furan and the enhanced capacitance properties of its polymer in acetonitrile electrolyte containing boron trifluoride diethyl etherate

• The low-potential polymerization of 2-(thiophen-2-yl)furan into polymer (PTFu) was reported.
• The electrochemical performance of PTFu was studied in three different electrolytes.
• The specific capacitance of PTFu electrode reached 392.0 F g−1 at 5 A g−1 and had 67.0% retention after 500 cycles.
• The addition of boron trifluoride diethyl etherate into acetonitrile electrolyte benefited to enhance the specific capacitance and stability of PTFu electrode.

ABSTRACTIn this study, a new simple hybrid poly(2-(thiophen-2-yl)furan) (PTFu) was easily electrodeposited by direct anodic oxidation of 2-(thiophen-2-yl)furan in acetonitrile solution containing 0.1 M lithium perchlorate (LiClO4). The oxidation onset potential of 2-(thiophen-2-yl)furan monomer in this medium was measured to be 0.90 V, which was lower than those of thiophene (1.47 V) and furan (1.28 V). The structure and morphology of PTFu were characterized by Ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, and thermal analysis. The electrochemical capacitance properties of PTFu electrode in three electrolytes were also investigated by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscope techniques. The electrochemical results showed that the specific capacitance of PTFu electrode was enhanced to 392.0 F g−1 from 249.4 F g−1 at 5 A g−1 and the cycling stability was also enhanced to 67.0% retention from 25.5% retention after 500 cycles when the equivalent boron trifluoride diethyl etherate (BFEE) was added into the acetonitrile electrolyte. Furthermore, the PTFu electrode in ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BmimPF6) showed a lower specific capacitance value (209.4 F g−1 at 5 A g−1) and an improved stability (67.6% retention after 600 cycles). These results indicated that the conducting polymers based on furan should be a promising electrode material for supercapacitor applications when the electrolyte based-BFEE is used.