MIL-53(Al)/Bi₂WO₆ composite for asymmetric supercapacitor application

In this work, transition metal oxide (Bi₂WO₆ ) and metal organic framework (MIL-53(Al)) were used to prepare a composite. The MIL-53(Al) and Bi₂WO₆ powder were synthesized through hydrothermal route and the MIL- 53(Al)/Bi₂WO₆ composite was prepared through impregnation technique. FESEM-EDX, XRD, FTIR and multi-point BET were used to characterize the MIL-53(Al), Bi₂WO₆ and composite. Electrochemical study was performed by employing a potentiostat and a 3-electrode cell, where platinum wire taken as counter electrode, active material-coated graphitic carbon felt as the working electrode and Ag/AgCl taken as reference electrode. MIL-53(Al) and Bi₂WO₆ were tested separately to determine the electrochemical efficiency, and it was found through galvanostatic charge-discharge method that they both have low energy densities when compared to the composite. The energy density of the composite was found to increase due to the characteristic changes resulting from the combination of MIL-53(Al) and Bi₂WO₆. Compared with the pristine MIL-53(Al) and Bi₂WO₆, the composite has exhibited higher specific capacitance of 554 F g^-1 at 0.5 A g^-1 and the lowest equivalent series resistance (ESR) resistance was obtained in electrochemical impedance spectroscopy study, which confirms that the MIL-53(Al)/Bi₂WO₆ hybrid has improved its performance as electrode material for supercapacitor application. (author)