Phase dependent electrochemical characteristics of bismuth ferrite: A bifunctional electrocatalyst for Supercapacitors and Dye-Sensitized Solar Cells

Different phases of bismuth ferrite (BiFeO3, Bi2Fe4O9, Bi25FeO40) have been synthesized hydrothermally with the assistance of polyethylene glycol (PEG) and employed as an electrocatalyst for supercapacitor and dye-sensitized solar cells (DSSC). The impact of PEG on the crystal structure and phases is analyzed using X-ray diffraction (XRD). More experimental measurements are done to analyze phase dependence on the shape, vibration, and optical response. Cyclic voltammetry and galvanostatic charge-discharge (GCD) results show the phase -dependent electrochemical characteristics and the sillenite phase Bi25FeO40 (BFO-10) of 10 mL PEG has a higher specific capacitance (CS) of 351 F g-1 at 4 A g-1 due to the increment of Bi stoichiometry. In addition, an asymmetric supercapacitor (ASC) is assembled by BFO-10//AC and observed with a higher energy density of 70 Wh kg-1, the corresponding power density is 3240 W kg-1, and an excellent life cycle. The same samples are used as a counter electrode (CE) in DSSCs, Bi25FeO40 CE assisted cell delivering a maximum short circuit current (JSC) of 4 mA cm-2 than the other phases of BFO. The higher electrocatalytic activity, conductivity, and lower charge transfer resistance are responsible for the improvement. These investigations reveal that the sillenite phase of Bi25FeO40 is a better choice for future energy storage and conversion devices.