New synthesis method for a core-shell composite based on α-Bi₂O₃@PPy and its electrochemical behavior as supercapacitor electrode

New composite based on polypyrrole (PPy) and bismuth oxide (α-Bi₂O₃) was investigated as supercapacitor electrode. The α-Bi₂O₃ was obtained by hydrothermal route at 500 deg C for 2 h. Cyclic voltammetry was used to electropolymerize PPy on graphite electrode (GE) or on GE/α-Bi₂O₃. The X-ray diffraction profile of Bi₂O₃ revealed the α-Bi₂O₃ monoclinic structure with space group P2₁/c. The scanning and transmission electron microscopy images showed that PPy coated α-Bi₂O₃. Raman spectra showed that PPy inhomogeneously coated α-Bi₂O₃, but it was still possible to obtain a α-Bi₂O₃@PPy core-shell hybrid composite with highly ordered α-Bi₂O₃ with electronic interaction between the oxide and the polymer chain of the polymer. The GE/α-Bi₂O₃@PPy composite electrode (type I supercapacitor) displayed a predominantly capacitive profile with low impedance values and good electrochemical stability after 50 charge and discharge cycles. The specific capacitance of α-Bi₂O₃@PPy composite was found in the range of 634 to 301 F g^-1 to gravimetric current of 3 and 10 A g^-1, respectively. (author)