Anodic hybridization of fluorinated layered perovskite nanosheet with polyaniline for electrochemical capacitor

A layered perovskite was fluorinated by polytetrafluoroethylene (PTFE) and then exfoliated to prepare a solution of fluorinated-perovskite nanosheets. Dion–Jacobson-type layered perovskites, RbLaNb2O7 and KCa2Nb3O10, were prepared in solid-state reactions at 950 and 1100 °C, respectively. The perovskites were fluorinated using PTFE at 400 °C, upon which their color changed from white to gray or black and their electrical conductivity increased to the order of 10−4–10−5 S/m. The tetrabutyl ammonium cations (TBA+) in each fluorinated layered perovskite were first intercalated by tetrabutylammonium hydroxide (TBAOH) in H2O and then exfoliated in an acetonitrile solution for electrodeposition. Aniline was added to the solution as a monomer and electrodeposition was carried out in the acetonitrile solution for formation of a hybrid film. X-ray diffraction patterns confirmed that the polyaniline molecules could be intercalated within the interlayer space. Despite the fluorination, the volumetric filling fractions of polyaniline in the interlayer space were around 0.4 and 0.2 for the respective samples from RbLaNb2O7 and KCa2Nb3O10. The electrochemical specific capacitances of the deposited hybrid films increased steeply from below 50 F/g to above 230–250 F/g owing to the fluorination.