Preparation and characterization of RuO2/polypyrrole electrodes for supercapacitors

• Up to now, it is first reported that RuO2/PPy composite electrode was prepared by thermal decomposition oxidation and electrodeposition.
• Also this paper reveals the growth mechanism for PPy particles covering RuO2 films, which resulted in sharp increase for PPy particles size when the deposition time was over 20 min.
• In addition, specific capacitances of 657, 553, 471 and 396 F g−1 were achieved by cyclic voltammetry (CV) measurement at the scan rate of 50 mV s−1 as deposition times were 10, 20, 25, 30 min, respectively.
• Charge–discharge performance is stable.
• The results have a certain theoretical and practical significance.

Polypyrrole (PPy) embedded RuO2 electrodes were prepared by the composite method. Precursor solution of RuO2 was coated on tantalum sheet and annealed at 260 °C for 2.5 h to develop a thin film. PPy particles were deposited on RuO2 films and dried at 80 °C for 12 h to form composite electrode. Microstructure and morphology of RuO2/PPy electrode were characterized using Fourier transform infrared spectrometer, X-ray diffraction and scanning electron microscopy, respectively. Our results confirmed that counter ions are incorporated into RuO2 matrix. Structure of the composite with amorphous phase was verified by X-ray diffraction. Analysis by scanning electron microscopy reveals that during grain growth of RuO2/PPy, PPy particle size sharply increases as deposition time is over 20 min. Electrochemical properties of RuO2/PPy electrode were calculated using cyclic voltammetry. As deposition times of PPy are 10, 20, 25 and 30 min, specific capacitances of composite electrodes reach 657, 553, 471 and 396 F g−1, respectively. Cyclic behaviors of RuO2/PPy composite electrodes are stable.