Electrochemical characterization of RuO2-Ta2O5/polyaniline composites as potential redox electrodes for supercapacitors and hydrogen evolution reaction

Abstract RuO2-Ta2O5 electrode covered with polyaniline (PANI) was prepared by sintering and electrodeposition. X-ray photoelectron spectroscopy confirmed the presence of RuO2-Ta2O5 and PANI and the strong interaction between RuO2-Ta2O5 and PANI in the RuO2-Ta2O5/PANI composite. The crystalline structure of RuO2-Ta2O5/PANI was verified by XRD. SEM analysis revealed that the RuO2-Ta2O5/PANI electrode had a nano-fibrous morphology with a crystal plane and some pores. The supercapacitive performance of RuO2-Ta2O5/PANI was evaluated by cyclic voltammetry and charge-discharge chronopotentiometry. RuO2-Ta2O5/PANI had a high specific capacitance (428 F/g), specific energy (26.7 Wh/kg at a discharge current density of 0.5 mA/cm2), and power density (2.4 kW/kg at a discharge current density of 4.0 mA/cm2). The attractive capacitive properties of RuO2-Ta2O5/PANI may be attributed to the porous morphology of RuO2-Ta2O5 covered with PANI. In addition, the as-prepared RuO2-Ta2O5 and RuO2-Ta2O5/PANI electrodes had Tafel slopes of −55.8 and −69.2 mV/dec, respectively, which make them potential H2 evolution electrocatalysts.