Microstructural improvements of the gradient composite material Pr_(0.6)Sr_(0.4)Fe_(0.8)Co_(0.2)O_3/Ce_(0.8)Sm_(0.2)O_(1.9) by employing vertically aligned carbon nanotubes

摘要

Ionic-electronic conductor composite materials are widely employed to improve the ionic conductivity of solid oxide fuel cell electrodes, making them more compatible with the solid oxide fuel cell materials. The addition of an ionic conductor implies, however, a decrease of the cathode active area for the oxygen reduction reactions. In addition, the ionic conductor particles are usually dispersed and isolated, limiting the enhanced properties to certain areas. In order to avoid this drawback and improve the ionic conductivity of the electrode, vertically aligned carbon nanotubes (VACNTs) have been synthesized and employed as template for the deposition of Sm_(0.2)Ce_(0.8)O_2 (SDC) particles. Subsequently, these SDC-VACNTs have been coated with a Pr_(0.6)Sr_(0.4)Fe_(0.8)Co_(0.2)O_3 (PSFC) perovskite phase, leading to the formation of the desired composite material. Attending to the obtained results, it is proved that the new composite material exhibits a significantly better electrochemical performance, due to a better distribution of the ionic conductor and the burning of the carbon nanotubes (CNTs), which result in the improvement of the microstructure.