Characterization of CeO 2 microspheres fabricated by an ultrasonic spray pyrolysis method

CeO 2 is one of the main catalysts for solid oxide fuel cell (SOFC). It is critical to find a green and cost‐effective fabrication method for CeO 2 at scale. In this study, the CeO 2 microspheres were prepared by one‐step ultrasonic spray pyrolysis of cerium chloride solution at 700 °C. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) study demonstrate that the prepared CeO 2 microspheres exhibit a particle size of 0.01–1.08 μm with a mean particle size of 0.23 μm, and more than 94% of the particles have a diameter less than 0.5 μm. But the presence of residual Cl in the fabricated CeO 2 microspheres blocks the active sites and leads to the significant degradation of SOFC performance. The formation mechanism and distribution of residual Cl in the fabricated CeO 2 microspheres were systemically studied. The water washing method was shown to effectively reduce the residual Cl in the CeO 2 microspheres. Overall, this work provides a clean manufacturing process for the preparation of SOFC electrode/electrolyte materials.