A yttria-stabilized zirconia (YSZ) cathode functional layer (CFL) was fabricated using a co-sputtering process to improve the oxygen reduction reaction (ORR) in solid oxide fuel cells (SOFCs). To optimize the yttria molar percentage and achieve a nano-granular structure with enhanced grain boundary density, the DC sputtering power for the metallic yttrium target was varied at 10, 30, and 50 W. Structural and compositional analyses were performed using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and X-ray diffraction (XRD). The results indicated that a DC power of 30 W resulted in a well-developed grain structure with high grain boundary density and an yttria composition close to the optimal molar percentage of 8-10 mol %. Under these optimized conditions, the SOFC with the co-sputtered YSZ CFL achieved a maximum power output of 9.22 mW/cm² at 450^oC, representing approximately a 43% enhancement compared to the reference cell. This highlights the significant potential of co-sputtering for future low-temperature SOFC applications.

Pinhole-free ionic conductors are critical to achieve optimal performance in thin film-solid oxide fuel cells (TF-SOFCs). However, nanoscale defects, especially pinholes, can induce current leakage and contribute to cell failure by creating electrical short circuits. This study introduced a novel methodology for detecting pinholes in yttria-stabilized zirconia (YSZ) thin-film solid oxide electrolytes. The approach utilized selective adsorption of silver (Ag) nanoparticles generated via a spark discharge generator (SDG). Analytical techniques, including focused ion beam (FIB), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), were employed to investigate interactions between Ag nanoparticles and nanoscale defects. Results showed that nanoparticle-based diagnostic methods were efficacious for defect characterization, offering a solution for enhancing the quality of thin-film electrolytes.

In this study, Yttria-stabilized zirconia (YSZ) functional layers were applied with different thin-film fabrication process such as sputtering and atomic layer deposition (ALD) to enhance oxygen reduction reaction (ORR) for solid oxide fuel cells. We confirmed that the YSZ functional layer deposited with sputtering showed relatively low grain boundary density, while the YSZ functional layer deposited with the ALD technique clearly indicated high grain boundary density through scanning electron microscopy (SEM) and X-ray diffractometry (XRD) results. The YSZ functional layer coated with the ALD technique revealed that more ORR kinetics can occur using high grain boundary density than the functional layer deposited with sputtering. The peak power density of the SOFC deposited with ALD YSZ indicates 2-folds enhancement than the pristine SOFC.