In this study, we employed an infiltration technique to create a nanostructured functional layer, enhancing the electrochemically active area in solid oxide fuel cells (SOFCs). We infiltrated Pr₂NiO_4+δ (PNO) into a porous GDC electrolyte, resulting in a nanostructured catalytic layer. We characterized its microstructure and cross-sectional morphology using field-emission scanning electron microscopy (FE-SEM). The electrochemical performance was assessed at 750°C with a NiO-YSZ/YSZ/GDC half-cell configuration. The reference cell without PNO infiltration achieved a maximum power density of 2.07 W/cm², while the cell with 0.05 M PNO infiltration reached an improved value of 2.55 W/cm². These results demonstrate that by optimizing the infiltration concentration of PNO, we can fabricate a high-performance nanostructured functional layer without adding extra thickness, confirming infiltration as an effective strategy for enhancing SOFC performance.