High performance Zn-doped Pd catalysts for PEM fuel cells via ultrasonic spray assisted interface reaction

In this study, palladium–zinc (PdZn) electrocatalysts with different Zn contents were synthesized by the ultrasonic spray (US) method and supported on activated carbon to evaluate the effectiveness of this approach for PEM fuel cells (PEMFCs). The results showed that Zn addition influenced the structural and electrochemical properties of the catalysts. The 3 wt.% Zn-doped catalyst exhibited the highest electrochemical surface area (19.1 m²/g_Pd), whereas higher Zn contents were associated with a decrease in this value. Crystallinity analysis revealed that 5 wt.% Zn provided the highest degree of crystallinity, while further Zn addition (10 wt.%) led to a reduction, indicating that excessive Zn may disturb the crystal order. Polarization and fuel cell performance tests confirmed that Zn content plays a decisive role in activity: the 3 wt.% Zn-doped catalyst achieved the highest power density of 69.96 mW/cm², while the 5 wt.% sample showed balanced performance due to its more ordered crystal structure. In contrast, excessive Zn loading promoted agglomeration and reduced catalytic performance. These findings demonstrate that the US method is effective for preparing PdZn/C nanocatalysts and that controlling Zn incorporation is important for stable and efficient PEMFCs operation.