Combinatorial Screening of Pd–Co–Au and Pd–Zr–Cu Systems as Potential Catalysts for Formic Acid Oxidation

High Resolution Image Download MS PowerPoint Slide This study presents a systematic investigation of two optimized Pd-based alloy catalysts, Pd 2 Co 6 Au 2 and Pd 8 Zr 2, for the formic acid oxidation reaction (FAOR). Scanning electrochemical microscopy was employed to screen Pd–Co–Au and Pd–Zr–Cu catalyst arrays, leading to the identification of compositions with the highest FAOR activity for subsequent evaluation. Structural and electrochemical analyses reveal that Pd 2 Co 6 Au 2 possesses a CoO-enriched interfacial surface, which promotes OH adsorption and facilitates CO oxidation, thereby enhancing the CO tolerance and long-term stability. In contrast, Pd 8 Zr 2 benefits from ZrO 2 -induced modulation of the Pd electronic structure, exhibiting high initial activity but diminished durability due to CO accumulation. Overall, Pd 2 Co 6 Au 2 achieves an optimal balance among catalytic activity, CO tolerance, and operational stability. Although Pd 8 Zr 2 exhibits higher initial mass and specific activities, it suffers from a more rapid performance degradation. Both catalysts outperform pure Pd, underscoring their potential for efficient FAOR. Notably, the direct formic acid fuel cell employing Pd 2 Co 6 Au 2 delivers a maximum power density of 116.71 mW cm –2 at a current density of 389.04 mA cm –2 .