A bifunctional pincer-palladium molecular catalyst for hydrogen/oxygen fuel cells

The design of novel high-performance fuel cells is one of the fundamentals of modern green energy. The heterogenization of well-defined molecular complexes represents a powerful strategy to translate precise control over active-site geometry and electronic structure into practical energy conversion devices. Herein, we report a pincer palladium molecular complex, [(PNP)Pd(CH 3 CN)]BF 4 , that was successfully integrated into membrane-electrode assemblies (MEAs) and evaluated as a bifunctional electrocatalyst in operational H 2 /O 2 fuel cells. The complex catalyzes both the hydrogen oxidation reaction (HOR) and oxygen reduction reactions (ORR), exhibiting high performance as an anode catalyst with a maximum power density of 419 mW cm −2 . This high HOR activity is attributed to efficient heterolytic hydrogen splitting via metal-ligand cooperation enabled by the pincer architecture. These results open a new avenue towards the implementation of pincer palladium complexes as a promising new class of bifunctional molecular catalysts for fuel cells.