Geometrically Ordered Triangular-Atom-Unit Zn-PtCo Intermetallic for Highly Efficient and Durable Fuel Cells

Developing highly efficient and stable Pt-type oxygen reduction reaction (ORR) catalysts is crucial for proton exchange membrane fuel cells (PEMFCs). PtCo intermetallic has exhibited excellent ORR stability and activity among the Pt family, while its applications remain significantly challenging due to intractable Co dissolution issue. Here, we present a partial geometrically ordered Zn-decorated PtCo intermetallic (Zn-PtCo IMC), where Zn atoms can enter into the lattice of PtCo and partially replace Co atoms to construct a stable triangular-atom-unit structure. Consequently, the Zn-PtCo IMC-based fuel cell delivers an exceptional power density of 1.98 W cm^-2, significantly outperforming that of disordered Zn-PtCo and commercial Pt/C-based fuel cells. Importantly, Zn-PtCo IMC is capable of retaining 61.2% mass activity (MA) after undergoing a 120k-cycle accelerated durability test. Detailed mechanism investigations reveal that the presence of geometrically ordered triangular atoms can effectively weaken the O* adsorption capacity and enhance the Co atom diffusion energy barrier, thereby substantially enhancing activity and stability.