Engineering a Porous PtCo Catalyst Layer via Multilayer Sputtering and Acid Leaching for Enhanced Oxygen Reduction Reaction

Developing high‐activity, low‐platinum‐loading catalysts for the oxygen reduction reaction (ORR) is crucial for proton exchange membrane fuel cells (PEMFCs). This work presents a novel strategy to enhance the performance of PtCo catalysts by combining multilayer magnetron sputtering with postacid treatment. PtCo catalysts with varying architectures (cosputtered, two, four, and six layers) were deposited onto SGL carbon paper. The results indicate that the ORR activity is strongly influenced by the catalyst layer thickness and sputtered modes, with the four‐layer structure exhibiting the optimal balance. More importantly, acid treatment of the four‐layer catalyst selectively leached Co, as confirmed by XPS, resulting in a microporous Pt‐rich structure. This structural evolution significantly increased the electrochemical active surface area (ECSA) from 43.5 to 58.6 m 2 /g. Consequently, the acid‐treated catalyst achieved a remarkable mass activity of 0.31 A/mg at 0.9 V versus RHE, which is the highest among all samples, and it also demonstrated superior durability in accelerated degradation tests. This study demonstrates that architecting catalyst layers through multilayer sputtering followed by acid leaching is an effective approach for creating high‐performance, porous ORR catalysts.