Structure evolution of PtCu nanoframes from disordered to ordered for the oxygen reduction reaction

Crystal structure engineering of platinum (Pt) based disordered alloys to chemically ordered intermetallics has triggered increasing attention in promoting their performance towards the oxygen reduction reaction (ORR). However, a systematic experiment of comparing the catalytic performance in different crystal structures is rarely reported. Herein, the widely-watched PtCu nanoframes (atomically disordered) are firstly synthesised to in-vestigate their structure-properties relationship. Subsequently, rhombohedral PtCu intermetallics (L11 structured, atomically ordered) which were rarely reported before are fabricated by appropriate high temperature treatment. The L11-PtCu delivers significantly enhanced durability (only 15 % attenuation after 30,000 cycles) while decreased initial activity (0.44 A mgPt-1) for ORR compared with their disordered counterpart. In virtue of in-situ STEM experiment assisted by the state-of-the-art 3D tomography, we reveal that the ordering process improves the resistance against Cu leaching meanwhile results in the collapse and aggregation of the NFs. This work provides a visual understanding of Pt based electrocatalyst in different crystal structures for proton exchange membrane fuel cells in the future.

Automated summary

The study compared the catalytic performance of platinum-copper alloys in different crystal structures for the first time, revealing that the rhombohedral PtCu intermetallics have significantly enhanced durability but decreased initial activity. Through in-situ STEM experiment and 3D tomography, it was showed that the ordering process improved resistance against copper leaching while causing collapse and aggregation of nanoframes.