Phosphorization Treatment Improves the Catalytic Activity and Durability of Platinum Catalysts toward Oxygen Reduction Reaction

Modification of Pt catalysts to achieve satisfactory activities for commercialization of proton exchange membrane fuel cells has attracted numerous attention in recent years. In this work, phosphorization treatment has been developed to enhance the catalytic performance of Pt catalysts toward oxygen reduction reaction (ORR), including both the activity and the durability. By treating Pt with tri-n-octylphosphine at 300 °C for 3 h, Pt nanoparticles can transform to Pt₂P nanoparticles with slightly increased sizes. After the phosphorization treatment, the catalytic performance of Pt catalysts can be enhanced markedly, with a factor of 10.3 enhancement in mass activity and a factor of 10.2 enhancement in specific activity, respectively. More importantly, long-term stability tests (30 000 cycles of accelerated durability tests) demonstrated that the excellent durability could be obtained after the phosphorization treatment, with a drop of 9.1% in mass activity, showing another advantage of the method reported in this work. Given the highly improved catalytic performance, one can anticipate that the nanocrystals composed of Pt and P atoms would shed new light on next-generation energy conversion and storage devices, and offer an efficient phosphorization treatment strategy for promoting activity and durability of Pt electrocatalysts.