Optimizing the ORR performance of PtMnM ternary intermetallics by tuning the surface strain

This study is led by Prof. Deli Wang (School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology). In this work, the activity and stability of ORR are improved by regulating the strain and electronic structure of ternary intermetallics. Electrochemical results show that PtMnM ternary intermetallics exhibit better ORR activity than binary PtMn intermetallics.

The strain can be precisely modulated by changing the type of transition metal, thus the Pt-Pt atomic spacing can be optimized to effectively reduce the strong adsorption of the reaction intermediates. On the other hand, the electronegativity difference between the introduced third metal and Mn lead to a negative shift of the d-band center. Interestingly, the ORR performance of PtMnM/C exhibits volcano relationship relative to both the Pt-Pt interatomic distance and d-band center.

“Identifying the descriptors that control catalytic performance is key to design catalysts with high activity and stability. As indirect descriptors related to catalytic activity, modulating the interatomic distance and d-band center can effectively enhance the ORR activity. Due to the highly ordered atomic arrangement, Pt-based intermetallics can provide uniform and controllable strain effect on the platinum surface, and exhibit excellent oxygen reduction activity and stability, which is considered to be a promising cathode catalyst for fuel cells.” Wang says.

A few implications thus emerge for designing an Pt-based intermetallics for ORR: 1) a moderate Pt-Pt interatomic distance is expected for the ideal adsorption/desorption of the reaction intermediates. 2) Selecting suitable transition metals to enhance the bond strength between Pt and transition metal in Pt-based intermetallics is important to improve the ORR stability.

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Optimizing the ORR performance of PtMnM ternary intermetallics by tuning the surface strain

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