Mechanism of Pt3Co nanocatalysts to improve the performance for oxygen reduction reactions: DFT study on oxygen adsorption and durability of different facets

Pt3Co nanocatalyst shows better oxygen reduction reaction (ORR) activity and durability toward Pt. In this paper, the oxygen adsorption, durability and the ORR mechanism of Pt3Co are investigated based on density functional theory (DFT) calculations by CASTEP code. The adsorption energy of O atom at each site on (100), (1 1 0), and (1 1 1) surfaces indicated that the adsorption strength of O atom on Pt3Co surface follows the order (100) > (110) > (1 1 1). In addition, the ORR mechanism is explored through the electron density difference, d -band center, and the ORR elementary reactions. The results are consistent with the tendency for adsorption energy and prove that the O hydrogenation step is the rate-determining step on Pt3Co (1 1 1). Furthermore, the calculation of surface Pt vacancy formation energy reveals that the Pt3Co (1 1 1) catalyst has the best durability. The results could guide the design of surface crystal orientation of Pt3Co nanocatalyst for ORR.