The effect of alloying on the oxygen reduction reaction activity of carbon-supported PtCu and PtPd nanorods

In this study, we have investigated the effect of alloying on the modification of the d-band vacancies and oxygen reduction reaction (ORR) activity of PtPd and PtCu nanorods (NRs). PtCu and PtPd NRs with various ratios can be prepared successfully by a facile formic acid reduction method. The number of unfilled d-states (H_Ts) value of Pt nanoparticles is decreased due to the formation of NRs, and further decreased due to the alloying with different metals. For the Pt3Pd NRs, the H_Ts value is as low as 0.3056, suggesting that they have lower unfilled Pt d-states, and more d-band electrons transfer from Pd to Pt, leading to higher ORR activities than Pt/C. Besides, the electron transfer number (n) of Pt3Pd NRs towards the ORR is 3.7, meaning that they complete the O₂ reduction to water and exhibit low hydrogen peroxide production during the ORR. As a result, the correlation between the H_Ts and ORR performance of PtPd and PtCu NRs highlights that the one-dimensional (1-D) structure and the electronic modification effect from Pd to Pt result in the excellent ORR activity and durability of Pt3Pd NRs synergistically.