Enhancing Oxygen Reduction Activity via Tailoring Microstrain in PdMo Nanoalloy through Repetitive Hydrogen Absorption–Release
Ying Chen, Mingzi Sun, Menghao Wu, Cheng Zhu, Haijing Li, Zih‐Yi Lin, Hangxuan Li, Haozhe Xu, Dong Li, Xiaoting Chen, Sung‐Fu Hung, Juncai Dong, Bin Liu, О. Ф. Демиденко, Bolong Huang, Yujing Li
Abstract
The catalytic activities of noble-metal electrocatalysts are heavily correlated to their defective surface structures. However, controllably constructing surface defects on noble-metal nanocrystals remains a great challenge. In this work, an electrochemical method is developed to tailor the surface structure of the PdMo nanoalloy electrocatalyst, involving H absorption followed by its subsequent release near the surface of Pd. The optimized PdMo nanoalloy electrocatalyst exhibits an oxygen reduction reaction (ORR) half-wave potential ( E 1/2 ) of 0.929 V (vs reversible hydrogen electrode, RHE) with a specific activity (SA) as high as 5.09 mA/cm 2 at 0.9 V (vs RHE) in an alkaline electrolyte, ∼10.6 times that of the state-of-the-art Pt/C electrocatalyst. Density functional theory calculations together with ex situ and in situ electrochemical and structural characterizations unravel that the microstrain generated at the PdMo nanoalloy surface by electrochemically induced H absorption–release can downshift the d-band center of Pd (the ORR active site) in PdMo to decrease oxygen binding and promote *OOH to *O transformation as well as *OH desorption for fast ORR. This work provides a surface defect engineering strategy to develop high-performance noble-metal electrocatalysts for energy applications.