Femtosecond Laser Irradiation Induced Atomic Structure Modulation of Pd Nanocubes for Efficient Ethanol Oxidation Reaction

Laser irradiation is an efficient strategy for modulating surficial atomic structures, especially introducing lattice defects. Here, we successfully introduced defects on the exposed (200) surfaces of the Pd nanocubes (Pd NCs) using a femtosecond laser irradiation method, which enhances the catalytic activity of the nanoparticles toward ethanol oxidation reaction (EOR). The results indicate a positive correlation between the defect-induced microstrain and the laser fluence, and the catalytic activity exhibits a volcano-shaped relationship with the laser fluence, which is attributed to the increased microstrain and the variation in the exposed surfaces from (200) to (111). Furthermore, the atomic structure evolution mechanism of Pd NCs under laser irradiation was elucidated by a coupled finite element method and molecular dynamics (FEM-MD) model. The results indicate that surficial atoms of Pd NCs rapidly diffuse, creating numerous vacancies that collapse into defects upon cooling and accumulate on the (200) surfaces. Meanwhile, the rapid heating and cooling process induces tensile stress in the surface atomic layers of Pd NCs. The catalytic mechanism was revealed using density functional theory (DFT) calculations. This study highlights the role of femtosecond laser-induced structural modifications in the surface atomic structure.