Femtosecond Pulsed Laser Effect on Mechanical Stability and Photoelectrocatalytic Activity of Au–Pt Nanorods

Abstract Harnessing solar energy for chemical transformations has gained increasing attention as a pathway toward cleaner and more modular chemical synthesis, with the potential to reduce reliance on conventional thermocatalytic processes. Here, we employ femtosecond (fs) laser irradiation to induce morphological restructuring of bimetallic Au–Pt nanorods (NRs) through processes associated with curvature-driven surface diffusion, surface smoothing, and localized interparticle coalescence. We systematically investigate the influence of fs-laser treatment on the structural, optical, mechanical, and photoelectrochemical properties of Au90Pt10NRs. Irradiation with 800 nm femtosecond laser pulses decreased the average nanorod length from 47.1 ± 5.6 to 37.7 ± 3.9 nm and the average aspect ratio from 3.7 ± 2.8 to 2.5 ± 2.2 (n = 150), while increasing the average width from 12.8 ± 2.0 to 14.6 ± 1.8 nm, with particular emphasis on the trade-off between mechanical robustness and photoelectrochemical performance. The laser-treated nanorods also exhibited an increase in average contact stiffness from 7.7 ± 1.1 to 10.6 ± 1.6 μN/nm, corresponding to an approximately 38% increase. In contrast, laser treatment attenuated the longitudinal localized surface plasmon resonance response and reduced the photoelectrochemical response, including an approximately 10% decrease in photocurrent density after the first 1000 s of illumination relative to the untreated nanorods. These findings reveal a structure–property trade-off in which femtosecond laser processing enhances mechanical robustness while attenuating plasmonic and photoelectrochemical performance, providing a framework for balancing structural durability and functional activity in plasmon-enhanced photoelectrocatalysts for solar-hydrogen production.