Discovering Hybrid Plasmonic Nanocatalysts for Solar-Chemical Energy Conversion via Femtosecond Pulsed Laser-Induced Atomic Redistribution in Bimetallic Au-Pd Nanorods

Abstract

Utilizing solar energy for chemical transformations has attracted a growing interest in promoting the clean and modular chemical synthesis approach and addressing conventional thermocatalytic systems’ limitations. Photoelectrochemical (PEC) cells enabling the conversion of solar energy to storable and transportable fuels could address the existing challenge of mismatch between renewable energy supply and demand. Understanding the electronic and thermal properties of metal nanoparticles and their interactions with other materials is imperative to improve PEC cells’ efficiency. PECs typically consist of architecturally sophisticated photoelectrocatalysts assembled into a structure designed to optimize light harvesting and catalytic chemical transformations. Physical and chemical processes critical to PEC cells’ operation occur at the electrode-electrolyte interface. After plasmonic excitation of metal with incident light, the plasmon can quickly dephase through electronsurface scattering on a few femtosecond (fs) time scales, generating nonthermal electrons. Before non-thermal hot electrons lose energy to the surrounding medium, they can excite electronic or vibrational transitions in adsorbed molecules on the nanoparticle’s surface, thus enabling photocatalytic reactions.Under light irradiation, noble metal nanoparticles, particularly those characterized by localized surface plasmon resonance, commonly known as plasmonic nanoparticles, generate a strong electromagnetic field, excited hot carriers, and photothermal heating. Plasmonic nanoparticles enabling efficient absorption of light in the visible range have moderate catalytic activities. However, the catalytic performance of a plasmonic nanoparticle can be significantly enhanced by incorporating a highly catalytically active metal domain onto its surface. In this study, we demonstrate that femtosecond laser-induced atomic redistribution of metal domains in bimetallic Au-Pd nanorods (NRs) can enhance its photocurrent response by two-fold compared to parent Au-Pd NRs. We induce structure changes on Au-Pd NRs by irradiating them with femtosecond pulsed laser at 808 nm to precisely redistribute Pd atoms on AuNRs surfaces, resulting in modified electronic and optical properties thereby an enhanced catalytic activity. We also investigate the trade-off between the effect of light absorption and catalytic activity by optimizing the structure and composition of bimetallic Au-Pd nanoparticles. This work provides insight into the design of hybrid plasmonic-catalytic nanostructures with well-tailored geometry, composition, and structure for solar-fuel-based applications.This material is based upon work supported by the National Science Foundation under Grant No. 1904351. Figure 1