Metallic nanoparticles are emerging as a new class of photocatalysts, based on their ability to strongly absorb sunlight and convert it into chemical energy. Their high optical absorption, over a broad range of the solar spectrum (from visible to near-infrared wavelengths), makes them a promising alternative to costly semiconductor catalysts. However, most studies of plasmonic photocatalysts are based on ensemble measurements, in which nanoparticle heterogeneity conceals many important and interesting structure-dependent catalytic properties. Additionally, existing single-particle analysis methods, either require a fluorescent product or lack the required spatial resolution to address critical questions about how precisely the nanoparticles will perform and can be controlled. Therefore, despite major progress in this field, a more sensitive measurement scheme is needed in order to determine the potential role of plasmonic nanoparticles in photocatalytic reactions.
Vadai’s research will focus on the first direct experimental investigations of hot-carrier induced photochemistry at the single nanoparticle level. In particular, she will study the plasmon-driven photocatalysis reaction of water reduction, using environmental transmission electron microscopy (ETEM) and electron spectroscopy to observe and understand the reaction pathways and kinetics with nanometer-scale spatial resolution and millisecond time resolution. These measurements will enable a deeper understanding and optimization of hot-carrier driven photochemistry, potentially opening new, efficient, and low-cost routes to renewable solar fuel generation. The main objectives of this research include: bimetallic nanoparticle synthesis and ensemble catalytic characterization, in situ measurements of single nanoparticle photocatalytic behavior using Stanford’s ETEM, and investigation of the effect of nanoparticle size and shape on hot-carrier mediated catalysis.