High-Energy Hot Electrons from Ultraviolet-Plasmonic Rhodium Nanoparticles for Plasmon-enhanced Photocatalysis

Duke University, Durham NC

Investigators

Abstract

Considering the limited supply and environmental impact caused by the consumption of fossil fuels, harnessing abundant sunlight to produce clean energy fuels and desirable chemicals is of great societal benefit. Recently, a special family of metal nanoparticles has been proposed for use as photocatalysts that can effect solar harvesting and help perform the desired chemical reactions. These nanoparticles are characterized by strong light absorption due to the effect of the small nanoparticle size on the metal's electronic structure (the plasmonic effect). In this project, Dr. Jie Liu is exploring the mechanism of plasmonic photocatalysis and the influence of the physical and chemical properties of these nanocatalysts on their catalytic activity and product selectivity. The research has broader impact for the design of high-performance plasmonic photocatalysts of economically important chemical reactions such as carbon dioxide capture. Dr. Liu is actively involved in education and outreach activities. He organizes campus-wide social and networking events for graduate and undergraduate students through Duke University Network in Nanoscience and Nanotechnology (Duke N3). He also involves high school students in his research through the NC SEED program, which supports and encourages talented, disadvantaged North Carolina high school students to pursue graduate degrees in chemistry and physics. With funding from the Chemical Catalysis Program of the Chemistry Division, Dr. Liu of Duke University is developing a fundamental understanding of how ultraviolet-plasmonic rhodium (Rh) nanoparticles catalyze photocatalytic transformations and how the properties of the plasmonic metal nanostructures determine their photocatalytic activity and product selectivity. The charge-transfer process between the plasmonic Rh nanoparticles and adsorbed molecules on their surface, a critical step in activating reactants in photocatalytic reactions, is studied by spectroscopic methods. Two photocatalytic reactions, namely ethylene epoxidation and carbon dioxide reduction, are studied as model reactions to obtain understanding on how hot electrons from the plasmonic photocatalysts enable kinetically sluggish or thermodynamically unfavorable reactions. The effects of the chemical and physical properties of Rh nanoparticles, including size, shape and resonant energy, on their catalytic activity and selectivity is also under investigation. In addition to the experimental investigation, density functional theory (DFT) calculations are conducted to obtain the potential energy landscape in elementary steps of the reactions and elucidate the mechanism of the hot electron induced photocatalytic transformations. Dr. Liu is also actively involved in education and outreach activities with broad impact on his local community. He organizes campus-wide social and networking events involving graduate students and undergraduate students with strong presence of women scientists in these events. He also involves high school students in the research through the NC SEED program, which supports disadvantaged North Carolina high school students to pursue graduate degrees in chemistry and physics.