(524g) Elucidating Photothermal Reaction Mechanisms with Hybrid Ag-(?-Fe2O3) Plasmonic Catalysts

Plasmonic catalysis has been the focus of immense research over the last decade, applying the local surface plasmon resonance (LSPR) effect of many metallic nanoparticles for selectively depositing energy at a particular reaction coordinate. Integrating plasmonic catalysts in a photothermal reactor, reactions of interest can be driven at lower temperatures and milder conditions, and catalyst selectivity and efficiency can be tuned with control of the LSPR band of the metal co-catalyst.

In this work, we apply a heterogeneous Ag-(α-Fe₂O₃) catalyst in a novel photo-thermal reactor, aiming to investigate the role of the plasmonic Ag nanoparticles in catalytic oxidation of methane. We employ emerging synthetic techniques for precise control of Ag nanoparticle size and shape, synthesizing 10-50 nm Ag nanocubes, spheres, rods and plates, which cover an LSPR absorption range of 300-800 nm. We measured the rate of the catalytic reaction by monitoring the residual CH₄ concentration with an online mass spectrometer. Using reaction rate vs. light intensity data for this system, we demonstrate that this heterogeneous catalyst drives catalytic oxidation of methane through a plasmonic-hot carrier injection mechanism. We compare the efficiency and selectivity of varied Ag nanoparticle morphologies in our hybrid catalyst, observing how changes in the LSPR band of the metal co-catalysts impact reaction outcomes. This study furthers our understanding of how photo-thermal reaction mechanisms can be tuned with precise nanoparticle design.