Plasmonic Purification: Visible-Light-Driven Generation of Reactive Oxygen Species for Water Disinfection

Increasing access to clean drinking water is a global sustainability goal¹. Solar energy can disinfect water through the generation of reactive oxygen species (ROS), but current methods utilize ultraviolet (UV) light, which makes up only 5% of the solar spectrum. Visible-light-driven ROS generation is a promising alternative but stable, highly absorbing materials with the proper oxidation and reduction potentials are necessary.

Here we report on the fabrication and characterization of a plasmonic photocatalyst for visible-light-driven ROS generation. Our plasmonic photocatalyst is a broadband absorber capturing 90 % of the solar spectrum centered around 600 nm. We test its ability to generate ROS in a custom-built continuous flow microreactor allowing rapid real-time measurements of H₂O₂ generation. Under UV filtered AM1.5G illumination our photo-microreactor generates ~5 μM H₂O₂ per minute. We will discuss the performance and stability of our plasmonic photocatalyst and propose a reaction pathway for visible-light-driven ROS generation. The effects of photocatalyst geometry, residence time in the photo-microreactor and excitation spectrum will also be discussed.

1) World Health Organization. 2012. Progress on Drinking Water and Sanitation. Geneva, Switzerland: WHO Press.