Single-Molecule Imaging of Reactive Oxygen Species on a Semiconductor Nano-Heterostructure for Understanding Photocatalytic Heterogeneity in Aqueous.

We constructed a single-molecule fluorescence imaging technique to monitor the spatiotemporal distribution of the hydroxyl radical (•OH) on TiO 2 -attached multiwalled carbon nanotubes (TiO 2 -MWCNTs) in aqueous. We found the heterogeneous distribution of •OH is closely related to the composition and heterostructure of the catalysts. The dynamic •OH production rate was evaluated by counting the single-molecule fluorescent bursts. We further confirmed the production of •OH on TiO 2 -MWCNTs mainly occurred via electron reduction during the aqueous photocatalytic process. Our study reveals the mechanism of reactive oxygen species involved photocatalytic reaction and guides the design of advanced semiconductor photocatalysts.