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 (center dot OH) on TiO2-attached multiwalled carbon nanotubes (TiO2-MWCNTs) in aqueous. We found the heterogeneous distribution of center dot OH is closely related to the composition and heterostructure of the catalysts. The dynamic center dot OH production rate was evaluated by counting the single-molecule fluorescent bursts. We further confirmed the production of center dot OH on TiO2-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.

Automated summary

We developed a single-molecule fluorescence imaging technique to investigate the distribution and production of hydroxyl radicals (·OH) on TiO2-attached multiwalled carbon nanotubes (TiO2-MWCNTs) in aqueous solution. Our results demonstrated that the heterogeneous distribution of ·OH is closely related to the composition and heterostructure of the catalysts. By counting the single-molecule fluorescent bursts, we were able to evaluate the dynamic production rate of ·OH. Moreover, we confirmed that the production of ·OH on TiO2-MWCNTs mainly occurs through electron reduction during the aqueous photocatalytic process. This study unveils the mechanism of reactive oxygen species involved in photocatalytic reactions and provides guidance for the design of advanced semiconductor photocatalysts.