Kinetics of the Photoelectron-Transfer Process Characterized by Real-Time Single-Molecule Fluorescence Imaging on Individual Photocatalyst Particles
Jinghua An, Xiaoting Song, Wenbo Wan, Yanzheng Chen, Haibin Si, Huichuan Duan, Lu Li, Bo Tang
Abstract
Uncovering the underlying kinetics mechanism of the charge carrier during the transfer process is of fundamental importance in pursuing outstanding photocatalytic activity. However, it still remains a challenge owing to the rapid reaction rate of the charge carrier on the surface of photocatalysts. Here, in situ single-molecule fluorescence microscopy is employed to study the photoelectron-transfer kinetics in real time for an individual TiO2-tipped carbon nanotube (TiO2-tipped CNT) using a redox-responsive fluorogenic probe. A visual transport process for electron transfer from TiO2 nanoparticles to CNT is obviously observed via single-molecule fluorescence imaging. Based on the fluorescent product formation rate, the kinetics information of the photoelectron-transfer process can be obtained. The kinetics analysis results show that heterogeneity of catalytic activity caused by the photoelectron reactive sites exists in an individual TiO2-tipped CNT heterostructure, which is always masked in the ensemble measurement. After applying an adaptive high-resolution algorithm, which considers temporal and spatial factors into consideration simultaneously, the dynamic heterogeneity of special location on CNT within the TiO2-tipped CNT heterostructure in product formation is revealed with 40 nm spatial resolution. Moreover, we prove that the photoelectron-transfer distance on CNT can be up to 16.82 μm. These results give a deep insight into the kinetics information of the photoelectron-transfer process and a policy toward designing better photocatalysts.