To reveal and understand the molecular interactions and the mechanism of chemical reactions at heterogeneous interfaces are important in order to design an efficient photoenergy conversion system. We have been studying the photoenergy conversion processes occurring on a variety of nanocatalysts using single-molecule fluorescence imaging techniques and gain information related to spatial and temporal heterogeneities in reactions, which are always masked by ensemble averaging.

Single-molecule fluorescence microscopy has been used to investigate photocatalytic reactions at the heterogeneous interface. We synthesized novel fluorogenic probes to selectively observe the catalytic reactions. Such probes are designed to become fluorescent upon the reaction with target species under photoirradiation. The position of individual fluorescent products can be determined with several tens nanometers spatial resolution by two-dimensional Gaussian fitting. In addition, the quantitative analysis of fluorescence intensity trajectory or fluctuation can reveal the underlying properties of individual catalysts.

The proper understanding of structures and reactions at heterogeneous interfaces can develop the general concept of chemistry and help advance the emerging applications of nanocatalysts for environmentally and economically sustainable uses. 

References: 

[1] T. Tachikawa, S. Yamashita, T. Majima, J. Am. Chem. Soc., 2011, 133, 7197–7204.

[2] T. Tachikawa, T. Yonezawa, T. Majima, ACS Nano, 2013, 7, 263–275.

[3] Z. Bian, T. Tachikawa, P. Zhang, M. Fujitsuka, and T. Majima, Nat. Commun. 2014, 5, 4038/1-4038/9.

[4] Z. Bian, T. Tachikawa, P. Zhang, M. Fujitsuka, and T. Majima, J. Am. Chem. Soc. 2014, 136(1),  458-465.