Electron transfers in graphitized HZSM-5 zeolites

In the present work, we report the electron transfers occurring after ionization of the guest molecules of t-stilbene incorporated in graphitized HZSM-5 zeolites and we compare these results with the data obtained previously for graphite-free zeolites. Complementary diffuse reflectance UV-vis and Raman scattering spectroscopies provide evidence for stabilization of long lived charge separated states as observed in non-graphitized ZSM-5. The spectral features indicate that these species are located in the channels of the zeolite structure. However, the pulsed EPR technique shows strong coupling between unpaired electrons and the C-13 atoms in the case of graphitized zeolites while this interaction is not observed in normal zeolites. This is assigned to the presence of charge transfer complexes in the close vicinity of graphite areas and to the possible electron transfer to the graphitized domain. Using cyclic voltammetry, an electrochemical response is observed for the first time in such systems demonstrating the role played by graphite in the electron transfers.

Automated summary

This study reports the electron transfers after ionization of t-stilbene guest molecules in graphitized HZSM-5 zeolites, with evidence of long-lived charge separated states observed through UV-vis and Raman spectroscopies. Strong coupling between unpaired electrons and C-13 atoms is found in graphitized zeolites, indicating the presence of charge transfer complexes near graphite areas. This study also demonstrates an electrochemical response in such systems for the first time, highlighting the role of graphite in electron transfers.