Verifying the Charge-Transfer Mechanism in S-Scheme Heterojunctions Using Femtosecond Transient Absorption Spectroscopy.
Chang ChengJianjun ZhangBicheng ZhuGuijie LiangLiuyang ZhangJiaguo YuPublished in: Angewandte Chemie (International ed. in English) (2023)
The S-scheme heterojunction is flourishing in photocatalysis because it concurrently realizes separated charge carriers and sufficient redox ability. Steady-state charge transfer has been confirmed by other methods. However, an essential part, the transfer dynamics in S-scheme heterojunctions, is still missing. To compensate, a series of cadmium sulfide/pyrene-alt-difluorinated benzothiadiazole heterojunctions were constructed and the photophysical processes were investigated with femtosecond transient absorption spectroscopy. Encouragingly, an interfacial charge-transfer signal was detected in the spectra of the heterojunction, which provides solid evidence for S-scheme charge transfer to complement the results from well-established methods. Furthermore, the lifetime for interfacial charge transfer was calculated to be ca. 78.6 ps. Moreover, the S-scheme heterojunction photocatalysts exhibit higher photocatalytic conversion of 1,2-diols and H 2 production rates than bare cadmium sulfide.