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Photoinduced Charge-Transfer Dynamics in WO₃/BiVO₄ Photoanodes Probed through Midinfrared Transient Absorption Spectroscopy
- Grigioni, Ivan, Abdellah, Mohamed, Corti, Annamaria, Dozzi, Maria Vittoria, Hammarström, Leif, Selli, Elena
- Journal of the American Chemical Society 2018 v.140 no.43 pp. 14042-14045
- absorption, electrodes, electron transfer, electrons, spectroscopy, tungsten oxide, wavelengths
- The dynamics of photopromoted electrons in BiVO₄, WO₃, and WO₃/BiVO₄ heterojunction electrodes has been directly probed by transient absorption (TA) midinfrared (mid-IR) spectroscopy in the picosecond to microsecond time range. By comparison of the dynamics recorded with the two individual oxides at 2050 cm–¹ with that of the heterojunction system after excitation at different wavelengths, electron-transfer processes between selectively excited BiVO₄ and WO₃ have been directly tracked for the first time. These results support the charge carrier interactions which were previously hypothesized by probing the BiVO₄ hole dynamics through TA spectroscopy in the visible range. Nanosecond mid-IR TA experiments confirmed that charge carrier separation occurs in WO₃/BiVO₄ electrodes under visible-light excitation, persisting up to the microsecond time scale.