Nanoseconds-resolved transient FTIR spectroscopy as a tool for studying the photocatalytic behavior of various types of bismuth vanadate.

• BiVO4: negative correlation between photoactivity and O vacancies. • BiVO4: transient changes in FTIR for dozens of nanoseconds. • BiVO4: Changes in transient IR spectroscopy correlate with photoactivity. Bismuth vanadate is an appealing candidate for photocatalysis. In a quest to clarify the effect of phase and shape on its photocatalytic activity, four types of particles, differing in phase and shape, were prepared, characterized and studied. Monoclinic particles having a prismatic shape as well as tetragonal particles were found to be more active towards Cr(VI) reduction than a mixed phase or octahedron-shaped monoclinic particles. A negative correlation was found between the activity and the concentration of oxygen vacancies near the surface. Transient IR measurements following pulsed excitation revealed temporal changes in the spectra, prevailing for dozens of nanoseconds. A negative correlation between the duration of the IR transient signal and the photocatalytic activity was found. The observations made by the transient step-scan FTIR technique clearly demonstrate the potential of this technique as a tool for understanding, rationalizing, or even predicting the activity of photocatalytic materials. [ABSTRACT FROM AUTHOR]