Modifying the Electron-trapping Process at the BiVO4 Surface States via TiO2 Overlayer for Enhanced Water Oxidation
Emre Usman a, Mahsa Barzgar Vishlaghi a, Abdullah Kahraman a, Navid Solati a, Sarp Kaya a
a Koc University, Turkey, Sarıyer Rumeli Feneri Yolu, Turkey
Proceedings of nanoGe Fall Meeting 2021 (NFM21)
#SolCat21. (Photo-)Electrocatalysis: From the Atomistic to System Scale
Online, Spain, 2021 October 18th - 22nd
Organizers: Karen Chan, Sophia Haussener and Brian Seger
Poster, Emre Usman, 277
Publication date: 23rd September 2021

BiVO4 is one of the most promising photoanode candidates to achieve high efficiency photoelectrochemical water splitting1. However, its poor surface catalysis and extensive surface recombination hampers its water oxidation activity. Surface modifications such as cocatalysts or passivation overlayers are utilized to improve the water oxidation kinetics or to decrease the charge recombination at the surface of the photoanode, respectively2. However, for the passivation layers it is often non-trivial to identify the recombination or trapping channels which are hindered. Also, it is difficult to observe such processes using non-steady state measurements. Herein, using transient photocurrent (TPC) measurements with short white LED pulses we observed the photogenerated electron trapping process at the BiVO4 surface, which is related to surface states V5+/V4+. We also showed that TiO2 overlayer grown by atomic layer deposition (ALD) can be used to fine tune the extent of this process. We observed that the extent of the trapping process depends on the thickness of the TiO2 overlayer, and there is a trade-off with the passivation of the trapping process and the increased charge transfer resistance at the interface.

This work was supported by The Scientific and Technical Research Council of Turkey (TÜBİTAK) (Grant number: 114Z305).

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