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O: Fachverband Oberflächenphysik
O 57: Focus Session: Semiconductor Surface Chemistry – from Reaction Mechanisms to Well-Ordered Interfaces II
O 57.4: Vortrag
Mittwoch, 29. März 2023, 16:15–16:30, GER 38
Oxygen vacancy occupancy influences oxygen evolution on BiVO4 — •Nicklas Österbacka, Hassan Ouhbi, and Julia Wiktor — Chalmers University of Technology, Gothenburg, Sweden
Bismuth vanadate, BiVO4, is one of the best semiconductor photoanode materials for photoelectrochemical water splitting. Oxygen vacancies are abundant in the material and greatly affect its photoelectrochemical properties. If present at the surface, these defects could additionally directly influence the oxygen evolution reaction. The electronic occupancy of the defect states may also play a role, but are seldom considered in mechanistic studies.
In this work, we use hybrid density functional theory to show that the surface oxygen vacancy in bismuth vanadate is most stable in its fully ionized state. We investigate how this affects the mechanics of the oxygen evolution reaction and compare the pathway with those involving the unionized surface vacancy and the defect-free surface. To quantify whether or not vacancy ionization is beneficial, the thermodynamic overpotentials required to drive the reaction are also computed and compared.