Role of oxygen defects at the interface between photoanodes and protective layers

In photoelectrochemical cells, semiconductor electrodes are usually interfaced with protection layers to extend their stability. Here, we consider TiO₂, the most widely used material as a protection layer, interfaced with a bismuth vanadate photoanode (BiVO₄, denoted as BVO), a promising oxide for photoelectrochemical water splitting [1, 2]. Recently, through a combined experimental and computational study, we showed that atomic arrangements at the interface between BVO and TiO₂ can have a marked impact on the electronic properties and photoelectrochemical performance of the photoanode [3]. Here we explicitly consider the additional effect of defects in TiO₂ and their impact on the interfacial band alignment and the photoanode properties. We perform first-principles molecular dynamics simulations of the BVO/TiO₂ interface with varied oxygen defects and identify their role in thin and thick TiO₂ protective layers. Our results give insight into design strategies to optimize photoanode/protection layer interfacial geometries and ultimately the performance of BVO photoanodes.

[1] G. Melani et al., ACS Energy Lett., 9, 10. 5166-5171 (2024).

[2] A.M. Hilbrands et al., J. Am. Chem. Soc., 145, 43, 23639-23650 (2023).

[3] D.H. Wi, K. Ishisone, Z. Xi et al., J. Am. Chem. Soc., 147, 34, 30851-30862 (2025).