Tuning the interface between photoanodes and protective layers to optimize the performance of photoelectrochemical cells

Bismuth vanadate (BiVO₄ abbreviated as BVO) is a promising photoanode for photoelectrochemical water splitting. However, it is not chemically stable in strongly acidic or basic solutions. In order to operate a BVO photoanode stably in such solutions, a protection layer must be added on top of BVO and titanium dioxide (TiO₂) has been the material of choice, showing great improvement of the photoanode stability. However, the transport mechanism of photocarriers at the BVO/TiO₂ interface is not yet understood, thus limiting our ability to design optimal interfaces. Here we carry out first principles molecular dynamics simulations of BVO/TiO₂ interfaces with various atomistic structures, using the Qbox code (http://qboxcode.org/); we adopt computational strategies similar to those recently used to investigate the tuning of the surface composition of BVO to improve its catalytic ability [1,2]. We discuss how the structural properties of the BVO/TiO₂ interface, which experimentally may be tuned by varying the sample preparation methods, affect the electronic properties and the photocatalytic performances of BVO. Our results give insight into design strategies to optimize interfacial geometries.

[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).