Favorable band alignment for photocatalysis at the strontium germanate interface with silicon

Photocatalytic water splitting is a promising strategy for large-scale clean energy production. However, efficient and low-cost solid-state photocatalysts are still lacking. We present here first-principles calculations to investigate the suitability as photocathode of an epitaxial layer of strontium germanate on a Si(100) single crystal. Conduction and valence bands offsets at the interface between these two semiconductors were determined using state-of-the-art approximations of density functional theory for the accurate prediction of band alignments. The resulting type-III band line-up is also confirmed by inspection of the spatially resolved density of states. It is concluded that the electronic structure of the investigated heterostructure is favorable for photocathodic functionality.