  Perovskite photoelectrodes are being extensively studied in search for
photocatalytic materials that can produce hydrogen through water splitting. The
solar-to-hydrogen efficiency of these materials is critically dependent on the
electrochemical state of their surface. Here, we develop an embedded
quantum-mechanical approach using the self-consistent continuum solvation
(SCCS) model to predict the relation between band alignment, electrochemical
stability, and photocatalytic activity taking into account the long-range
polarization of the semiconductor electrode under electrical bias. Using this
comprehensive model, we calculate the charge-voltage response of various
reconstructions of a solvated SrTiO3 surface, revealing that interfacial charge
trapping exerts primary control on the electrical response and surface
stability of the photoelectrode. Our results provide a detailed molecular-level
interpretation of the enhanced photocatalytic activity of SrTiO3 upon
voltage-induced restructuring of the semiconductor-solution interface.
