Surface reconstruction tunes band edges and lattice-oxygen reactivity on BiVO4(010) photoanodes

Abstract

We unveil how reconstruction-driven surface chemistry controls interfacial electronic levels and reactivity at aqueous BiVO₄(010) interfaces. Dielectric-dependent hybrid functional molecular dynamics is applied to six electrochemically stable surface terminations of BiVO₄(010). In the electrochemical environment, Bi-rich terminations shift the band edges upward by 0.3–0.5 eV relative to vacuum, whereas V-rich ones shift them downward by 1.0 eV. O-rich surfaces feature peroxide-derived states near the VBM that can act as hole traps, and oxygen-deficient V-rich surfaces exhibit V 3d mid-gap states associated with V-centered polarons. After introducing two electrons via a bulk-like oxygen vacancy, excess charge localizes as small polarons on V sites for all terminations; on O₂²⁻-terminated O-rich surfaces, localization coincides with the (spin-mediated) formation of a doublet superoxo-like O₂⁻ species. This work delivers a termination-resolved picture linking the surface composition to band alignment, trap states, and lattice-oxygen reactivity, with clear implications for PEC optimization.