Moreover, it is useful to compare energy positions between hematite and titanates data recorded using the same experimental conditions, as in F.M.F. de Groot et al. In that report, similar to our finding, the O 1s -Fe eg and O 1s -Ti t2g bands are clearly degenerate. Hereafter we express all energy positions relative to O 1s -Fe t2g , at 529.9 eV, and then consider relative positions from the literature. -Fe t2g at 529.9 eV. Typically, Fe d-orbital splitting in hematite is 1.4 eV, while Ti d-orbital splitting for Ti 4+ ion, like TiO2, is 2.7 eV. The peak position we could assign to O 1s -Ti eg is 533.5 eV, i.e. D = +2.2 eV instead of the expected one at D = +2.7 eV. To explain this difference, one could consider strong distortion effects of the octahedral symmetry, or a highly disordered surface, affecting the expected crystal field splitting. But in this case, the dip at ~532 eV between the A and B spectral regions in Figure , would be less pronounced compared to our spectra. Thus, we cannot assign the B peak in Figure to pure contribution of Ti eg band and we address this peak as signature of OSS. The presence of these surface states, with highly oxidized character, leads to increase of charge transfer rate between the photoanode and the electrolyte, increasing the overall PEC activity. We probe the same surface states as the ones suggested by the PEC data. Indeed, photocurrent measurements directly probe the contribution of these OSS at the overall charge transfer, while NEXAFS probes OSS as unoccupied levels through transition of core level electrons.